Specifications
OPERATION MANUAL  MODEL : ZMA - ZEN MYSTERY AMP!  REV 1 MAR 2014 
Biasing your Mystery Amp 
Biasing your mystery amp is easier than almost every other tube amp on the 
market thanks to an extremely well thought out and tested set of controls. 
These controls consist of four meters (one for each output tube) and four knobs. 
The meters consist of a left and right pair representing the corresponding output 
tubes on each side of the amp. Since the goal is to have each pair of tubes 
perfectly match, you simply use the bias balance control. 
!
STEP 1 
Install tubes and hook up speakers. Never turn on amplifier without speakers 
connected. 
!
STEP 2 
Turn master gain (volume) control all the way down (counter-clockwise) 
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Right Channel 
Bias Level
Right Channel 
Bias Balance
Left Channel !
Bias Balance
Left Channel !
Bias Level










