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Reinforcing fixed bridge!?

Luttgutt - 3-23-2010 at 09:37 AM

Hi!
I was wondering wether it is possible to reinforce the bridge area from under the face of the oud, (for example, with a 2mm thick peace of spruce that is exactly the shape of the bridge)? If yes, should I glue it on the inside)?

P.S. I have seen it done by a guitar maker, reparing a guitar. i think it was a link from Dr.oud.

http://www.frets.com/FRETSPages/Luthier/Technique/Guitar/Structural...

Thanks

Aymara - 3-23-2010 at 02:55 PM

Hi Old Northman

Quote: Originally posted by Luttgutt

..., with a 2mm thick peace of spruce that is exactly the shape of the bridge ...

From my understanding the peace needs to be larger than the bridge's shape, but that would affect the sound in a negative way.

I think, it would be a good idea to tell us, what's the intension.

Need help from makers!

Luttgutt - 3-23-2010 at 03:16 PM

Well Aymara, as I wrote before, I want the strings to be 2mm higher at the bridge. And I found a way to do that And I love the sound.
But I know now that it puts extra presure on the bridge.
So I am thinking is this a good way to reinforce the bridge??

What are the plusses?
what are the minuses?

Please, oud makers and knowers, help!

Sazi - 3-23-2010 at 04:05 PM

What is the reason? Is the bridge making the soundboard dip? You could try putting a couple of small braces under the outside edges of the bridge like Dincer does, you can see what I mean in the photo show on his web page...

http://www.oudmaker.com/photoshow.php

By the way, this is a great slide show for anyone interested in oud construction, thanks Dincer, enjoy your retirement.

Aymara - 3-24-2010 at 12:24 AM

Quote: Originally posted by Sazi

What is the reason?

I remember another thread from Luttgutt some weeks ago, where the bridge got loose, because of a pickup, that was placed on top on the bridge.

Quote:

You could try putting a couple of small braces under the outside edges of the bridge like Dincer does, ...

That would avoid bending of the soundboard, but not that the bridge might get loose because of high string tension.

How about using strings with lower tension (too)?

Luttgutt - 3-24-2010 at 06:41 AM

Beautiful slide, thanks Sazi!
But I see Aymara's point.

That is true Aymara! The board did not bend, but bridge went nicely out in the end.
But maybe it was badly glued (because Mr. Sukar had a time pressor when he made me the oud- since I had to travel).
In that case, I am thinking maybe the board WOULD bend when I glue the bridge properly.
So maybe I do need those bracings??

My question remains:

Does liming a peace of wood, on the inside of the sound board, under the bridge help strenthening?

P:S: the sound I had is the sound I have deamd of all my life!
So I am not giving up

Thanks for your help guys!

Dr. Oud - 3-24-2010 at 08:58 AM

Quote: Originally posted by Luttgutt

Hi!
I was wondering wether it is possible to reinforce the bridge area from under the face of the oud, (for example, with a 2mm thick peace of spruce that is exactly the shape of the bridge)? If yes, should I glue it on the inside)?...

the repair link was for a steel string guitar, not an oud, and it was to repair a damaged face, not reinforce it for higher tension, like your situation. I think you are risking damage to the face by increasing the torsion with the higher bridge. Reinforcing the face in any way will not avoid this risk. The glue joint can withstand a certain amount of stress, then the wood will fail, and the bridge will come off with some of the face with it. I would advise you to return the bridge to it's original height and try small increments of higher tension strings instead. The stress will still be higher, but may not be as risky as what you have described.

Luttgutt - 3-24-2010 at 10:27 AM

I see!

Thank you Dr.

I'll use Daniel Mari strings, and restring such that I get only 1,5mm extra hight, and hope for the best.

But I have to say again that the sound with the higher bridge was extatic... too bad the bridge could not tolerate it :shrug:

Aymara - 3-24-2010 at 10:55 AM

Quote: Originally posted by Luttgutt

... too bad the bridge could not tolerate it :shrug:

Maybe it would (2mm), if you use lower tension strings ... maybe the low tension Kuerschner set instead? Maybe ask him by mail, if his strings could compensate the tension raise of the 2mm. But explain exactly, what's the problem ... don't forget to mention the string length.

Sazi - 3-24-2010 at 02:07 PM

Here is a possible option...

One is a Cuban Laúd bridge and the other is a Bellucci guitar bridge, it is like a cross between a floating bridge and a fixed bridge, and would solve the torsion problem. You could then set the saddle at your preferred height. You would probably want to get a luthier to do it for you though...

ScreenShot040.BMP - 114kB

fernandraynaud - 3-24-2010 at 10:40 PM

I was exactly thinking of what Sazi shows us. I though that my experiment would be to make or buy a tailpiece, then make grooves in the top of the bridge and use it as a sort of floating bridge. If it works you could shape the top and still be able to revert to the way it was when you remove the tailpiece. I have never done it but it shouldn't be too hard.

But let's think for a moment. WHY does the tone improve with your stringing up and over the top (that is what you're doing, right?).

I would say that you are twisting the soundboard. The exact stress that causes the bridge to come unglued, or to break off, is what is changing the timbre. You can imagine: the portion of the soundboard nearer the tail of the instrument is lifting and the portion near the soundhole is being pushed down. I doubt it's just additional downward pressure on the soundboard, but who knows?

But we know that there are timbre changes that don't last. You can stretch things a certain way and the changes are a result of a temporary state of affairs, like a material that is stressed near the breaking point, or a structure that is bending, and in time a new equilibrium emerges without the improved timbre. I have had that happen. So it might be that you cannot maintain that dream tone. You'd have to try.

If you can create a temporary tailpiece or temporarily attach one, and run the strings over the bridge and it sounds interesting, then you could leave it like that and see what happens, if the change "holds". That's what I'd try. With maybe a tailpiece like this:

http://www.allparts.com/12-String-Trapeze-Tailpiece-Chrome-p/tp-063...

drive 3 screws into the end-piece of the oud, I assume there is an endpiece, and it should hold. Padding under the plate should make the whole operation reversible with no damage, just unscrew and fill the 3 holes if you change your mind. If not this particular tailpiece, something like it? You might not need a separate hole in the tailpiece for each string, maybe a hole per course is OK? If you like it maybe you can have a wooden one made?

If you can't produce the dream tone under these conditions, maybe if you raise the effective bridge with a saddle, this time of course without risk of ungluing the bridge? Of course you have to keep changing the angle on the neck if you add height, and you will run out of regulation room pretty quickly. Then you might have to raise the fingerboard to have a decent action? Chasing the dragon?

So REALLY you need to go back to basics and try to understand how your dream timbre is being produced. Ideally if you can speak Arabic, and you can produce some soundfiles that demo the effect, maybe you can enroll Sukar himself in the project, maybe it's a variation on the "moving horse" that he hasn't thought of? Do you have a recording of your dream timbre before you had to back off?

Aymara - 3-25-2010 at 12:30 AM

Quote: Originally posted by fernandraynaud

Ideally if you can speak Arabic, and you can produce some soundfiles that demo the effect, maybe you can enroll Sukar himself in the project, ...

Such a sound comparison might even be helpful here in the forums ... we have a lot of very experienced luthiers here

But I would use GOOD quality sound files, not highly compressed MP3s, which kill all overtones. Ogg Vorbis files at 224 KBit/s (quality setting 7) are ideal ... they give CD quality and Windows Media Player 11 can play them ... for older versions you'll need THESE codecs. You could use Audacity for recording and saving to Ogg.

Luttgutt - 3-25-2010 at 05:37 AM

WOW!!

Thanks guys!!

Sazi, thanks a lot. Nice pics, and good thought.

Fernand, that was excellent reading you provided me with :bowdown:

1- Fernand, before the bridge went out, I had change back the "overbridge" stringing, to a USUAL stringing (but with a litle adjustment, so that it was only 2mm higher).
The sound was not as good, but almost! So I was happy with that!!

So I know now that overstringing is out of the question! And my new methode is good enough for me. But still the bridge went off (probably because the glue was already weekening!?)

2- I tried also a floating bridge right in front of the fixed bridge. The result was OK. But not the same

And I was afraid the pressure with deform the sound board (can it?).

Isn't oud with different kind of bridge supposed to have different "structure"?
As far as I can see (on the inside of Sukar ouds) there are NO difference between the two!? (I have both Sukar floating and fixed bdg). Is that strange?

3- Yes I DO HAVE a video of my DREAM sound (LUCKELY).
Taken on my mobile phone camera. Not good quality, but I can still recognize that "dream sound".
I tried to post a link. Did not (F.) work (excuse my language).

P.S. Fernand, if you want I can try to send you the video (then I need your e-mail).

Yours

Sazi - 3-25-2010 at 01:12 PM

Quote: Originally posted by Luttgutt

Isn't oud with different kind of bridge supposed to have different "structure"?
As far as I can see (on the inside of Sukar ouds) there are NO difference between the two!? (I have both Sukar floating and fixed bdg). Is that strange?

I've checked my ouds also and the bracing is no different, except the best sounding floating bridge one actually has less bracing - no small braces either side of the bridge. ( It sounds more open and resonant).

In any case, the fixed/floating combination should put LESS pressure on the soundboard, allowing it to vibrate more freely and /or allowing higher tension strings for a more dynamic sound.

One thing I have found with the sound in relation to bridge height is that it is often a bit louder and more dynamic with a bit more string clearance over the soundboard, and as you have noticed, a small increase is enough to hear the difference.

Anyway, good luck!