Crossover Nylon String Guitar

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Philip Secrist
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Joined: Tue Mar 06, 2012 5:24 pm

Crossover Nylon String Guitar

Post by Philip Secrist »

First of all, Happy New Year folks! I am taking a risk of offending the true classical guitar builders here, but I have a client that would like a nylon string guitar with a 1-7/8 inch nut width, a soft cutway, and a radiused fretboard. He is not a classical guitar player but a steel-string player. I have built a couple of 650 mm scale length 1937 Houser-sized fan-braced guitars with soft cutaways and bolt-on necks with the standard 2-inch classical nut that sounded great! Do I dare to do this again but with a 1-7/8 inch nut width a 16-inch radius neck (and adjust the string spacing at the bridge)?

I like the body size of the Ramirez 663. 575 mm scale length guitar. Would it be insane to build a similar design with a 1-78 inch nut width a 16-inch radiused neck and 650 mm scale length? Also, has anyone used a Spanish neck modified for a soft cutaway or is it not plausible? Again, I know I am on the edge of Classical guitar construction heresy here but he would like a crossover! Is there a better plan out there that would be a great crossover guitar for this client?

Thanks in advance!! :)
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Barry Daniels
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Location: The Woodlands, Texas

Re: Crossover Nylon String Guitar

Post by Barry Daniels »

No one would be offended by that type of build. Go for it. Sounds like a great idea. The cutaway side could just be glued to the side of the heel block. Kind of a hybrid design that I am sure has been done before.
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Alan Carruth
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Re: Crossover Nylon String Guitar

Post by Alan Carruth »

So long as you don't go much narrower than 1-7/8" at the nut it should be fine.

I've been using a slight radius (say, about 26") on my classicals all along, and nobody says anything, even if they notice it. A totally flat fingerboard teds to go concave over time due to the continued shrinkage of the ebony, and this makes barre chords difficult, at least. A bit of radius helps a lot up front, and should keep it from developing worse problems later.
Gilbert Fredrickson
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Re: Crossover Nylon String Guitar

Post by Gilbert Fredrickson »

The D'Aquisto nylon string jazz guitar is a fine "crossover" guitar.
Philip Secrist
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Joined: Tue Mar 06, 2012 5:24 pm

Re: Crossover Nylon String Guitar

Post by Philip Secrist »

Thank you all. Actually, I did order the plans for the D'Aquisto nylon string jazz guitar recently. I have no experience with an oval soundhole, however. I suppose I could modify it for a round soundhole? Thank you for your helpful responses!
Brent Tobin
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Re: Crossover Nylon String Guitar

Post by Brent Tobin »

I heard from a reputable source many years ago (can't remember just off hand) that the oval soundhole was not just for aesthetics. D'Aquisto believed that if a water hose would shoot a stream of water farther when pulled into an oval, sound would project farther from a guitar with an oval soundhole than a round one.

Brent
Better to have a bottle in front of me than a frontal lobotomy
Philip Secrist
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Joined: Tue Mar 06, 2012 5:24 pm

Re: Crossover Nylon String Guitar

Post by Philip Secrist »

Has anyone played the D'Aquisto nylon string jazz guitar or heard it played? Also, yes, Brent, the reason for the oval soundhole does make sense. I have no experience cutting an oval soundhole, but I suppose I could create an oval template to route the soundhole to, right? ... especially where it is a one-off guitar. Not sure what the best technique is though. Also, what is the best method of routing for the rosette? Any suggestions would be helpful! Thanks!
Alan Carruth
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Re: Crossover Nylon String Guitar

Post by Alan Carruth »

Brent Tobin wrote:
" D'Aquisto believed that if a water hose would shoot a stream of water farther when pulled into an oval, sound would project farther from a guitar with an oval soundhole than a round one."

I caught that talk of his at the GAL convention in Boston back in the '70s. Keep in mind that, although he was a fine craftsman and heir to D'Angelico's knowledge, Jimmy was also, as he said, 'invited out of' high school at the age of 18. His knowledge of physics was rudimentary at best. The hose shoots further because pinching it down restricts the area of the end, which speeds up the flow at the cost of volume: there's less water coming out, but it's moving faster. This is easy to check with a hose and a bucket. 'Projection' in an acoustic sense is a much different thing. He also said, in that talk, that maple was the best wood for flat tops as well as archtops, and rosewood was not good, and that MOP was 'acoustically dead', so that shell inlay, particularly around the edge of the top, would kill the sound.

I mean this as no disparagement of the man. My older brother was similar in many respects, although my dad made him hang in until he graduated high school at 21. My brother put together about one complete English sentence in a day, but if he knew what something was supposed to do, or what it should look like, he could make one. Like Jimmy, all of his know-how was out at the ends of his fingers, in a sense. I always wanted to be somewhere near as good a 'maker' as my brother.

At any rate, given an oval sound hole with the same area as a round one I would expect the sound to be, at least, quite similar so long as the oval is not too narrow. There is a lot of drag in the air flow around the edge of the hole, and since an oval hole with the same area has more edge the drag would be higher. There's also the possibility that the radiation efficiency would be different, but that would require some work to figure out. You do see elliptical speakers from time to time, and there might be some literature on that.

For the few oval sound holes I've made I just cut out a template and used it to mark it out. Once the hole was cut I used a marking gauge to cut the channels, guiding off the edge of the hole. If one were doing this all the time an ellipse trammel would make some sense, but it might be tricky to make one small enough that would be tight and precise.
Philip Secrist
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Re: Crossover Nylon String Guitar

Post by Philip Secrist »

Thanks, Alan. I always appreciate your knowledgeable approach to questions like these! You wrote,

"At any rate, given an oval soundhole with the same area as a round one I would expect the sound to be, at least, quite similar so long as the oval is not too narrow. "

Just considering the soundhole shape and not other potential build or material differences, am I safe to conclude that if I used a round soundhole with the same area as the oval soundhole on the D'Aquisto design, that the sound would be similar? I do want to build a nice crossover guitar, but my client is not fond of the oval soundhole look.
Alan Carruth
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Re: Crossover Nylon String Guitar

Post by Alan Carruth »

I can't give you a hard and fast answer on this: I don't have any data on oval/round sound hole comparisons, so I can't be sure. As far as I know, the effective area and location of the hole are the big variables. Notice 'effective' area; a jagged hole with lot of drag might well act like a smaller opening at some frequencies. One maker talked on-line about using a shotgun to make a sound hole, and there was some discussion about the best range, bore size, shot choice, and choke, but I don't know if anybody actually made the guitar and tried it out. I do know that a 'rose' in the sound hole, either one of the parchment 'layer cake' ones or a carved rose, reduces the power of the 'main air' resonance by a lot, without altering the frequency much. There's a lot of flow through the hole at that frequency, and the 'screen' adds a lot of drag. But that's a long way from an oval hole. I'd expect that, so long as the aspect ratio of the hole is not too large, and the center is in the usual place, the shape won't affect things much. I did have one student who made a guitar-shaped hole, and it doesn't seem to have made a lot of difference in the sound, although it was a lot of extra work.
Gilbert Fredrickson
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Re: Crossover Nylon String Guitar

Post by Gilbert Fredrickson »

There is a really nice oval cutting tool which Jimmy used to cut that sound hole.
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