Marshall TSL60, TSL601 and TSL602 High Gain Option

You can adjust the bias yourself with a simple multimeter from the outside of the amp. There is only one bias screw on the left side of a three pronged male plug on the back of the amp.

The bias trim on the TSL 60 is very different and much simpler to adjust than the DSL/TSL 50's and 100's which have two trim pots. The center tap on the TSL 60 is ground and the left tap measures the left tube and the right tube and a setting of 80 is good. Just set your multimeter to DC Millivolts and dial in the tubes.

The second most asked question is "what setting do I use on my multimeter" The answer is Millivolts!

The third most asked question is "do I use the black or negative lead for the middle test prong?" The answer is yes!

The fourth most asked question is "do I bias the amp in standby?" The answer is no! The amp must be in the play mode to adjust the bias.

The fifth most asked question is "do I have to have a speaker plugged in?" The answer is YES! You MUST have a speaker load on the amp.

The sixth most asked question is "what do I bias KT77's at?" The answer is EL34's, E34L's, KT77's and the big bottle JJ 6CA7's all bias up to 80mV at the test points.