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FX Pedals

Universal Audio UAFX Astra Modulation Machine Pedal

Universal Audio has taken a selection of their finest DSP-powered emulations of classic effects and packed them into thoughtfully designed, ultra-robust guitar pedals that are a tone chaser’s dream come true. The Universal Audio Astra Modulation Machine puts three legendary modulation effects at your feet — a bucket brigade chorus, a flanger/doubler, and a vintage amp tremolo — all of which uncannily bottle realistic analog character and vibe. With true bypass switching and an optional buffered bypass, the Astra Modulation Machine keeps your core tone intact while allowing you to layer on swathes of gorgeous modulation. 

Chorus Brigade

Based on the beloved Japanese chorus ensemble effect that hit the streets back in 1976, the Chorus Brigade conjures up the lush, swirling analog chorusing popularized by guitar legends such as Andy Summers, Jeff "Skunk" Baxter, and Brian May, as well as modern players like John Frusciante, Alex Turner, and Kevin Parker, among others. The Chorus Brigade features two modes: a set-it-and-forget-it chorus and a tweakable vibrato with Depth and Speed controls. Additionally, Universal Audio included the original big gray pedal’s preamp level control for driving the effect into some seriously glorious saturation!


Making its debut in the late 1970s, a bright blue rack-unit flanger and doubler found its way into the rigs of countless guitarists during the 1980s and 1990s. Universal Audio perfectly captured this “meta” effect, which used bucket brigade circuitry to mimic the analog tape flanging effect that was heavily employed by psychedelic bands in the 1960s. Unabashedly lo-fi, the Flanger/Doubler pulls off a range of effects, from unstable-tape-machine wow and flutter to underwater wooshing — all with a deliciously scooped tone and loads of grit.

Trem 65

When it comes to tremolo, nothing is quite like the optical tube tremolos featured on vintage tube combo amps — the ones boldly mislabeled “vibrato”! The Trem 65 serves up that wide-swing sound in spades, with switchable sine and square wave modes, so you can keep it subtle or go in for the hard chop. And for an even more dramatic effect, switch into stereo mode for wall-to-wall panned tremolo!

Two additional free effects: X90 Phaser and Dharma Trem 61

As if the three awesome stock effects weren’t enough, Universal Audio sweetens the pot with two free effects when you register your Astra Modulation Machine — the X90 Phaser and Dharma Trem 61 — which can be loaded onto the pedal via USB. The X90 Phaser gives you access to the “script” and “block” versions of the iconic orange phaser pedal; the Dharma Trem 61 emulates the unique vintage harmonic tremolo circuit installed in certain brownface, blonde tube combos, with a modern dynamics processor that lets you ramp up or ramp down the tremolo speed to a defined rate.

UAFX Control app for even more control

Download the UAFX Control app for iOS or Android and expand your sonic options. The app lets you witch between true bypass and buffered bypass on your Astra Modulation Machine. Plus, the app lets you change the behavior or the right footswitch to choose a preset, tap tempo, or both.

Universal Audio Astra Modulation Machine Pedal Features:

  • 3 classic modulation effect emulations powered by UAD DSP
  • Chorus Brigade conjures up the 1970s big gray unit’s lush, analog chorus and vibrato
  • Flanger/Doubler re-creates the characterful blueface bucket brigade rackmount flanger
  • Trem 65 offers warm, opto tube-style tremolo with sine and square wave modes
  • 2 free effects upon registration: X90 Phaser and Dharma Trem 61
  • Operates in mono, dual-mono, and stereo modes with automatic mono/stereo detection
  • Rugged enclosure with top-notch components
  • True bypass and optional buffered bypass modes
  • UAFX Control app expands functionality