LICENSED PEDALS BUILT BY VFE PEDALS is a DIY site with lots of pedal projects for the hobbyist to build. They are best known for amp-based FET drive circuits, such as the Supreaux Deux & Umble.


VFE is proud to support by offering these pedals as licensed designs through the Pedal Wizard. You can now build these pedals without needing to solder or assemble anything, including your choice of paint color, knobs, graphic and more.

3-6 week build time











When set out to revise and improve the Professor Tweed (based on the classic Princeton amp), they decided to step away from the inspiring amp's circuit and concentrate on developing a solution superior both in tone and usability.


The result is a circuit that is much more flexible and refined than its predecessor, and captures a wider variety of Fender-like tones. This pedal has a very effective and flexible Tone control that varies the sound from fat and warm when set fully counterclockwise, to full at the center, to thin and bright at the clockwise end.


As for the Gain knob, it can adjust the sound from almost clean, to a warmed-up light overdrive, to a medium overdrive, to a quite gainy overdrive. Each stage is set up to produce a moderate amount of gain while avoiding hard clipping in the JFET itself. The result is a refined overdrive with a natural note decay that reacts very well to the guitar's volume knob.


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Demo clips courtesy of FarEye

Through the years since the English Channel (based on Vox AC-30) was released, polished the manner in which the different valve stages used in guitar amps are adapted to JFET-based circuits. This involves taking several aspects into account, such as the effective frequency response of the stage after considering parasitic capacitances, input and output impedances, gain and dynamic range, and clipping characteristics. now presents Britannia, a fully redesigned adaptation of the AC-30 for use as a guitar pedal which has been optimized for playing into a clean solid-state amp. This pedal was designed to be a simple way of attaining the sounds that were made famous by many artists, including The Beatles, Tom Petty, The Edge, and Brian May, to name a few, without having to invest in or carry around the real thing.


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Around 1965, Marshall introduced a few amps built around an 18 Watt EL84 powered circuit. While these models were intended for practice, the sound was much better than other small amps. Unfortunately, only a few hundred of these combos were manufactured over the next three years.


After hearing the sound samples of this amp circuit, decided to give this circuit a try as a distortion stompbox with FETs in place of the tubes.


Although the components designated do not look to be typical Marshall, they do produce results very similar to the soundclips of the amp. Great rock and blues sounds are readily available with this circuit.


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The Flipster,'s only circuit primarily intended for use with a bass guitar, was released in June 2004. It was another adaptation of a vintage tube amp for use as a distortion pedal, namely the Ampeg SB-12 Portaflex introduced in 1965.


Several bass players in the DIY-fx community acted as beta testers during its development, and while the resulting circuit captured a good deal of the target sound, it had higher gain and the overall frequency response was inaccurate due to impedance differences.


In this "next generation" version named Ginger, each stage has a pair of clipping diodes at the gate to avoid hard clipping in the JFET stages. Additionally, each stage has been adjusted to provide overall circuit gain more faithful to the Ampeg SB-12 Portaflex.


While the circuit is intended for use with a bass, it also provides excellent overdrive for a guitar and the flexible tone controls allow a great deal of fine-tuning.


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The Supreaux Deux differs from other FET-based designs based on tube amps, since we had the benefit of owning the actual amp to compare with the stompbox version. The revisited circuit captures much of the amp's tone. The brilliant treble response is replicated, along with the Tone control range. A sweet overdrive even kicks in at nearly the same point in the Volume pot's rotation!


Many sounds, from Albert King-type tones to a Led Zeppelin sonic blitzkrieg to sparkling clean can be produced with the Supreaux Deux. Be sure to work your guitar's volume knob and your pick attack when playing with this circuit, as it is very sensitive and dynamic.


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The Thunderchief project, released in March 2004, was the first circuit that was developed using the tubes-to-FETs process - in an effort to capture some of the legendary magic of the Marshall Super Lead.


The circuit's performance was good, but there were issues. There was no tone stock, and like many tube-to-FET distortion designs, and it had too much gain to accurately ape the sound of the amp. developed a tone stack using an active second order high pass filter combined with deep bass boost capability. They used second generation Fetzer Valve circuitry to make the distortion characteristics more representative of the vacuum tubes in the amp. Finally, the gain range was updated, and now yields a much more amp-like gain range.


Inspired by the Marshall Super Lead, the new circuit a was givenname befitting its thunderous sounds: THOR.


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There are numerous pseudo-vibrato implementations built around modified chorus and phaser pedals. Several shortcomings to these approaches exist, such as: non-sinusoidal modulation, uneven frequency modulation across the audio band, poor noise performance, limited bandwidth, and intrinsic time delay.


The Tri-Vibe is built on the OTA LM13600 chip to solve many of these problems. But that’s not the only challenge - the LFO needs generate a suitable modulation signal for vibrato use. Most phaser and chorus pedals adapted for vibrato mode, the lack of "proper" modulation vs. time produces an unappealing "motion sickness" characteristic. By using a more natural sinusoidal waveform, the Tri-Vibe produces a unique, vintage vibrato sound.


The VFE version updates the 3-way mix switch into a variable mix knob, so you can go from subtle swirl to full-up vibrato and every shade in between.


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There has always been much talk about the mystical hand-built amps that a particular man sells for around $10,000 each. Some claim these are the greatest amplifiers known to man, while others maintain it's all hype.


The team set out to distill the available information and come up with a circuit that was, at the very least, heavily influenced by the amps. They opted for the preamp section only, since the "precision power amp" is intended to be clean and not readily distort.


The resulting circuit is called Umble. The circuit uses the gain stages from the '70s ODS model and the tone stack from the front section of the '97 ODS model. While nothing can replace an original, the Umble sounds much smoother and more like the famous recordings than you would get from digital modelers.


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One of the first amps to offer distortion at lower volumes was the Boogie MkI amplifier. As told by Randall Smith, the designer of the Boogie amp, these amplifiers were born of a practical joke on a guitarist friend. Mr. Smith modified a Fender Princeton to have considerably more gain and power, but appear stock. As the story goes, Carlos Santana play-tested the amp and was impressed. Carlos was quoted as saying the amp "really boogied!" Thus, the name of the amp was born.


The amp is basically a Fender design, but modified to produce large amounts of preamp gain. The circuit is named Uno, in homage to both the Boogie version number and Carlos Santana.


The old blues player's trick of reducing the Bass control at high gain settings works very well with this circuit.


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