Testing DC offset in your amp or receiver is one of the easiest tests to perform and can greatly benefit your speakers and your sound quality. This is not a lesson on adjusting the offset, more of a lesson on checking and what to do if the offset is too high. ***Not for vacuum tube equipment*** Tube gear should not be run without a load connected to the amp. You should somewhat know the architecture of your amplifier; not all solid state amps will test this way, but most do.
Tools needed :
DC voltmeter or Digital Multimeter
Remove your speakers from the terminals and select and aux source with nothing attached to the aux input. Volume minimum, tone controls off or flat, and balance centered. Turn the amp on and allow to warm up for 2-3 minutes. Place the positive probe (usually red) in the positive terminal, and negative (usually black) into the negative terminal. Check for DC voltage in mV. Do the same for other channel. After 8-10 minutes retest.
You will hopefully see a number close to 0mV. As the amp warms it may drift a bit but should never really go over 10-20mV. The closer to 0mV the better.
So what if the number is over 20mV? You may have a transistor issue that needs to be addressed or, the amp may just need to be aligned as the bias has drifted. Having a correct DC offset can make a world of difference in the sound quality of your amp. This is fairly easy testing and can be very beneficial. If this post helps and you get results please let me know and leave a comment below.
-mike