In January I bought a guitar and a small practice amp. As I noted back then the amp has
lots of effects which saves me buying an array of pedals. It has one problem though: it is
very loud. And by that I don’t mean that it goes to
11, but that it goes from zero to hero already
around 2: below is too quiet, above too high, and the optimal setting in the middle is too
hard to find.
There’s simply not enough (useable) dynamic range. I could turn down the input volume from
my guitar, but that changes the sound unfavourably (I get lower signal-to-noise ratio, and
many of the effects rely on high input level to work satisfactorily).
To solve the problem I measured the resistance through the speaker to 6.2 Ohms, hooked a
57.4 Ohm resistor in series with it (for a total of 63.6 Ohms) and a 8.2 Ohm resistor in
parallel with that. Substituting 63.6 and 8.2 for R1 and R2 in
1/R1 + 1/R2 = 1/R, the
formula for calculating the combined resistance in a parallel circuit, and solving for R
gives a combined resistance of about 7.3—close enough for my purposes.
The result? Most of the output from the amp now bypass the actual speaker, shunted off
into a resistor where it is converted to heat rather than sound; the volume dial has a
much greater effective range, making it much easier to adjust to a sensible level; and my
neighbours are much happier.