Acoustic Guitar Construction

Dave Bagwill wrote:....especially with a cantilevered neck....

Pretty well all necks are cantilevered, so Dave, are you referring to an adjustable neck (what I often call a tilt neck) or something else? I know Rick does his "gapped hardware" neck joint. Are you referring to that?

I should have used a more generic term - any system that keeps the fretboard off the top. I'm not concerned right now about the string angle to the bridge, just the upper bout concept.
I just happened across Turner's picture doing a web search.

Thanks Trevor for your input that your books reflect what you build and what you know relative to the basics. As I said before, they are worth the money. They, along with the Somogyi books, are the ones I re-read the most often.

Dave Bagwill wrote:I should have used a more generic term - any system that keeps the fretboard off the top.

Ah, OK. You mean the fretboard extension is cantilevered. There's lots of permutations on that theme, from the Stauffer tilt-neck to the Humphrey Millennium. My tilt neck, pic above, is a permutation on the Stauffer theme. Doolin does an interesting adjustable neck, too.

John Link wrote:Thanks Trevor for your input that your books reflect what you build and what you know relative to the basics. As I said before, they are worth the money.

No worries, John. I'm pleased you're enjoying them and thanks for the write-up.

As long as this topic has become active again, I thought I would post a tidbit from the "design" volume every now and then. The math can get tedious even to one who likes math (such as myself), but it shows that the authors did a great deal of work to draw relevant studies from a range of well established sources into what affects guitar design. It is way better, in my view, than appealing to vague theories, of which there are many in the endeavor we all love so much.

Tidbit: They cite basic facts about how we hear that affect strategies for designing guitars with appealing sounds. Hearing borders on an illusion when comparing it to the results empirical measurement yields, they say and I believe them. I have known for a long time that (up to a point) loudness makes sounds otherwise the same as softer versions more appealing as long as it is within a certain range of decibels. The book delves into the phenomenon of loudness as it pertains to guitars and finds that the initial attack of a note, coupled with the existence of multiple harmonics above a certain order, leads to the aural impression of satisfying loudness. They suggest lower mass soundboards with adequate flex - but not excessive - are a way to achieve this. Such a soundboard moves a reasonable amount of air and starts up quickly. BINGO. This makes sense whether one follows the math and physics or not, and is noted in plain English. It is also backed up with an analysis of what happens when a single note from a plucked string is recorded and then played backwards, that is, without the initial attack that our brains use to form the impression of loudness. Even though that initial attack is eventually heard, because it comes at the wrong end of the sensation, the note is not perceived as loud. This despite the fact an equal amount of air has been moved during playback of both versions of the sound. I have not done it yet, but intend to follow up with a recording from one of my instruments to experience this for myself. I am not doing this out of doubt, rather just because I want the actual experience. I doubt I ever would have thought to try this without the stimulus from the book.

And so, there is practical info in the design section. If you want appealing loudness, work on getting a faster response to the plucked note. Use their suggestions or develop your own. There is more to it than just decibels.

When Rienk said earlier his brain hurts when reading the design volume I understand. Yet there are a lot of summaries of the nature I detailed above that wrap it all up in a way that I have not seen before. I might post a few others as I re-read the design volume.

I just finished reading both volumes cover to cover. My brain is tired, but in a good way. :-)

The cost of these volumes is comparable to (possibly less than) what one would pay for college textbooks of similar size and quality. I consider these top-rate books and well worth the price. To put it another way, even if you only plan to build one guitar for yourself I think that by reading these books you'll be likely to increase its value (in terms of sound and playability) by more than the cost of the books.

The Design volume is math-heavy, especially in the earlier chapters, and it may be a bit much for someone without an engineering background. I'm an electrical engineer and software developer specializing in digital signal processing so the math was not a problem for me, but because I'm impatient I just skimmed most of the derivations to get to the end results. The derivations need to be there in order to substantiate the conclusions, but you can certainly apply the resulting formulas without following every step. You can also just read the section summaries if you want to skip the math entirely, although it's useful to understand the theory behind the conclusions and how to apply them to other designs. The later sections are less math-intensive and should be easy enough for most people to follow. Personally I felt the most valuable chapters were about frequency response and how to affect it with design decisions and adjustments after construction, and the authors' approaches to experimentally measuring wood characteristics and guitar frequency response should be doable by anyone with a computer and willingness to learn/use readily available software. If you can tell when a guitar top is "optimal" by tapping it and listening, well good for you but I can't and a frequency response curve is more helpful to me.

The Build volume is much more hands-on and the photographs are very well done. It does presume a degree of woodworking experience and might not be a good first book for someone just starting out, but it doesn't presume experience with building guitars and I found a lot of really useful information in it. I did not have the sense that the authors were holding back essential information; I don't expect them to tell us everything they know in a finite-sized book but they seem to be genuinely trying to convey as much value as practical in the space available. Like the Design volume it uses metric units throughout, except in cases like string gauges where there's a precedent for using inches. That's fine by me as I'm happy to use metric units anyway, but if you're accustomed to working in inches then be prepared to adjust your methods or do a lot of conversions.

Overall I feel I've gotten more than my money's worth and I'd recommend these to anyone serious about designing and building guitars with an engineering approach. If you're really not into creating guitars that way and prefer a more intuitive (non-numerical) way of thinking then these might not be the best books for you, but I think they have a lot to offer even for those who prefer a less analytical approach.