Official Blackstaramps Forum

I personally would return it and pay the extra to get a new amp with a warrantee. There could be any one of 100 different things wrong, none of which are easily fixed by the typical user.

Probably a tube problem. Try replacing the preamp tubes. If that doesn't help then replace the power amp tubes and rebias the amp.

Yes, re-bias.

First thing I would do is get it off the floor and/or tilt it back 20-30 degrees. That will help prevent the lows from resonating with the floor. Agreed. Before attacking the problem with a band aid (EQ) determine the root cause (guitar, speaker, amp placement, your position relative to the speaker).

Maybe a cold solder joint at a tube socket. As the amp heats up the solder changes a little.

I've found volume issues are sometimes due to dirty tube sockets or cold solder joints at the sockets.

Shouldn't be a problem. The 8 ohm output of each head into each of the two 8 ohm stereo inputs of the cab.

Try getting a parametric EQ to put in front of the amp, or in the effect loop. The Empress ParaEQ is a popular one.

Check if the tubes are good (buy one new 12AX7 and swap it to different preamp tube positions to see if the problem goes away).

Loop Master could probably help you out:

http://www.loop-master.com/channel-util ... -c-29.html