Made all the difference.... I bought my Marshall TSL 122 combo amp in 2007 completely wrecked, hot wired and rigged and i think i got every mainboard release Marshall put out for this over the years. They finally hit the mark on this latest rev. and thank god. This amp has amazing redeeming qualities even from the first. It's just never been stable until those last changes were made to the mainboard 4-5 years ago? I had to reinstall again after i blew my amp out trying to bias with a matched duo pair (I know I'm an idiot) instead of quad. Bitten so many times, not shy i had to get her going again. She's back up and running and I couldn't be more grateful. It's a shame Marshall didn't get this right from the beginning. It always has potential and I recommend people pick one up regardless the horror stories, get rev 20 and some new tubes and you are golden

My amp sounds better than ever with this board. No bias drift so you can gig worry free. It was relatively easy to install, just number every connection with masking tape and connect it back and you will have a new amp. I'm very pleased, there is no ground, no strange noises as before, just sound heaven.The price of the new board is the same as a tech will bill for the bias drift mod.You will not be disappointed.

Replacement board was perfect. Package perfectly.
Thank you

This circuit board is worth every penny. It cured my amp of unstable runaway bias, strange noises, pops and exploding electrolytic filter caps. I could have fixed the old board, but I decided to get this because it is quite an upgrade compared to the late '90s boards...the resistors are metal film now and actually the CORRECT value (a nice surprise), and the board itself is made of a much more sturdy material. Unfortunately it still uses 2 cents a dozen capacitors. Way to go Marshall. ANYWAY when I fired my amp up after installing this, I could easily set the bias, something I was never able to do, and the voltage is rock solid. It was all over the place before. The amp sounds FANTASTIC and the buzzzzzzzz, funny noises, popping and runaway bias are gone. Marshall should be ashamed of themselves for the sub standard GARBAGE they originally put in this amp.

I needed that Main Board, AES had it, they shipped it fast, and i had it...love these guys....the amp is 10 times better than it ever was and couldn't be more pleased. Will shop their store again!!