Ακριβής αντιγραφή από το manual http://www.devicemanuals.com/guide/Amplifier/Fender/Fender-%2794-Twin-Amp-Manual-T1RNd01EZz.html
"LOW POWER OPTION
The Fender Twin can be run with only two output tubes instead of
four. This is done by removing the inner two 6L6GC tubes (the 2nd
and 3rd large tubes, counting left to right), and setting the IMPEDANCE
SELECTOR SWITCH to one-half of the total speaker load; e.g.,
with a total speaker load of 16 ohms connected, the OUTPUT IMPEDANCE
SWITCH should be set to 8 ohms. (Remember — half the
tubes, half the impedance.) This will produce 60 watts RMS in the
OUTPUT HIGH setting, and 15 watts RMS in the OUTPUT LOW setting."