INTRODUCTION
Thank you for your purchase of the Electronic Audio Experiments Model feT! This
manual is an in-depth guide for properly using and enjoying your pedal.
The Model feT is my humble homage to the venerable Model T amplifier manufactured
by Sunn in the early 1970s. The original Model T was Sunn’s effort to compete with
Marshall –by borrowing the Super Bass design (itself a shameless re-iteration of the
Fender 5F6A Bassman) and adding their signature ultralinear power amplifier. This
power amp, inspired by Dynaco tube hi-fi equipment, produced a formidable 150W of
power with more clean headroom than the typical guitar amps of the time. Sunn was
short-lived in its success, but the Model T developed a cult following because of its
massive power output, deep bass response, and (in my opinion) its stark and imposing
aesthetic. In conjunction with down-tuned guitars, a kick from the right distortion pedal,
and enough patience to let a power chord feed back for 30 minutes, the amp redefined
the sound of heavy music.
The Model feT itself comes from a long line of “amp-in-a-box” pedals intended to
capture the sound of hard-to-find vintage amplifiers. The DIY pedal website
Runoffgroove popularized the notion that JFETs, a type of transistor, could be used to
emulate triode vacuum tubes (ironically, Sunn itself was early adopter of this practice in
the Concert Lead/Bass amplifiers). Because JFETs are what as known as “depletion
mode” devices, they may be biased in a manner akin to triodes. With allotments made
for standard pedal operating voltages, simply dropping JFETs into the schematic of a
tube amp can produce a convincing approximation of the amp in question. Without the
contributions of ROG, this project would likely not exist. However, this method is not
without limitations: JFETs do not perfectly mimic tubes, and many JFET amp
emulations do not include any references to power amps, despite the power amp being
critical to overdriven tones. A Model T pedal designed with this formula may suffer from
a thin, harsh sound lacking in headroom—a far cry from its namesake.
The Model feT widens this scope by including an emulated power amp, making it a
more complete emulation. After all, without an ultralinear power section, there is very
little distinguishing the Model T from a Super Bass or 5F6 Bassman. I also performed
thorough simulations to account for the subtle but critical differences between the
frequency response and impedances of JFETs versus triodes, which more accurately
reproduces the frequency response of the original amp. As a result, I believe this to be
the most accurate Model T reproduction in solid-state format.
The Model fet may serve as an overdrive pedal into an existing amp, as a preamplifier
going direct into a power amp (alternately into the effects return of an amp bypassing
the preamp), or even into a DAW running a cab simulation. In any of these applications
