Mike's Oud Forums

oud braces

Onglon - 11-11-2017 at 02:16 AM

hi!

quick question, which must sound awfully naive, but why does a oud need braces (on the inside of the soundboard)?


best

MattOud - 11-11-2017 at 09:26 AM

hopefully someone who knows more can help...
My take, from observation of my ouds, is that they have been made with individual pieces(panels) for the soundboard rather than one solid piece(panel). I am unsure why this is other than perhaps it is very difficult to find such a large piece necessary for the soundboard surface area without any blemishes, whereas with smaller pieces you can cut and find pieces that are less blemishes. This being said, the pieces are now unattached and therefore need a support to hold them together, ie. bracing.
However, along with this, it seems to me that some master luthiers have mentioned in their oud building process, that the inside of the OUD also can be created carefully, and mathematically, to bounce sound frequencies better and are experimenting all the time to figure out better techniques, much of which they would keep proprietary I imagine.
Maybe someone can tell us more on this. Cheers.

suz_i_dil - 11-13-2017 at 10:03 AM

I think at first because of structural reason dont you think ?
If we take the soundboard of a baglama for exemple it is unbraced but see how thick it is...An oud soundboard being so more large i cannot imagineA how thick it should be a without brace to be stable. Maybe so thick it would be totally mute
Just a thought, i'm not sure that's the reason
best

jdowning - 11-13-2017 at 03:14 PM

The sound boards of ouds and lutes are made very thin to respond efficiently to the low power input of the plucked strings so the first requirement of the braces - as suz_i_dil notes - is to structurally support (or brace) the sound board to prevent collapse under string tension. But, of course it is not as simple as that!

The braces also divide up the sound board into non symmetrical areas that (if properly done - an art in itself) allows a sound board to effectively respond acoustically over a wide range of sound frequencies.

A sound board ideally should be as stiff as possible both along the wood grain direction longitudinally and across the wood grain, consistent with low wood density. The stiffer the wood the higher the speed of sound transmission through the wood. Braces have some influence (in ladder braced instruments like ouds and lutes) on cross grain sound transmission.
Any wood grain deviation from perfectly straight in a sound board will result in reduced sound transmission and reduced acoustic efficiency.

If properly glued together multiple piece sound boards are just as strong as a single piece sound board so the braces are not there to stop a multiple piece sound board falling apart. Ouds made by some of the most renowned luthiers have sound boards made up of multiple pieces (up to six pieces in some cases). This allows a knowledgeable luthier to piece together a more perfect sound board (acoustically) than might usually be found in a one or two piece sound board. It also allows adjustment to cross grain stiffness where required.
Not knowing the science behind sound board design, I conducted a few experiments for my better understanding about five years ago with the results posted on this forum here:

http://www.mikeouds.com/messageboard/viewthread.php?tid=12601

and here:

http://www.mikeouds.com/messageboard/viewthread.php?tid=12819#pid87...

All a bit long winded in detail but may be of interest.


newlife_ks - 11-14-2017 at 12:10 AM

These threads are definitely worth reading, thanks for posting, jdowning!