I don't know if I should post this here or in class D or in subwoofers but I have a subwoofer hooked up to my tube amp through the speaker level inputs. When the amp has the switch on but has gone into standby mode I get a faint buzzing sound out of the speaker it is hooked up to. This has actually happened with two different subs, both class D; the class a/b amp didn't seem to do it.
If I disconnect the amp from the speakers it goes away. If I reverse the speaker wire polarity to the sub amp it doesn't change. Both the main amp and the subwoofer amp are both plugged into the same outlet.
I was already planning to convert the speaker level input to line level and run it through a dayton dsp-lf so that may solve the problem but I'm just curious what might be causing it.
If I disconnect the amp from the speakers it goes away. If I reverse the speaker wire polarity to the sub amp it doesn't change. Both the main amp and the subwoofer amp are both plugged into the same outlet.
I was already planning to convert the speaker level input to line level and run it through a dayton dsp-lf so that may solve the problem but I'm just curious what might be causing it.
In standby the class D is probably powered down - this could be a ground loop, with current leaking into the speakers when the subwoofer circuit monitoring it is powered down through semiconductor junctions. The inputs of an opamp are only high impedance if its powered up. Most ICs look like a bunch of diodes to the power rails when no power is present.
That makes sense.
The AB plate amp I have still generates a fair amount of heat in 'standby' so I figured I'd try D. The AB amp when switched on at the power cord thumps loudly so that wasn't a good solution for it still being on when it was in standby. I haven't tried the class D switched with the amp to see if it thumps.
The AB plate amp I have still generates a fair amount of heat in 'standby' so I figured I'd try D. The AB amp when switched on at the power cord thumps loudly so that wasn't a good solution for it still being on when it was in standby. I haven't tried the class D switched with the amp to see if it thumps.