The TC Helicon Critical Mass is a vocal stompbox that makes one singer sound like a crowd. TC Helicon describes it as a studio-quality vocal stompbox for large group-sound effects: one footswitch unlocks an eight-voice unison choir engine that makes a single vocal sound like a fully tracked group, with subtle timing and pitch variations across each voice1.
It sits in the company's line of vocal pedals for players who sing, alongside units like the TC Helicon Duplicator and the TC Helicon Harmony Singer 2, but its job is group sound rather than tuning or harmony1.
What the Critical Mass does
The pedal's engine is an eight-voice unison choir, engaged with a single footswitch. Each of the eight voices carries subtle timing and pitch variations, so the doubled voices do not line up perfectly, which is what keeps the result sounding like a group of people rather than one voice stacked cleanly1.
Beyond the unison choir, MusicRadar reported at launch that the Critical Mass packs three four-voice gang styles and four melodic choir styles, including unison, octave up, octave down, and up and down, with reverb and octave effects onboard2.
| Style group | What it gives you |
|---|---|
| Four-voice gang styles | Three gang vocal styles for a smaller crowd sound2 |
| Melodic choir styles | Four styles including unison, octave up, octave down, and up and down2 |
| Reverb and octave effects | Onboard, per MusicRadar's launch report2 |
For comparison, harmony pedals such as the Boss VE-2 Vocal Harmonist and TC Helicon VoiceTone H1 generate pitched harmony lines against your vocal, while the Critical Mass is built around doubling and group textures, with its octave-based styles rather than chord-following harmonies2.
Controls, connections and power
TC Helicon keeps the hardware simple: one footswitch unlocks the eight-voice unison choir engine1. Connections are XLR in and XLR out, and the pedal supports 48V phantom power, which matters if you run it with a condenser microphone or a mixer supplying phantom power. It runs on a standard 9V power input, the same kind of supply used by most guitar pedals, and it is true bypass, so your vocal signal passes through unprocessed when the effect is off1.
Where it came from
TC-Helicon launched the Critical Mass in April 2017. MusicRadar's Michael Astley-Brown reported the unveiling, noting that the pedal was available immediately at $149.992.
"The Critical Mass is available now for $149.99"
Videos
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Questions
Is the TC Helicon Critical Mass true bypass?
Yes. TC Helicon lists true bypass among the pedal's features, alongside XLR in and out and 48V phantom power, so the signal passes through untouched when the effect is off.
What power supply does the Critical Mass need?
The Critical Mass runs on a standard 9V power input, the same supply used by most guitar pedals. TC Helicon also lists 48V phantom power among its features.
Does the Critical Mass do harmonies or just doubling?
Its core effect is an eight-voice unison choir doubling engine, not harmony generation. It also offers gang and melodic choir styles that include octave up and octave down variations, plus reverb.
How much did the TC Helicon Critical Mass cost?
When TC-Helicon launched the pedal in April 2017, MusicRadar reported it was available immediately at a list price of $149.99.
Sources (2)
- CRITICAL MASS, TC Helicon
- TC-Helicon reaches Critical Mass with Gang Vocal and Choir FX pedal, MusicRadar, 2017-04-24
