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I think it likely that 'high' stress levels can cut down on the sound. I've been doing some tests that involve using a tall saddle to raise the strings 18mm off the top of a classical guitar (don't try this at home!), and it does seem to be a bit harder to move the top when it's set up like that. Of course, it's also hard to sort out all of the changes in the forces on the top when you make that sort of change, and there's a lot more of that experiment to do, so don't take that as gospel.

The question is, what's 'high' stress? Compared to what I just did to my poor test mule, doming the top is nothing. I sure don't want the job of trying to figure out just where 'normal' stress ends and 'high' stress begins.

Doming the top has one really useful effect: it makes it much less likely to crack when the humidity drops. Here in 'Guitar Hell' (New England), that's a biggie, and I'm going to keep doing my tops even if it does cost a little sound.

Just reading Alan's reply has reminded me to mention the fact that my "theory" only applies to a bridge & seperate tailpiece style of instrument (Archtoped family of instruments & Selmers e.t.c,being the styles of instrument I build) where the strings energy is driving the soundboard up & down through a floating bridge as opposed to a fixed bridge style where the bridge is being rotated/rocked by the strings. I could see that if you have too much preload on the top plate of a fixed bridge, this would have the ability to hinder the bridge in it's action of driving the plate as Alan refers to in the first part of his post.

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Nick Oliver

http://www.oliver-guitars.com

Do you want to know what I think? No?

I think we should shoot the next person who starts out a steel string guitar question with "that's what Stradivarius did".

Violins are hardly relevant to anything about guitars.

Old Art Overholtzer sure made a bad name for himself, but in teaching about the "stress free" guitar, he emphasized excellent joinery, making the parts fit without forcing them together. I think that is a lesson every novice should learn, and practice.

In arching a top or back, not much stress is built in. Once sides are bent, I like them to be at rest in the forms. Don't you profile the sides before gluing on the top and back? Don't you shape the bottom of the bridge to match the top?
These are all stress-reducing practices.

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Thank you for that, Alan. I've let go of the notion that Overholtzer's book planted in me years ago.

Jim

Nick Oliver wrote:
"....my "theory" only applies to a bridge & seperate tailpiece style of instrument ....."

Some years ago I made archtops with as 'hook' style tailpieces. Rather than using a tail gut to take the string tension down to the end pin the tailpiece itself was 'L' shaped, with the lower arm hooking over the end of the guitar. There was a gut, but it only held the tailpiece from popping off. With this setup it's pretty easy to vary the down force on the bridge: the strings will make a line toward the pivot point on the side when they leave the saddle. You can move pivot point up and down, thus changing the break angle, and observe the changes in tone.

I found that I got more sound from low downbearing angles, and, in particular, when I went beyond a certain point it would kill the tone. I was using the hook tailpiece to get more break angle, becuase I had heard that more downbearing would equal more sound. T'ain't so. There probably is a minimum break angle, below which you loose sound, and when the angle is low it's not very sensitive to changes in any case. Still, since then I've used normal tailpieces, more or less, and stayed with break angles of less than ten degrees or so. This has the added benefit of reducing the down stress on the top.

David Newton writes:
"Violins are hardly relevant to anything about guitars."

Agreed.

Thanks Alan, some good info there based on your experience/findings, which to me is more valid than theory. I would love to be able to build a guitar to try each theory I have but unfortunately economics prevent me from doing so. So your experiences are much appreciated and thanks for passing on your findings.
Bob Benedetto had a section (as an 'extra') on his DVD set that also tackled the string break angle topic by placing the anchor point at various different distances from the bridge. Whilst it showed some interesting results & similar to yours in respect that more downbearing = more volume wasn't so, the display was set up on a solid beam and so never related in a true sense back to a carved soundboard or resonating plate and how it would react, so your experiment is a valuable result.

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Nick Oliver

http://www.oliver-guitars.com