User Manual
TECH 21, THE COMPANY
Tech 21 was formed by a guitarist possessing the unusual combination of a trained ear and
electronics expertise. In 1989, B. Andrew Barta made his invention commercially available to
players and studios around the world. His highly-acclaimed SansAmp™ pioneered Tube
Amplifier Emulation in professional applications for recording direct and performing live, and
created an entirely new category of signal processing. There have since been many entries
into this niche, yet SansAmp continues to maintain its reputation as the industry standard.
With a full line of SansAmp models, Tech 21 also offers effect pedals and MIDI products, as
well as “traditional” style amplifiers for guitar and bass. Each product is thoughtfully and
respectfully designed by B. Andrew Barta himself with the player in mind. Our goal is to pro-
vide you with flexible, versatile tools to cultivate, control, refine and redefine your own indi-
vidual sound. Tech 21 takes great pride in delivering consistent quality sound, studio to studio,
club to club, arena to arena.
PRODUCT OVERVIEW
The Hot-Rod Plexi is inspired by vintage amps of the same nickname. While those hulking
stacks are known to sound best at ear-bleed levels, this pedal can painlessly transform your
existing amp without pulling a muscle or mandatory rig cranking. With the Hot-Rod Plexi, you
can completely change the personality of a clean amp or use it as an instant mod to a dirty
amp.
Portions of our all-analog SansAmp technology have been incorporated into the Hot-Rod
Plexi to generate the organic tube amp distortion characteristics. In Stock mode, it’s as if you
have the signal path from the input jack to the speaker jack (without the speaker emulation)
of a stock ‘68 Plexi. Hot engages an extra “12AX7” pre-amp gain stage. With its own level
control, Hot can kick in up to 28dB of pre-amp boost --a pretty insane amount of gain.
Tech 21’s all-analog circuitry merges vintage sounds with modern dependability so you
get the same consistent sound, all day and all night long.
As with each Tech 21 product, the controls are designed to give you the flexibility to obtain
your desired sound. It is our hope that the Hot-Rod Plexi will be useful tools for stimulating
your creativity and, ultimately, providing the inspiration to play your best.
THE INS AND OUTS
1/4” INPUT: 1megOhm instrument level. For normal operation, signal level to Input
should be close to that of a standard electric guitar (approx -10dBm / 250mV). The input is
designed with the same sensitivity and loading characteristic as a tube amp.
Also switches battery power on/off, so be sure to unplug when not in use.
1/4” OUTPUT: 1kOhm low impedance output drives long cables without loss of signal
integrity, even in bypass.
APPLICATIONS and CONTROLS
Use with any amp --tube or solid state, vintage or modern. NOTE: You can also achieve the
same results using the Hot-Rod Plexi in conjunction with our own SansAmp Tube Amplifier
Emulators.
LEVEL: Adjusts the output level of the unit.
TONE: Very musical, specialized low pass filter that shifts the high cut from 10kHz to
1kHz. At maximum (note indicator at 5 o’clock), it’s flat. As you reduce the setting, it will
decrease the high end without losing mids or getting muddy.
THUMP: Controls the low end for the resonant frequency of a 4x12 cabinet. Cut or
boost from the 12 o’clock position.
DRIVE: Adjusts the overall amount of gain and overdrive, similar to when the output
section of a tube amp is being pushed. Highly interactive with the level of your guitar. For
instance, you can clean up the amount of distortion by decreasing the guitar’s volume
(except in very extreme settings) without having to change the setting on the pedal.
Conversely, you can increase the amount of distortion by simply increasing the guitar’s
volume.
HOT: The Hot function is like having an extra “12AX7” pre-amp gain stage. Activated via
its own footswitch, you can kick in up to 28dB of pre-amp boost. The range allows you to go
from a state of mild overdrive to insane gain.
MODES
STOCK / BYPASS: The left footswitch engages and disengages the pedal, as indicated by
the corresponding LED. In Stock mode, it’s as if you have the signal path from the input jack
to the speaker jack (without the speaker emulation) of a stock ‘68 Plexi.
HOT: The right footswitch engages and disengages the Hot function. NOTE: the pedal
must activated (Stock engaged with LED lit) or there will be no effect.
NOTEWORTHY NOTES
1) Tech 21 controls are unusually sensitive and tend to perform well beyond what
would be considered “normal.” So you need not set everything at max to get maximum results.
2) To find the best settings for interacting with your other gear, you may need to use radi-
cally different settings for each individual way you use it. You need not be discouraged or suspect
something is wrong with the unit. If you’ve got your sound, you’ve simply found the right balance to
complement each individual piece of gear. We recommend you start with the tone control at max
and cut as necessary.
3) Tech 21 pedals have exceptionally low noise levels. However, they may amplify
noise emanating from the input source. To minimize noise, we recommend active electronic instru-
ments have the volume set at unity gain/maximum and tone controls positioned flat. If you need to
boost, do so slowly and sparingly. Also check for pickup interference by moving your guitar or
turning the volume off. Be aware single coil pickups are more likely to generate noise.
4) Placement notes: For best results, plug your guitar directly into the Hot-Rod Plexi. This
will preserve the interactive nature of the unit. Otherwise, we recommend this basic guideline:
Place the following effects BEFORE the Hot-Rod Plexi:
Compressor, Envelope Filter, Wah.
Place the following effects AFTER the Hot-Rod Plexi:
Chorus, Distortion (other), Echo, Reverb, SansAmp, Volume Pedal.
5) Buffered bypass eliminates the shortcomings associated with “true bypass”
(pops and clicks, and high-end loss when multiple pedals are connected together), as well as signal
loss associated with other types of switching circuits.
6) Custom actuators. All Tech 21 pedals feature smooth, silent-switching actuators that are
licensed by other major manufacturers.
7) LED indicator light. When battery begins running low (around 6 volts), the LED will
become noticeably dim.
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