B52 AT112 ECC803S V1 Option

These are all adjustable bias amps and all you need to check and adjust the bias is a Multimeter if you're using the B52 method. A more accurate method is to use a bias probe and a Multimeter, or our all-in-one Eurotubes "Pro One" bias probe that reads both the plate current and the plate voltage simultaneously. These are available under the "Related Products" tab.

You can use our Generic Bias Video for reference.

The video below explains the difference between bias probe types.