There are 8 cards on a Dolby A301 (4 for each channel). The four left side cards (but to the right of the huge power supply/meter module) are for one channel, the four right cards are for the other channel. The four cards are made up of a control card - an amp card - and two compressor cards. Of the two compressor cards there are two bands of compression that each card handles; one card handles bass and lowmid compression - the other card handles highmid and treble compression. You will end up pulling the bass lowmid compression card for each channel (disabling those bands of compression). It should be going from left to right, cards 3 and 7. To pull a card, simply take out it's two front screws and pull the card handle straight to you till you feel the card come out of it's edge connector (like PCI cards in a computer). You can leave the card in the A301, it will just be sticking forward an inch not making contact with the back edge connector. By the way, all the cards have a label on their sides (Amp/Control/Compressor) however the compressor cards don't say if they are set for the high two bands or the low two bands. I think if someone wanted to put the time into it, the pulled compressor cards could be modded/adjusted and put back into the unit for selective 4 band compression instead of 2. The Dolby Cat 22 card mod does basically the same thing as pulling the card on the A301, as when you clip the two resistors you are taking the bass and low mid compressors out of the circuit. Let us know how it works for you.