The RetrogradeFX Underthruster is a compressor pedal that takes its cue from the studio rack: Pedal of the Day described it as "looking and sounding like a true studio rack compressor that has just been squished down into pedal form"1. It is inspired by the dbx 160 Series compressors and uses a Blackmer Voltage Controlled Amplifier (VCA) at its core, the same gain element that made those rack units a studio standard1. If you are new to this effect type, see our guide to Compressor Pedals.
How it sounds
Pedal of the Day reported that the Blackmer VCA results in "smooth compression with little to no distortion"1. The reviewer's verdict on the pedal as a whole: "Really quiet as far as compressors go (like REALLY quiet), it has a ton of tonal options, studio-grade sound and a slick"1. For players who want transparent level control rather than colored squash, that combination of low noise and a studio-style circuit is the pedal's main selling point.
The controls: Threshold, Ratio and Gain
The Underthruster keeps its control section simple, with three knobs1:
| Control | What it does |
|---|---|
| Threshold | Sets the sensitivity level, suited to everything from quiet guitar signals to studio applications1 |
| Ratio | Adjusts the degree of compression, with maximum compression when turned fully clockwise, sending the effect into limiter territory1 |
| Gain | Sets the output level after the compression, making up for signal loss, or acts as a clean boost with the Ratio turned all the way down to 1:11 |
The LED Gain Reduction meter sits alongside these controls and, in Pedal of the Day's words, "intuitively and accurately measures your feedback in real time"1. Watching it as you play makes setting the Threshold and Ratio straightforward: you can see exactly how much compression is being applied rather than judging by ear alone.
Videos
Pedal of the Day
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Questions
What is a Blackmer VCA?
A Blackmer Voltage Controlled Amplifier is the gain element at the heart of the Underthruster's circuit. In a VCA compressor, the amplifier itself changes how much signal it passes, which is how the compression is applied. Pedal of the Day noted that the Underthruster's use of a Blackmer VCA results in smooth compression with little to no distortion, the same approach associated with the dbx 160 Series studio units that inspired the pedal.
How does the gain reduction meter on the Underthruster work?
The Underthruster has an LED Gain Reduction meter on its face. According to Pedal of the Day, it intuitively and accurately measures your feedback in real time, showing you how much compression is being applied as you play. That makes it easy to dial in the Threshold and Ratio by watching the meter rather than guessing by ear alone.
Is the Underthruster a quiet compressor?
Pedal of the Day's reviewer described it as really quiet as far as compressors go, and praised its tonal options and studio-grade sound. The Blackmer VCA design, with little to no distortion, is part of why it stays clean.
Does the Underthruster have an attack or release control?
No. The Underthruster uses a simple control section with just three knobs: Threshold, Ratio and Gain. There is no separate attack or release control; the compression character comes from the VCA circuit, and the player shapes the effect through the Threshold and Ratio settings.
Sources (1)
- RetrogradeFX Underthruster VCA Compressor, Pedal of the Day, 2018-03-26