JFT Class-A Transistor Colour


  • Full Kit
  • Step-by-Step Guide
  • Supported
  • Intermediate

Thick, musical saturation that shines on any source.

Part of the magic of vintage solid-state gear is that, because transistors were expensive, they used as few as possible, so each one had to work harder. And when transistors are pushed to their limits, they begin to distort in beautiful ways. The JFT Colour is designed by this philosophy: choose great-sounding transistors and then make them work very hard.

The JFT employs two class-A saturation stages to create a complex, layered character. In the first stage, a NOS JFET generates asymmetrical distortion, clipping the bottom of the waveform but not the top. This type of saturation, which is associated with triode tubes, thickens and warms up the signal while maintaining its integrity. In the second stage, five transistors form a primitive discrete opamp which operates just on the verge of instability. This stage applies a subtle layer of harmonics which give the Colour a “finished” sound.

MKII Improvements

In 2019 to celebrate the fifth anniversary of the Colour Format, we redesigned the first three Colours, the 15IPS, CTX, and JFT, to use only discrete, class-A transistor circuitry. You could think of this as the opposite of an update—we’ve reversed the technology of the Colours back to the late 60’s. The result is an authentic vintage character that’s more nuanced and refined.


  • Discrete, class-A saturation circuitry
  • NOS 2SK170 transistor for musical, tube-like harmonics
  • Compatible with the Colour format
  • Blue PCB
  • Full, step-by-step assembly instructions and guaranteed support

Customer Reviews

Based on 5 reviews
Peter B
Fantastic module

Super easy to build, and a perfect in-between for when you don't want full-on distortion/fuzz, but everything else is too subtle.

Great all-rounder when you need a little more musical distortion

I have a number of Colour modules that all sound amazing - some are more specialised and others get put on anything and everything.

I can see why this is in the Primary Colours. The CTX is more subtle and can be used on anything, the 15ips has 'a sound' which I often use for bass, kick and some vocals; the JFET works on anything when you need a bit more obvious distortion.

Once recorded a valve guitar amp in desperate need of servicing. The drive channel sounded unbearable when you cranked the gain and the guitarist refused to use any other amp available. Adjusted the tone control, swapped mic's, turned them off-axis, moved the position, changed the preamp - but it still sounded shrill every time you turned the gain up on the drive channel. I turned the gain down until it was just breaking up and then put it through the JFET to get it going - it sounded perfect. Great to have when you need a bit more distortion but still want it sounding musical.

cool 60's-70's ish transistor crunch

was it sugar pops that made the crunchy popping sound? reminds me of an early transistor guitar rig. Bitey, quick, tasty distortion. Good dynamic response, I expect this one to be very useful in the studio on my midi sax guitar, keyboard and synth tracks and a key component of my developing live rig. Mojo to Go

Paul Najar
Nice Colour

This was my first colour build. It was easy and quick. The sound is great for a transistor based saturation even at hi gain. It doesn’t seem to crap out very easily. It’s early days but so far I like it on guitar and am keen to try on bass and and vocals. We shall see. Recommended.

Joseph Chudyk
Instant Beautiful Mixable Distortion

I've also been using the mkI for five years. The mkII has so much more of a smoother distortion characteristic that I find myself reaching for more and more in a mix. Right now I have a pair set up for a parallel mix that I can send any element in Pro Tools to for added weight, warmth or pure destruction. It offers a different harmonic flavor that the other colour modules don't offer. Again, another piece of my setup that I can't do without.

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