I had this kind of unwanted behaviour with my acoustic guitar mostly on low F#/G in E-string and octave higher in A-string:

"the worst cases where a note decays very rapidly are caused by the guitar body having a very STRONG resonance response at that note. What happens is, the body likes to vibrate at this frequeny so much that it "sucks" the energy from the string very quickly, and the note dies. If you look carefully, you'll probably notice that the initial amplitude of the string vibration is larger than average, but the decays is also very rapid."

I did the experiment were i covered about 1/4 of soundhole with piece of cardboard that i taped on to the guitar top. The dead notes almost completely disappeared what gave me the clue of the problem that it got something to do with the tone of guitar top and body being too close together causing F# and G-notes died rapidly like stated above.

Since the guitar had great potential (light weight and nicely build, great sound otherwise) i decided to do radical experiment and shaved one of the back braces about 1/5 lower removing quite little material. I also tryied to keep the shape of brace almost the same. I did this in three stage were i removed little wood from brace and put strings back and let it stay and adjust for day and then removed more etc. Everytime the tone got better and better. After the last shaving the dead notes on F#/G became almost unnoticable. I know they are there because i know what to listen but i believe most folks won't notice anything wrong with these notes anymore.

The overall tone/note of the guitar body became somewhat lower but now the bass and treble notes are also louder and guitar seems to vibrate more freely than before shaving the back brace.

Has anybody else done this kind of thing themself? This is really an suprising thing to me since i believe with skills you could make every guitar sound alot better and louder by retuning the top and back. I wouldn't touch the top myself and risk ruining the guitar but experienced luthier could and can do magic to dead sounding guitar by retuning its top and back.

BTW. the guitar is early 2000 Gibson J-185 with maple back and sides. Four back braces, two lowers are quite wide and thick. I shave the thick one right below the brigde. I would have like to shave the other one also close the end block but couldn't get my hand fit inside the guitar box

This message has been edited. Last edited by: Johnny,