From the maker:

Description:
Blackstone’s current standard product is a very small (4.4″x 2.4″) battery-powered floorpedal called the Mosfet Overdrive 2S. 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 Blackstone circuit is also unusual in that it interacts with the inductance of your guitar’s pickups to get its unique dynamic response. It is very sensitive to playing dynamics, but translates them into changes in waveform distortion, rather than passing them on as changes in output level. This gives you a greater range of expression in your picking technique, but at the same time evens out volume differences. Because the guitar’s pickups and controls are actually part of the input stage, you can get anything from a juicy, harmonic-laden lead sound to a barely-breaking twang with just the guitar’s volume control.

The Mosfet Overdrive is designed to provide these sought-after distortion characteristics entirely on its own. It is not a “boost” pedal meant to cause distortion to occur in your amp. The ideal amp to use with it is the one that best gets the clean sound that you like. The Blackstone will take it from there.

Specs
Controls:
Bypass footswitch
Channel footswitch
Pilot light
(red or amber to indicate channel, off to indicate bypass)
“Red” channel drive adjustment
(minimum at 12:00, clockwise increase for single-coil pickups, counterclockwise for humbucking)
“Red” channel level adjustment
“Brown” channel drive adjustment
“Brown” channel level adjustment
Post-distortion EQ adjustment
(cuts midrange at 750Hz, up to 10dB)

Connectors:
Input: 1/4″ phone
Ouput: 1/4″ phone
Power: 5.5 x 2.1mm barrel jack, center negative

Power:
one 9V battery, alkaline recommended
or 9VDC AC adapter (not supplied)
Power consumption: ~ 17 mA

Internal adjustments:
Stage 2 Gain, Stage 2 Treble
(adj. w/jeweler’s screwdriver)

Bypass switching:
True mechanical bypass

User-replaceable components:
Socket-mounted capacitor that limits output presence
Socket-mounted capacitor that tunes Red Channel bass at counter-clockwise setting

Other:
Cast aluminum chassis with power-coat finish, Carling switches, FR4 (Epoxy-Fiberglass) plated-through-hole circuit boards, No electrolytic or tantalum capacitors in the signal path. Made in USA.*

Dimensions:
4.4″(112mm)W x 2.4″(61mm)D x 1.25″(32mm)H to top of enclosure, 2″(51mm) Ht

Initial thoughts:

This is a pedal I’ve been curious about for a long time initially because of the unusual form factor and flush mounted jacks. I even sent a note more than a year ago to John Blackstone and asked about his experience with its usability as a bass pedal. He responded quickly and politely, but indicated he thought it would be ‘ok’ at best.

I took his advice and moved on to other GAS induced purchases. Then the fateful day came when I cheap “buy it now” sale appeared while surfing the darkest wilds of e-bay. Flush with cash from a slew of personal sales, I impulsively purchased it.

Looking into the product manual a bit more, I decided to toy with the socket mounted caps on the insides and tweak internal knobs freely to see what I could hear!

Video Overview

Samples

Positions for Testing(in o’clocks):

1. 1: red level 10, red drive 3 eq: 5 (flat)
2. 2: brown level 10, brown drive 4, eq: 7 (scooped)
3. 3: brown level 10, brown drive 4, eq: 5 (flat)

Note: Headphones or good speakers required. Bass samples!

Active J

P Bass

Picture Gallery

Construction and cosmetic concerns:

The fact that the pedal has no obvious knobs is the first thing that catches most people’s attention (mine included), but closer inspection reveals small board mounted pot shafts that sit just above the fact of the board. These pots are a loose enough that you can turn them with the edge of a pic or a fingernail, but you are not likely to change settings accidentally. Since these pots are board-mounted and peek through the front chassis I would assume this pedal is a little more vulnerable than average to damage from having a beer (or other liquid spilled on it). Additionally, in doing some research on the pedal I found some comments/concerns about the stomp switches being mounted directly to the board. That said, in the couple of months that I’ve been using it the pedal seem nothing if not solid. The pedal is pretty tightly packed in the small box and one of the compromises that has been made is the jacks and power supply connector are very close together, so those that rely on wide flat pedal board connectors will have an issue getting everything to fit. The case itself is coated in a thick black covering (powder-coat?) that has a matte finish and a bit of texture to it which seems extremely durable.

In addition to the external controls, there is also a pair of tweak-able trimmers inside, a buffer switch, two user swappable capacitors. This bad-boy has been designed to be a tweaker’s wet dream. So if you are the one knob, plug-and-play type you may want to look elsewhere.

Conclusion:

I think this is a very high quality pedal that is designed with the serious gigging artist in-mind. You can spend quite a bit of time getting this pedal configured to sound good with your gear, and just leave it alone forever after. Despite not being designed or recommended for bass, I found that after switching the internal capacitors (see video) to larger values I was able to get a little more low-end out of the pedal. Frankly, it wasn’t that bad to begin with! This pedal isn’t designed to be an over-the-top type drive, but rather a natural two-channel grit with an amp-like response and I think it succeeds with flying colors. As of this review it has taken a top spot for me as a low gain dirt pedal.

It’s a wonderful time to be a bass player.

As always, if you have any questions, leave a comment or let me know

Note: A rating of 5 = acceptable and should considered a ‘good’ basic score