Official Luthiers Forum!

With the ideas imparted on John Mayes' Advanced Voicing DVD fresh in my mind, and knowing that many of you thin the perimeter of the top on the lower bout after glueing it to sides, I'm wondering how you reconcile the two procedures. I know there are probably old threads dealing with each topic in isolation, but I'd like to hear some ideas about how each process influences the other.

1. For those of you who thin the soundboard edges, do you leave the top a little tighter when voicing it to compensate for this subsequent thinning?
2. When you thin the soundboard perimeter, are you concentrating more on it's deflection, the overall tap tone, or a combination of both? How do you know when you've finished?
3. How far inboard of the soundboard edge does this thinning begin and how would that influence the result?

I know I'll get some thought-provoking and informed responses, so thanks in advance!

Cheers
Pete

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Cheers
Pete

What is working well for me right now is to leave it a tad tight to my ear when voicing the braces and tapering the outer 3-4" of the lower bout with an air sander after the top is glued on but before binding. I tap the lower bout while thinning and try to hear the tone become more resonant and feel it vibrate back against my finger. The edge usually winds up around .085-.090 in my case. I've done this on the last 16 or 17 and they definitely sound more like what I am after. I think it is a very valuable tool in the voicing process and becomes more valuable the more experience you gain. I still have much to learn.
One caution, if you thin to .085 and use herringbone or a wide Abalone purfling it's easy to rout off the remaining top leaving only a small amount still attached to the kerfed lining. That makes me nervous. I usually just use a single .060 bwb purfling on a top that has been voiced this way. I've always wondered if herringbone used at full thickness didn't actually relieve the edges of the top a little without any further thinning and have some subtle effect on the tone.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I agree with Terry and do much the same thing.

In addition, while thinning the perimeter I am looking for a very slight "give" in the bridge plate area when pressed with my thumb. If you want your top to move it needs to be able to move... YMWYTMV (your mileage with your thumb may vary)

Dan Roberts(former head luthier at SCGC) has posted before on the SCGC forum to the effect that the reason the PW(forward shifted/scalloped) models gets thin purfling strip is because the wider herringbone that they normally use on the standard models (like the OM) would cause the top to be too loose and result in loosing definition in the sound.

Here's another post I found by him...
"The VA is also advanced X and scalloped however it is mahogany and has herringbone purfling. The mahogany gives it more clarity and brightens the tone balancing the rich fullness of the bracing configuration, and making the bass slightly less boomy. The deeper cut purfling isolates the top and gives it better string to string separation as well as making it slightly more responsive to a light attack.

On the rosewood PW the tone could easily get muddy, so to balance this as well as allow us to make it slightly cheaper we use a single strip of purfling on the top. This tightens up the tone slightly but also makes it slightly less responsive than the VA, which has the deeply cut herringbone purfling."

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Jeremy Douglas