Egnater Renegade 112 Owner's Manual page 13

Bias: Power Tube Bias
Advanced theory (for those who care):
Those of you with electronic knowledge
may notice we are referring to current draw
but are making measurements in millivolts.
Ohms law states that I=E/R or current (I)
equals voltage (E) divided by resistance
(R). Inside the amp are one ohm resistors
in the cathodes of the output tubes. The
external test points allow access to those
resistors. When you measure across those
resistors at the rear panel test points, you
are reading the DC voltage drop across a
one ohm resistor. Referring to ohms law,
if R=1 in the formula, then I = E or cur-
rent equals voltage. So when you read for
example, 60mV you are also seeing the
equivalent numerical value of current or
60mA. You may have also figured out by
now that since you have separate adjust-
ments for each tube pair, it may be possible
to use alternate tube types at the same time.
Your suspicion is correct. You "tweakers"
can combine different types by installing
one type in the EL34 sockets and another
type in the 6L6 sockets. Be sure to adjust
each pair for the proper range. This way
you can combine the characteristics of the
different types. The range of the bias ad-
justments are such that you should have not
problem adjusting for just about any type
of compatible tubes.
WARNING:
DO NOT be tempted to run your tubes hot-
ter than the maximum values in the chart.
You may find it sounds really cool as you
destroy your expensive tubes and possibly
damage your amp, of course voiding your
warranty! Also, in case you haven't found
out the hard way yet, power tubes get
extremely hot (as high as 800 degrees)!!!!
NEVER touch the tubes while the amp is
on. Always allow at least 5 minutes for the
tubes to cool before touching them after
turning the amp off.
RECOMMENDED BIAS SETTINGS
6L6/5881
EL34/6cA7
E34L
6550
6V6 (JJ ONLY !!!!!!!)
KT66
KT77
60mv to 70mv
65mv to 75mv
70mv to 80mv
70mv to 80mv
30mV to 40mV
60mv to 70mv
65mv to 75mv
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