Body template for my nylon string archtop project

[Brian Evans]

For grins and giggles: Length is 20 3/4, width is 16", it's obviously asymmetric from side to side. Neck will join at the 12th fret on the bass bout and 14th fret on the treble side. The lower bout is slightly asymmetric as well, kind of in a Stratocaster kind of way. I will no doubt fine tune the shape, I may move the tail block up a bit closer to the bridge. It's going to have a fully floating fingerboard, as archtops do, and five fan braces from the neck block all the way down the body, stopping before the recurve. The idea is to engage virtually all of the top. You can see the circle drawn across the upper waist area - the lower bout closely conforms to that circle, the bridge is at the center of the circle, and that is what I hope will be the really live top area. The sound hole will be quasi-circular, in the upper bass bout about where the writing is. No transverse braces at all, back unbraced and carved to be a very responsive live back. Top is adirondack, back is looking like it will be maple if I can find a nice piece. Sides will be maple, and I am toying with laminating them with veneer, if I can figure an effective way to glue it with stuff I have on hand, to keep them stiff.

Brian

[Alan Carruth]

While having the hole up in the corner will lower the 'main air frequency, I don't think that's all that useful. A normal sized hole in the usual pace puts the 'main air' pitch at around G on the low E string, or maybe a bit lower. Since the resonance has some band width this gives you at least a bit of fundamental all the way down to the lowest open string note, and upward from there to more or less the open A string pitch. Moving it up to the corner drops that down to E or F, but doesn't increase the band width, so you lose some fundamental on notes above G or so. In theory you get mre on thelowest note, and notes below that, of course, but unless you play in drop D a lot that's not really much use.

I've also seen some evidence that the hole in the normal position contributes some complexity to the sound, at least on normal Classicals. It's sort of complicated, but along with the top long dipole mode it gives rise to some 'extra' air resonances that can fill in gaps in the usual mode structure. It seems to be one of those instances where cut and try has homed in on a pretty optimal configuration. Granted, there's no way to know whether your archtop will behave in the same way. OTOH, you're already making a lot of changes, so why not stick with at least some of the 'tried and true' stuff?

[Brian Evans]

Probably because there would be three fan braces running right through the sound hole, if it was in the middle. You seem pretty convinced I am wasting my time here. I am basically following the published Benedetto model for a nylon string archtop, from the carving pattern to the bracing pattern to the placement of sound holes. The minor changes to body shape I am making amount to a half inch push in the body outline, and a slightly different upper bout. Considering everyone thinks putting a massive cutaway in the upper bout is just fine, I think my changes are kind of minor.

Thanks for your comments anyway, even if I see them as negative. I respect your experience. Actually, your comment on the main air pitch makes me think I am going in the right direction. The girl this guitar is intended for does a lot of composing and improvising in tunings where the sixth string is tuned down to D.

[Barry Daniels]

Brian, keep in mind that Alan's opinion is backed by a lot of experience. I just see him trying to help prevent you from disappointing results. However, I recommend you build this guitar as you have designed it. The design is not actually radical. And I don't think any guitar build is a waste of time.

[Randolph Rhett]

I think the assumption was you wanted feedback. It's fine if you intended this as a build log. Looking forward to seeing your progress.