How do I set/adjust the bias on my tube amp?

There are various schemes for bias adjustment and many amps are self biasing. It really depends on the amp, not the tubes. Contact the manufacturer for their recommended procedure. Or let us know what amps you have and perhaps someone here is familiar with them. If any type of test equipment is required it is usually a common voltmeter.

Myraj, Herman is 1000% correct. I cannot add anything to it. You need to list the amplifier.

Herman & Trelja,
It is a pair of custom made 300B monoblocks by Kevin Brooks. There appears to be a bias adjustment screw by each 300b tube.
Your comments and help are appreciated.
Thanks!

I have never been 1000% percent correct before. I am very proud.

CAUTION: The voltages you are dealing with are very dangerous.

The following applies to typical SET circuit topology. Since I am not famliar with these amps it may not apply. There should be a resistor in the path between the cathode and ground. The cathode leads are the larger pins. If you measure the DC voltage across this resistor and then divide it by the value of the resistor it will give you the bias current. I would think somewhere around 50 milliamps (.05 amps) but it really is dependent on the design of the amp. Some amps have small jacks where you insert your voltmeter probes so you do not have to open the amp. The designer will then specify a certain voltage for the adjustment based on the value of the sense resistor and the desired current.

If too low you will clip the signal during loud passages. Too high will cause the same problem and also cause the amp to run too hot.

It would be best to contact the designer and get his recommended procedure and bias level.