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sydney
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[*] posted on 12-13-2005 at 04:21 AM
Question to Oud Makers only


Hello oud masters, :bowdown:

My question is ...

Can Floating Bridge Oud be converted to normal Bridge oud?


Thank you




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Emad
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[*] posted on 12-13-2005 at 05:38 AM


Yes.

If you put a new top with it.

Dincer




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[*] posted on 12-13-2005 at 09:35 AM


As Dincer implies, the soundboard structure and bracing is very different for a floating bridge. The sound of the oud would be different with unpredictable results. Otherwise, there is no risk converting from a floating bridge to a conventional one, unlike the reverse. Converting a conventional glued on bridge to a floating bridge is likely to fail with a collapse of the face.



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[*] posted on 12-13-2005 at 11:26 PM
Normal bridge


Quote:
Originally posted by Dr. Oud
As Dincer implies, the soundboard structure and bracing is very different for a floating bridge. The sound of the oud would be different with unpredictable results. Otherwise, there is no risk converting from a floating bridge to a conventional one, unlike the reverse. Converting a conventional glued on bridge to a floating bridge is likely to fail with a collapse of the face.


Hello master Richard,

I thank you for you kind input.

Unpredictable sound / result is a worry if one wanted to go on with such a change to a floating bridge oud but as long as you see this won't danger the oud then I guess it is worth changing if it will save running around for a special strings length as well as special tension too.

Thank you




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Emad
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[*] posted on 12-14-2005 at 10:26 PM


Quote:
Originally posted by sydney
Quote:
Originally posted by Dr. Oud
As Dincer implies, the soundboard structure and bracing is very different for a floating bridge. The sound of the oud would be different with unpredictable results. Otherwise, there is no risk converting from a floating bridge to a conventional one, unlike the reverse. Converting a conventional glued on bridge to a floating bridge is likely to fail with a collapse of the face.


Hello master Richard,

I thank you for you kind input.

Unpredictable sound / result is a worry if one wanted to go on with such a change to a floating bridge oud but as long as you see this won't danger the oud then I guess it is worth changing if it will save running around for a special strings length as well as special tension too.

Thank you


Yes I know I'm not a maker Emad but I asked an Iraqi maker and Richard is probably right, you can go ahead with the converting.




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Ronny
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[*] posted on 12-16-2005 at 07:37 PM


I am not an oud maker either and I know a thing or two about physics so naturally when I read the question it sparked my curiosity and I have been itching to participate in the thread. Excuse the intrusion Emad, but I have been thinking about this interesting question as Statics problem, I would deduce that for an oud which has been constructed to perform optimally for a particular type bridge, the following probably apply:

- Floating bridge type: Force on the soundboard is mainly downward with a small component at the base of bridge parallel to the soundboard. The resultant force is not as great as the fixed bridge type. In this case I would think that the bracing doesn't have to be as stout as the fixed bridge type and the top/brace system can be lighter than fixed bridge type.

- Fixed bridge type: The tension in the string produces a torque which causes the bridge to sympathetically rock back and forth as the string vibrates setting corresponding vibrations in the soundboard. The taller the bridge the less tension is required to produce the same torque since you have more "leverage" here. So ouds with taller bridges should be louder with the same tension and other variables being equal within practical limits.

So it sounds to me that to convert from floating to fixed might be taking a risk of damaging the soundboard. Unless of course the bracing is always made like the fixed bridge type. The maker of the oud should be able to give a definite advice.

Just my thoughts here. I would be very interested in what actually happens if you go ahead with this modification.

Elie
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[*] posted on 12-17-2005 at 04:52 AM
RE: Your Participation


Quote:
Originally posted by Elie Riachi
I am not an oud maker either and I know a thing or two about physics so naturally when I read the question it sparked my curiosity and I have been itching to participate in the thread.

So it sounds to me that to convert from floating to fixed might be taking a risk of damaging the soundboard. Unless of course the bracing is always made like the fixed bridge type. The maker of the oud should be able to give a definite advice.

Just my thoughts here. I would be very interested in what actually happens if you go ahead with this modification.

Elie


Elie,

Your Participation is welcomed indeed. I am sure you understand why I directed my question to oud makers.

I have taken some photos of the inside of the oud but they came out too bright that bracing can not be seen. I really wanted to share them with all the oud makers to help them help me. But since things are not a 100% secure to change and I am not skilled enough to go on with the change.

I guess it is wiser to leave the oud alone. It took one good oud maker a lot of effort to make it as such. I do not think I should do something I am not sure of.

I am so thankfull to all the masters who helped me with their answers in this regards.




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[*] posted on 12-17-2005 at 07:53 AM


If the problem is string length, I have an idea for you, make some permanent extensions of string tied to the end of the bowl where you normally tie the strings and then tie the regular strings to these extensions. Where you tie to the extension will of course be before the bridge. Another approach would be to make or have made an extension plate (like you find on violins, cellos, stand up bass and arch-top guitars.)

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[*] posted on 12-18-2005 at 05:23 AM
Your Ideas


Hi Elie :wavey:

Very nice of you that you cared about this problem of mine. Man, it is annoying that I can not use the strings I bought a while ago because they are short for the floating bridge style.

I find the second idea is more reasonable. It will still make the oud look good and will do the trick. Actually I can make the extension plate my self. I can make it out of reasonably thin brass to give it that old look. I will let you know about it when I do it.

Thanks Elie.

Stay well




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Emad
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[*] posted on 12-18-2005 at 09:12 AM


Quote:
Originally posted by Elie Riachi...
So it sounds to me that to convert from floating to fixed might be taking a risk of damaging the soundboard. Unless of course the bracing is always made like the fixed bridge type. The maker of the oud should be able to give a definite advice....

OK Mr. Science, - while the physics of the vibration moments may lead you to believe the fixed bridge requires greater structural integrity, there are some fatctors you need to factor in:
1. The floating bridge is usually tuned higher or with heavier strings to produce the same or greater volume than a fixed bridge. This induces a relatively higher load downward than the fixed bridge's torque load.
2. The fixed bridge's torque moment is offset somewhat by the tension component through the soundboard itself, resisted by the tail block. The forces at the bridge arwa are therefore mitigated to the rockin' (and rollin') in the imediate area of the face, which requires lighter bracing and edge support to produce the same volume as would the floating bridge.
3. Historical evidence of conversions and uninformed builds of floating bridge ouds have often resulted in a collapse of the face under the floating bridge.
4. The structural details of the original (and successful) Bashir design executed by Mohamed Fadel Hussein show a more robust structure - a thicker soundboard, heavier braces and additional edge supports (corner blocking).
-just a bit of empirical evidence to ground your theory...:wavey:




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[*] posted on 12-18-2005 at 03:18 PM


Quote:
Originally posted by Dr. Oud

OK Mr. Science, - while the physics of the vibration moments may lead you to believe the fixed bridge requires greater structural integrity, there are some fatctors you need to factor in:
1. The floating bridge is usually tuned higher or with heavier strings to produce the same or greater volume than a fixed bridge. This induces a relatively higher load downward than the fixed bridge's torque load.
2. The fixed bridge's torque moment is offset somewhat by the tension component through the soundboard itself, resisted by the tail block. The forces at the bridge arwa are therefore mitigated to the rockin' (and rollin') in the imediate area of the face, which requires lighter bracing and edge support to produce the same volume as would the floating bridge.
3. Historical evidence of conversions and uninformed builds of floating bridge ouds have often resulted in a collapse of the face under the floating bridge.
4. The structural details of the original (and successful) Bashir design executed by Mohamed Fadel Hussein show a more robust structure - a thicker soundboard, heavier braces and additional edge supports (corner blocking).
-just a bit of empirical evidence to ground your theory...:wavey:


Hi Doc,

I figured that the tension would be higher on the floating to increase the downward component and bring the volume to the level of a fixed bridge with lower tensions as you stated in (1).

I am guessing with higher tensions of the floating type the strings are tied to the end of the bowl and pull it towards the neck (not the case in the fixed type) causing the bowl to want to expand at the waist or middle and that is probably the reason for the corner blocking in (4). The absence of corner blocking in the case of a conversion of from fixed to floating may have lead to the collapse as a result of the budging of the bowl in the middle and not just the downward force.

Do you think that heavier bracing is needed for a floating type or would it be more effective to use the corner blocking and lighter bracing (I am thinking that the latter would be optimal, I may try that when I build my third oud)?

But according to your account that the floating types you know of are built stouter, then if that is the case for certain then I do not see a risk of physical damage as a result of the conversion to fixed.

Oh I just thought of the banjo; here you have a floating bridge, corners locked down, a thin membrane for sound board and no bracing other than the longitudinal bar extending from neck to bottom and the closed back types are louder than you know what.

Very interesting thread. Thanks all.
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[*] posted on 12-18-2005 at 05:19 PM


Quote:
Originally posted by Elie Riachi....I am guessing with higher tensions of the floating type the strings are tied to the end of the bowl and pull it towards the neck (not the case in the fixed type) causing the bowl to want to expand at the waist or middle and that is probably the reason for the corner blocking in (4). The absence of corner blocking in the case of a conversion of from fixed to floating may have lead to the collapse as a result of the budging of the bowl in the middle and not just the downward force.

Do you think that heavier bracing is needed for a floating type or would it be more effective to use the corner blocking and lighter bracing (I am thinking that the latter would be optimal, I may try that when I build my third oud)?

But according to your account that the floating types you know of are built stouter, then if that is the case for certain then I do not see a risk of physical damage as a result of the conversion to fixed.

Oh I just thought of the banjo; here you have a floating bridge, corners locked down, a thin membrane for sound board and no bracing other than the longitudinal bar extending from neck to bottom and the closed back types are louder than you know what.

Very interesting thread. Thanks all.

The expaning waist is an interesting thought, especially as I am experiencing the same phenomenon myself. Perhaps my own bridge should be converted to fixed? The corner blocks would certainly help avoid the side poping out, but I have not heard of that type of failure. I know that some floaters simply deepress the face until it's unplayable or collapse completely into the bowel. The fixed bridge also pulls at the tail, but through the soundboard itself. I think the force is very similar at the end of the bowel, but very different in the bridge area.
As for the banjo - the dynamics of a skin membrane vs a thin wooden plate don't seem to be very similar to me, but maybe my layman's brain just can't grasp the concept. Perhaps you could enlighten us in that area, professor?:shrug:




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[*] posted on 12-18-2005 at 06:07 PM


I found a picture of when I did this conversion from fixed to floating brige oud. I was verry worried about that phenomenon and although Iam not a physics major or a wood worker by any means I came up with a way of stoping the downward pressure from the floating brige. I used Jameel's (TM) ;) lap sanding technique to fit them and I clamped them to each side under the braces so that it barely rests on them. So far my oud hasnt collapsed.
The down sides I have experianced doing this conversion is that for some odd reason the action is really high now. Either the neck shifted when I took the face off? or Iam using to high a brige for a floating brige oud. Another thing is that the sound is extremely bright in the nylon strings and absolutely dead in the wound strings. The wound strings now sound more like a guitar would sound like. I can blame the fact that I resused the same face to do the oud which was bad quality to start with. My workmanship isnt the greatest concidering all I had was a saw and carpenter's glue so I was restricted in that sence.

I wonder tho if using such stopers for the brace was a bad idea sound wise? is it stoping the brace from vibrating?


Now I dont know really what the effect on the sound was from this
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[*] posted on 12-18-2005 at 07:50 PM


Samir,
It sounds like the sound board isn't doing its job and you are mainly getting the vibrations from strings. This could happen if the bridge is on a brace or too close to one. Or maybe there isn't enough tension in the strings to supply the downward force, like the good Doc mentioned, floaters end up needing more string tension.

Well Doc (I know it is a deep subject, the well that is:D) it was just a thought about the banjo. I also heard of new acoustic guitars having only one brace!
Could it be as the strings of the floater pull the edge of the bottom towards the neck which in turn pushes that end of the sound board along with it creating a crate around the bridge. While the fixed bridge will also pull the board towards the neck but it pulls upwards also raising the action over time as this happens and the oud is not completely dead in this case? Just some thoughts!

Regarding the busting at the sides for us humans seems to work the other way -- when we bust out, its all around especially at this time of the year with all the festivity foods and desserts.
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[*] posted on 12-18-2005 at 08:58 PM


I am hesitant to express a point of view in this thread, because:
1/ I am not an oudmaker
2/ I lack the scientific knowledge of the other posters

But here's my .02c worth.
I do not think one should generalise that ALL floating bridge ouds have thicker sound boards, that ALL floating bridge ouds need heavier gauge strings to perform optimally and that ALL makers use similar bracing patterns in their floating bridge ouds.

I base this on the fact that I have tried a few different gauges of strings on my Bashir style oud by Nazih Ghadban.

The heaviest of these (and therefore the best if higher tension is the measure) was a set of Aquila Nylgut Arabic strings. At first I liked them, but I soon realised they did not sound as good (on that instrument) as the lower tension Pyramid lute strings that were fitted previously. I have now fitted a super light set of Pyramid lute strings. I had to use a slightly higher bridge to avoid buzz, but the sound, whilst not quite as loud, is excellent. The lower tension also allows me to play faster and cleaner.

The vibrating stringlength is 60 cm. For those interested, here are the gauges and tensions:

cc .650 mm = 3.3 kg - (PVF unwound) 32.36 Newton

All other strings are Silver- plated wire wound on special
multifilaments with high tensile strength and low tension.

gg .906 mm = 3.4 kg 33.34 Newton
DD 1.010 mm = 3.4 kg 33.34 Newton
AA 1.017 mm = 3.6 kg 35.30 Newton
FF 1.025 mm = 3.6 kg 35.30 Newton
C 1.237mm = 3.6 kg 35.30 Newton

I don't know a thing about torque and AFAIK the only thing that rocks backward and forwards is the guy playing it, but I know what I like ;)

Regards,

Greg
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