Chasing down hum, buzz, and noise

A few grounding fundamentals solve the vast majority of noise complaints. First, placement: effects like chorus, delay, and reverb belong after your gain stage — put them before it and they'll amplify noise. Hum or buzz is almost always a grounding problem — improper grounding, a missing ground, or a ground loop. Ideally your rig connects to earth ground (the outlet's third prong) at exactly one point. - If you have multiple grounds, try a ground isolator on all but the first ground plug. - An ungrounded rig may need a single ground connection added. Note that most pedal power supplies isolate your pedals from ground, even with a 3-prong plug. Running two amps and hearing hum? That's a classic ground loop — worth reading up on ground-loop fixes specifically. If a true-bypass pedal "pops" when you switch it, that's from a difference in ground voltage between the pedal and whatever it feeds. A buffer at the end of your chain usually cures it — or, if you'd rather avoid buffers, a transformer isolator.