Mike's Oud Forums

Something Completely Different - Metal Bowls - and a Colascione

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jdowning - 12-28-2014 at 11:01 AM

Some years ago while working for a period earning a living as an heritage tinsmith, I made a copy of a 19th C French guitar by Grobert entirely in tin-plate complete with brass strings. It was not intended to be played - just for display as a demonstration of the tinsmith's craft.

This time around I thought that it would be interesting to make a working instrument with a metal bowl. Why? - just because I can (or once could when eyes were clearer and hands steadier!).
The instrument that I plan to make is a Colascione - a long necked lute that was introduced to Europe from Turkey via Italy it is thought around the mid 15th C - and prevailed in Italy as a popular folk instrument until recent times. This instrument has been chosen because the bowl is relatively small in size so will be a bit easier (and safer) to handle during the fabrication process - compared to say a full sized oud or lute.

As I have measurements on file of a surviving 17th C Colascione (the Dean Castle Collection, Scotland) it will be used as a basis for this project. The Dean Castle Colascione has an ivory bowl, 3 strings and a string length of 75.6 cm. - clearly a costly instrument in its day no doubt made for a rich dilettante rather than a street musician. This is a mid sized or Mezzo-Colascione. See attached images.

Some earlier discussion about the possible origins of the European Colascione is posted here on the forum:

http://www.mikeouds.com/messageboard/viewthread.php?tid=7096#pid438...

The attached engraving by Marin Mersenne, 1636 compares the European version of his time with a Middle Eastern counterpart.


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jdowning - 12-28-2014 at 01:00 PM

More information about tinware and tinsmithing can be found here:

http://www.mikeouds.com/messageboard/viewthread.php?tid=8565

Although I have in the past made segmented chandelier bodies and fancy fruit/flower bowls from tin plate I have never made a lute bowl from sheet metal so there is no guarantee that this project will succeed - but no harm in trying.
I will be using tinplate for fabricating the bowl - the stuff that food containers are (or once were) made from - thin sheet steel coated on both sides with pure metallic tin. The soft tin coating prevents the steel from corroding in moist conditions except in areas that are scratched or damaged where the steel is exposed.
The tinplate that will be used for this project is 0.38 mm thick (0.015 inch) and is relatively soft so can be easily bent with only finger pressure.

The tin segments of the bowl will be joined by soldering using a temperature controlled soldering iron (to prevent burning of the tin coating) and a 50/50 lead tin alloy solder that melts easily and sets quickly (a kind of metallic glue) - speed of working is important for this class of fabrication where two hands often seems insufficient. An acid paste flux (to ensure joint cleanliness during the soldering process) will also be used in the interests of speed of work. When using lead based solders and acid fluxes it is important to have adequate air extraction facilities to ensure that no fumes generated are inhaled or come into contact with eyes or skin - and to wear plastic protective gloves.

jdowning - 12-30-2014 at 05:41 AM

The bowl section is semicircular with wider side ribs to increase the overall depth. To simplify the fabrication work the number of ribs has been reduced to a total of 9 from the original 15. Once the metal bowl has been fabricated the neck and end blocks (of wood) will be 'retrofitted' and glued into place. Also a conventional wooden end clasp and side strips will be glued to the exterior surface as on the original. These components provide wooden joint surfaces required for attachment of the sound board - necessary for thin ivory (less than 1mm thick) as well as thinner tinplate.

As the bowl section is semicircular the central ribs will all be identical and symmetrical. A pattern for the ribs was created first by drawing a full size section of the bowl to determine the maximum rib width and included angle between the ribs. A rib former was then made by cutting two half sections of the sound board profile from thin Masonite, hinged together with adhesive tape and set at the included angle (21) with wooden blocks glued in place.
The required rib profile is then represented by the inside edges of the former.
The rib profile is then traced onto a paper strip taped over the the former and the edges rubbed with a fingertip tipped in graphite powder (or rubbed with a pencil).





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jdowning - 12-30-2014 at 06:00 AM

The rib pattern on the paper strip is then taped to a sheet of tinplate and the rib profile carefully cut out with a sharp knife. The knife transfers the rib profile onto the tinplate as a fine cut line in the surface.
The rib pattern is then cut out using hand shears or tin snips following the scribed line exactly - not as easy as it might first appear requiring practice, good lighting, good eyesight and a steady hand.
Any slight wrinkling of the cut edges is then removed by dressing with a smooth faced hammer on an anvil.

The accuracy of the pattern is all important and must allow for any potential cumulative errors during the course of fabrication as these cannot be corrected as work proceeds (as they can with wooden rib construction).

Microber - 12-30-2014 at 01:09 PM

Hey John, I like the idea of a metal bowl very much.
But I think some people here in the forum will find it's a crazy project.
I look forward to see more.

Robert

jdowning - 12-30-2014 at 04:29 PM

An essential tool for soldering tinplate is a temperature controlled soldering iron - a cheap soldering iron that can reach temperatures in excess of 1000F (535C) will burn the tin coating.
The best tool for the job is made by the 'Weller' company (W60P - W100P series). Temperature is controlled by an ingenious system that depends upon loss of magnetism of a magnet at a critical temperature (the Curie Temperature). In the 'Weller' iron this phenomenon is used to operate a switch to turn off power when the tip of the iron reaches a fixed temperature (600F, 700F and 800F) dictated by a ferromagnetic sensor in the tip.

For this project I will be using a Weller W60P iron with a 1/4 inch chisel tip operating at 700F.

jdowning - 12-30-2014 at 04:48 PM

Having made the rib pattern the ribs are marked out by tracing around the pattern placed on a sheet of tinplate using a sharp pointed scriber. Each rib is then accurately cut out by hand with tinsnips and the edges dressed smooth with a hammer - as described for making the pattern.
Each rib is then easily bent by hand to roughly the required contour (the sound board profile).
No mould is required to fabricate the bowl. Each pair of ribs is held edge to edge and 'tacked' in position with spots of solder - working along the length of each rib joint from one end to the other.
Once each rib has been tacked the joint on both sides is coated with a thin film of acid paste flux and the soldering iron is then run the full length of the interior surface melting the spots of solder as it goes into a solid homogeneous joint.
The attached image shows the first three ribs assembled.

jdowning - 12-31-2014 at 05:02 AM

The ribs are now assembled and trimmed to form the basic bowl. Total time to reach this stage would be an afternoon's work - say about six hours for a relatively experienced worker starting with marking out the ribs.

As the weather has turned frigid it is currently not comfortable to work in my workshop so this will be a good time to assess the structural viability or otherwise of the bowl and to decide whether or not to proceed further with this little project.

The rib joints are very thin (about 0.4 mm) and relatively fragile so can separate if the bowl, in its current state, is subject to flexing. Some additional joint reinforcement might, therefore, be worthwhile as a precaution. First thoughts would be to reinforce each joint with small soldered tabs of tinplate spaced at say 5 cm intervals along the joint. We will see.

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rootsguitar - 12-31-2014 at 05:31 AM

Artful! It's one thing to think of such a project but you are uniquely able to create this instrument.

I look fwd to hearing the sounds and hope you can continue with the project.

I know this may be a tangent but it could be possible to fill the bowl with a small amount of water and create an unusual effect by striking it then plucking the strings.

The Metallic Bowl Effect " MBE" :


http://youtu.be/d-u-BUuhtMM


Water could be added through the rose

Happy new year!

SamirCanada - 12-31-2014 at 05:55 AM

wow John! that's a very interesting project! I wonder about how it will sound as well!

so will it be a spruce top or a tin top?

faggiuols - 12-31-2014 at 09:37 AM

Jdowning

Your arguments are always interesting!
I wish I had two days every day to read them with care ..
I printed that about silk strings but they are not even halfway .. you update it faster than I can read it.
anyway thanks because you share your studies with all members ..

jdowning - 12-31-2014 at 10:03 AM

Although the guitar that I made was all tin plate - including the top and braces(!) - it was never intended to be functional musically.
The intent here is to only make the bowl of tin plate - the remainder of the instrument will be of conventional wood construction including the top and bracing of spruce. The Dean Castle Colascione has a separate inset rosette like an oud so this will have the same arrangement that will allow testing of different sound hole diameters (to determine optimum air resonance frequency). The neck joint will be made vertical (like an oud) a simpler arrangement found on some other surviving Colasciones - not sloping as on a lute. There will after all only be three strings so the width of the neck joint may be reduced accordingly.

I do not expect that a metal bowl will have any acoustical effect not otherwise found in a conventional wooden bowl - but of course it will be impossible to make any meaningful comparison in the absence of an equivalent all wood instrument.

Advantages of a metal bowl might be low cost and speed of fabrication. Also the ribs may be decorated by engraving, acid etching or embossing although here everything is to be kept plain and simple. A metal bowl might also be easily copper electro plated at low cost if so desired.
Tinware of the 19th C was often coated with several layers of a hard baked on varnish that was supposed to imitate Japanese lacquer work - known as japanned ware - very popular for the time period. This finish was both durable in preventing corrosion as well as decorative. This is the finish that I likely will apply - but using modern self curing varnishes.

Although I shall measure bowl volume (before gluing on the top), so that air resonance frequency may be accurately calculated, adding water to the bowl on the completed instrument with a spruce top would obviously not be a good idea (but would have been possible with a tin plate top).

A happy, healthy and successful new year to all.

jdowning - 1-1-2015 at 05:46 AM

Here is a video of a duet of Colascione and Baroque guitar that might be used to compare the sound of wooden and metal bowl versions - although the instrument in this recording is a larger and with 4 strings.

https://www.youtube.com/watch?v=Dx_joJkG6rI

A surprisingly strong sounding bass accompaniment.
This is confirmed in an early 18th C publication by Ernst Gottlieb Baron ('Study of the Lute', 1727 - translation by Douglas Alton Smith) where he criticises his contemporary Herr Mattheson for suggesting that the lute was lousy for accompaniment of singers in church or opera as it cannot be heard - the colascione being more suitable. The author counters sarcastically "He .. forgets that the colascione .. is only the bass of a lute, and could not be more than the whole instrument, especially since it is quite reasonable that more can be done with many strings than with three, four or six courses. But it is a fault in his nature that he was not able to perceive the special delicacy in chamber music accompaniment with the lute ...."

jdowning - 1-3-2015 at 09:54 AM

Not having made tinware for over 6 years or so my soldered fabrication work leaves something to be desired. However, with some additional soldered structural reinforcement the bowl should be strong enough for the task.

The main additional structural component is a baffle plate located at the neck block position. This has been cut from tin plate and soldered in position. The little soldering tabs on the baffle were cut using a 'nibbler' or 'notcher' tool that can cut where tin snips cannot go (a tool used by electronics workers for hand cutting circuit boards). The space behind the baffle will be filled with wood slices epoxy glued in place as a retrofitted neck block.
Additional reinforcement at the other end of the bowl is a decorative 'necklace' soldered in place.
Total weight of the completed metal bowl is 320 grams.

Apart from the wooden neck block, wooden strips are to be epoxy glued around the upper edge of the bowl to provide a gluing surface for the sound board. Assembly of the sound board to bowl and other wooden components of the rest of the instrument will then use conventional hot hide glue.

It has been decided to make this an instrument with four rather than three single strings - to increase the choice of tuning possibilities.

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mavrothis - 1-3-2015 at 11:18 AM

Really enjoying this! Can't wait to hear the result!

mav

jdowning - 1-3-2015 at 12:59 PM

Thanks Mav - let's hope the end result does not disappoint!

The main obstacle to progress will now be weather as I am reluctant to spend on inefficient electrical heating of my workshop when it is minus 30 C outside. On Sunday the temperature may be on the plus side so will plan to complete metal work on the bowl then.

There is not a lot of information available about the surviving originals. Thinking ahead, the sound board bracing is likely to have been uncomplicated. A sound board X-ray of the 19th C Colascione MIR 912 in the Germanisches Nationalmuseum, Nrnberg shows three substantial braces - two on each side of the sound hole and one just in front of the bridge. I plan on this smaller instrument to only have two braces (providing sound hole support) with the sound board 3 mm thick at the centre tapering to about 2 mm at the edges.

narciso - 1-5-2015 at 03:52 AM

Yet another very interesting project, and fine workmanship, as ever! Thanks for sharing jdowning!

A while back on this forum there was a discussion about what sort of relevance the material used for the ribs has on sound.
I can't seem to find the thread unfortunately, but I remember someone pulled in a physics argument to the effect that the material is irrelevant because the shell structure is stable with respect to vibrational excitations, i.e. those vibrations which propagate in the soundboard

That seemed to me a bit oversimplistic because even if the bowl shell remains inert in that sense, then taking the physics perspective a little further one still has to consider the absorbance/reflectance boundary conditions (b.c.'s) on sound waves incident at the bowl surface. These are likely to be quite sensitive to differences in the rib material; they arguably control the character of the marked reverb effect one hears from ouds in particular ( much stronger than that of a guitar body)

I wonder if it will be possible able to draw any qualitative conclusions in this respect on the basis of your work here with tin ?



nedal - 1-5-2015 at 04:15 AM

Hey John, that is a very Interesting Project, that might interest you to, Mr. Phillip Shahin from Tarshiha, Palestine had made Ouds with a Carbon-fiber Bowl.
this is a video with Mr. Tareq al Jundi trying those Ouds

https://www.youtube.com/watch?v=hTa0NpgL7Uo

jdowning - 1-5-2015 at 04:42 PM

Thanks for your interest and comments everybody.

narciso - perhaps the discussion that you had in mind is here?

http://www.mikeouds.com/messageboard/viewthread.php?tid=14572

nedal -there is also some mention of the plastic bowled ouds by Mr Shahin (and others). No doubt the discussions about this and that of instrument acoustics will continue (and continue to be unresolved).

I don't expect that a metal bowl will have any detectable influence on the sound produced compared to that of a wooden bowl all other factors being equal (which they can never be). This project will not provide any qualitative conclusions in respect of different bowl materials.
I am curious about why lutes with such a small bowl should perform so well (i.e. to be clearly heard) as bass continuo instruments in large auditoria (churches, opera houses and the like - or in open spaces as an instrument of the streets) as historical record would have it. The sound board surface is small in area so one might expect low frequency sound projection due to this component to also be muted? This then would leave the strength of projection of the air resonance component of the bowl (that I am particularly interested in here). I suspect that the relatively high position of the sound hole (relatively closer to the neck block) typically found on this type of instrument may have something to do with it. We will see.

narciso - 1-6-2015 at 02:08 AM

Thanks jdowning for digging up that relevant thread. I think I'd seen a different one previously, but the gist of it was the same.
As you say, it is hard to see how a small tin bowl could have delivered a loud basso continuo
Perhaps it was assembled as a cage rather than as a sealed shell? This would free up vibrational modes of the ribs, such that amplification could be achieved by resting on an auxiliary resonating chamber

jdowning - 1-6-2015 at 06:09 AM

I am not aware of any surviving members of the lute family that have any such a complexity of bowl construction narciso. The Dean Castle colascione that I examined first hand did not, neither does the example in the Germanisches Nationalmuseum MIR 912 - see attached XRay image.

http://www.europeana.eu/portal/record/09102/_GNM_662380.html

It should be remembered when considering the interior surface of lute and oud bowls that the larger instruments have the rib joints reinforced with paper strips glued in place with hot hide glue. Attached is an example of an old Arabic oud where the paper covers typically covers at least 50% of the interior surface of the wood - the remainder of the wood surface is coated with hard hide glue. So if the bowl interior is thought to be a reflective surface nowhere is the wood of the bowl exposed.
Instruments with smaller bowls such as mandolins often had the entire interior surface covered with paper glued in place with hot hide glue. The Dean Castle colascione is an example.

As I currently visualise it, for a bowl structure to produce audible sound it would have to be free to vibrate in the air (like the bottom plate of a violin or less so that of a guitar). However any such vibration would be effectively damped by the body of the player.
Furthermore the primary driving force behind bowl flexing (if any) might be the strongly pulsating low frequency air resonance mode (that might be felt by the player). A stiffer bowl might flex less than one that is less stiff structurally (so here relative rib material stiffness and thickness might possibly play an insignificant part) - the former case increasing the air resonance frequency for a given sound hole diameter and the latter lowering the air resonance frequency. More significantly, a luthier might (should) adjust the air resonance frequency by altering sound hole diameter, the number of sound holes and the position of the sound hole(s) to suite the acoustic objectives sought in the instrument under construction.



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jdowning - 1-7-2015 at 11:51 AM

Another historical reference to the colascione is found in 'Musurgia Universalis' by Athanasus Kircher, Rome 1650.

The attached image shows a three string colascione (here named a colachon) alongside a theorbo - the colascione being a longer instrument (assuming that they are engraved to about the same scale). Oddly the tuning of the colascione is given as c', c'' and g'' which means that if strung in gut string length would have to be about 30 cm or so - hardly a bass continuo instrument!

The fret spacings are interesting if drawn proportionally to scale.



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jdowning - 1-7-2015 at 12:15 PM

Now that the metal work of the bowl is complete the wooden interfaces - neck block, tail block, end clasp and side strips - must be configured, shaped and glued in place.

The neck block is made from 9 mm thick slices of 'yellow poplar' (it is not a poplar but a species of magnolia tree) - rescued years ago from an old desk found thrown in a 'dumpster'. This is a relatively soft but stable and easily carved wood. Each slice was sawn out roughly to size with a coping saw and then shaped to fit by carving with a knife and finished with a small woodworking rasp. Grain direction of the slices is arranged to cross like plywood. High precision of the fit is not required as the slices will be glued in place with gap filling epoxy.

The block is left well oversize for final trimming after all of the other wooden additions to the bowl are finally in place.

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jdowning - 1-8-2015 at 01:08 PM

Searching for more information about the three stringed colascione/colachon (not the German 6 course, lute like, callichon or gallichon of Baron's era) this discussion on the 'Forum des Musiques Medievales' may be of interest.

http://www.apemutam.org/forum/viewtopic.php?f=13&t=396

Unfortunately the general consensus is that as there is no known surviving written music for the colascione - it being an instrument of the street musician or associated with the itinerant Comedia dell Arte theatre groups - it will be impossible now to recreate the music or performance style of the instrument as it was in the 16th and 17th C.
So once this project is completed I can feel free to experiment unhindered by 'historical correctness' restraints!

The Kircher engraving of a colachon would seem to have been copied from Mersenne (?) complete with the tuning arrangement of an octave and a fifth and the strange fret configuration. The fret configuration may be misleading as there is some historical evidence to suggest that the fret spacing was approximately equal temperament as for the lute.
I have checked the Mersenne original text but can find no description of the fret spacing for a colascione although he does number the frets in his engraving of the instrument.

jdowning - 1-20-2015 at 12:11 PM

Further research reveals that there is a (sole?) surviving manuscript of music for colascione - or rather the 'soprano' version known as the colascioncino tuned an octave higher than the larger colascione (its string length being about 50 cm). Domenico Colla and his brother Bresciani toured Europe giving recitals during the second half of the 18th C - Domenico being a virtuoso player of the 2 string colascioncino (played with a wood bark plectrum) . There are six sonatas written for the instrument with bass accompaniment (colascione or guitar?) - a some pages from the sonatas are attached for information. Fancy stuff - I could not find recordings on YouTube - too difficult for modern performers perhaps?

This attempt to present the colascione as a high art instrument appears to have failed, the instrument being then regarded as a curiosity by the audiences although the skill of the performers was appreciated.



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jdowning - 1-20-2015 at 12:32 PM

Due to the curvature of the end of the bowl it has been decided to make the wooden clasp in three main section to obtain a close fit.
The lower part of the clasp is to be made in segments hot bent to fit the curvature of the bowl with ebony lines between the segments. Not sure how this will work out.
A rubbing on paper was first made of the end of the bowl to determine the approximate size and geometry of the segments.
The ebony lines were easily bent on the attachment to my propane heated bending iron - specifically designed for bending lines and purfling. Ebony is brittle so plenty of heat is required with gentle persuasion to avoid breakage.
The attached image shows the clasp segments, with lines glued in place, roughly assembled. These will now be fitted and glued together on the bowl before final trimming and shaping.

All a bit fancy to set off against the plain metal of the bowl.

jdowning - 1-24-2015 at 10:35 AM

To obtain a close fit to the bowl, the segments of the clasp lower section must be fitted and glued together on the bowl itself.
The bowl was first covered with kitchen KlingWrap plastic film as protection and the individual segments cut to size, joints planed flat and glued together piece by piece using adhesive tape to hold everything together as work proceeded. A bit like making an oud or lute bowl.
Fish glue was used as a strong quick drying adhesive - soluble in water so adjustments can be made in the event of any inaccurate fit. This is a tricky fitting and assembly task hence the benefit of using ebony lines at the joints to disguise any slight discrepancies - an old luthier secret! In the event only one joint required resetting the remainder being OK.

The back of the assembly was then covered with thin cotton cloth glued in place - for strength when being handled and shaped at the next stage.

The rough assembly was then smoothed with a single cut file and trimmed to a close to final shape with a fine razor saw. Figured maple and ebony are brittle woods to work with so a sharp file is required for all shaping work. The file also smoothly cuts the wood so that the maple is not stained by fine ebony dust (as it would be if abrasive sand paper was used).

A central ebony disc - hand filed to fit - has yet to be glued in place. A contrasting brass button will eventually be installed on the disc for attaching a shoulder strap required for supporting the completed instrument when being played.
As an additional decorative feature, the maple pieces are to be 'fluted'. This will also provide additional flexibility of this component for a close fit when finally clamped and glued to the bowl.

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jdowning - 1-25-2015 at 11:25 AM

The fluting is made with a half round file and finished with a curved cabinet scraper. Guide slots are first made with a round file in each section to prevent the half round file slipping sideways while filing and causing damage.
This component of the clasp is now almost complete and ready for final fitting and gluing to the bowl.

Microber - 1-26-2015 at 01:58 AM

Wonderful little hand fan !
Very tasteful, as usual, John. :applause:
Can't wait to see the wood/metal combination.

Robert

jdowning - 1-26-2015 at 07:37 AM

The design will be dictated in part by the wood to metal physical considerations so may change and evolve as work proceeds.
The attached image shows the remainder of the clasp partly assembled to give some idea of how it should look when finished. What started out to be a basic simple construction is getting a bit more fancy!! The clasp and side strips on the bowl will look even more decorative once varnished as they are made from highly figured tiger stripe maple.

Additional interior reinforcement of the bowl rib joints has been achieved with tabs soldered in place.

jdowning - 2-10-2015 at 07:49 AM

The wooden clasp and side strips have now been glued to the metal bowl with epoxy cement ready to be trimmed.
I do not use epoxy for instrument construction so have not tested the effectiveness of this particular brand by 'PC' but it seems to work OK for wood to metal joining. It is a two part epoxy and comes in a convenient dispensing double tube. Unlike hide glue where maximum joint strength requires perfect fitting of smooth surfaces, epoxy has some gap filling latitude but requires the surfaces to be 'roughed up' for optimum joint strength. The joint surfaces must also be 'squeaky' clean. The metal surfaces were first washed with detergent and then cleaned with alcohol. Epoxy is messy stuff to work with so plastic gloves must be worn and metal surfaces protected with painter's tape against any cement squeeze out.

The thin metal edges of the bowl are quite flexible so conform to the hot bent wood pieces - too well as it happens - as there is now some slight deformation of the edges of the bowl but the edges are now suitably stiffened by the wood.
To level the edges of the bowl some material must be trimmed - the precise amount determined in the usual manner by laying the bowl inverted on a flat surface (packed equally levelled front and back) and tracing around the bowl with a pencil. In this case a flat sided carpenter's pencil was ideal for the job. The maximum amount of material to be trimmed is about 2-3 mm.

jdowning - 2-10-2015 at 03:18 PM

The sides of the bowl have now been trimmed using a fine razor saw to cut a guide line for a knife to cut completely through the wood components. The exposed surplus metal was then removed with curved tinsmith shears and filed level. Furthermore the exposed edges of the metal ribs have been filed at an angle (towards the inside of the bowl) to a 'knife edge' to minimise the amount of metal needed to be removed for the final levelling operation on an abrasive surface.
Getting close!

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jdowning - 2-12-2015 at 07:09 AM

Now that the bowl distortions resulting from fabrication work have been corrected and the bowl edges levelled the sound board geometry (determined by tracing around the bowl edges onto card) must be adjusted to determine final bridge position and sound hole position and diameter - the latter dimensions dictating the position of the two braces. Wooden supports for the brace ends have yet to be glued to the bowl interior as hot hide glue will be used for gluing sound board to bowl.

At the same time the volume of the bowl has been measured and is 3660 cm. This is needed in order to calculate the air resonance frequency.

From the revised geometry, the bowl is about 4% larger than the Dean Castle model so string length will be 79 cm rather than 76 cm. It has been decided to have three (rather than four) single strings as on the Dean Castle original. Three single strings appear to have been the norm for colascioni of the 17th C. Tuning will be (A440 standard) G 98 Hz g 196 Hz d' 294 Hz. String tension per string will likely be in the 4Kg to 4.5 Kg range.
Calculated air resonance frequency with a sound hole diameter D of 7.8 cm - assuming a 'dead zone' diameter of 0.67D - is 177 Hz, just about 2 semitones below the pitch of the middle string which should be about right. We will see!

SamirCanada - 2-12-2015 at 07:14 AM

I am loving your progress on this John!

very intrigued to hear the results! do you have a lute of similar dimensions so we can hear the difference?

jdowning - 2-12-2015 at 09:44 AM

Hi Samir - no I do not have a lute of similar dimensions to this so I am looking forward to the final acoustic result as well! The project will provide some additional data concerning air resonance frequency determination.

I also intend to fret the instrument with Pythagorean fret spacings - as the early Tanburs on which the Colascione is thought to have been based would have been fretted (as were the early fretted shorter necked ouds). The Pythogorean spacings are determined by ratios of string division 1:2, 2:3, 3:4 and so on. This means 18 frets to the octave (compared to 12 for the European equal temperament fretting) - additional double frets being at the 1st , 3rd, 6th, 8th, 10th and 11th positions. The long neck allows sufficient space between the double frets at these positions (about 0.6 cm to 1 cm). However, more on that later.

For those interested in the air resonance calculation see the attached sheet. This assumes that the inner area of the soundhole (diameter 0.67D) that I call the 'Dead Zone' has minimal participation in the resonant air flow through a sound hole - confirmed by my recent resonance chamber trials reported recently on the Forum.

http://www.mikeouds.com/messageboard/viewthread.php?tid=14874

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jdowning - 2-18-2015 at 12:00 PM

The remaining wood/metal interfaces have now been epoxy glued to the bowl and levelled - these are two short liners that the brace ends will be glued to and a maple plate glued to the neck joint position to cover the ends of the metal ribs. The liners will stiffen further the area in which the sound hole is located.
A decorative metal collar has also been glued to the bowl at the neck block position as additional reinforcement of the ribs. All that remains is to finish and clean up the wooden components.

The neck and peg box have been drawn full size and will be made from solid maple. The neck joint will be slightly narrower than on the Dean Castle instrument.

I have a number of sound board blanks in stock glued up and ready for finishing. The smallest of these is a two piece rough sawn spruce blank. Nothing special but it has a 'ring' to it when tapped that sounds promising. The wood was cut from a log years ago on a large commercial, power feed band saw with a 6 inch wide blade so the saw marks are quite deep. The first task then is to hand plane the saw marks out. The sound board will then be reassessed for suitability.

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jdowning - 2-19-2015 at 12:38 PM

The current low humidity winter conditions (about 45% RH) are ideal for working the sound board. The neck blank material must also be brought into the house from covered outside storage for final drying.

The neck and peg box proportions have been determined from full size drawings and a template for the peg box has been made from card. For ease of working/handling and economy of material the peg box will be made separate from the neck and the two parts joined together with a glued 'V' joint. The original had neck and peg box made in one piece.
No CAD (Computer Aided Design) drawing here!

The peg box is similar to that of a violin as found on original colascioni. To keep things as simple as possible and avoid fancy, time consuming carving, the head of the peg box will be left with a plain flat 'scroll' to which some decorative embossed detail will be added.

Brian Prunka - 2-19-2015 at 01:56 PM

I am looking forward to hearing more about your fretting approach.

jdowning - 2-20-2015 at 10:56 AM

This colascione when complete will be very much an instrument for 'hands on' research including fretting (and, hopefully, so advancing my limited knowledge and appreciation of the complexities of temperament as applied to fretted instruments). Research into the instrument is ongoing.

It is generally accepted that the colascione (or calascione) was introduced to Naples, Italy by Turkish prisoners in the late 15th C where they were observed playing a long necked three stringed instrument - shaped like a spoon - that they called a 'Tambura'. It is impossible to now know what form of 'Tambura' or long necked lute was being played from the multitude of types in use across the entire Ottoman Empire or how it was fretted or the musical style - even if we knew from where in the Ottoman Empire the prisoners in Naples came from. No doubt the style of music and unfamiliar intonations raised admiration among the local population allowing the performers to be eventually integrated into Neapolitan society so starting a long tradition with this new instrument the colascione.

The colascione's Turkish (i.e. Ottoman Empire) origins tend to be confirmed by early writers Marin Mersenne (1636) who compares the colachon (French for colascione) to a single stringed Turkish instrument (that looks like a Tanbur), Kircher (1650) who calls the instrument "A type of Turkish Trichord commonly known as a Colachon" and Bonanni (1776) who published an engraving of a "Calascione Turchesco" that again looks like a Tanbur - see attached images.

Both the Mersenne and Kircher engravings of a Colachon although unlikely to be precise in their execution indicate some peculiarity of the fretting. Mersenne identifies the frets by number and French tablature alphabet icons but makes no mention of fret spacing in his description of the Colachon. The description of the fretting may be in some other part of his massive theoretical work but I have yet to find it. Both authors show some closely spaced frets - here identified in the Kircher engraving - where each fret closer to the nut is drawn heavier in gauge than the lower fret of the pair - an arrangement that would be necessary to avoid string contact with the lower fret when stopping the upper fret. Exactly what the fretting is meant to be is not clear but may suggest some kind of quarter tone fretting?

The performance of the colascione in the folk idiom may have had a strong middle eastern flavour Here is how it appeared to Englishman C. Burney visiting Naples in the late 18th C.
"The national music here is so singular (i.e. unique) as to be totally different, both in melody and modulation, from all that I have heard elsewhere. This evening in the streets there were two people singing alternately; one of these Neapolitan Canzoni was accompanied by a violin and calascione. The singing is noisy and vulgar, but the accompaniments are admirable and well performed............ The modulation surprised me very much: from the key of A natural, to that of C and F, was not difficult or new; but from that of A, with a sharp third, to E flat, was astonishing; and the more so, as the return to the original key was also so insensibly managed , as to neither shock the ear, nor to be easily discovered by what road or relations it was brought about". Burney then later describes a similar experience with a singer accompanied by a colascioncino (or discant colascione), mandoline and violin he again writes "It is a very singular species of of music, as wild in modulation, and as different from all that of the rest of Europe as the Scots (?!), and is, perhaps, as ancient, being among the common people merely traditional"
Other writers have commented in a similar vein describing sudden modulations (to the European ear) from major to minor keys.
We will never know but I have to wonder if what these writers heard was similar to Anatolian folk song, with baglama saz and frame drum accompaniment, as performed today?


Saz fretting is variable but an interesting article in English describing the fretting and other aspects of performance can be found here:

http://www.khafif.com/rhy/saz

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jdowning - 2-20-2015 at 11:22 AM

Another point of interest is that the Saz comes in a variety of sizes, open string length 112cm (Meydan), 104cm (Divan), 88cm (Baglama), 80cm (Tanbura), 56cm (Cura Baglama) and 48cm (Cura Tanbura) and so does the colascione to judge from surviving museum specimens.
So the full size colascione would have been in the range 100cm to 114cm string length, the Mezzo-colascione in the 70cm to 95cm string length range and the colascioncino with a string length around 50cm to 57cm range (i.e. tuned an octave below the large colascione)

So my experimental Mezzo-colascione with a 79cm string length is about equivalent to a Tambura saz.

jdowning - 2-23-2015 at 11:33 AM

The neck and pegbox will be made from Sycamore (a kind of soft Maple) as I have several sawn planks of this wood purchased from a wood yard 40 years ago as old air dried surplus stock. The planks were black though exposure to the air so goodness knows how long they had been in store before I bought them - several decades no doubt - so the wood should be pretty stable by now.
Rough blanks for the neck and pegbox have been cut and are final drying in a warm kitchen at low Relative Humidity.
There is some organic stain in the wood (due to the high sugar content of the wood prior to air drying) - typical with this species of wood. The stain does not affect wood strength and is otherwise of no consequence as the neck and pegbox will be stained black when completed.

The neck joint is currently being fitted using the drawing board as an accurate layout surface. The neck joint is to be vertical - as on an oud - not sloping as on a lute as there is plenty of width available at the neck joint. The neck joint will be reinforced with a screw through the neck block.

The Dean Castle colascione is not perfectly symmetrical the neck being offset to the bass side, the grain of the sound board wood sloping towards the treble side and the joint of the two piece sound board being made well over on the treble side. See my attached sketch made when the instrument was examined 35 years ago.
My project colascione will not replicate this asymmetry.



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jdowning - 2-24-2015 at 09:54 AM

My sketch illustrating the Dean Castle colascione's lack of symmetry is, of course exaggerated but it does bring into question the sound board originality when compared to the costly construction of the rest of the instrument (ivory/ebony ribs, ivory engraved panels and the carved ivory lion or dog head on the pegbox).
It should be remembered that many of the old instruments in the European museum collections are fakes - from the workshop of instrument dealer Leopoldo Franciolini actve in Florence between 1890 to 1910 - sold then to unsuspecting antique instrument collectors. These 'instruments' may have been completely bogus or made from some genuine parts recovered from original instruments or, at best, mostly original with some 'improvements' or repairs. Most have been weeded out from the major instrument collections and properly attributed to the 19th workshop of Franciolini.

As I recall, a number of the instruments in the Dean Castle collection that I examined at the time were suspect in my opinion. The colascione appears to compare in proportion and construction to some of the other genuine colascioni in the major European collections (see attached images - including that of the Dean Castle instrument). However, the sound board, bridge and rosette, being of lesser workmanship/materials than the rest of the instrument, may be later additions - possibly at the hands of Franciolini?
For comparison a 'lute' in the Stearns collection of instruments - originally purchased from Franciolini - has a parchment rosette similar (but superior) in design and execution to that of the Dean Castle instrument. See attached images.

Not that any of this will have much influence on the design of this experimental colascione that is only inspired by the Dean Castle model and is obviously not intended to be a copy apart from the general proportions.

One interesting point of detail seen in the attached images as well as in the iconography is the positioning of the three tuning pegs - sometimes one on the treble side of the pegbox sometimes two. The 'logical' arrangement might be to have the two pegs on the bass side for convenience of tuning - the second and third courses being tuned an octave apart? (Unless, of course, a player is left handed).

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jdowning - 2-26-2015 at 10:07 AM

Due to persistent extreme sub zero temperatures it is best not to run machines in my unheated main workshop such as the band saw. Progress is therefore currently restricted to limited work with hand tools and set up/layout work that may be done in comfort of the house.

Now that the neck joint has been made, the neck blank must be temporarily attached to the neck block in order to layout the neck geometry and adjust neck alignment. The neck has, therefore, been attached with a long wood screw passing through a hole drilled in the neck block. This hole was drilled by hand and rises at a slight angle to the surface of the neck joint towards the fingerboard surface. For everything to remain in alignment after the screw has been tightened a pilot hole at exactly the same angle as the screw hole in the neck block must be drilled in the neck blank.
This was achieved by first making a guide hole for the drill in the neck blank with a nail of the same diameter as the screw hole. The bowl was placed and held in correct alignment with the neck blank and the nail - guided by the screw hole in the neck block - was driven a short distance (about a cm or so) into the neck blank with a hammer. The resulting short hole in the end of the neck blank was then used to guide a drill bit of the same diameter as the nail to lengthen this pilot hole for the screw.
For this operation a standard wire nail had to be modified by filing the pointed end into a flat surface - in effect making the nail into a punch. Otherwise the pointed end of the nail - acting like a wedge - would have followed the wood grain and thrown the guide hole out of alignment.

So far so good. Now to temporarily assemble the neck blank to the bowl.



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jdowning - 2-26-2015 at 10:45 AM

With the screw fully tightened the neck joint surfaces are a perfect fit so work can proceed with establishing the final centre line of the neck in relation to the bowl and to check that the upper surface of the neck blank is in the same plane as the sound board. As it happens the final centre line is offset by about 4mm from the centreline of the blank at the nut position. No problem as plenty of extra material has been allowed in the oversized blank.
The plane of the neck upper surface - checked with a metal straight edge - is in perfect alignment with the sound board joint surface.

As it is difficult to assess how much 'pull up' of the neck under full string tension - if any - there will be, I will probably plane back the finger board joint surface a few mm and make the fingerboard correspondingly thicker at the nut end. This will allow for some action adjustment (by planing back the fingerboard) in future without having to reset the neck.

If the neck is to be glued to the bowl with hot hide glue then the screw will be replaced with a nail that may be driven quickly into position with a few taps of a hammer before the glue has had time to gel (a second or two). This is the traditional method used by European luthiers, the nail (or nails) providing proper alignment and clamping force as well as some reinforcement of the neck joint.
On the other hand, if a screw is to be used a slower setting synthetic glue - such as PVF or epoxy must be employed. I am tempted to use the latter adhesive for convenience given the good alignment of the neck at this stage. Should this be the decision, the screw will be waxed before assembly so that it may be easily removed at a later date allowing the neck to be cut off with a saw should any neck reset work be necessary.

Lots of waste material now to be removed from the neck blank!

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jdowning - 2-27-2015 at 11:55 AM

For ease of handling the peg box will be made separately from the neck (rather than in one piece with the neck).

The sides of the peg box taper from nut to 'scroll' so the first step is to drill the three pilot holes for the pegs through the parallel sided blank to ensure that the pegs when fitted run 'square' to the peg box.

The sides of the blank are then cut and planed smooth to the required taper.

Finally the profile of the peg box is laid out on the tapered blank, cut out and shaped approximately to size with a coping saw and wood rasp. The cavity of the peg box will next be carved out before the peg box is finished to size.

jdowning - 2-28-2015 at 11:45 AM

Before cutting the pegbox cavity, the three peg holes have been cut to size with a peg reamer. This provides full peg box width guidance for the reamer. The peg arrangement - unlike the Dean Castle model - is to be two pegs on the bass side and one on the treble side

The first step in cutting the pegbox cavity is to drill out as much waste material as possible. The cavity is then carved out close to finished size with chisels. As on the Dean Castle colascione the cavity is wider at the top of the pegbox and tapers down to a width of about 5 mm at the bottom.

The neck blank has now been trimmed of most of the waste material and is being allowed to season further in a warm dry place before being finishing to size. This will allow any hidden stresses to be dispersed - stresses that might otherwise cause deformation of the completed neck.

jdowning - 3-1-2015 at 12:45 PM

The first sound board blank has grain 'run-out' revealed by planing so is rejected and a second choice has been selected from stock. This sound board blank has already been partially worked so will save a bit of time. Final thicknessing has been done first with a fine set block plane working across the grain direction alternately, followed by a cabinet scraper to remove any plane marks and bring the surface to a smooth and level state. Final finishing is done with a scraper blade that cuts to produce fine shavings. I never use sandpaper that abrades the wood surface to produce an inferior finish.

The two braces have been cut and planed from a piece of spruce split from a billet rather than sawn. This ensures that there is no grain run-out for maximum strength and sound transmission. The edges of the braces have been cut straight and square on a shooting board.

jdowning - 3-3-2015 at 12:21 PM

Peg box meets neck!

The peg box has been glued to the neck blank with a simple scarf joint. A wooden dowel will be added later for additional strength. The peg box and neck will now be carved and finished as one piece.

I do not make violins so this violin type carved peg box is a first for me. The decorative 'scroll' will be kept plain and simple to save time.
To level and finish the bottom of the peg box cavity a scraper tool has been made from a cheap screwdriver. The screwdriver tip has been ground to an angle and sharpened and honed like a chisel. The sharp cutting edge is then turned into a hook by forming a burr on the sharpening oil stone. This burr - that would normally be removed when sharpening a chisel - is left in place and removes fine shavings when used as a scraper - being dragged along the bottom of the cavity.
Screwdrivers are low cost readily available tools and are made from hardened steel so can be used to quickly make custom purpose wood chisels.

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jdowning - 3-4-2015 at 12:37 PM

The sound board has been planed and thicknessed - measuring about 2.5+ mm over the neck block area reducing to about 2 mm at the sound board edges. The sound board edges may be later cut for a half depth binding - as on the Dean Castle model. The surface will be hand scraped to final finish after the sound hole has been cut and prior to bracing.

The sound hole will be open as on a guitar so that experiments with different diameters may be carried out. Later, a fancy parchment rosette may be added similar to that on the Dean Castle colascione.

I cut open guitar sound holes - for speed, accuracy and convenience - with a router that has a baseplate modified with a series of radial placed holes at different radii from the cutter bit. The router then spins around a nail to cut the required diameter.

The sound board blank is first firmly clamped to a flat piece of MDF board and a standard nail of appropriate diameter is hammered vertically through the sound hole centre in the blank into the board underneath. The nail is then cut off to a short length (about 5 mm or so). The nail is then positioned into the appropriate hole in the base plate to cut the required diameter. Needless to say, care must be taken to check (and double check) that the set up is correct before starting up the router!
For this project I used a solid carbide router bit 3 mm in diameter set to cut a slightly oversize sound hole diameter of 8.4 cm (compared to 7.9 cm calculated). This will give some scope for adjustment of sound hole diameter later. The router bit is set to a depth that cuts through the full sound board thickness and partly into the MDF board underneath.

So far so good. A nice clean vertical circular cut of the required diameter.

This method can, of course, also apply to the cutting of oud circular sound holes.

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jdowning - 3-5-2015 at 12:24 PM

The X-ray image of the Germanisches National museum colascione previously posted show a guitar like bracing - relatively wide braces on each side of the sound hole with their ends set into shallow supporting pockets cut into the interior rib liners. As wooden liners are a necessary part of the metal bowl construction I am following a similar design here. The brace ends must fit precisely without forcing or 'springing' the ribs of the bowl

The plan - once the braces have been fitted precisely into the pockets - is to temporarily clamp the braces to the sound board with clamps set through the sound hole. The sound board will then be removed with the braces clamped in position and the brace locations precisely reference marked. The clamps will then be removed and the braces glued to the sound board where marked. If all goes well the brace ends should then fit exactly into their respective pockets when the sound board comes to be glued in place. We will see!

jdowning - 3-6-2015 at 12:34 PM

The inside edge of the sound hole is reinforced with full depth black-white-black purfling made by 'sandwiching' plain maple veneer between maple veneer stained black. The glued veneers - with non-stick oven paper on either side - were taped to a cardboard tube of about the same diameter as the sound hole with the grain of the veneer running parallel to the axis of the tube. No hot bending of purfling made this way is required. The pre-formed purfling was further reinforced with a piece of black fine silk fabric (paper would do just as well) glued on top of the 'sandwich' as a final layer.

Once the glue had cured slices - about 4 mm wide - were cut, freehand, from the 'sandwich' using a fine tooth razor saw - the cardboard tube providing the necessary support during the cutting process. Additional segments were cut for spares or use on another future project.

The segments, with ends trimmed square with a razor blade, were then glued and taped to the inside edge of the sound hole. Four pieces and a bit were required - the last piece being the most difficult to fit precisely.

The excess material was trimmed using a scraper blade so that the purfling was made level with the sound board surface. A properly sharpened scraper blade is the best (perhaps the only) tool for the job as it quickly removes fine shavings from the end grain purfling without causing grain 'tear out'.



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jdowning - 3-7-2015 at 12:24 PM

The sound hole inner edge has been completed with a solid strip of ebony to protect the vulnerable end grain purfling. The ebony had to be hot bent to fit.

With the neck temporarily screwed to the bowl and alignment checked the finished sound board was placed over the two braces and aligned with the bowl centreline. Two small trigger operated clamps were then arranged - passing through the sound hole- to hold the upper brace in position. The sound board with clamps attached was then lifted from the bowl and the ends of the brace marked exactly with several layers of adhesive tape to provide positive, precise registration for the brace when being finally glued into position. This was just a 'dry run' test to check the viability of the method. Seems pretty straight forward! The braces will be glued one at a time to ensure an optimum fit without need for further fine adjustment to the fit of the brace ends. Hopefully this arrangement will ensure fast and perfect registration of the sound board when being glued in place.

The little clamps - made in China - cost less than a dollar each from a local 'Dollar' store. They do not provide a lot of clamping pressure but are fine for this particular application. Clamping pressure is released with the press of a button. The clamps can also be arranged to press in the opposite direction - rather than squeeze - if required.

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jdowning - 3-8-2015 at 11:54 AM

The first brace has been set up for gluing. The hide glue is to soak in water overnight so this brace will be glued tomorrow.

In the meantime other components are being prepared.

One great thing about this project is that the instrument only has three tuning pegs to make and fit! I have a quantity of lute pegs in stock - rough blanks turned as a batch years ago from Brazilian 'boxwood' or Castello. This is not a true boxwood but is very similar and is often used as a substitute for the real thing. I will use the same wood for the fingerboard.

The peg shank taper is cut with a peg shaver or cutter (a kind of giant pencil sharpener) made using my peg reamer - so ensuring the exact peg shank taper.

My pegs are made in the style of the old lute pegs - the peg heads being simply cut flat with a chisel (not fancy curved as on a violin or on some modern ouds). In keeping with the metal to wood theme of this project I may add a decorative 'silver' ring to each finished peg. More on that later.

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rootsguitar - 3-9-2015 at 08:09 AM

looking great! You've been putting in some good hours.

I had to let you know I had the good fortune of seeing a Colascione played live last night...by musician Will Morris.

There were also two lutes & a percussionist.

Ron McFarlane's band Ayreheart at a small irish pub. Great music.

The instrument added bassier sounds in a welcome way & could see it being used in a lot of settings...






jdowning - 3-9-2015 at 11:57 AM

The Ayreheart group have posted a number of pieces on YouTube that include a colascione. Here is one - an arrangement of the late 16th C lute composition by John Dowland (no, not directly related although both the family names are Irish!)

https://www.youtube.com/watch?v=MzF3SVBzjCY

and another

https://www.youtube.com/watch?v=I6kHuN_0OfE

The Will Morris example of a large colascione has four(single) courses that seems to be the norm for modern performers - usually (?) with the courses tuned either a fourth apart (like the 3rd, 4th, 5th and 6th strings of a classical guitar) or a fifth apart - G D A E for example. I am not sure if either tuning is historically authentic as colascione performance was an oral, unwritten tradition - obsolete and forgotten since the 19th C - and what little written evidence that survives is from observers who were not players of the instrument. However, if today it works musically 'go for it' - although I suspect that the Italian folk instrument was originally fretted in a much more interesting manner than the (approximately) 12 tone Equal Temperament fretting of a lute.

This project colascione is a smaller three course instrument (Mezzo-colascione) - the early colascioni having only two or three strings - and we know from historical record that the tuning of a three stringed colascione in the 17th C was an octave and a fifth. So this project instrument, with a 79 cm string length, will end up being tuned G g d' (A415 pitch standard).

jdowning - 3-10-2015 at 11:37 AM

The second brace has been glued to the sound board and while the glue is left overnight to cure the three pegs have been shaped, fine sanded and burnished.
Each peg measures 75 mm overall in length.

Peg collars and end dots have been added as a decorative feature - made from 1.5 mm diameter soft tin wire (available from hardware stores as lead free solder - it is actually an alloy of 96% pure tin and 4% pure silver). This metal looks like silver but does not tarnish black like silver so tin was often used in the past for inlay work in place of silver for this reason.
Pure tin, of course, is the coating on the tin plate ribs of the project bowl.

The procedure for making and fitting these peg collars is described in an earlier project on this forum - posted here on 1-11-2010.

http://www.mikeouds.com/messageboard/viewthread.php?tid=8488&pa...

jdowning - 3-16-2015 at 11:47 AM

The sound board braces have been planed to final shape and the sound board dry fitted to the bowl ready for gluing. The precise registration of the brace ends into the pockets in the bowl liner will allow fast, correct positioning when gluing the sound board to bowl where 'speed is of the essence' when using hot hide glue.

The neck/pegbox assembly has been shaped close to final dimensions and the neck has been aligned and glued to the neck block. The upper surface of the neck has been planed level with the bowl sound board joint surface. Final finishing of the neck will be done after the sound board and fingerboard have been glued in place

The fingerboard blank has been made from two butt joined pieces of Brazilian boxwood (the raw boxwood billets being only about 38 cm in length) and has been planed flat ready for gluing to the neck. The fingerboard increases in thickness towards the nut by 1 mm.

With the neck and bowl centrelines in alignment the bridge may now be precisely positioned and glued to the sound board (to be done prior to gluing the sound board to the bowl).

To keep things initially as plain and simple as possible (to save time in progressing the work) the usual inlay work such as sound board and fingerboard edge banding will be omitted but will be added later after the instrument is otherwise complete. I am particularly interested to find out how much influence the sound board edge banding may have on the overall acoustic response of the instrument - measured by 'before and after testing.

jdowning - 3-17-2015 at 11:40 AM

With the sound board temporarily taped to the bowl, the bridge blank has been positioned with tape and the string height at the bridge determined using a steel straight edge laid on packing at the nut position (1mm string height above the fingerboard) and 16th fret position (3.5 mm action above the fingerboard). With string height determined the bridge blank was drilled for the three string holes and carved to shape.

In preparation for gluing the bridge, its position on the sound board has been temporarily marked with three layers of adhesive tape - an aid for precise registration, important when working quickly with hot hide glue,

The bridge will now be finished and stained black before gluing. After gluing the bridge in place, ebony 'dots' will be added to each end of the bridge as a plain decorative feature.

The bridge material is European Pear wood cut from a small tree in my neighbours garden many moons ago (with permission!) and air dried in small billets for peg or bridge making. Nice close grained wood for carving and relatively low density.

jdowning - 3-19-2015 at 11:42 AM

The completed bridge has been stained black with 'Indian ink' available from any stationary or office supply store. This ink is shellac based so dries quickly and penetrates well to a dense dark black. For convenience in handling the bridge when staining and gluing a wooden 'toothpick' has been pushed into the central string hole.

To glue the bridge strong dry granulated hide glue (Lee Valley cat#56K50.01) has been mixed with about 50% water by volume and left overnight for all water to be absorbed. The glue - in a clean glass jar - has been heated in a pan of simmering (just boiling) water until fluid enough for use (the glue runs off the glue brush in a steady stream). The water bath prevents overheating and so spoiling the glue and its strength.

The bloom strength of the glue is rated at 260g so it is very strong - drying to a glass hardness - but gels quickly so set up must be uncomplicated. The set up was tested with several 'dry' runs to determine the optimum position for the spring clamps so that they do not slip and spoil the job. In fact clamps are not essential as the bridge may be held (with great patience) in place with only finger pressure for a few minutes until the glue sets - I prefer to use clamps particularly at the thin, flexible ends of the bridge to ensure that they lay in contact with the sound board surface. A flat board is also temporarily positioned under the sound board as extra support during the gluing operation.

With the bridge glued in place and glue 'squeeze out' cleaned up with a sharp chisel, the next operation is to glue sound board to bowl. The same batch of glue,slightly diluted, will be used for this operation as high strength is not required or desirable for the soundboard to bowl joint.

Before I forget, a maker's label with completion date has been glued inside the bowl (I assume that this project will soon be finished - in 2015 - God willing!)

jdowning - 3-21-2015 at 11:39 AM

With relative humidity in our wood stove heated kitchen at an ideal 50% the sound board has been glued to bowl with hot hide glue. The glue has been diluted a little to extend the time until it gels - tested on a scrap of wood. This allows maximum working time but there is still a need to work quickly.

As counter top working space in the kitchen is restricted the pegbox has been wrapped in protective 'bubble wrap' - the long neck of the colascione presenting some difficulty in handling without risk of knocking breakable stuff off nearby shelving. As it happens all went well without mishap.

Both joint faces were given a coat of glue brushed on and the sound board pressed in place and clamped using strong elastic adhesive tape (3M binding tape from Lee Valley cat#25U03.30) starting with the brace end positions, then the neck block location followed by the remainder of the joint. As it is not possible to complete the procedure before the glue starts to gel it is necessary to go over the entire joint again with a hot iron to seat those few sections that have not closely joined. Those areas are first moistened with a little hot water applied with a small brush to soften the glue before being re-taped - once the glue is seen to remelt with the heat application.


The instrument will be left in a warm place overnight for the glue to fully cure. After removing the tape the joint will be checked again for proper fit and any corrections made (the glue reconstituted with heat and moisture - a benefit of hot hide glue). The sound board edges will then be trimmed to size.

The glue pot goes into the refrigerator to prevent bacterial spoiling and the glue will be used again tomorrow for gluing the fingerboard to neck. Reheating hide glue will cause deterioration of the glue strength but a third reheat is acceptable for this application after which the remaining glue will be thrown out.

antekboodzik - 3-23-2015 at 12:17 AM

What kind of tape do you use? Doesn't it tear small wood fibres, when removing?

Another question I would like to post, is that certain violinmaker told me, that 'used' (reheated many times) hide glue is even better that a fresh batch. However, as he's working in a full time, he reheats (and adds dry glue or water, as he needs) almost everyday.

jdowning - 3-23-2015 at 11:39 AM

The adhesive tape used is made by the 3M company (see previous post) and is often used by the luthier fraternity for this application. Other 'Masking' tapes of this type will also work but this brand is strong and will stretch before breaking so can apply a reasonable clamping force. Another way of clamping is to quickly wrap string (or elastic rubber strip) around the bowl and sound board.
When removing the tapes they should be pulled folded back on themselves to minimise any risk of grain tear out of sound board fibres. Any micro fibres that may be raised by the tape will be removed when the sound board surface is later finished smooth with a scraper blade.

When I attended wood working classes at school over 60 years ago only hot hide glue was used (synthetic glues were then an expensive curiosity). The traditional cast iron glue pot was heated up in the morning and left on for as long as needed. The colour of the glue was dark brown (!) - so was not in optimum condition for strength - but maximum strength is not required when gluing woodworking joints such as dovetails, mortice and tenon etc where the strength is in a properly made accurate joint - the glue just holds everything together. In the class work a lot of glue was used in the course of a day so was constantly being replaced.
The same applies to violins where maximum strength is not necessarily desirable - especially in the gluing of the top and bottom plates that may need to be removed in future for repairs. The brittle nature of the cured glue of correct strength allows the plates to be separated without damage with the insertion of a sharp thin knife blade into the joint.
More critical is the gluing of fixed bridges to lutes, ouds, guitars and the like so I use freshly made glue for that work and reheat the same batch of glue for less critical applications. I am not running a commercial luthier enterprise so the glue pot is usually only in use for half an hour or so in a day. It is then sealed air tight and put in the fridge to keep until next required - which may be a few days later as time permits. I only make enough glue required for the work in hand (small quantities) to avoid waste.
My glue pot is a glass jar with sealed lid (the kind used for jam making) heated in a pan of hot water at just below simmering point. From experience and previous trials with a thermometer, glue temperature is held within a range of 140 to 160F (60 to 70C). Above that temperature the glue will burn and spoil.
The dry glue is placed in the glue pot and just covered with water. The glue will absorb the water in a matter of an hour or two but I usually leave it soaking overnight for good measure. When the glue is hot and liquid I will test the gel time on a scrap of wood before use and by rubbing between thumb and finger to test viscosity, 'tackiness' etc. All down to experience.
I do not add dry glue to the heated mix (to be avoided in my opinion) but make the glue viscous enough in the first place to require dilution by adding small amounts of hot water as required.

After about 4 reheats any glue that is left over (small quantity) is thrown away. The remaining glue is removed from the jar by adding hot water to dilute the glue residues. A dash of chlorine water (Javex bleach) is then added, the jar filled with fresh water, sealed and left standing for a few days This kills any remaining organic material that is deposited as a white suspension and is poured down the drain to leave a bacterially clean jar for the next batch of glue.

[file]34789[/file] [file]34791[/file] [file]34793[/file] [file]34795[/file]

jdowning - 3-24-2015 at 11:43 AM

The sound board and finger board edges have been trimmed to size, fingerboard levelled and neck shaped close to finished size. Pegs have been preliminary fitted to check that there is sufficient string clearance in the peg box prior to final finishing.
I will add a couple of decorative ebony/bone dots to each end of the bridge (bits left over from another project).

Once final shaping is completed, the neck and pegbox will be stained black and clear varnished. The bowl (metal and wood components) will be clear varnished. I had thought of applying a translucent red finish for a bit of dramatic effect but could not achieve satisfactory results on metal test pieces.

So the colascione in its simplest and currently largely unadorned state - is almost complete.


jdowning - 3-25-2015 at 11:12 AM

The neck has been shaped and finished to size ready for staining. I use small bronze spokeshaves for the basic shaping followed by a scraper blade before final sanding smooth.
The shape of the neck profile is determined accurately by sight and 'feel' - I do not fuss around with templates for this class of work.
The little spokeshaves are sold as a set of three by Lee Valley (Cat# 61P10.10) and are comfortable to use.

Continuing the metal/wood theme a small solid brass knob has been fitted to the end of the bowl to serve as a button for a supporting shoulder strap. Again this is an item that I already had in stock and so avoids me having to make one (a wide range of these small knobs are sold by Lee Valley - listed in their Hardware Catalogue).

[file]34823[/file] [file]34825[/file] [file]34827[/file]

jdowning - 3-31-2015 at 11:48 AM

The neck and peg box have been stained black and given a sealing coat of diluted oil varnish. The bowl has also been given a preliminary protective coat of clear oil varnish. Further varnish coats will be applied so this operation could take some time to complete.

In the meantime the air resonance frequency of the bowl has been measured by tapping the bridge and recording the impulse signal at the sound hole on a Zoom H2 digital recorder. The signal is quite strong - the air pulse being felt by my hand positioned above the sound hole.
Analysing the audio signal using 'Audacity' software, the attached spectrum analysis shows a pronounced air resonance frequency of 212 Hz. This value is about three semitones higher than calculated - 179 Hz -assuming a sound hole 'dead zone' diameter of 0.67D (see previous post on page 2). It is also a higher value than the second string pitch tuned at g 196 Hz (A440 standard) - tuning G g d' - by nearly 2 semitones.
Had this instrument been a perfect Helmholtz resonator, the calculated air resonance frequency - using the full sound hole area as 'active' - would be 240 Hz or about 3.5 semitones higher than 196Hz.

It will be interesting to see how the acoustic response turns out to be. Cutting a half depth rebate and banding around the edge of the sound board would make the bowl/sound board combination less stiff and so would tend to lower the air resonance frequency. By how much? - hard to say without trying.





[file]34872[/file]

jdowning - 4-1-2015 at 11:52 AM

The G g d' tuning of a colascione is the early 17th C system noted by Mersenne. The later tunings varied. According to Franz Jahnel ('Die Guitar und Ihr Bau' 1963), the number of strings on the colascione increased from two to five - the three string full size version being tuned E A d.
This implies that the half full size length of the fancy versions of mezzo-colascioni (such as the Dean Castle example) may have been tuned an octave higher at e a d' - equivalent to the 4th, 5th and 6th strings or bass section of an equivalent 6 string guitar.

Six stringed classical guitars are designed so that the air resonance frequency of the body coincides with (or just below) the pitch of the 5th string. Therefore, if the project colascione is tuned e165 Hz, a220 Hz, and d'294 Hz to represent the tuning of the bass section of an equivalent six string guitar, then the measured air resonance frequency of 212Hz - being less than a semitone below the pitch of the second string (or 5th string equivalent on a six string instrument) - should be about right for optimum bass response.

Both tuning configurations will eventually be tested to establish the optimum acoustic response for this instrument.

jdowning - 4-5-2015 at 11:57 AM

Attempts to clear varnish the metal bowl have not been satisfactory so the bowl has been given a black 'Japanned' finish, a traditional coating for tinware - in this case the brushed on matt black enamel will be given a protective overcoat of hard clear varnish.

The nut will be made from cow bone from stock prepared earlier from raw bone obtained from a local butcher. The two contact faces have been squared and made flat on a sanding block. The bone has already been prepared and de-greased but will be further de-greased by immersion for a few days in purified gasoline (the stuff sold for use in camping stoves) - just to be sure. An important step as any residual grease in the bone will eventually leach out into the surrounding wood.

Bone preparation procedure was previously posted here:

http://www.mikeouds.com/messageboard/viewthread.php?tid=10403#pid70...

[file]34934[/file] [file]34932[/file] [file]34928[/file] [file]34930[/file]

jdowning - 4-14-2015 at 11:31 AM

Varnishing of the metal and wooden parts of the bowl and the neck is now complete but will be left for a few more days in a warm place to harden fully. I have used a 'Spar' oil varnish from a local hardware store. It gives a gloss finish that I don't particularly like but the varnish should be durable enough. The sound board is, of course, to be left unvarnished.

Stain, dust and varnish that has partially plugged the string holes in the bridge has been removed with a bit mounted in a jewellers drill.

The same procedure applies to the peg holes using a peg reamer. The stain in the wood acts as a useful indicator of the correct peg fit that should be tighter at the peg head end of the shank than at the smaller diameter free end. This avoids risk of breaking the peg by twisting if it should stick at the free end of the shank. The peg shank will be left extra long to accommodate any initial wear at the peg box. It remains to drill the string holes in the shanks.

jdowning - 4-14-2015 at 11:43 AM

The bone nut blank has been finally de-greased with lacquer thinner available from any hardware store and fitted in place. To ensure precise contact with the wood of the fingerboard and pegbox all varnish and stain has been removed.
The next step will be to finally shape the nut and file and polish the string grooves before fitting the strings. At that point the nut will be held in place with a small spot of fish glue - just so that it does not fall off and get lost at any time.

It will be interesting to see how the instrument stands up to full string tension.


[file]34970[/file] [file]34972[/file] [file]34974[/file]

jdowning - 4-17-2015 at 11:56 AM

The colascione has now been strung and brought up to full tension to evaluate the action. No frets fitted at this stage.

Tuning is G g d' so conforms to the tuning of the tambura mentioned by Tinctoris on his visit to Naples in the late 15th C and the 17th C Colascione described by Mersenne that was a development of the tambura.
The tonal range G to d' is the physical limit for plain gut strings.

For this test I have just used strings in stock - Pyramid 0.44PVF for d', 0.63 PVF for g and a worn wound #1017 for G. Total tension for the three strings about 157 Newtons (or about 16Kg) - feels about right for me as a lute player. Pitch standard is A440.

First sound of the open strings is recorded on the attached audio clip - a kind of unusual powerful 'growl' - with a lot of sustain (about 20 seconds) for such a small bowl.

As the colascione was an instrument of the streets and obsolete by the beginning of the 19th C (so an unwritten oral tradition) - the only idea of how it may have sounded and been played is in this parody written by Kapsberger in the 17th C for the Chitarrone or Tiorbo.

https://www.youtube.com/watch?v=bnlOpCmlLGY

[file]34976[/file]



[file]34979[/file]

jdowning - 4-18-2015 at 11:45 AM

The string tension is still stabilising but action height at the 16th fret position is about 3.5 mm treble to 4 mm bass (measured from underside of string to surface of the fretboard). This is probably a bit on the high side even with frets installed and allowing for the amplitude of vibration of the long bass strings.

A revised sound clip is a bit clearer than the original previously posted which has now been deleted.

For information the spectrum analysis graph of the recorded signal is attached as is the spectrum graph of the air resonance measured at the sound hole by tapping the bridge with the strings damped but up to full tension. The latter shows an air resonance frequency of 197 Hz - matching the pitch of the middle string at g 196 Hz. Interestingly the air resonance test on the unfinished instrument gave a value of 212 Hz - the only difference being the addition of the extra mass of two ebony dots on the bridge and the instrument being under full string tension. The difference is a bit surprising so will run the test again to ensure the strings are completely damped and do not influence the measured result. The long neck under tension may have something to do with it?



[file]34983[/file] [file]34981[/file]

[file]34985[/file]

jdowning - 4-19-2015 at 04:19 AM

I have re-run the air resonance test and the result of the spectrum analysis shows an air resonance frequency of 200 to 201 Hz - very close to the pitch of the middle string (g 196 Hz). For this second test I made sure that there was no influencing effect from the strings by taking more care to completely damp any string vibration - at the neck joint position and between sound hole and bridge - using cloth strips. The previous test shows some influence of string vibration from an undamped section between the neck joint and bridge location.

This result is about a semitone lower in measured air resonance frequency from the preliminary test on the instrument when tested unstrung and without the ebony 'dots' at the ends of the bridge. The air resonance frequency measured then was 212 Hz.

For this tuning (G g d' at A440 standard pitch) an air resonance pitch of about a semitone or two lower should provide optimum reinforcement of bass response. This might be achieved by reducing the diameter of the sound hole slightly or by making the sound board more flexible by thinning around the edges (or by installing a 1/2 depth binding) - modifications that will be tested in future.

Note that this instrument because of its stiff construction around the sound hole area, stiffer sound board and relatively high sound hole placement, behaves a bit more like a true Helmholtz resonator than an oud or lute.
For purposes of calculating the air resonance frequency - the central 'dead zone' diameter of the colascione sound hole - based upon these measured results - is about 0.56D rather than about 0.67D as it would be in the case of a single sound hole oud or lute.
For a true, perfectly rigid Helmholtz resonator with centrally positioned sound hole the whole area of the sound hole diameter D is used to compute the air resonance frequency i.e. there is no central 'dead zone' where little air flux takes place across the sound hole area.

At this stage no changes or alterations will be made to the instrument set up and it is time to consider how the colascione should be fretted.

jdowning - 4-20-2015 at 02:41 PM

A quick check on the calculated effect on air resonance frequency for this instrument, by reducing sound hole diameter - indicates that the sound hole diameter would need to be reduced to about 7cm (from the current 7.8 cm diameter) to achieve about a one semitone reduction in air resonance frequency or about 6.5 cm for a full tone reduction. These are all rough estimates as the diameter of the sound hole 'dead zone' measured from my (albeit scientifically imperfect) sound hole acoustic trials indicate that the 'dead zone' diameter/ full sound hole diameter tends to diminish proportionally as sound hole diameter reduces.


jdowning - 4-22-2015 at 07:02 AM

I should mention that the air resonance test results have not been corrected for air temperature which does make some small difference. For calculation purposes an air temperature of 20C is assumed but house temperatures in Winter/Spring conditions may range anywhere between say 15C and 25C. The speed of sound in air at 20C is 343 m/s, at 15C it is 340 m/s and at 25C it is 346 m/s. So given this environment - without a temperature measurement at the time of the test - a tolerance on the measured air resonance frequency should be taken into consideration.

The air resonance frequency is directly proportional to the speed of sound in air. So, for example, a measured frequency of 200 Hz should strictly speaking be given a potential tolerance range of +201.7 Hz to -198.3 Hz - assuming of course that my test apparatus is of high scientific precision (which it is not).

jdowning - 4-22-2015 at 11:40 AM

The fingerboard has been levelled and crowned ready for fitting the frets. I suspect that these surviving fancy versions of the mid sized colascione like the Dean Castle example may have had the courses tuned a fourth apart and fretted like a lute or guitar (i.e. more or less 12 Tone Equal Temperament) - so that they might be played in consort with guitars, mandolins and the like. On the other hand the early full sized version of the colascione played solo by street musicians or to accompany voice or unfretted instruments such as the fiddle may have had a somewhat more complex fretting arrangement based upon Pythagorean scaling.

So the plan for this experimental instrument is to first fret in accordance with Pythagorean scaling just out of curiosity and to test the practicality (or otherwise) of working with some of the close spaced fret arrangements with 18 frets to the octave on a 79 cm vibrating string length instrument. The close spaced frets range from about 5 mm to 10 mm apart.

For convenience I have used the on line Hoffman fret calculator to establish the theoretically correct fret spacing here:

http://www.modoantiquo.com/temperatur/temperatur_en.html

The frets, of course , may be moved around to test other temperaments including the 17 fret to the octave fretting arrangement for the Tunbur described by 10th C philosopher Abu Nasr Al-Farabi - the original text translated and analysed in detail by Chris Forster in his recent encyclopedic, beautifully produced book 'Musical Mathematics - on the art and science of acoustic instruments', 2010, Chronicle Books, San Francisco. Contents and excerpts here:

http://www.chrysalis-foundation.org/musical_mathematics.htm

The Al-Farabi Tunbur had two courses tuned a fourth apart so would require retuning the top string down from d' to c' on this experimental mezzo-colascione. Interestingly the early late 15th C description by Tinctoris of a 'tambura' being played in Naples by Turkish prisoners gives the tuning of a three stringed instrument oddly as "to the octave, fifth and fourth". Presumably Tinctoris meant that the top two strings were tuned either a fourth or a fifth apart?

jdowning - 5-3-2015 at 12:01 PM

Before fitting the frets the sound board has been further cleaned up using a cabinet scraper blade to remove a few fine shavings. A 'before and after' resonance test showed a drop in measured air resonance frequency of 2 Hz i.e. from 201 Hz to 199 Hz at an ambient temperature of 15C. At this frequency range the human ear might just detect a drop of 2 Hz. Not much but I think that this will explain the difference in the measured air resonance frequency when the instrument was first completed (212 Hz) and now (201 Hz) as the sound board was finished to be thinner around the edges than in the centre - a difference of about 0.5 mm - except in the area between the bridge and the bottom of the bowl where the sound board has been left full thickness of about 2.5 - 3 mm. This thinning made the sound board more flexible and so lowered the air resonance frequency as should be expected - all else being equal. ( the trapped air inside the bowl acts like a cushion or spring so any increased flexibility of the walls of the resonance chamber - i.e. the bowl/sound board structure - will soften the spring effect of the trapped air and so lower the air resonant frequency).

In this case the sound board - small in area and relatively thick compared to an oud or lute - has no bracing below the very stiff upper section where the sound hole is located. So one might expect removal of even a small amount of material from the vibrating area to have some reasonably significant effect. This effect will be further tested later when the sound board edge is to be rebated and finished for a half depth binding so further reducing the sound board stiffness around the edges.
In the case of an oud or lute the same effect would be achieved by reducing the stiffness of the multiple sound board braces - a more complex procedure to control and predict no doubt.

For information the attached Audacity spectrum analysis is attached to compare with the graph previously posted.

Selection_146.png - 40kB

jdowning - 5-13-2015 at 11:59 AM

As the air resonance frequency is about where it should be, it has been decided at this stage - and before fitting the frets - to rebate the sound board edge for a half depth binding mainly to assess the effect, if of any significance, on lowering the air resonance frequency. The frequency should be lowered somewhat.

I have also added my maker's brand to the sound board area over the neck block - a lute maker's tradition. The brand was made from sheet brass high temperature brazed together, filed to shape and fitted to a wooden handle. In use the brand is heated to a temperature high enough to scorch the wood using a propane flame.

The rebate for the half binding is cut with two tools - a purfling cutter to scribe the inner edge of the rebate and a special plane to cut the rebate. The rebate width is 4 mm. I made both of these tools from brass - as reported a while back on this forum.
Once the rebate has been cut and finished the air resonance frequency will be measured again to assess the effect before fitting and gluing the binding/purfling.

jdowning - 5-13-2015 at 12:02 PM

Here is the post on how to make the purfling cutter.

http://www.mikeouds.com/messageboard/viewthread.php?tid=5796#pid346...

jdowning - 5-13-2015 at 12:05 PM

..... and here is the tutorial on how to make the little rebate plane

http://www.mikeouds.com/messageboard/viewthread.php?tid=7435

jdowning - 5-15-2015 at 11:41 AM

In addition to the half depth binding ebony finger board 'points' will be added to reinforce the bottom edges of the fingerboard - as found on the Dean Castle colascione. The points extend to the front edge of the neck block. A metal template will be used for marking out the points on ebony prior to shaping.

The half depth rebate has been finished to about 1mm depth with a low cost nail file or 'emery board'. The rebate where it meets the points must be cut with a chisel as the rebate plane cannot get in close enough.

With the rebate finished the air resonance frequency has again been tested and measured as 195 Hz - a drop of 6Hz from 201 Hz. This is only about half a semitone so not of great significance. No doubt when the half binding is glued in place the air resonance frequency will return to around 200 Hz!

jdowning - 5-16-2015 at 11:38 AM

The ebony points must be fitted before the half binding. They have been cut and filed to shape and rebated into the fingerboard/soundboard. The rebate is first outlined with a knife (using the points as a pattern) and then cut out to depth with chisels. The points shown here have not been hammered and glued tightly into place until further fine adjustments have been made to the depth of the rebate. There will also be a strip of ebony inlaid across the top of the points at the end of the fingerboard.

Small 'cranked' chisels are useful to cut out narrow rebates. These are easily made from small diameter high carbon steel rod (broken drill bits, sewing needles etc)- softened by heating to bright red heat in a propane flame and hammered to shape. Then further filed to shape after cooling. The chisel edge is re-hardened by heating to a dull red colour and then dropping it to cool rapidly into a can of old engine oil (or just stick it into a potato!). The hardened cutting edge is then sharpened and honed in the usual way.

jdowning - 5-30-2015 at 11:56 AM

With the inlaid ebony 'points' completed and the half depth rebate around the edge of the sound board finished the half depth binding has been made up and glued in place ready for scraping down level with the sound board surface.

The binding is the same as that around the sound hole edge with black-white-black purfling and solid ebony outer edge. The purfling has been made by gluing dyed maple veneer together (like a plywood sheet) from which strips are then cut with a saw. The saw marks are removed and the strips brought to the required thickness by drawing each strip though a block of wood in which slots of varying depth have been cut with a router. A block plane held stationary at an angle over the strip does the cutting operation.

The tightly curved purfling around the bottom edge of the sound board was made the same way as that of the sound hole purfling - preformed on a mold. The disadvantage is that the colour of the end grain does not exactly match that of purfling cut from longitudinal grain veneer. I shall be varnishing the binding so the colour difference may not be so distinct when finished.

The ebony outer edging has been hot bent to fit. The whole binding assembly has been made in pieces (rather than one or two continuous strips) for convenience in handling and economy of material. For convenience of handling I have used PVA carpenters glue to secure the binding - the sections being clamped tightly in position with adhesive tape.

All the binding strips have now been glued in place ready for scraping down to sound board thickness with a scraper blade. To prevent damage to the sound board surface, the corner of the scraper blade has been covered with adhesive tape.

I expect to finish the edge binding tomorrow so will then again measure the air resonance frequency to see if there are any changes resulting from adding the half depth binding.

Note that half depth binding is a style of sound board edge reinforcement found on surviving lutes of the 17th/18th C as well as on some old ouds. It is also found on the Dean Castle mezzo-colascione.


[file]35490[/file] [file]35492[/file] [file]35494[/file] [file]35496[/file]

[file]35498[/file]

jdowning - 6-1-2015 at 11:43 AM

The half depth binding has now been finished and levelled with a scraper blade. The outside edge will eventually be refinished and sealed with varnish.

Measuring the air resonance frequency gave a value of 203 Hz (G#3) raising the frequency - as expected - back to the original measured value (i.e. plain sound board edge without the half depth binding).
To reduce the air resonance frequency further will necessitate reducing the sound hole diameter. However, I first plan to tune the two melody strings a fourth apart (rather than a fifth apart) following the Al-Farabi instructions for fretting the 10th C tunbur. So with the top string tuned to d' (at A440 standard -maximum pitch for a gut string of length 79 cm) the second string will then be a220Hz. In this case the current air resonance frequency at more than a semi tone lower in pitch should be about right. We will see.

The string 'action' is still quite a bit too high. I do not want to reset the neck so will first plane back the fingerboard (excess thickness was deliberately left at the nut end for this purpose). If that is not enough, the bridge may be redrilled (with the string holes about 2 mm lower this would match the string hole height of the Dean Castle instrument that was measured as 4 mm above the sound board -but a bit on the low side I think).



[file]35506[/file] [file]35508[/file]

Luttgutt - 6-2-2015 at 07:55 AM

A True Beauty!!

jdowning - 6-2-2015 at 11:29 AM

Thank you Luttgutt!

By planing down the fret board, the action (underside of string to fingerboard surface) is now just over 3.5 mm at the 7th fret position (1/3 string length) at full string tension. This location coincides with the join in the two part fingerboard so has been marked for future convenient reference with a piece of ebony inlay (now nobody can see the joint - more luthier trickery!).

The string action is measured with a simple, easily made tool - a tapered piece of hard wood with the depth (measured with calipers) marked along the length.
At the last fret position (fret #27) the action is 5 mm. I will use 0.58 mm diameter nylon (low cost, ordinary fishing line) for the frets so the action above the frets will be around 3mm at the 7th fret. As fret spacing is quite close in places the frets will be single rather than double tied.

The Pythagorean fret spacings - measured from the nut - have been marked on a strip of wood and transferred to the fingerboard with pencil marks. This is how the 16th C lutenists like Dowland did it and so - no doubt - did the early ud and tunbur players. Total number of frets to start with is 27 - but there is space for more.

Tying nylon frets is hard on the fingers (gut frets would be better but too costly for this project) so a small set of pliers helps a bit in making the frets tight. The fret knots are sealed by melting the cut ends with a small soldering iron and the frets slid into position - the taper of the neck providing added tension.

Tying frets is one of my least favourite luthier jobs so the work will be spread over a couple of days. Seven frets tied - only 20 to go!

[file]35510[/file] [file]35512[/file] [file]35514[/file] [file]35516[/file]

jdowning - 6-8-2015 at 11:29 AM

Nylon frets require a special kind of knot due to the slippery nature of the material - a knot familiar to fishermen. The attached images should make it clearer than words alone.

A suitable length of line is required that allows sufficient surplus length to obtain a good grip and exert sufficient tension once the knot has been tightened and the fret drawn into position. About 15 cm or so should be adequate for this instrument.
A 'figure 8' knot is first tied at one end and the free end passed under the strings and around the back of the neck to the bass side (the fret knots should always be on the bass side of the neck). The free end is then passed first through the underside of the loop at the bottom of the 'figure 8' and then through the underside of the loop at the top of the 'figure 8'.

The knot is then pulled tight and the fret pulled up as tight as possible onto the neck at a position some distance (about 5 cm) above the final location of the fret. For good measure a simple half hitch knot is then tied over the knot and the surplus material cut away to leave two free ends about 3mm in length. The free ends are then melted back to the knot - using a small soldering iron - so sealing the knot against unravelling.

The fret is then slid down the neck to its final position - the taper of the neck adding additional tension to the fret to hold it tight against the fingerboard surface.

Still five frets to tie to completion - boring!
Once all of the frets have been tied to the theoretical positions marked on the fingerboard they will require further adjustment to allow for the increased string tension (and hence increased pitch) caused by stopping a string against a fret. The proportional increase in pitch depends upon fret diameter, string diameter, string material, string tension of the open string, vibrating string length (of the stopped string), strength of sounding a string, and string 'action' or clearance above a fret. Final adjustments will be made 'by ear'- a compromise until everything sounds in tune.





[file]35560[/file] [file]35562[/file] [file]35564[/file]

jdowning - 6-9-2015 at 11:57 AM

The fretting is now complete with the sealed fret knots arranged on the bass side of the neck. Nylon fret knots are not very elegant (compared to gut) but they will have to do.

Pythagorean fret spacing of long necked lutes is unfamiliar ground for me so I have referred to the expertise of others for guidance.
The fret spacing - measured from the nut - is in accordance with the calculated values given by the free on-line 'Hoffman' fret calculator (Advanced version) with additional values provided by Paul Beier' string and fret calculator software. This gives more fret positions than I will likely end up using but unwanted frets are easily removed.

As the colascione was most likely developed from the Ottoman tambura of the late 15th C it will be interesting to initially follow the Pythagorean fretting arrangement proposed by Al-Farabi for the 10th C tunbur fitted with two melody strings tuned a fourth apart. This fret arrangement is identical to the principal tuning system proposed by Safi Al-Din in the 13th C for the seven fret positions of an oud.

A table of the Pythagorean intervals is available for reference here in Wikipedia.

http://en.wikipedia.org/wiki/Pythagorean_interval

Referencing this table, the fret positions for the Al-Farabi's 17 fret to the octave tunbur (total 20 frets on the neck) starting at the nut is Unison(P1), Minor Second (m2), Diminished Third (d3), Major Second (M2), Semiditone (m3), Diminished Fourth (d4), Ditone (M3), Perfect Fourth (P4), Diminished Fifth (d5) Augmented Fourth (A4) Perfect Fifth (P5), Minor Sixth (m6) Augmented Fifth (A5) Major Sixth (M6), Minor Seventh (m7) Augmented Sixth (A6), Major Seventh (M7), Octave (P8), Diminished Ninth (d9), Augmented Unison (A9?) and Major Second (m9?). The appropriate Pythagorean ratios are given in the table.

[file]35566[/file] [file]35568[/file]

jdowning - 6-13-2015 at 03:22 PM

With the frets in their theoretical 'Pythagorean' positions it is now necessary to 'fine tune' the fret positions to allow for pitch variations caused by stopping a string at each fret - as previously noted.
Adjustments will first be made 'by ear' checking/comparing intonation of the two melody strings - by intervals of unison or octave or pure fourth or pure fifth - at various fret positions. As a double check the intonation and temperament will be verified using tuning software that provides deviation in cents from 12 tone equal temperament tones. So, for example, the ditone E or Pythagorean major third, ratio 81/64 at the Al-Farabi 6th fret position should measure 7.8 cents more than the equal temperament value of 400 cents (100 cents = an equal tempered semitone).

However, all precise theoretical measurements aside, it is immediately apparent - on preliminary testing of the current stringing/tuning arrangement for this instrument - that tone pitch, particularly in the higher fret positions, may be noticeably modified by axial movement of the stopping finger to produce a vibrato effect. This is an embellishment technique that is used by modern classical guitarists as well as by Middle Eastern players of long necked lutes such as the baglama saz - so imitating in accompaniment the vocal gymnastics of their singers.
Vibrato was also used by fretted instrument players in Europe from at least before the early 16th C so is likely an historically valid technique for the colascione.


jdowning - 6-14-2015 at 11:37 AM

My set up for fine tuning of the fret positions is to use a low cost 'lapel' clip on microphone (The Source #2616448) input directly to my PC sound card. This is mounted on the colascione with a simple Z shaped clip cut from tinplate and lined with felt to protect the sound board surface. This little microphone provides a signal strong enough for the purpose.

I am testing instrument tuner software 'AP Tuner' and 'Tune!It' both shareware but free to download and use for a limited time. The latter program is a lot more complex and sophisticated and includes an extensive library of historical temperaments, auto sound card calibrator, 3D spectrum display, wave form graphing, inharmonicity analysis etc. etc. and even a facility for ear training. Accuracy of both programs is 0.1 cent. Screen display images are attached for information.
AP tuner can be used indefinitely without registration whereas Tune!It costs about $10 US for registration after 30 days trial. I am tempted to purchase the Tune!It software if these trials live up to expectations.


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jdowning - 6-15-2015 at 01:49 PM

For information I have just successfully tested AP Tuner and Tune!It - both designed for Windows - on Linux using the Wine Windows interface.

Also tested as working (in PC virtual environment VirtualBox) in Windows 10 June 2015 prelease version.

jdowning - 7-4-2015 at 12:09 PM

The frets have been 'fine tuned' using the tuner software set to A440 equal temperament and measuring the off-set in cents for each fret position and string. So - for example - the first fret position (diatonic semitone) at 90.225 cents (ie 90 cents) is off-set from the equal temperament position by -10 cents (there are 100 cents to an equal temperament semitone) and fret 12 (augmented fifth), for example differs from equal temperament by +16 cents.
The tuners can measure to 0.1 cent but that level of accuracy is not required as the human ear can only detect pitch differences of 2 or 3 cents at best.

Currently the colascione is tuned A a d' (or A2 A3 D4) at A440 standard - the third (bass string) being a worn Pyramid wound #1010 at 3.5 Kg tension, second string plain Nylon 0.6 mm diameter tension 3.6 Kg and the top string Pyramid PVF 0.37 mm diameter at 4 Kg tension. The tuning of the top string is chosen because is about the maximum pitch allowable if plain gut stringing was used (as it would have been originally). In fact the instrument at this tuning could be strung entirely in plain gut with a top string of 0.40 mm diameter, the second 0.53 mm diameter, and the third 1.04 mm diameter - all at equal 3.5 Kg tension.

With the current stringing arrangement the final fret positions are a compromise due to the different string materials, diameters and construction each requiring a slightly different fret location to remain precisely in tune as measured by the tuners. All plain gut stringing might be a bit better in this respect. In any case if tone vibrato is then factored in, high precision in fret location is perhaps not really a practical objective.
So, at the end of the day, if it sounds right to the player it is right!



jdowning - 7-7-2015 at 04:24 AM

As this is primarily an experimental project, the air resonance frequency spectrum and sound board frequency spectrum (with the sound hole blocked) have been measured for comparison purposes.
The audio signals were recorded with an H2 Zoom digital recorder analysed with Audacity software. The most prominent frequency peaks up to 2000Hz have been marked for information and reference.

The air resonance spectrum (measured over the open sound hole with strings under tension and damped) on tapping the bridge show clear frequency peaks for the G and D harmonics (A440 standard reference pitch). Comparing this with the sound board frequency spectrum indicates that the small bodied colascione should respond primarily to its air resonance frequency characteristics rather than those of the soundboard.

As the strings are initially to be tuned to A2 A3 D4 it will be interesting to see how the overall measured frequency spectrum for the instrument at this tuning will turn out.
It is also planned to test tuning G2 G3 D4 ie with the interval of a 5th between first and second strings rather than a 4th - both tunings being possibilities according to historical record.
One might predict from the air resonance spectrum that the G2 G3 D4 tuning would work 'best' acoustically?

I also plan to test stringing pitched an octave lower ie A1 A2 D3 and G1 G2 D3 although this would mean that all plain gut tuning would not be feasible as the third string (at a string length of 79 cm) would have to be of higher density than plain gut - ie metal wound on gut/silk or loaded gut/silk - but still an historical alternative.

The other tuning possibility to be tested is E3 A3 D4 (like the bass string tuning of a guitar) - easily accomodated with all plain gut stringing - or an octave lower with a wound third string.

The overall frequency spectrum could be modified to some (unknown) extent by locally reducing sound board thickness. This action would affect both sound board and air resonance response but would be non reversible.
Alternatively, and more predictably, the sound hole diameter may be adjusted (made smaller) to modify the air resonance response (to a lower frequency range). As this is an action that may be undertaken reversibly, this will be tested later as a separate experimental trial sequence.
Ultimately the colascione will be 'finished' by fitting a parchment rosette in the sound hole.


jdowning - 7-9-2015 at 02:11 PM

With the current stringing - first string 0.37 mm PVF, second Nylon 0.6 mm and third Pyramid wound #1010 - tuned as D4 A3 A2 and D4 G3 G2 - attached for information and comparison are the Audacity frequency spectrum graphs showing the most prominent frequency peaks.

The colascione with either tuning is quite loud and resonant. If anything the G2 G3 D4 tuning sounds a bit 'richer' in tone.

Next to restring the instrument to sound an octave lower in pitch i.e. A1 A2 D3 and G1 G2 D3.

jdowning - 7-11-2015 at 11:53 AM

The colascione has been restrung to test tuning and octave lower as A1 A2 D3 and G1 G2 D3.

Strings used are those that I have to hand so not ideal - first string Pyramid 0.63 PVA, second Pyramid wound 1010 and third Pyramid wound 1027. String tensions are A1 2.7 Kg, A2 3.5 Kg. D3 2.9 Kg and G1 2.2 Kg, G2 2.8 Kg and D3 2.9Kg.

The attached spectrum analyses, for information and comparison, show some of the more prominent harmonics with the strings sounded open.

For comparison the two attached sound clips are for open strings for G2 G3 D4 and G1 G2 D3. On balance I prefer the richer more resonant sound of the G1 G2 D3 stringing. Interestingly the fundamental tone G1 is not prominent in the spectrum graph although the bass string sounds loud enough. The top D3 string 'sings' nicely in the upper fret positions.



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jdowning - 7-17-2015 at 11:49 AM

A preliminary assessment of the variation of air resonance frequency with sound hole area for this instrument was undertaken in two ways:

1) by covering the soundhole with 2 mm thick card and then recording the air resonance signal (generated by tapping the sound board just in front of the bridge with all strings damped) - the card being moved in 5 mm steps until the whole sound hole area was uncovered.

2) by covering the soundhole area with 2 mm thick card squares each with different soundhole diameters and measuring the air resonance signal.

The results - air resonance frequency (obtained from 'Audacity' spectrum analysis) against sound hole area - are plotted on the attached graph for information.
The difference in the curve profiles is primarily due to different sound hole geometries - full circle area compared to segment of a circle area. Changes in air resonance pitch are easily distinguished by ear as soundhole area varies.
The loudest air resonance frequency occurs at the point when the sound hole is uncovered to an open area of about 35 cm (77% of the full sound hole area of 45.4 cm). This corresponds to an air resonance frequency of 192 Hz G3 which is also the air resonance frequency of the open sound hole there being about a 6 Hz bandwidth tolerance in the measured frequencies.



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jdowning - 7-19-2015 at 11:57 AM

Having established the measured air resonance frequencies for various sound hole areas is is possible to use the 'calibration' graph previously posted to predict the 'optimum' sound hole diameter for a particular open string tuning.

By way of example, for an open string tuning of G1 G2 D3 the resonance frequency signal at the sound hole was recorded with each string sounded open for soundhole diameters 7.6 cm, 4.1 cm and 1.9 cm and spectrum analysed with Audacity to determine the peak frequencies G1 G2 D3 and their harmonics. The attached spectrum analysis charts are attached for comparison.
As might be expected (by reference to the air resonance 'calibration' chart), the 4.1 cm diameter sound hole (area 13.2 cm) equates to a maximum dB for frequency D3 and the tiny 1.9 cm diameter sound hole (area 2.8 cm) gives the loudest response at frequency G2.
That this small diameter sound hole actually worked was something of a surprise. Indeed all three selected sound hole diameters worked well with this particular open string tuning - the sound just differed in tone 'colour' in each case.
On balance I think that I prefer the 4.1 cm diameter soundhole result with its slightly softer bass and stronger first string response.




jdowning - 7-20-2015 at 11:50 AM

Calculating the air resonance frequency based upon the full (single) sound hole area for musical instruments such as ouds, lutes and guitars does not agree with the calculated frequency for a perfect Helmholtz resonator - giving higher than measured values.

Some comparative resonance chamber tests with varying sound hole diameters and chamber depths/volumes can be found here:
http://www.mikeouds.com/messageboard/viewthread.php?tid=14874&p...

For the relatively flexible and shallow bodies of instruments, the mass flow of air oscillating at resonant frequency within the boundaries of the sound hole is concentrated around the outer perimeter so that there is a 'dead area' in the sound hole centre where there is minimal air movement. The diameter of the dead zone appears from tests to vary between about 0.5D and 0.8D where D is the open soundhole diameter. The active area of the soundhole is then used to predict the air resonant frequency of an instrument.

For this colascione with a bowl volume of 3660 ml the 'dead zone' diameters for the 7.6 cm diameter soundhole works out to be 0.55D and for the 1.9 cm and 4.1 cm diameter sound holes 0.48D. Had the bowl geometry been such that the space below the sound hole had been deeper it is anticipated from the resonance chamber trials that the 'dead zone' diameters would have been a greater proportion of sound hole diameter.

jdowning - 7-22-2015 at 02:42 PM

So, for the current open sound hole diameter of 7.6 cm blocking the central area with a disc of diameter 0.55D (4.2 cm diameter - representing the 'dead zone' of the sound hole) should not significantly affect the acoustic response. The validity of this data - based as it is upon resonant chamber trials by MIT researchers and confirmed by my own trials - will next be put to the test.

The measured air resonant frequencies for the temporary test soundhole diameters of 7.1 cm, 6.4 cm 5.7 cm, and 4.1 cm on the colascione allows the 'active' sound hole areas for each diameter to be calculated. Applied to the full sound hole diameter of the colascione (7.6 cm) the equivalent 'dead zone' diameter for each test sound hole result may be determined. So, for example, the active area of the 4.1 cm diameter soundhole calculated from the measured air resonance frequency of 148 Hz is 10.2 cm (compared to the open area of the soundhole of this diameter = 13.2 cm). If the colascione sound hole (diameter 7.6 cm) is then blocked with a central disc to form an open ring shaped sound hole of area 10.2 cm, the disc diameter would be 6.7 cm and the ratio of dead zone diameter d to open sound hole diameter D would be 6.7/7.6 or 0.88. Likewise, dividing the measured air resonant frequency for the 4.1 cm diameter sound hole (148 Hz) with the 7.6 cm sound hole diameter frequency (198 Hz) gives a normalised value of 148/198 = 0.75. The datum points obtained by repeating the calculations for the remaining test sound hole diameters have been plotted on the attached graph for information.

It can be seen that the curve f/f0 against d/D for the colascione is not identical to the curve obtained from the resonance chamber tests performed at MIT athough it is of similar profile. The difference is likely(?) due to the assymetric, shallow geometry of the colascione sound box and sound hole placement compared to the symetrically positioned sound hole and greater depth of the resonance chamber. In other words the colascione is even less perfect as a Helmholz resonator than the symetrical, steel test chambers.
So a second series of tests will be undertaken to verify the air resonance frequencies of the colascione fitted with central discs of various diameters to form open ring type sound holes.
Will, for example, an open ring sound hole of area 10.2 cm give the same acoustic result as an open circular sound hole of 4.1 cm - both having the same 'active area' (10.2 cm)?
Time will tell.



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jdowning - 7-23-2015 at 11:42 AM

The normalised 'ring sound hole' graph has been updated to include datum points for test sound hole diameters of 1.9 cm, 2.9 cm and 4.9 cm.

Note that although this data has been obtain by tests on the colascione it will also apply to any instrument with a single round sound hole and lute/oud like bowls. It therefore might be used as an aid to fine tuning of the air resonance frequency of an oud by blocking the central area of the sound hole with a circular disc of appropriate diameter. Here the normalised curve for the colascione might be more representative for an oud than the MIT curve.

From the colascione curve it can be seen that a solid disc of proportion d/D = 0.45 placed in ther centre of a sound hole will result in a lowering of the air resonance frequency of less than half a semitone. Interestingly, the old lute and oud makers seem to have understood the relationship of sound hole diameter to air resonance judging from the attached examples where the diameter of the inner circle in the rosette designs is about 0.45 D.
So these traditional rosette designs might seem to indicate to a luthier that it is OK to fill in the central area to 0.45D diameter (if they so wish) without having any significant effect on the air resonance frequency. Beyond that limit increasing the relative diameter of the central solid disc will have a proportionally increasing effect in reducing the air resonance frequency for a given sound hole diameter.

The presence of a rosette does not usually significantly affect the air resonance frequency compared to an open sound hole unless the rosette pattern is particularly dense so blocking most of the air movement at the more extreme d/D ratios (in cases where a central solid disc is used to tune the air resonance frequency).

The next series of tests will be to instal central discs of increasing diameter in the colascione sound hole to measure the effect on air resonance frequency and so validate the attached curve of f/f0 against d/D.

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Hibari-San - 7-23-2015 at 01:12 PM

Thank you so much for sharing your researches.
You're helping me to understand those kind of things way better.
I'm pretty sure a lot of others too ! :wavey:


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