David Halliday
Member
I have an odd issue with my C4200 amp.
This is a 4 channel amp with 2 x 2 channel boards sharing a common PSU.
When I use two channels from the same board and leave the other board unused its fantastic and super low noise,
However, If I use one channel from each board I now get a low level mains hum in the speakers (you do have to put your ear pretty close to hear it is still there and annoying.)
I was suspecting a ground loop as it goes away if I remove one of the RCA connections to the pre-amp but not sure that makes sense. As we are now back to case 1 where I am now only using a single board. Also I did check the signal ground (outer part of the RCA connections) all 4 are connected together so it seems the signal ground is shared between both amp boards as I would suspect.
I also tried a different pre-amp but see the same.
Anyone else got a C4200 and see the same?
This is a 4 channel amp with 2 x 2 channel boards sharing a common PSU.
When I use two channels from the same board and leave the other board unused its fantastic and super low noise,
However, If I use one channel from each board I now get a low level mains hum in the speakers (you do have to put your ear pretty close to hear it is still there and annoying.)
I was suspecting a ground loop as it goes away if I remove one of the RCA connections to the pre-amp but not sure that makes sense. As we are now back to case 1 where I am now only using a single board. Also I did check the signal ground (outer part of the RCA connections) all 4 are connected together so it seems the signal ground is shared between both amp boards as I would suspect.
I also tried a different pre-amp but see the same.
Anyone else got a C4200 and see the same?