Engl Screamer Thunder & Classic 50 High Gain Option

These are adjustable bias amps and all you need to check and adjust the bias is 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 all available under the "Related Products" tab.

You can use the "Generic Bias Video" we made using a Marshall 800 for reference. 

The video below explains the difference between bias probe types.