The Darkglass Microtubes B1K is a bass overdrive and distortion pedal built by Darkglass. Darkglass describes it as "a phenomenal tribute to one of Darkglass's most legendary distortion circuits in a compact and intuitive format," packing what the company calls the classic Microtubes sound into a small and straightforward format12. Darkglass introduced it as the first of its kind from an all-new lineup, the Spot Series of mini pedals32.
The core of the pedal is its parallel signal design: your clean input signal stays in the chain at unity gain while the overdriven signal sits alongside it, and the Blend knob sets the ratio between the two2. That is the arrangement bass players usually want from an overdrive, because it keeps the low end of the instrument intact while adding saturation on top.
What it does to your sound
Darkglass positions the B1K as the Microtubes distortion tone in a small, straightforward format1. The overdrive side of the circuit sets the saturation, and the clean side, fixed at unity gain, keeps the fundamental of the bass present no matter how hard the drive side is pushed2. Guitar World's writers note that Darkglass "kick-started a revolution in bass pedals with their Microtubes overdrive models," which is the circuit family the B1K draws from42.
Two internal DIP switches shape the character further. Grunt adds a low-end boost that Darkglass says will "massively thicken your sound when engaged," and MBoost gives a 6 dB lift from 300 Hz to 1 kHz, a range chosen to help a bass cut through a mix2.
The controls
Four knobs sit on top of the pedal, and two switches live inside. Darkglass's manual describes the enclosure as having a magnetic bottom lid you open to access the internal controls2.
| Control | What it does |
|---|---|
| Level | Sets the volume of the overdriven signal2 |
| Drive | Sets the amount of saturation in the overdriven signal2 |
| Blend | Mixes the clean input signal with the overdriven signal; clean stays at unity gain, turn clockwise to blend in more clean signal2 |
| Tone | Controls the high frequency content; a variable low pass filter from 3 kHz to 8 kHz, turn counterclockwise for a brighter sound2 |
| Grunt (DIP switch) | Low-end boost to thicken the sound when engaged2 |
| MBoost (DIP switch) | Subtle 6 dB boost from 300 Hz to 1 kHz to cut through the mix2 |
Because the clean signal is fixed at unity gain and the Level knob only sets the overdriven signal's volume, the Blend knob gives fine control over the ratio between the two paths2. In practice that means you can dial in a small amount of grind over a full-range clean tone, or run the pedal nearly fully wet.
Power and connections
The B1K runs on a regulated 9V DC adapter with a center-negative plug only. Darkglass's manual warns that unregulated power supplies or higher voltages may damage the unit and void the warranty2.
There is no battery option: the pedal requires a regulated 9V DC center-negative adapter, and Darkglass cautions that the wrong supply can damage the unit and void the warranty2.
Specifications from the manual2:
- Voltage: 9V DC, center negative
- Current consumption: ~17mA
- Input impedance: 1MΩ
- Output impedance: 1kΩ
At roughly 17mA the pedal is light on a pedalboard power supply. To activate the warranty, Darkglass asks owners to register the product's serial number at mypedal.darkglass.com, and to contact support@darkglass.com before shipping a product back to the company2.
History: the first Spot Series pedal
The B1K was introduced as "the first of its kind from an all-new lineup," the Spot Series, and Darkglass's own copy calls it a tribute to one of its most legendary distortion circuits32. The Spot Series format puts the Microtubes distortion tone in a mini pedal, with the less-used controls moved inside the enclosure31.
How it differs from other Microtubes pedals
Darkglass's product page currently lists the B1K as sold out, so it is not available directly from the maker at the time of writing1.
Videos
The Bass Channel
Patrick Hunter
Bass Bonedo
Questions
What does the Grunt switch do on the Darkglass B1K?
Grunt is a DIP switch inside the B1K's magnetic bottom lid. When engaged it provides a low-end boost that Darkglass says massively thickens your sound. It works alongside the MBoost switch, which gives a 6 dB boost from 300 Hz to 1 kHz to help you cut through the mix.
What is the difference between the Microtubes B1K and the B7K?
The B1K is a mini pedal from Darkglass's Spot Series, built around the Microtubes distortion circuit with four knobs and two internal DIP switches. The B7K is a full-size Microtubes pedal from the same maker with a larger control set. The B1K was introduced as the first of an all-new Darkglass lineup.
Is the Darkglass Microtubes B1K analog?
Yes. The B1K is listed as an analog circuit, and it runs on a regulated 9V DC center-negative adapter drawing about 17mA. It has no digital signal processing; the clean blend mixes your untouched input signal with the overdriven signal.
How much current does the Microtubes B1K draw?
Darkglass's manual lists the current consumption as approximately 17mA at 9V DC. That is low enough that it places little demand on most pedalboard power supplies, though it must be fed by a regulated center-negative adapter.
Is the Darkglass Microtubes B1K discontinued?
Darkglass's product page for the B1K shows it as sold out, so it is not currently available directly from the maker. It was unveiled in July 2022 as the first pedal in the Spot Series. Darkglass support can be reached at support@darkglass.com.
Sources (4)
- Microtubes B1K, Darkglass
- Microtubes B1K Manual, Darkglass
- Microtubes B1K by Darkglass Electronics, RockBoard PedalPedia, 2026
- Best overdrive pedals for bass 2026: The ultimate in bass saturation at all price points, Guitar World, 2026-06-01
