Official Luthiers Forum!

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

_________________
Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

I've seen a sketch of this years ago. Looked silly to me.

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.

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

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

_________________
Wood Creations by Kent A. Bailey
EXCELLENCE IN SCULPTURE, CARVING, LUTHIER, ARCHITECTURAL MILLWORK AND DESIGN

http://www.kabart.com

Dennis: Think Overholzer may have built classicals in this fashion,this was years ago. He has since passed on.

_________________
A person who has never made a mistake has never made anything!!!

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,

_________________
It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

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

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.

_________________
My Facebook Guitar Page

"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

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.

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.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Thanks for the input, everyone.

Dennis

_________________
Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

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.

_________________
David Malicky

Deleted by me. Misunderstood the question.

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.

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..:^)

_________________
"After forty-nine years of violin building, I have decided that the search for a varnish is similar to the fox hunt. The fun is in the hunt."
Jack Batts Maker and Repairer of Fine Violins