Please help, I brought a NAD S250 to drive my PSB Image series speakers (5 speakers), keep my Yamaha as pre-amp. Unfortunately, as soon as I connected the speakers hear a loud humming noise from all channels. Did I buy broken product from audiogon or this is the way amplifier works. Never used a dedicated AMP before.
You are going to have to trouble shoot this by disconnecting the pre and see if the hum goes away. If yes, then reconnect and begin disconnecting sources until it goes away. The idea is to isolate where it comes from.
If you are into multiple outlets, than may also hurt. A common plug-in scheme can help in these cases.
Leo, I acually tried the following: -turning off the pre-amp: sound still exists - Then I disconnected the input to the AMP from Pre-AMP, no humming sound through the speaker
What is that mean?Does that meanthere is nothing wrong with the AMP itself?
I also, unpluged all my devices (cable box, Satelite Box, VCR, DVD) fom the power outlet, now only the pre-amp (turned-off) connected to the AMP, still speaker makes the humming (hissing) noise.
You are proceeding in a correct fashion and are, at this point, a little past where I can help you....but you are obviously on the right track.
Does the symptom change when disconnecting the RCA from ANY source to pre?
IS EVERYTHING CONNECTED TO SAME OUTLET?
You may want to disconnect 1 input wire from pre-to-amp at a time. Vague possibility that 1 of these has bad ground. TURN OFF POWER 1ST....ZAP!
If you find a bad RCA wire, replace them both with some EITHER homebrew wires or some non-monster cables. Without regard to the real or imagined sonic benefits of Monster Cable, the COMPANY sucks.
Get an outlet tester and put it in your kit while you're at it. It is possible to have a hot/neutral or ground/neutral reverse. Not Likely unless you have let me work on your electric.
Keep going thru it a piece at a time until connecting something starts the problem.
One last thing.....In your first post, you say HUMM.....probably 60hz, which is symptom of ground loop. In your last post, you say hissing.... like maybe an egg frying noise. Makes a difference! Keep updating as you go thru this.
Leo- thanks for the help Actually, I found out that the big humming noise was my cable connection, as soon I disconnecetd the cable, humming sound go away, but still there is small hissing noise from the speakers, especially from the tweeter.
On the other hand I need find out how to get rid of the ground loop issue, also still need to find out that hissing noise from the tweeter, even though its not loud.