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I'm drawing up plans for an ABG. OK, Before everyone tells me they don't work, I know that, but I'd like to have a go anyway. I've made 3 Solid-body basses and a semi-solid sort of 'Rick Turner Tribute' bass so now I want to make an acoustic. In fact I have a rather nice ABG (a Furch) and I want to see if I can Make something as good or better.
So my question is this. If I make the top and back a cylindrical form rather than the usual spherical, what radius should I use? I know some people have done this in the past. I believe Mr Klepper did and so did Stefan Sobell and the Howe-Orme instruments had a 'sort-of' cylindrical front.
Dores anyone have any opinions?

bump...I see this has gone a couple of days...

Dave-
That's a pretty unusual question, and I don't have a clue. However, you could try dropping a pm directly to Rick Turner (if you haven't done so already)- I think he's got a collection of Howe-Orme instruments, and might have some ideas. And, of course, he knows a thing or two about basses.
Most builders are quite helpful and open; my recommendation would be drop an email directly via the OLF or the builder's website and see what happens. Some folks type faster than others, so specific questions are more likely to get an answer.

Cylindrical form doesn't appeal to me much because of the added problems in binding, but it's an interesting idea. Of course, with an acoustic bass, I suppose the bridge is 'way down' the lower bout, so the usual 'domed' top geometry could be tricky.

Cheers
John

BUMP!

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DES - Shepherd, MI

I really like the cylindrical top and back, and may return to that form after having gone spherical. For the top I plan to use a 25 foot radius and for the back a 15 foot radius but may soften that to a 20 foot radius.

John

"Mr. Klepper"???

Either my father secretly built guitars, or you must think I'm a really old fart.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Last night I saw someone playing a mexican mariachi style acoustic bass at the bar.  It had a huge body depth, maybe 12" at the deepest point and the two halves of the back met at a ridge along the joint.  It looked like the two halves of the back were bent on an iron before being jointed.  I would estimate that the heal, and neck block were about 8", so a mega radiused back. Anyway it was  a really big guitar.  Maybe this is a way to get the helmholtz resonance down to the bass frequencies?

A guitarron (not an ABG) has enough air in the box to actually resonate at bass frequencies. An ABG does not. You could get the "helmholz" (A,O) frequency of an ABG into the bass range (as low as you like, really) by making the soundhole small enough, and/or putting a duct on it. But then the volume of the box's bass would be very low, and it's bandwidth very narrow. Which is more or less why ABG's do not work.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

"Mr. Klepper"???

Treat it as a mark of respect Howard.

I make instruments for the fun of it and I don't like making the same thing twice so part of the fun is putting the strings on and finding out what it sounds like. The ABG I have, has an under-saddle pickup so I can play it amplified if I need to but its nice to be able to plunk along to a CD to practice tunes without having to drag out the amp and plug everything in.
I took the bass to England on holiday with a French pal and we played in a few pub sessions. People said the bass sounded good and my pal was playing a pretty dang noisy cajun accordion!

Here is a picture of the lower bout profile of a Stefan Sobel guitar


I added a grid of 1 inch squares to it.  Sorry for the poor quality.
I did some measurements and I must be nuts???
Top 8 foot radius
Bottom 4 foot radius
The reason I did all this is... like some of you, I'd like to try building a guitar like this someday.  It would be interesting to see the top bracing he uses on this.

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Rick Hubka
Chemainus BC Canada

Rick, thanks for the information, that's really interesting. And I don't think you're nuts! I have heard that Stefan Sobell uses a very tight curve on the backs of his guitars
I sent him an E-mail asking if he could give me any advice but, as yet, I haven't had an answer.

Frankie Montuoro may be able to help you with this, too. He has restored many Larson instruments, which had a pronounced cylinder form, although I don't know if they ever made ABGs. He is also a super nice fellow and loves to talk about these instrument.

http://www.montuoroguitars.com/

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck