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Ok now my top is Englemann Spruce and it's average thickness is around .130. I will further remove more material with a sander once everything is assembled. I cut braces out of Sitka spruce and the average width of the braces are about 9mm as called for on the plans, I cut out preliminary scallops but will finish them later on. Now I can hear a clear, but a little high pitched ringing sound when I tap the lower bout, so what do I aim for? do I aim for a lower pitched ringing sound when I tap it? This is for a dread...

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

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Tap tuning by ear is a very subjective thing. What you may think is "high pitched", may be a deep drone to another tester. Only doing this over and over will give you your own point of reference. I think anyone honest will admit there is a lot of voodoo in tap tuning. For what it is worth...

Alan Carruth, a luthier in New Hampshire, has developed a pseudo-scientific approach I have used with great success. It involves a signal generator (in my case a laptop with appropriate software), a large speaker (a practice amp turned on its side), and tea leaves.

Others try to shoot for a specific note by using a high quality guitar tuner. Richard Hoover of Santa Cruz Guitars showed me to hold the top by suspending it on the thick pad of my thumb and "feeling" the tap. He claimed the tone didn't matter as much as feeling a deep resonance on my fingertip. Of course, if I didn't feel the resonance, he didn't actually tell me what to do to get there . I guess you got to have some trade secrets.

Finally, I noticed that the tone I get on a loose plate is not too far off from what it is when the box is assembled and the pressure of the strings is on. Hardly scientific, but if the tone is much sharper than I get from holding a guitar I like, muting the strings and tapping on the top, I probably won't like the sound of the finished guitar.

Good luck!

rlrhett wrote:
"Alan Carruth, a luthier in New Hampshire, has developed a pseudo-scientific approach I have used with great success."

'Technical' approach? Please?

Lots of people have contributed to the development of this Chladni method, from Fred Dickens in the '70s to Mark Blanchard now. My only claims are that I was one of the first to try it on steel string guitars (as far as I know), and I've been willing to write articles and such about it.

It's hard to do good science on anything as subjective as guitar sound, but we're chipping away at it. For now we can say the this method seems to work at least as well as any other in obtaining consistent results, and it's easier to communicate than some other methods. As has been pointed out, there's always a subjective judgement when you talk about a 'high' or 'low' tone, and what exactly is 'clear', and when does the 'fundamental go away'? If I show you a picture of a pattern, and tell you it occured at 330 Hz, that's pretty unequivocal. We can argue about what it 'means', or why it works, but the pattern itself is real data, and can at least potentially be duplicated on another guitar.