Noise after restringing a classical guitar

Question

I just restring-ed my classical guitar. It was fine before the restringing. But now when I make a rest-stroke, besides the normal produced sound, there is another noise entailed. The noise sounds very suggestive that it is produced by something vibrating. This only happens to the 6th, 5th, 3rd and 2nd strings. The problem also disappears when I use a free-stroke.

Any suggestion on the cause of the problem, and how to solve it? Somehow I feel this is a very common problem, and I must have faced it in the past but I cannot remember how to deal with it, or it just vanishes by itself after a while.

Answer 1

Three things which I have had happen to guitars which were the cause of sympathetic vibrations:

1) a manufacturer's label glued to the inside of the guitar body (removed the label)

2) a small portion of kerfing inside the body became unglued (applied a small amount of wood glue under the offending piece)

3) the very end of a tied-off (without ball end) nylon string at the bridge was vibrating (trimmed the string end so it had less extra material to vibrate)

The best way to find the problem is to move your ear around the instrument to localize the sound and then place your finger on suspect areas to see if you can alter it or make it go away. Sometimes you can tap the sound board to cause the vibration which is helpful when reaching inside the body since your arm will dampen the strings.

Answer 2

Occasionally, the machine heads, particularly on well used guitars, have a loose point. When the string is tuned, the knob part is slightly loose in the gear.To alleviate the problem, de-tune the string slightly, then tighten past the loose point.