Mike's Oud Forums

Oud in break

sylvainbd - 11-8-2014 at 05:44 AM

Hi friends

Do you think it is good for my instrument to loosen his strings during several days ? Sometimes i do that but i don't want to weaken the neck ...

Thank you for your reply

faggiuols - 11-8-2014 at 03:46 PM

I do not have an answer for you, but I'm interested in the answers.
oud has a delicate texture especially about the torsion of the bridge on the soundboard. I think that to loosen the strings during several days is a good thing. I'm curious to know the opinion of the experts on the forum.

jdowning - 11-8-2014 at 05:13 PM

Unless you are using gut strings at a time when relative humidity happens to be high (to avoid premature string breakage) keep the instrument tuned and at proper string tension - otherwise you will be spending a lot of time retuning to pitch and bringing the oud back to its stable 'full voice'.

sylvainbd - 11-10-2014 at 08:22 AM

Thank you for your answers Jdowning and faggiuols.

I don't use gut strings, only nylon classic strings.

I already did a long break and i saw a natural correction of the action from 3mm to 2.7mm for 7 days in break ...
Is it dangerous to repeat this operation 2-3 times/ years for the instrument or not ? Maybe it is better to do nothing ?!...

jdowning - 11-11-2014 at 09:03 AM

Reducing the string tension for a period of time is not going to damage your oud. When you reduce the overall tension you might expect the string action at the neck joint to also reduce somewhat as the bending stresses on the neck and neck joint are correspondingly reduced. However, when you retune the oud and bring the strings back to full tension you might expect to see the action return to where it was before - so nothing gained really.
Do you continue to play the oud at the lower string tension? If not then not only will the oud be silent and out of service during the break period but will take time afterwards to be brought back to a stable tuned position.

If you want the action to remain at 2.7 mm (without resetting the neck) you might try restringing the oud at a lower overall string tension if it sounds OK at the lower tension?

Over time the neck of an oud will tend to permanently pull up slightly under string tension (under a load that might amount to up to about 50Kg) due to the slow redistribution of the internal stresses in the wood (a phenomenon known as 'creep'). A lower overall stable string tension would help to reduce this inevitability.

sylvainbd - 11-11-2014 at 12:00 PM

Thank you for your council ;) I will try a low tension string set. I think it is the better way to preserve my instrument, particulary the neck ... I never try it before. Maybe the sound will be good !

sylvainbd - 11-11-2014 at 12:08 PM

Thank you for your council ;) I will try a low tension string set. I believe that is the better way to preserve my instrument, particulary the neck ...

faggiuols - 11-12-2014 at 12:41 AM

hello Jdowning and sylud
I would like to know if the string tension (and thus deformation) acts more on the connection neck - inner block, or the system bowl-soundboard, or both?
thanks for the reply.

jdowning - 11-12-2014 at 05:21 AM

The whole instrument is more or less affected by deformations due to string tension however an oud bowl, from an engineering perspective, is very stiff (resistant to bending as a beam under load) due to its depth (rib thickness or thinness has little influence) and 'egg shel'l like geometry. The 'weakest part' of an oud in resisting longitudinal bending is at the neck joint where the bowl has the least depth and so has the least stiffness. Furthermore, due to the abrupt change in geometry at the neck joint, stresses at the joint are magnified (known as a 'stress raiser' or a point of 'stress concentration' in engineering terminology).
The neck itself will also tend to slightly 'bow' longitudinally under tension. The sound board will also dip in front of the bridge due to string tension causing the bridge to rotate slightly.

For information - I included a diagram of the stresses acting on a neck joint as part of this investigative work concerning nailed necks posted 3 years ago on this forum (posting date 11-21-2011)

http://www.mikeouds.com/messageboard/viewthread.php?tid=12428

faggiuols - 11-12-2014 at 07:51 AM

Quote: Originally posted by jdowning  
The whole instrument is more or less affected by deformations due to string tension however an oud bowl, from an engineering perspective, is very stiff (resistant to bending as a beam under load) due to its depth (rib thickness or thinness has little influence) and 'egg shel'l like geometry. The 'weakest part' of an oud in resisting longitudinal bending is at the neck joint where the bowl has the least depth and so has the least stiffness. Furthermore, due to the abrupt change in geometry at the neck joint, stresses at the joint are magnified (known as a 'stress raiser' or a point of 'stress concentration' in engineering terminology).
The neck itself will also tend to slightly 'bow' longitudinally under tension. The sound board will also dip in front of the bridge due to string tension causing the bridge to rotate slightly.

For information - I included a diagram of the stresses acting on a neck joint as part of this investigative work concerning nailed necks posted 3 years ago on this forum (posting date 11-21-2011)

http://www.mikeouds.com/messageboard/viewthread.php?tid=12428



hello Jdowning
I do not know if I understood well. I wanted to know is if the tension of the strings produces a deformation of type A, B or C according to the scheme which I am attaching.
sorry no precise design but do not ever learned how to draw!

thanks
[file]33329[/file]

SamirCanada - 11-12-2014 at 08:11 AM

Hi John I agree that in theory the bowl should be stiff, and yes it has great resistance to pressure is applied downwards onto the back at the apex. but I am sure you have also observed that with relatively little force its possible to deform the sides of the bowl easily either horizontally or lengthwise this of course only untill the soundboard is mounted on the bowl so I am thinking the bracing and the top is also taking some of the load.

jdowning - 11-12-2014 at 08:25 AM

Yes, of course the sides of a bowl will deform easily if there is no braced sound board in position - but that is not the situation with a completed oud where the edge of the sound board glued in place supports the edges of the bowl against deformation. The braces also play a part.