D.W. Fearn VT-3 User Manual
Page 19
21
T H E O RY O F O P E R AT I O N
This circuit description refers to only one channel. Both channels are identical,
sharing only the power supply. (See Figure 3.)
Input section
The INSTRUMENT input jack is fed directly to the grid of the first amplifier
stage, a selected 6N1P. The input impedance is very high (1 megohm) for proper
loading of the musical instrument.
The first stage is capacitively-coupled to the grid of the output stage.
Figure 3. VT-3 Block Diagram
Output Stage
The output tube is the second section of the 6N1P. It is operated as a cathode
follower, capacitively-coupled to the custom output transformer. A resistive net-
work on the secondary of the transformer provides proper loading and matching to
the input of the external microphone preamplifier.
From Instrument
To Guitar Amp
Mic Level Output
to Preamplifier