The TWA Krytical Mass is an octave fuzz pedal made by TWA (Totally Wycked Audio). Its fuzz circuit is inspired by the vintage Maestro Bass Brassmaster1. TWA describes it as producing "fat, formidable fuzz with a pronounced octave up as well as a more subtle octave down and a scorching, filter-like sweep on sustained notes"1. It carries a US list price of $2992, and a "Critical Mass Reaction" LED array indicates effect status and can be set to cycle or stay steady-on3.
Like all TWA pedals, the Krytical Mass was manufactured in a limited batch of 100, and the timing of a next batch is unpredictable.
What it does to your sound
The Krytical Mass is an octave fuzz: it layers a pronounced upper octave harmonic and a more subtle lower octave harmonic over the fuzz1. The "reactive" part is how it responds to your playing. The sensitivity control adjusts the fuzz intensity and is responsive to picking dynamics and guitar volume settings5, and muted notes cut the fuzz off almost like a noise gate, which TWA says yields a super-tight, synth-like pulse1. Sustained notes get a scorching, filter-like sweep1.
The Krytical Mass's controls reflect its Brassmaster-inspired design. Its four toggle switches include one high pass filter and two low pass filters, alongside a 3-way mids knob4. The high pass filter toggle shapes how much low end reaches the fuzz circuit, while the two low pass filter toggles shape the top end of the octave and fuzz character4. Combined with the mids control, these switches give the player a set of voicing options before the fuzz and octave circuits do their work4.
The Krytical Mass is a fuzz pedal whose circuit is inspired by the vintage Maestro Bass Brassmaster, an octave fuzz design1. Its controls reflect that heritage: four toggle switches, including one high pass filter and two low pass filters, plus a 3-way mids knob4. A "Critical Mass Reaction" LED array indicates effect status and can be set to cycle or hold steady3.
The controls
The control set splits between knobs and a bank of toggle switches. The maker's page and the release coverage describe them as follows.
| Control | What it does |
|---|---|
| Sensitivity | Adjusts fuzz intensity; responsive to picking dynamics and guitar volume5 |
| Edge | Adjusts the overall brightness of the fuzz3 |
| Bias Voltage | Adjusts the transistor bias to taste, accentuating 2nd-order harmonics for more lows or higher-order harmonics for more complex waveform content1 |
| Transformer polarity switch | Toggles between positive and negative phase transformer wirings for additional tonal options1 |
| Four toggle switches | One high-pass filter, two low-pass filters, and a 3-way mids control4 |
The HPF switch activates a high-pass filter5, which is useful for taming low end, particularly on bass. The bias voltage adjustment is the deepest of the knob controls: leaning it toward 2nd-order harmonics keeps more lows in the sound, while leaning toward higher-order harmonics produces more complex waveform content1.
The pedal also carries a "Critical Mass Reaction" LED array that indicates effect status and can be set to cycle or stay steady-on3.
Expression pedal control
The fuzz sensitivity can also be controlled by an external expression pedal, which Delicious Audio's coverage describes as allowing dynamic manipulation of the fuzz while you play4. That makes the reactive character hands-free: rock the expression pedal to swell the octave fuzz in and out rather than working the guitar's volume knob.
Power, bypass, and build
The Krytical Mass runs on 9 VDC and requires an external power source, so there is no battery option3. Bypass is mechanical true bypass3, which GuitarPlayer's review confirms as mechanical on/off with true bypass5. The pedal is made in the USA and carries a 3-year warranty3.
Maestro Bass Brassmaster roots
The circuit is inspired by the vintage Maestro Bass Brassmaster, a bass fuzz whose transformer-based octave character has made it a recurring reference point for builders. The Brassmaster's design lives on in DIY circles too: General Guitar Gadgets sells a Maestro Brass Master replica project kit and PCB, built around a 42TM018 transformer, with controls including a Harmonic Hi/Low toggle, a Bass Volume potentiometer, and a switch selecting Brass 1 or 2 modes6. That project is recommended only for builders with some experience assembling effects6.
The Krytical Mass is not a straight clone, though. Where the Brassmaster replica keeps its small fixed control set, TWA's version adds the bias voltage adjustment, the transformer polarity switch, and the filter toggles14, and GuitarPlayer's reviewer found it more straightforward than TWA's own earlier prototype while keeping a wide tonal range5.
Limited batches and availability
TWA builds its pedals in small runs. Like all TWA pedals, the Krytical Mass was manufactured in a limited batch of 100, and the maker states the timing of a next batch is unpredictable1. As of October 2026 it is sold out with no new production scheduled; Godlyke keeps a waitlist by e-mail1. Players hunting a TWA octave effect may also encounter the TWA WX-01 Wahxidizer, an envelope-controlled octave fuzz filter wah distributed by Godlyke, or the TWA Microchasm Octave Box Fuzz.
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Mike Hermans
Godlyke Inc.
Godlyke Inc.
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Questions
What is the TWA Krytical Mass based on?
Its fuzz circuit is inspired by the vintage Maestro Bass Brassmaster, a bass fuzz from the 1970s. TWA's version keeps the transformer-based octave character but adds modern controls, including a bias voltage adjustment, a transformer polarity switch, and filter toggles.
Does the TWA Krytical Mass run on a battery?
No. It runs on 9 VDC power and requires an external power source, so there is no battery option. Plan on a spot on a power supply rather than a daisy chain or battery clip.
Is the TWA Krytical Mass true bypass?
Yes. It uses mechanical true bypass switching, so with the effect off the signal passes through without buffering. GuitarPlayer's review also describes it as mechanical on/off with true bypass.
Can I use an expression pedal with the TWA Krytical Mass?
Yes. An external expression pedal can control the fuzz sensitivity, which lets you manipulate the fuzz dynamically while playing, sweeping the intensity of the octave effect in real time.
Is the TWA Krytical Mass still in production?
Like all TWA pedals it was made in a limited batch of 100, and the timing of any next batch is unpredictable. Godlyke keeps a waitlist by e-mail.
Where is the TWA Krytical Mass made?
It is made in the USA by Totally Wycked Audio and distributed by Godlyke. It carries a 3-year warranty.
Sources (6)
- KRYTICAL MASS®, Godlyke Distributing, Inc.
- Guitar Pedal X, Guitar Pedal X, 2023-12-18
- New Gear: TWA Releases Krytical Mass Reactive Octave Fuzz, Bass Musician Magazine, 2023-09-06
- TWA Krytical Mass Fuzz, Delicious Audio, 2023-09-26
- Shelved for 15 years of tinkering, Totally Wycked Audio's homage to the early '70s Maestro Bass Brassmaster, the Krytical Mass KM-01 Reactive Octave Fuzz, is finally here. And it's totally Wycked…, GuitarPlayer (www.guitarplayer.com), 2024-01-08
- Maestro™ Brass Master™ Clone: Bass Fuzz Kit, PCB & Schematic, General Guitar Gadgets, 2014-05-12
