"Arfa Daily is a ****wit "

So, today, I did the mods that the customer was asking for. The value and
type of a coupling cap in the overdrive channel was changed. The input
circuitry was stripped and simplified to standard Fender style - i.e. a
68k series resistor from input jack to the grid of the first 12AX7, and a
1M grid return to deck.


** Does nothing.

The fixed negative bias to the grids of the output tubes was
disconnected, and the injection point decked, and the cathodes were lifted
from deck and returned instead via a 100 ohm 4 watt resistor, bypassed by
100uF.

** Ruins the amp.

The cathode voltage now rises up with increasing drive level and at full
drive biases the tubes almost completely off.

This result is gross waveform distortion of the crossover kind - same as
severely under biasing the amp.

Very bad mod.


I also put an additional 1 ohm resistor in the cathode path, so that I was
able to measure the idle current of the output stage. This settled at
about 130mA, or just over 30mA per tube, which was exactly what the author
of the mod notes suggested it should be.

** So ****ing what.

That is only the idle current.


I have to say that after carrying out these mods, the amp did seem to have
a much 'smoother' more Fender-like sound, and was still capable of
producing pretty much its full normal output of around 30 watts.

** Utter bull****.

As anyone with a functioning scope, dummy load and eyes can see.



..... Phil