Origin Effects RevivalDRIVE User Manual

6
Inside the RevivalDRIVE:
Some Key Amp Design Concepts
Understanding a little more about how valve amps actually work will help you get the most
out of the RevivalDRIVE. Below, we decipher some terms that may or may not be familiar
to you and explain how they relate to the pedal’s unique range of controls.
BRIGHT CAPS
Some amplifiers have components known in the trade as “bright caps” wired across their
volume controls. Bright caps act like a high-pass filter, allowing all frequencies above a
certain point to bypass the volume pot. Because these high frequencies are effectively at
full volume from very early in the pot’s travel, this allowed vintage non-master-volume
amps to deliver a clean sound with lots
of bright, sparkly top end when the
volume knob was set low. The “treble
bleed” circuits attached to the volume
pots in some guitars are there for
exactly the same reason.
The RevivalDRIVE lets you experiment
with two different bright cap settings –
GB and US – via the BRIGHT CAP
switch on each channel. The capacitor
values of the US setting are based on a
Fender Twin Reverb, for that bright,
glassy top end heard on many classic
studio cuts from the late ‘60s and early
‘70s.
For the GB setting, we have drawn inspiration from values introduced to the Marshall
1959 Super Lead circuit in the late ‘60s. Here, an unusually large capacitor allows not just
highs but also mids to bypass the volume control. Consequently, the volume knob doesn’t
behave in the usual manner. As you turn the volume knob up from zero, the signal is
pretty much all there almost immediately, with lows and distortion steadily increasing as
you turn the knob clockwise. The volume knob effectively becomes a high-gain tone control.
Because they are created by actual capacitors acting on the RevivalDRIVE’s unabridged
amp-style signal path, you will find that these bright cap settings accurately reproduce the
volume knob behaviour found on the original amps. As the volume knob is turned up, the
audible effect of the bright cap is reduced. The low and mid frequencies steadily increase
Bright cap switch on a 1966 Fender Twin Reverb

Origin Effects RevivalDRIVE Specifications

General

Bypass	True Bypass
Technology	Analog
Inputs	1 x 1/4"
Outputs	1 x 1/4"
Power Source	9V DC power supply (not included)
Input Impedance	1 MΩ
Output Impedance	1 kΩ
Type	Overdrive
Controls	Output, Blend, Highs, Lows, More/Pres, Gain
Channels	Mono