noise from bass unit of speaker

[ClassA]

Hi,
A low frequence noise (like onggggggg----) comes from the bass unit of speaker when my power amp (QUAD 405.2) is on. You can hardly hear it when your are 15~20cm away from the center of the unit and one channel is louder then the other channel. I just replace new caps for my 405.2. Is it the possible case that some cap are damaged by soldering issue or the power transistor is old?

 

[johnnyx]

Are you sure that the new caps are the right way round, and that you didn't damage any tracks when you changed them? I would check your work . Were the amps OK before you changed the caps?

 

[ClassA]

I think it may be caused by the mismatch between these two (L/R)OP amps.

 

[Nigel Goodwin]

That doesn't sound at all likely?, did the amplifier work OK before you changed the capacitors?. If so it's obviously something you did when you changed them, as already suggested.