If the noise is from the amp, the effects loop would be a good place to put the noise gate.
I seem to have found two schools of thought about noise gate placement: 1) Place it first, before anything else. This cuts the noise on the signal from the guitar before it hits any other effects or amplification. 2) Place it in the effects loop to cut any noise created and amplified through the effects and preamp. The problem with this is that any earlier effects have already been applied to the noise as well.
I am currently using a
Boss pedal, which I find quite effective at cutting the noise (particularly from the noisy Strat single coils) and convenient (with a foot switchable mute, useful when switching guitars). It has two sets of inputs/outputs and (as recommended by Boss) can be wired first in the input chain, and also has a section for the effects loop -- with the idea of operating at both points. Seems like a good solution -- just have both. Right now I am not using a lot of effects and haven't found a lot of difference with the effects loop part, so I am running it right now only as the first thing in the chain. That seems to work well (for guitar noise more than amp noise of course).
