Biasing:
The
biasing on the
amplifier was
reduced prior to
shipping as a safety
measure. Once the
amplifier has been
on for a while and is
fairly warm,
connect a
Multimeter to the
red and black
biasing terminals on
the top of the
amplifier, in between the transformer housing and the speaker terminals. (Shown above)
Set the Meter on DC Volts, and adjust the screw on the rear of the amplifier (Shown below)
until it reads between 1 and 1.2V. Or between 100 and 120 mA.
Repeat on the other
amplifier.
After about a
month or more of
running, or about
200 hours, check
and reset the bias.
After this, there is
no real need to
keep checking it,
unless the tube is
replaced, as the
bias will naturally
drift as the tube
ages.
These amplifiers give off quite a lot of heat, so please ensure that each one has adequate
ventilation.
Note
: bias adjusting screw on the rear of the amplifier, below the XLR input..