Official Luthiers Forum!

http://boingboing.net/2015/03/09/why-vi ... d-the.html

Be sure to click on the link to the MIT paper!

Cause the "H" hole was too hard ! lol Interesting read

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I'll resist mentioning the most obvious.

Alex

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Cool,
I would have guessed the F shape allowed the top to flex a certain way.
It looks way cooler than a circular hole.

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wah
Wah-wah-wah-wah
Wah

I think the published paper (in Proceedings of the Royal Society A) is open source, but if not and you want it, PM me and I'll take care of you.

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Jim Kirby
kirby@udel.edu

That's pretty interesting. As the shape changed over the years, I wonder if the builders consciously sought shapes which increased the length of the perimeter? Seems more likely to me that it was a series of happy accidents--trial and error, with some shapes giving more power than others. And then an eventual adoption of the f-hole shape. Not being a violin maker, I'm more interested in the f-holes as applied to arch top guitars. I know that several of our members have done a great deal of experimentation with sound hole size. I'll be real interested to read subsequent posts on this topic. Thanks for launching it.

Traditional F holes were just not another pretty face.... If you notice the F holes have side points. These side points are often located in the general area of where the bridge needs to be to start to dial in intonation. The inner points have been located by countless makers though the years at the presumed starting location for the bridge.

Remember too that when someone takes all of the strings off say an arch top the bridge is not glued on to the instrument and will not have anything holding it in place. Locating the bridge in the vicinity of the inner F hole points will usually get you pretty close to where the instrument would like the bridge for proper intonation.

As long as your frets are in the right place.............................!!
Tom

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A friend of mine sent the link to a physicist friend of his and he had this to say about the paper:

"I scanned through the paper referenced in the article about why f-shaped
holes are more "efficient." If that is indeed in the Proceedings of the
Royal Society, Isaac Newton must be rolling in his grave. And I hope nobody
shows it to Leo Beranek (age 100) as it would kill him. The math is
inapplicable rubbish. If it seems hard to understand why all the air flow
would be concentrated at the edges of a hole, that's because it's wrong. As
Jon Stewart once said "That sounds so crazy, it might just... be f@#kin'
crazy!" The importance of the f-shape lies not in it's effectiveness as an
acoustic vent, but rather in how it frees up the the sound board for
torsional vibration, made effective by the sound post."

When asked to explain a bit more in simple terms, the physicist then came back with this:

"The simple physics is that the air in the hole (and extending some small distance beyond it) acts as an acoustic mass. It is the mass that controls the flow (the real part of the impedance is negligible) ; it is also the mass that, together with the compliance of the air in the body (effectively increased somewhat because the body is not rigid) determines the Helmholtz resonance. No matter what you do with the shape of the hole, you have to get the mass required to get the right frequency. That determines the flow through the hole. It really is that simple. The problem is very closely analogous to that of a loudspeaker in a vented box ("bass-reflex") which Beranek http://en.wikipedia.org/wiki/Leo_Beranekanalyzed in his landmark 1954 textbook (still "the bible"): Acoustics. After 60 years of intense interest in loudspeaker enclosure design (and the great contributions made by A.N. Thiele) you'd think if there was some magic vent shape, that would have been understood long ago. Indeed one of Thiele's great contributions was to decisively disprove many such "free lunch" myths."

I'm a long way from understanding the math that was presented in the paper but I have to say that the effect of the f hole shape on the way it frees up the sound board makes more sense to me than the way it apparently allows air flow.

Pat

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Its just more fun to say "F-hole"

Maybe they should have started at the beginning of the alphabet?

It's not the shape of an F but the forte musical symbol. It's amazing the exact symbol that means loud in music notation actually increases the volume of the violin. Explain THAT Mr. Peabody!

Yeah, it's the musical symbol for loud, but also it's simply Italian for 'loud'. Maybe some folks should try an L to see if it works in English.