[sl_1800]

I'm glad you found it, I know how frustrating noise can be.

[rythmik]

Ok, you're not gonna believe this. I had moved the OB panels to the outside of my mains, because I wanted to experiment w/ putting the main monitors on the floor, tilted back ala Mapleshade's Bedrock stand. When I put the monitors back on stands, I decided to move subs back where the were, flanking the stand. To move the subs, I had to disconnect the speaker leads. When I hooked it back up.....the hum was GONE!    Dunno know why, but I'm happy anyway.

Thanks for all the feedback anyway.

My guess was the ground speaker pin was not connected properly before and and when that happen,  it used the wall plug power ground as the ground return path back to your power amp. 

But this reminds me a thing I really need to try. I need a volunteer with a true grounding problem, got resolved only by a cheater plug, good at soldering, with an easy to access amplifier mounting (for instance, OB sub will be perfect).  One of the Adcom amp uses a 10ohms/2W resistor between signal ground and power ground.  On our amplifer's power amp board, there is a good place to do just that. What one needs to do is to cut a jumper (will show picture when we are on it) and solder the resistor across the jumper. Let me know.  Appreciated and a small compensation available.

[corndog71]

Ok, you're not gonna believe this. I had moved the OB panels to the outside of my mains, because I wanted to experiment w/ putting the main monitors on the floor, tilted back ala Mapleshade's Bedrock stand. When I put the monitors back on stands, I decided to move subs back where the were, flanking the stand. To move the subs, I had to disconnect the speaker leads. When I hooked it back up.....the hum was GONE!    Dunno know why, but I'm happy anyway.

Thanks for all the feedback anyway.

My guess was the ground speaker pin was not connected properly before and and when that happen,  it used the wall plug power ground as the ground return path back to your power amp. 

But this reminds me a thing I really need to try. I need a volunteer with a true grounding problem, got resolved only by a cheater plug, good at soldering, with an easy to access amplifier mounting (for instance, OB sub will be perfect).  One of the Adcom amp uses a 10ohms/2W resistor between signal ground and power ground.  On our amplifer's power amp board, there is a good place to do just that. What one needs to do is to cut a jumper (will show picture when we are on it) and solder the resistor across the jumper. Let me know.  Appreciated and a small compensation available.

I could try this on mine.  I still have to build a box for my amp so access is easy.  Let me know where to connect it.

[rythmik]

I could try this on mine.  I still have to build a box for my amp so access is easy.  Let me know where to connect it.

That is great. Send me shipping address and I will get the resistor to you tomorrow. I will also send you the photos on what to do.

Thanks Rob.

[drphoto]

Yes, it all turned out to be one of leads to the servo had come loose, where the two drivers are connected in parallel. With the proper connections, everything is dead quiet.