Tube Amp Doctor (TAD)TAD is a German company established in 1993 which selects and matches electronic tubes and manufactures musical instrument accessories.
Package of 2Bias Master™ set of adapter probes for testing other types of tubes. For use with the S-TBM4-X Bias Master™ system.
Starting at $71.50
Bias Master™ system BM4 Measures Bias current of the vacuum tubes in your amp. Includes 4 probes and english/german operation manual. The Bias Master™ allows you to monitor the bias current safely and easily. While adjusting the Bias control pot of your amp, the Bias Master™ shows the actual result. This lets you set and evaluate the full reasonable biasing range your amp and tubes offer to find and set your personal perfect choice.