Vox VT80+ - Manual (Page 21)

21
Signal path
Your guitar sound passes through the following sections.
Refer to “Top and rear panels” (p. 7) in conjunction with this illustration.
EFFECT PRE AMP
GAIN VOLUME
EFFECT
MASTER POWER LEVEL
PEDAL MOD/DELAY REVERB
VALVE REACTOR
VALVE
ECC83 (12AX7)
Select one
of 33
What is Valve Reactor technology?
The Valve Reactor circuit used in the power amp of this VT20+/VT40+/VT80+/
VT120+ amp is based on new technology. Most of the sound creation and tonal
shaping is performed in the digital domain, but the Valve Reactor power amp is
100% analog. Passing the guitar signal through the analog power amp stage is an
important factor in capturing the feel and tone of the original amp that was
modeled.
Valve Reactor’s power stage is a miniature version of a true tube push/pull
power amp. It uses a 12AX7 tube (dual triode; in other words, two vacuum tubes
in one), and is similar to a real tube amp with an output transformer. The final
output stage is connected to a specially designed VariAmp power circuit. This
allows the output of the power stage to be continuously varied from minimum
output to maximum output.
This VariAmp power circuit is completely transparent – i.e., it does not modify
the signal – so the output tone will be the pure sound of a tube amp. The wide
dynamic range seen in a conventional tube amp is also maintained. This dynamic
range is a characteristic that is difficult to obtain from a solid-state amp; this is
why a tube amp sounds more powerful than a solid-stage amp of the same
output specifications. The output of the Valve Reactor power amp “reads” the
constantly changing impedance curve of the connected speaker system, and feeds
this information back to the vacuum tube. In response to this information, the
operation of the amp’s tube stage will vary according to the speaker load (imped-
ance). This too is an important element in the sound of a true tube amp.
By adjusting these characteristics, every sound of that amp model can be faith-
fully reproduced. This power amp technology, for which a U.S. patent has been
obtained, is unique to the VOX Valvetronix amps.