Acoustic Bridge Types ...

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CNCWorksNZ
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Acoustic Bridge Types ...

Post by CNCWorksNZ » Sat Nov 09, 2019 2:26 pm

.
A query that may solicit some in-depth Comments, I hope.

I'm building a Baritone Ukulele at present, (Instrument #13), and have noted that there are two distinct methods of constructing a Bridge for them. (Thanks Graeme McDonald for the Ukulele Book)!

1/ Classical Style, with the Strings tied off at the Bridge ...
2/ String Through - where the Strings are terminated on the inside of the SoundBoard with a Knot.
I can see that there is better Mechanical Integrity with the String-through method, but what are the differences in Sound?
Let's assume two identical Instruments but each with the differing Bridge style. What would the differences be? ... and why?

3/ Actually, there is a 3rd method, and that is to tie off the Strings at the Tail of the Instrument. Thoughts on this method would be appreciated also.

Murray.

seeaxe
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Re: Acoustic Bridge Types ...

Post by seeaxe » Sat Nov 09, 2019 4:31 pm

Ill be interested to hear what others say and I'll qualify my comments by saying I have made a sum total of 2 ukulele bridges and have never tested anything to do with this question...but imo

Assuming the bridge is securely fastened to the soundboard for either of the first two options, then it should not make any difference.
It wont improve the sound to fasten through the soundboard as it will (probably/possibly) require a stronger/thicker bridge plate to handle the high pressure at the knot.

I don't recall seeing any classical guitars fixing through the top and they have 6 strings and more tension (I think) than a uke, so why would you fix through when that is presumably harder to restring.

my 2c fwiw .....possibly less than 2c!!

Cheers
Richard
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Allen
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Re: Acoustic Bridge Types ...

Post by Allen » Sat Nov 09, 2019 5:34 pm

Can't say you'd ever be able to determine a difference in sound.

I far prefer the string through bridge. Can be with bridge pins or without. I like without. Nice clean look and it's actually dead easy to restring. But it's surprising how some people are confused by the process. I've had a few music shops call me up and ask how to do it when clients have brought them in for a new set.
Allen R. McFarlen
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kiwigeo
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Re: Acoustic Bridge Types ...

Post by kiwigeo » Sat Nov 09, 2019 6:28 pm

Arguments for a tailpiece.....shallower break angle over saddle, removes risk of bridge shearing off...less loading of lower bout (no bridge mass). But I don't think these factors really apply for a uke. My ten cents worth anyway.
Martin

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Mark McLean
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Re: Acoustic Bridge Types ...

Post by Mark McLean » Sun Nov 10, 2019 9:56 am

The physical forces are different to some degree (at least in my imagination). In the string through method the strings are pulling up on the soundboard, while pushing down on the bridge (which could improve their coupling). In the tie-down method the strings are putting a rotational force on the bridge, and trying to pull it off the soundboard.

But what would I know, I have never built a single uke - so you can have that for free.

CNCWorksNZ
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Re: Acoustic Bridge Types ...

Post by CNCWorksNZ » Sun Nov 10, 2019 1:02 pm

'
Thanks for the thoughts Guys. They tend to follow my train of thinking as well. Maybe I should not have put 'Ukulele' in my previous Post, as I assume that the Mechanics would apply to any Stringed Instrument with these types of Bridges.

Now ... about the difference with the 'Tailpiece' type, where we have a downforce on the Bridge with no rotational torque ... Thoughts?

Murray.

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Re: Acoustic Bridge Types ...

Post by blackalex1952 » Sun Nov 10, 2019 1:26 pm

The theory as I understand it: if the strings are tied off at the tail of a guitar or uke, then the instrument would fall into the archtop category, where the bridge is restricted to a verticlal up and down motion, as distinct to a combination of vertical and rocking motion for a bridge which has the strings anchored at the bridge. These two designs sound completely different and it is my opinion that the archtop design is unsuitable for a uke. With an archtop design, the break angle over the bridge needs to be around 12 degrees which would require modification to the design in order to achieve this, eg a bend in the soundboard (think of the old shellback mandolin , Selmer Maccaferri guitar and oud/lute style of instrument) or arched top style carving. The design won't work for flat soundboards, and gives a very different sound to the instrument. The archtop design favours long dipole and tripole modes of vibration. A fixed bridge moves in an entirely different way, the rocking motion when a bridge couples with the internal bracing of a guitar or uke activates the internal bracing where the ends of the bridge sit over the braces. This gives a very different sound to the sound of an arch top style instrument. I have seen and heard a few ukeleles which are of the archtop design. They are quiet and I have yet to hear one which sounds good. It might be something to do with the size of the instruments and the lack of energy needed from the nylon strings to drive such a design. The flat top uke can have a very light soundboard, which allows for a bright and projection sound due to the low inertia that a light soundboard has. If I was asked to make an archtop style ukelele, I would go for the traditional Italian bent soundboard or lute/ oud with ladder bracing in order to get the bridge angle right at the same time as keeping the soundboard thin enough to project the sound. But I doubt that the design would sound like a ukelele. As to the question regarding strings tied off at the bridge vs through the soundboard, I don't thing it would perceivably affect the tone. A good jig to accurately and simply construct the bridge, whatever way the strings attach would be the thing to focus on developing, both for accuracy and repeatability.
Cheers! Ross
"Everything I say on the topic is based solely upon inexperience and assumption!"

CNCWorksNZ
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Re: Acoustic Bridge Types ...

Post by CNCWorksNZ » Sun Nov 10, 2019 4:10 pm

'
Thank you Ross, this is the conversation that I was trying to initiate ...

So far, I'm more persuaded to the 'Tied through Bridge' for better Mechanical Integrity.

Murray.

RodC
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Re: Acoustic Bridge Types ...

Post by RodC » Mon Nov 11, 2019 5:18 pm

This is a quite useful and interesting discussion as I'm thinking of making an arch-top Uke to match my [not quite yet finished] arch-top.
I still need to do some more research and haven't decided on string type or size yet.
From reading the comments above, it sounds like the break angle will be a little bit important. :-)

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