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Upper bout deeper than lower bout? Anyone tried it?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=24599		 Page 1 of 1
Author:  Dennis Leahy [ Sun Nov 15, 2009 11:13 am ]
Post subject:  Upper bout deeper than lower bout? Anyone tried it?
Tradition has the lower bout deeper than the upper bout. [pure conjecture] I suspect that long ago someone discovered there was an acoustic advantage in having the top and back of the guitar non-parallel - long before anyone understood "standing waves", they stumbled on a way to prevent them.[/pure conjecture]

Luthiers build thin bodied acoustics, wedged bodies, and arm bevels - all because the picking/strumming arm of the player is draped over the lower bout. So, how about reversing tradition, and making the upper bout deeper and the lower bout shallower. The upper bout might need to be quite deep to make up for the lost internal volume of making the lower bout shallower, but from a player's perspective a deeper upper bout would not be terribly noticeable, and a shallower lower bout would certainly be more comfortable.

So, has this been done? (Almost everything imaginable seems top have been already tried on a guitar, if you're willing to look hard enough.)

Good idea? Bad idea? Anyone with a good sense of acoustic modeling from the conceptual (like maybe Al Carruth) have a clue as to how the overall timbre would be affected - assuming it could be worked out so that the internal volume was the same as another guitar of the same outline shape for comparison?

Dennis
Author:  wbergman [ Sun Nov 15, 2009 11:16 am ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I've seen a sketch of this years ago. Looked silly to me.
Author:  Dave White [ Sun Nov 15, 2009 11:47 am ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Dennis,

I could be wrong but I seem to remember that Sylvan Wells made one like this a year or two ago - can't see it on his website now though.
Author:  Bailey [ Sun Nov 15, 2009 11:52 am ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I actually saw and played a steel string guitar 20+ years ago that was about 3 in. deep along the top of the lower bout (where the arm drapes). It sounded and played great. It was, as I remember quite rounded in the back and definitely wider along the bottom from front to back. It was wood, not a preformed molded back like an Ovation. I don't recall, or probably didn't ask who the maker might have been (I wasn't into the Luthier thing at the time) but it was at a recording session with the Nitty Gritty Dirt Band and maybe I can throw out some feelers with old friends to see if anyone remembers.
Kent
Author:  Tom West [ Sun Nov 15, 2009 12:15 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Dennis: Think Overholzer may have built classicals in this fashion,this was years ago. He has since passed on.
Author:  Jon L. Nixon [ Sun Nov 15, 2009 2:19 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Overholtzer's book said that building a body with the upper bout deeper than the lower would cause it to behave like a megaphone and be louder than the usual method,
Author:  JohnAbercrombie [ Sun Nov 15, 2009 2:52 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
westca wrote:
Dennis: Think Overholzer may have built classicals in this fashion,this was years ago. He has since passed on.

Dennis-
You are correct- he mentions this in his book, with a picture of a partially-completed guitar.
Though some of his ideas about theory were 'interesting' (to be polite) and he did tend to be a bit 'sure of himself' on many things, his book is good reading. When it was published, it seemed like quite an 'industrial' approach to building- how times have changed!

I think that 'reverse wedge' guitars look 'funny', and I can't see how they would be more comfortable to play. the idea certainly hasn't 'caught on'.

Cheers
John
Author:  Rod True [ Sun Nov 15, 2009 3:22 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I too think it would look odd. The biggest thing I think hindering the idea is how it would be to hold. Say you want to play this guitar standing up, using a strap. The thinner lower bout would sit against your gut and the upper bout, being thicker would push the neck away from you. Bar chords would really be tough this way.
Author:  Alan Carruth [ Sun Nov 15, 2009 3:40 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I think comfort has as much to do with the directino of the taper as anything. I'll probably get flamed for saying it, but several women over the years have mentioned that a too-deep upper bout can be uncomfortable for them from time to time. I'll note that in the late 19th century, when Martin was setting the highly tapered body in stone, guitar was considered a suitable instrument for young ladies who did not have a piano.
Author:  Todd Rose [ Sun Nov 15, 2009 8:25 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Dennis, I made my first guitar the way you describe, thinking the same thoughts as you about it. It's not more comfortable, though. It's not significantly worse, either. People who pick up the guitar and play it without really looking at it first don't even notice. Surprising though it may seem, it just doesn't make much difference at all. But it's definitely not an improvement. If anything, I'd say it's slightly less ergonomic. It's possible that for certain individuals, depending on the way they hold the guitar, it could be a bit better, but not for most people.

It would be hard to explain in words why it's not an improvement. I'd suggest making a mock-up out of cardboard or styrofoam and check it out for yourself. I think you'll see.

As for sound, I doubt it makes much difference.
Author:  Dennis Leahy [ Sun Nov 15, 2009 8:36 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Thanks for the input, everyone.

Dennis
Author:  David Malicky [ Sun Nov 15, 2009 9:39 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
There is this post on mimf, discussed the effect of tapered vs. constant height sides:
http://www.mimf.com/library/tapered_sides.htm

We build all our student guitars at constant body height (4 1/8" inside dimension) and have not heard any unusual resonances. Using 13,500 in/s as speed of sound, a half-wave will fit a rigid 4 1/8" space at about 1640 Hz. But tap testing on our bodies shows no unusually strong or consistent peaks anywhere between 700 Hz and 4000 Hz. So if it's resonating, it appears to be no more important than the higher-order body modes. Pretty curious.
Author:  MRS [ Sun Nov 15, 2009 11:32 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
Deleted by me. Misunderstood the question.
Author:  Alan Carruth [ Mon Nov 16, 2009 1:50 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I've seen that peak, at about 1600 Hz, in the output spectra of guitars. It's pretty consistently 'there', but not too strong usually, and there's generally lots of other stuff going on to mask it. This is the 'resonant continuum' area, where ther'es so much coupling that it's difficult to attribute anything directly to any particular cause: I'm assuming that peak is mostly from the air resonance between the top and back, but it contributes to other stuff, and is influenced by other stuff as well.
Author:  ChuckH [ Wed Nov 18, 2009 12:34 pm ]
Post subject:  Re: Upper bout deeper than lower bout? Anyone tried it?
I went to McPherson Guitar factory in Sparta, WI last year and John Mayes was playing a guitar like you described that he called a reverse something or other. . . lol

Anyway, it looked a little silly but it sure sounded nice. Maybe it was just his playing..:^)
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