Marshall JVM 50 Watt Standard Retube kit

The JVM is similar to the JCM2000 series, though the test points are now internal so you have to pull the chassis to bias the amp. All you need is a Multimeter and the bias should be adjusted to between 35 to 45mV per side. You can use the DSL-TSL bias video for reference.

The most asked question is do you need a bias probe to bias these amps? The answer is no, a simple Multimeter is all you need.

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 between 35mV to 45mV per side at the test points.