Jon Blackstone crafts guitar distortion devices that generate low-order harmonics, and are responsive to dynamics. This is the type of distortion that re-shapes the body of the note, instead of coating it with a noisy fizz.
As a guitarist/inventor, Jon has pursued these characteristics for many years, using a variety of technologies including overdriven tube output stages. Interestingly, he has achieved the best results not with tube circuits, but with small-signal MOSFETs and an unconventional input stage.
Blackstone's current standard product is a very small (4.4"x 2.4") battery-powered floorpedal called the Mosfet Overdrive. It provides two footswitchable channels, each with its own drive and level settings, and true mechanical bypass.
Where the vast majority of overdrive pedals create distortion with a pair of head-to-toe diodes, the Mosfet Overdrive instead utilizes four gain stages, each contributing a small amount of soft clipping. This avoids intermodulation and the creation of fizzy high-order harmonics, just as in the best vintage amps. Those amps sound good in large part because the distortion does not occur at just one point.
The 3 main ways in which the Blackstone sounds different:
No fizz. Like a good amp, the Mosfet Overdrive imparts harmonics that seem integral to the tone, as opposed to a disconnected fizz. This is not just filtering after the distortion, but a tailoring of each stage to prevent the generation of high-order harmonics in the first place. It's glassy at low settings, becoming fat and midrangey when cranked. This is the opposite behavior of most pedals, which get thinner and fizzier at high settings.
Control it from your guitar. Another area where the Blackstone stands out is in how you can control it with the volume control on your guitar.
It doesn't "plink". Many distortion devices tend to over-hype attack transients, giving each note the same "chirp" regardless of what you're doing with the pick. The Mosfet circuit exhibits a minimum of this tendency. It only spits when you dig in. It emphasizes the body of the note, making it easier to get notes to hang on, but with none of the "auto-pilot" feel of a gain-riding compressor.