My HK TS7 sub pops and cracks/hums while being active for a few hours. When I power it of for a while and try again the problem is gone again for some time. I tried switching of the auto sense, but same error. The problem isn't worse when playing louder. It's allways loud, no matter the volume. It also happens when the sub is on "standby". Last I replaced all the quad opamps (input and limiter) and this solved the problem for a month. Now: same problem.... Any ideas? I was thinking of some caps, but can't seem to find any cap that "looks" bad (no good measurement equipment) ... Someone?
I would guess there is a cold solder joint on the board. Replacing components was probably not really related to a fix. More likely the problem was simply averted for a short while by handling the board. Spraying the board with a cooling agent (compressed air) when the problem is noticed might locate a bad solder joint. However, I hesitate to suggest anyone stick their hands inside a live component.