Elevated fretboard, effect on sound? Flamenco guitar-- pinging Al Carruth!

[Matthew Lau]

Dear MIMF--especially Al,

A few years ago, I found out about Muriel Anderson and had a bit of a crush.
Then, I met her in person and found out she could be my mom...but was still very impressed with her spirit, musicality, and heart.
I'd promised to build her a guitar.

She asked for a flamenca blanca or a harp guitar--so I chose the flamenca blanca!

I have the wood to build the guitar, and the mentorship of Randall Angella.
The only things is that I'm torn between using my modified Kif Wood bolt-on joint (which has structural advantages, easier to build, more friendly to the player) or a traditional spanish heel? Also, if it's a bolt on, I'm thinking of an elevated fretboard since it'd be super easy to do (and improve upper bout access).

Do you think it'd negatively affect the sound?

If this was a classical guitar or steel string, I'd have no problems.
My understanding of the elevated fretboard is that there is an increase in sustain and power due to the angle of pull (thanks to Al's harp guitar thread).
However, is that a bad thing on a blanca?

I'd love to hear your thoughts before I build the jigs.

-Matt

[Alan Carruth]

IMO the important number is the string height above the soundboard at the bridge. That will affect the tone; on a Flamenco it's generally about 7mm. This both reduces the torque load on the top, allowing it to be made thinner, and also facilitates the golpe.

One issue I could see with a raised fretboard would be that the strings would make an upward angle relative to the top. This is not sufficient to alter the sound, as Humphrey thought, but it does change the string load on the top, and could also make golpe more of a problem. Humphrey went to a sort of lattice brace system on the top, and I'm assuming that was to counter the upward pull of the strings. Adding bracing or making the top thicker for that reason would tend to make the guitar less responsive. I've found a bevel cutaway good for increasing upper fret access without messing up the tone.

[Randolph Rhett]

She's 56! You make it sound like she's some wizened old lady.

[Gordon Bellerose]

56!?
She's just a kid.

[Matthew Lau]

I'm only 33.

Granted, she's aged better than me.

[Matthew Lau]

IMO the important number is the string height above the soundboard at the bridge. That will affect the tone; on a Flamenco it's generally about 7mm. This both reduces the torque load on the top, allowing it to be made thinner, and also facilitates the golpe.

One issue I could see with a raised fretboard would be that the strings would make an upward angle relative to the top. This is not sufficient to alter the sound, as Humphrey thought, but it does change the string load on the top, and could also make golpe more of a problem. Humphrey went to a sort of lattice brace system on the top, and I'm assuming that was to counter the upward pull of the strings. Adding bracing or making the top thicker for that reason would tend to make the guitar less responsive. I've found a bevel cutaway good for increasing upper fret access without messing up the tone.

Hey Al,

Thanks for the fast response!

Do you think it'd be an issue if I had most of the waist/lower bout flat and just had the upper bout curve a la Mitch Lazaar?
This was another idea instead of just slanting the entire soundboard like Humphrey.

[Alan Carruth]

Humphrey was trying for an upward string angle relative to the soundboard of about five degrees, iirc. He assumed that this would be enough to make them work like harp strings. The tests I've done indicate that it's not. It does, however, seem to be enough angle to cause some problems. I'd simply try to keep the string pull more or less parallel to the sound board surface, which should avoid the sorts of troubles you get by pulling upward on the bridge. What the top does elsewhere may not matter so much.

[Matthew Lau]

Thanks!

Btw, are your prices current?
If I wasn't studying/friends with Randy Angella, I'd be budgeting for a Carruth guitar.

[Alan Carruth]

Yes, the guitar prices on my web site are current.