Acoustic Guitar Construction

I would be the amatuer builder who built one guitar that I am not happy with. It's my 2nd kit build Walnut / maple/ Bearclaw spruce (see Jack's number 2). I made the mistake of swapping out the sound board that Ken included for a "fancy" looking Bearclaw spruce top from LMI. (I thinned it to .110).

The guitar came out beautiful. I remember when building it that the top spouded like cardboard when i tapped on it. Being a new builder I didn't think much of it. Turns out the top Ken provided Sitka with straight grain was used on my Number three 000-14 (Eagle sound port guitar) and its my everyday guitar ,sounds awesome with great sustain and clarity, everyone that plays it loves it.

I should have stuck with what Ken sent in the Kit as my buddy built a Dread from Ken and it sounds and plays great.

This dread with the bearclaw top sits under the bed in a case unused and eveyone that plays it claims it to sound OK, or fair. To me its poor not very good, No sustain , no Clarity just muddy ,plain Blahhh. I tried three different sets of strings to no avail.

I spoke with Ken concerning this and he advised thinning the perimiter of the lower bout 1/16'' before deciding to remove the top and start over. I take this as good advise as it could save me alot of work if I have to remove and replace the top.

Any other recomendations or stories about poor sounding projects are welcome.

Thanks , Jack

What are some general guidelines for tuning the body?

For instance, when the box is closed, what is a favorable range of tones between the back tone and the top?
What is a good body resonance to shoot for?
Does the neck have to be attached to get the best readings?
I guess I need a book or something, but any help would be appreciated.

Dave Bagwill wrote:What are some general guidelines for tuning the body?

For instance, when the box is closed, what is a favorable range of tones between the back tone and the top?
What is a good body resonance to shoot for?
Does the neck have to be attached to get the best readings?
I guess I need a book or something, but any help would be appreciated.

Box resonances on a closed box are funny in that it is still hard to predict what will happen when the bridge is glued and the guitar is strung up to pitch. I have numbers I use for a strung up guitar. The actual numbers depend on the type and the size of guitar I am making.

Some common rules I use that I got from Trevor Gore: The resonances should not fall on a note, The top resonance should not be the same note (2 X) as the air resonance, an active back is set four semi tones from the top. A passive back is made stiff enough that it does not couple with the top.

I like my steel string top resonances for a medium size guitar (mostly what I build) to be either 170 or 180 hertz. The 170 can have a 90 hz air and the 180 can be 95. For the active back respectively I would shoot for 214 and 226 Hz.

I take spectrums of my just closed box. Generally on a steel string glueing on the bridge will lower the top resonance I have by about 10 Hz. Adding strings to pitch lowers the top resonance another 4 Hz.

My falcate classical guitars act different adding the bridge generally raises the top resonance frequency 6-8Hz, adding strings to pitch lowers the resonance about the same. I believe that my classical without a lower transverse brace is not fully braced until I add the bridge. The stiffness the bridge add has more effect than the mass of the bridge.