Omar Al-Mufti
Oud Junkie
Posts: 333
Registered: 3-14-2012
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Getting rid or excessive sympathetic resonance
Hi everyone,
One of my ouds produces a lot of sympathetic resonance.
I usually tune my ouds C F A d g c
The c triggers C sypathetic vibration and the g trigger in F.
I tried different kinds of strings in terms of tension and thickness. The sympathetic resonance would vary, but it is alwasy noticabliy there.
What is the reason and how to get rid of it?
This is the MAIN reason why I would avoid playing on that specific oud. If you could help, it will change my relation to that oud 
I appreciate any help.
Omar
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Brian Prunka
Oud Junkie
Posts: 2949
Registered: 1-30-2004
Location: Brooklyn, NY
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Mood: Stringish
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Are you referring to the sympathetic vibrations of the strings, or to the resonance of the bowl?
If it is the strings, then this is just physics and you can't get rid of it unless you mute the open strings.
If it is the bowl, then it is based on the size of the bowl and the soundhole(s). The only way to change the resonance is to change the size of the
soundhole. It is easier to add a ring to the soundhole to make it smaller, rather than make it larger, plus it has the option of being reversible.
However, an alternative might be to use a different tuning—if the resonance is F/C, then tuning your oud down a half-step (BEG#c#f#b) might
eliminate most of the offensive resonance since the open strings don't align with the resonance.
Every oud has some resonant frequencies, but the degree to which
they interfere with the sound varies. If you sing high note into the bowl, and gradually slide down, you can usually pretty easily determine the
approximate pitch of the oud's resonant frequency—it is where everything gets louder and it feels almost like the oud is singing back to you.
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Omar Al-Mufti
Oud Junkie
Posts: 333
Registered: 3-14-2012
Member Is Offline
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Thanks Brian!
The sympathetic resonace I meant is the vibration of the open strings. the open c would cause the open C to resonate long. So if i pick the c loudly
and then immediately mute it, C will continue resonating, which is sometimes too much. Same with the F and g.
The bowel has no such a problem.
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Omar Al-Mufti
Oud Junkie
Posts: 333
Registered: 3-14-2012
Member Is Offline
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Brian, is it possible to add/romve some wood mass from the oud or the soundboard so that the natural frequecy changes?
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Brian Prunka
Oud Junkie
Posts: 2949
Registered: 1-30-2004
Location: Brooklyn, NY
Member Is Offline
Mood: Stringish
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The main factors are the volume of the bowl and the size of the sound hole, not the mass of the bowl or soundboard.
The sympathetic vibrations you are talking about are simply part of how sound works and there is not really anything you can do about it. Most people
regard it as a part of the oud's overall sound and not a negative thing.
It sounds like your oud have a very responsive and active soundboard. If this is something you don't like, it makes a lot more sense to sell the oud
to someone who likes that sound and get yourself something different. Trying to modify the basic character of an instrument is just a frustrating
waste of time.
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Brian Prunka
Oud Junkie
Posts: 2949
Registered: 1-30-2004
Location: Brooklyn, NY
Member Is Offline
Mood: Stringish
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By the way, g is the 9th partial of F and typically wouldn't trigger a particularly strong response in the F string.
If it does, it's possible your instrument was designed to emphasize certain frequencies, and using a different tuning might mitigate that effect
somewhat.
The notes that typically produce a strong sympathetic vibration are the fundamental, 2nd, 3rd, and 4th partials (i.e., octaves and fifths). So g
would typically cause the lower C to vibrate (and vice versa), and c would cause F and C to vibrate (and vice versa).
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