One note sounding louder than others - resonance? What to do?

Question

When I play my guitar, the note A sounds annoyingly louder than other notes. This is most prominent with the open A string, though it happens in other octaves too.

I guess this is because of resonance. In fact, when I lightly press on the soundboard behind the bridge with my hand, I can make A sound like all other notes.

What is the accepted way to deal with this? Should I compensate for that by reducing the strength with which I play every A note (I don't have enough control to do that consistently)?

Or maybe, tune the guitar a half-tone higher or lower, so the "too loud" note becomes Ab or A#, which are probably less frequent?

Or stick gum to a strategic place on the soundboard, as some may suggest? (it seems that I might need something much larger than a gum though)

Answer 1

Open strings always sound different to fretted notes - more resonant and with more sustain. Players of string instruments learn to avoid open strings for that reason, and sometimes to take advantage of the different tone of an open string.

Other than that, it does seem that you've identified a resonant frequency in the body of your guitar. That is probably a symptom of a cheap guitar - better guitars will have been crafted to have a pleasing set of resonances, with no glaring anomalies.

A luthier may be able to fix this by shaving wood away, or by building up the soundboard. Depending on the value of your guitar, the cost of the luthier's time may not be warranted.

As your link, and Tim, have suggested, you might be able to achieve the same thing by sticking things to the inside of the soundboard; experimenting with different positions. The intention is just to damp the vibration of the part of the soundboard that resonates at that frequency.

Tuning up/down a half tone, while playing the same positions, would let you avoid the problematic frequency a lot of the time. However, it would prevent you from playing along to recorded music, and from playing with other musicians with normally tuned instruments. It may also affect your ability to sing along to your own playing, depending on your range -- although one semitone shouldn't make too much difference.

Of course, tuning down a half tone, then playing a fret higher to compensate, will not help at all - you will still be playing the problem frequency, and your guitar body will continue to resonate.

If you're not playing along to recordings or other players; or if you can get the other instrumentalists to tune to match you, you could detune by a fraction of a semitone. Even a very small change may be enough to take you away from the resonant frequency.

Answer 2

I'm guessing it's an acoustic with a round hole. A small piece of pipe lagging (sponge) stuck inside the guitar, under the bridge or surrounding area - you may have to experiment - with gaffer or duct tape, could solve this annoying problem, which may also show itself on the E string, as that is a harmonic of A, or the D string, which has A as its harmonic.The best solution would be to purchase another guitar. Better guitars are made so that sympathetic vibration, leading to unequal note volumes, is eliminated.

Answer 3

For an acoustic guitar, Try lighter strings and brass bridge pins. Lighter strings cause decrease in volume and the brass pins will make up for that.

Answer 4

I just had my Taylor fixed at a Guitar shop in Kelowna BC. I have the expressions system and the b string was way louder than the rest. The problem is a simple fix on the expression system. There are three adjusting slots below the bridge. One for the high e and b one for the d and g and one for the low e and a. Whichever string is annoyingly loud you back off that screw (very tiny allan wrench) a half turn or so and that lowers the volume for that string. Voila!