strange subwoofer thumping problem

I recently got a new amp ( powerbass ASA 1500d ) which is 3000w max. That is powering up 2 12inch Pioneer Premiers champion pro series..rated at 3000w peak and 1000rms each. The amp is grounded with a 4 gauge. My subwoofers would thump uncontrollably when I connected them to a channel on the amp. I had a friend connect the amp and thought it was going to be a simple swap..but when we connected the subwoofers to a channel, the subs would start thumping out loud frequencies. All the knobs were turned down on the amp and the sub setting on the deck was set to -15. We also disconnected the RCAs from the amp and tried connecting..still it would make the subs thump like crazy. I also switched out the glass fuse for an ANL 200amp one, but still the problem persists. any ideas on what is going on?

I'd bet the amp has a problem..............from what you say above, your amp was on while hooking it up.

i'd like to say that too, but when I bought it from a friend, the amp was working fine as he demoed it for me. I am taking it to be checked out tomorrow. All the dials were set to 0 on the amp, but when the "sonic filter" was adjusted the subs would make that continuous thump again.

Do you have a Pioneer Radio?

I have a Kenwood.

Turn the gain all the way down then set it correctly.  Check the Hot Topics forum for instructions.Support the12volt.com

Everything on the amp was turned down. The subwoofer on the deck was set to -15 and it would still make that continuous thump.

I see many problems like this, everything worked when I took it out.   Did you plug in the rca's before or after attaching the ground wire?

not sure. If I didn't do so, would I have fried the RCAs?

You could have blown a ground plane fuse in the head unit.  Common problem with Pioneer heads, less common with others but still possible.  Also, what's the net impedance of the subwoofers as wired to the amp?Support the12volt.com