Mike's Oud Forums

A question about Floating Bridge

Luttgutt - 10-17-2013 at 01:52 PM

Hi!

I am wandering why do the Luthiers make the floating bridge such that it is in contact all the way with the sound Board, while it is in contact only on its two end sides in violins, mandolines etc.?

And why do they tend to build them much longer?

Any boby has an explanation?

P.s. I am thinking of experimenting on one of my floating bridge ouds, by making some New floating bridges, and see the effects.

Any suggestions on shapes and matirials to use?

Thanks!

Jody Stecher - 10-17-2013 at 03:07 PM

I can provide only a small part of the answer. The violin top is arched and braced in a way that interacts with the two footed bridge to make an effective bowed instrument. It's not good for sustain when plucked. On banjos of various sorts the two footed bridges give a shorter sustain than bridges with 3 feet or the occasional full contact banjo bridge. It is only on mandolins from the early 20th century onwards that the two footed bridge is used, and that is only on adjustable bridges with metal posts. On the older round back mandolins —and on round back mandolins that are still being built today — the standard bridge is long and makes contact with the soundboard all the way across the length of the bridge. So this is an old idea for an almond shaped round back double strung instrument.

The "received wisdom" is that a floating bridge whose length is more than 50% of the soundboard width will have increased sustain and increased bass response. Of course this must interact with many other factors.

Brian Prunka - 10-17-2013 at 06:30 PM

This is interesting. Archtop guitars generally have floating bridges with two feet, but the Django style ones have full contact.

Curious as to whether a full-contact bridge would be an improvement on an archtop guitar.

Jody Stecher - 10-17-2013 at 07:13 PM

Quote: Originally posted by Brian Prunka  
This is interesting. Archtop guitars generally have floating bridges with two feet, but the Django style ones have full contact.

Curious as to whether a full-contact bridge would be an improvement on an archtop guitar.



And the sound of floating bridge ouds more resemble the tone of Django style guitars than they do other guitars... or other ouds.

If a full-contact Selmer/Django type bridge were put on a standard archtop f hole jazz guitar there would be no musical sound. Only buzz and rattle. The neck angle of (non Django) archtop guitars are set for a high bridge. A full contact bridge would have to have so much wood for the strings to clear the fingerboard that it might not result in much sound. The two footed bridges tend to be made of many parts. The wooden base, two metal poles on which the slotted bridge sits and hex nuts or wheels through which the poles pass, which can be used to adjust the height of the strings. I suppose the base of this kind of bridge can be made to have full contact with the soundboard. But I expect this has already been tried. On guitars. On ouds? I don't think that will ever happen. The neck angle would have to be drastically re-set to use this kind of adjustable bridge on an oud. Otherwise the action would be unplayably high

SamirCanada - 10-18-2013 at 04:27 AM

There are some makers such as Samir Azar and others who have experimented with a 2 and 3 foot bridge. I have also done it in the past and I didnt find any noted difference in terms of sound. You can try on your oud and see if you find a difference, but myself I found the height and position of the bridge being more influencial than the number of feet.

Also, I think in terms of longevity of the instrument, its probably best to keep it one peice so as to distribute the tension as much as possible. Kind of like walking on your wooded floor with flat shoes rather than with high heels :)

I wonder in terms of violins if luthiers started using a 2 footed bridge is to avoid puting pressure down on the glue joint line which runs across the center of the arched top and realized it sounds better.

Edward Powell - 10-18-2013 at 08:54 AM

the main reason of course is the difference in soundboard types.
the two types of wood soundboards are:
1) flat tops (very thin and strongly braced)
2) carved tops (very thick and maybe no or very little bracing)

on the thin flat tops you can't use a two leg bridge because:
1) too much pressure on too small an area would damage the thin soundboard.
2) the this surface needs a larger contact area to disperse the vibrations.

the thicker carved top actually NEEDS more focused pressure in order to transfer enough vibration to the top, hence: 1) a much higher string hieght, and 2) much smaller contact surface area.

Edward Powell - 10-18-2013 at 12:41 PM

another obvious reason is that with a flat-topped instrument it is very easy to fit a long flat bridge, but with an arch-topped instrument it would be very very difficult to shape the bridge to achieve full contact with an arched surface.

Dr. Oud - 10-19-2013 at 09:43 AM

Quote: Originally posted by Edward Powell  
another obvious reason is that with a flat-topped instrument it is very easy to fit a long flat bridge, but with an arch-topped instrument it would be very very difficult to shape the bridge to achieve full contact with an arched surface.
sorry, I disagree. Fitting the bridge to the face should be done by lap sanding the bottom of the bridge - place a piece of 80-100 grit sandpaper grit up on the face and rub the bridge on it to achieve the fir. This is easier with separate feet then a continuous foot.

Edward Powell - 10-19-2013 at 11:19 AM

Quote: Originally posted by Dr. Oud  
Quote: Originally posted by Edward Powell  
another obvious reason is that with a flat-topped instrument it is very easy to fit a long flat bridge, but with an arch-topped instrument it would be very very difficult to shape the bridge to achieve full contact with an arched surface.
sorry, I disagree. Fitting the bridge to the face should be done by lap sanding the bottom of the bridge - place a piece of 80-100 grit sandpaper grit up on the face and rub the bridge on it to achieve the fir. This is easier with separate feet then a continuous foot.


Yes, that is exactly what I am saying :)

Dr. Oud - 10-20-2013 at 11:45 AM

Quote: Originally posted by Edward Powell  
Quote: Originally posted by Dr. Oud  
Quote: Originally posted by Edward Powell  
another obvious reason is that with a flat-topped instrument it is very easy to fit a long flat bridge, but with an arch-topped instrument it would be very very difficult to shape the bridge to achieve full contact with an arched surface.
sorry, I disagree. Fitting the bridge to the face should be done by lap sanding the bottom of the bridge - place a piece of 80-100 grit sandpaper grit up on the face and rub the bridge on it to achieve the fir. This is easier with separate feet then a continuous foot.
sorry, I misunderstood. never mind.

Yes, that is exactly what I am saying :)

Luttgutt - 10-21-2013 at 09:23 AM

Thank you guys for Your valubale info..

Most appretiated.

What about the material? Do you think it is possible to use flamed mapel?
If not, what can I use?

Edward Powell - 10-21-2013 at 09:50 AM

MAPLE is an excellent bridge wood for ouds.

SamirCanada - 10-21-2013 at 11:23 AM

I concur with Edward, maple is great. I also think it looks very nice on cedar face or a lightly shellac'ed spruce top.

Dont need to spend more on flamed maple... and it is actually softer than other kinds of maple such a rock maple. but if you have some on hand sure, why not use it.

You can use any hard wood... any of the rosewoods, ebony. Walnut could be used but I think it would be a bit soft and absorb/dampen some of the vibrations then again maybe this is a good thing to round out the sound... best thing is to make a few of different height (a couple of mm here and there) to see which bridge imparts the best sound but also the best playability (I would aim for the lowest possible action without buzzing)

check out this chart, http://en.wikipedia.org/wiki/Janka_hardness_test
starting from 1200 and above I would say you are in suitable bridge material range so you can see what is available at your local suplier.

Luttgutt - 10-21-2013 at 01:06 PM

Hey! Thanks again guys!

I'll try the mapel.. and let you know.

hans - 7-4-2015 at 05:28 AM

Luttgut! How about the maple floating bridge?