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ikele
11-18-2009, 02:35 PM
Hi,
I was wondering how does bridge placement affect sound in ukes. I thought I could get some insights here!

Specifically I've noticed some concert models have the bridge positioned a bit upwards in the lower bout while others are are a bit down. And then sopranos are even lower, closer to the end of the body.
thanks!

Sven
11-18-2009, 09:33 PM
I make my sopranos wit a 13th fret connection to the body, just in order to get the bridge towards the middle of the soundboard. That is, the large bout, or the close-to-circular area that vibrates the most when you play.

I've built tenors with both 12th and 14th fret connection and the ones with 14th sounds better. But there are more variables between them so I'm not sure which means the most. I'm thinking that a 13th fert connection would work better with the body shape / scale length I'm using.

What you've noticed in concerts I'm not sure, could be a different realtion between scale length and total length (neck+body), or it could be perhaps that most sops have a 12th and some concerts 13 or 14.

Don't know if I make sense. Need coffee.

ATB / Sven

erich@muttcrew.net
11-18-2009, 11:32 PM
:agree:

In the last resort, the position of the bridge/saddle is dictated by the scale length, neck length and body length, as Sven points out.

The difference in sound, depending on where the bridge ends up, has to do with various factors, one of them being that the bridge "pumps" the vibrations into the soundboard. So you want to try and put it in a place where it can do that well, i.e. more in the middle, not too close to the edge, where the top is stiffened by the sides.

Imagine you have this big sheet of aluminum, like a screen door but without screens, just thin aluminim sheeting. OK, now you have a handle that you want to attach to the aluminum sheeting and what you want to do is blow out a candle located 4 feet away from your aluminum door. But you can't open the door. It's glued into the frame all the way around. OK, so now you have to put that handle somewhere. If you want to pump a lot of air as hard as possible, I guess you're going to put it in or near the middle.

It's not as simple as that, because your soundboard probably has a sound hole, it may not be rectangular, it may not be the same thickness across the entire area, it probably has braces to strengthen and stiffen it, and of course you are not trying to blow out candles.

So much for theory, now to the practical lessons learned:

First is a tiny little matchbox instrument we made a while ago. No matter how we tried, we could not get the scale length up to 120 mm, which was what we originally wanted. as that would have placed the bridge much too close to the bottom edge. The neck was already as long as could be so we simply had to go down to 110 mm scale. That put the bridge right where it needed to be.

Second is a cigar box uke made from a cedar box (we replaced the bottom with a piece of mahogany which added strength and also looked and sounded better). After thinning the top a little and glueing everything together we did some tapping and found that the "sweet spots" were not in the middle but closer to the top and bottom. We then did some tests with induced vibrations to confirm this. Anyway, the result was that the bridge ended up much closer to the edge than you would have thought based on aluminum door theory.

Just goes to show you: wood works in mysterious ways.

HTH,
Erich

WhenDogsSing
11-19-2009, 03:53 AM
:agree:

In the last resort, the position of the bridge/saddle is dictated by the scale length, neck length and body length, as Sven points out.

The difference in sound, depending on where the bridge ends up, has to do with various factors, one of them being that the bridge "pumps" the vibrations into the soundboard. So you want to try and put it in a place where it can do that well, i.e. more in the middle, not too close to the edge, where the top is stiffened by the sides.

Imagine you have this big sheet of aluminum, like a screen door but without screens, just thin aluminim sheeting. OK, now you have a handle that you want to attach to the aluminum sheeting and what you want to do is blow out a candle located 4 feet away from your aluminum door. But you can't open the door. It's glued into the frame all the way around. OK, so now you have to put that handle somewhere. If you want to pump a lot of air as hard as possible, I guess you're going to put it in or near the middle.

It's not as simple as that, because your soundboard probably has a sound hole, it may not be rectangular, it may not be the same thickness across the entire area, it probably has braces to strengthen and stiffen it, and of course you are not trying to blow out candles.

So much for theory, now to the practical lessons learned:

First is a tiny little matchbox instrument we made a while ago. No matter how we tried, we could not get the scale length up to 120 mm, which was what we originally wanted. as that would have placed the bridge much too close to the bottom edge. The neck was already as long as could be so we simply had to go down to 110 mm scale. That put the bridge right where it needed to be.

Second is a cigar box uke made from a cedar box (we replaced the bottom with a piece of mahogany which added strength and also looked and sounded better). After thinning the top a little and glueing everything together we did some tapping and found that the "sweet spots" were not in the middle but closer to the top and bottom. We then did some tests with induced vibrations to confirm this. Anyway, the result was that the bridge ended up much closer to the edge than you would have thought based on aluminum door theory.

Just goes to show you: wood works in mysterious ways.

HTH,
Erich

Interesting discussion...Thanks...:D

ikele
11-19-2009, 10:19 AM
Very interesting indeed, nice aluminum sheet analogy!
thanks for the input Erich and Sven!

I also was thinking that 'in theory' the middle of the lower bout should be the right place for the bridge, so whenever I see a bridge closer to the soundhole or to the butt I wonder how it would sound...

etkre
11-19-2009, 12:02 PM
This may have no relevance at all, but for whatever it's worth...

Drums work on the air pump principle, and there actually is a "sweet spot" to hit them to get the most volume and fullest tone. Hitting the drum dead center produces a muffled sound with pronounced bass. Hit near the rim and you'll get more "ping" and treble. The "sweet spot" lies somewhere mid-radius. This becomes extremely apparent while playing cross-stick (clicking the rim while keeping the butt of the stick against the skin), as you'll hear a major increase in volume. Drums do have a sound hole of sorts, it's located on the side of the shell.

Timbuck
11-19-2009, 12:05 PM
This may have no relevance at all, but for whatever it's worth...

Drums work on the air pump principle, and there actually is a "sweet spot" to hit them to get the most volume and fullest tone. Hitting the drum dead center produces a muffled sound with pronounced bass. Hit near the rim and you'll get more "ping" and treble. The "sweet spot" lies somewhere mid-radius. This becomes extremely apparent while playing cross-stick (clicking the rim while keeping the butt of the stick against the skin), as you'll hear a major increase in volume. Drums do have a sound hole of sorts, it's located on the side of the shell.
Very few banjo's and banjo uke's have the bridge in the centre of the skin.

Pete Howlett
11-19-2009, 12:17 PM
Oh dear...the dreaded sweet spot debate! Personally i don't think it matters so long as it is not at the extremes.

etkre
11-19-2009, 01:15 PM
Very few banjo's and banjo uke's have the bridge in the centre of the skin.

Exactly. Somewhere mid-radius, just like drumming.


Oh dear...the dreaded sweet spot debate! Personally i don't think it matters so long as it is not at the extremes.

I'd imagine it's certainly less pronounced in ukuleles. And it if it does have an effect, the quality of the sound would be in the ears of the beholder. Baroque guitars have the bridge very close to the end, and I find their sound quite charming.

ukantor
11-19-2009, 01:18 PM
Bridge placement certainly does have an effect on the sound a uke produces, but I wouldn't agree that one place is necessarily better than another. Too close to the edge is bad, but the range that can give a good result is quite wide.

There are many factors involved, and they all contribute to give the finished instrument its individual sound.

I haven't made enough ukes to be able to predict what mine will sound like. I just do the best I can, and breathe a sigh of relief when they turn out sounding good.

John Colter.

RonS
11-19-2009, 02:46 PM
Oh dear...the dreaded sweet spot debate! Personally i don't think it matters so long as it is not at the extremes.

Of course it matters, I'm surprised you would think that it doesn't.

Pete Howlett
11-19-2009, 10:52 PM
Ron - it doesn't on a ukulele. Obviously if the bridge is so close to the edge of the instrument it fails to drive the front then it does. However in my experience it doesn't matter all that much and I am pretty much excerised by this often spurious old chestnut. I would guarantee on a blind test you could not pick out a 12 fret to the body from a 14 fret, 'classic' concert from a Ditson concert. There just isn't enough subtlety in the instrument to command it. Now a guitar - you might have something there. I can nearly always 'hear' a 12 fret to the body instrument - more fundamentals and stuff.

Sven
11-20-2009, 01:41 AM
I suspect that Pete is right, and the drum analogy also makes sense. But there is another really good reason for my 13th fret connection.

It is... well... you know, 13 is... a rock number. It is sometimes used in tattoos even.

Kidding aside, it works great for me and I like the slightly longer neck.

RonS
11-20-2009, 07:52 AM
Ron - it doesn't on a ukulele. Obviously if the bridge is so close to the edge of the instrument it fails to drive the front then it does.

:)

So, are we talking degrees here?

Obviously this wouldn't work either
http://www.woodturnersresource.com/Images/UKULELE-2.jpg

Or is the "sweet spot" a large enough area that a 3/8" (10mm) movement forward or backward from the "standard location" isn't going to make much of a difference. At some point where one places the bridge will change the sound.

:)