Revv Owner’s Manual - 28
Set the bias:
1)
Place the black lead from your meter into the black bias test point on
the amplifier & the red lead into the red bias test point (The red test point
on the left is for V1 & V3 tubes, red test point on the right is for V2 & V4
tubes).
2)
Refer to the chart below for bias set points for the tubes being used &
slowly turn the trimmer in the clockwise direction until the value is
reached.
3)
Next, place the red lead into the other red bias test point & repeat step
2 for the other set of tubes. If 2 different pairs of tubes are being used,
refer to the chart below & set the bias accordingly.
4)
Re-check the settings of each bias test point & make any further
adjustments as required.
5)
Once the bias is set at the required settings, lock down the trimmer
lock nuts by turning the nuts clockwise while holding the trimmer shaft
with a screwdriver so as not to lose the setting. Do not over tighten the
nuts, just snug them. Once complete, return the rear baffle panel to the
rear of the amp & fasten it with the screws you removed. You are done!
BIAS CHART
(Measurements are for two tubes per bias point)
Note: The range setting is for experimentation. Power tube bias settings
change the sound of the amp & the range listed above is safe for experi-
mentation. The largest setting is considered the maximum setting &
should not be set above this setting. Running the tubes on the higher end
of the range will shorten the tubes expected life.
Type
KT88
EL34 6L6GC
Safe Range
90mV - 115mV 60mV - 85mV 80mV - 100mV
Recommended set point 105mV 75mV
90mV
5.5
5.6
