The classic sweeping effect of the MXR® Flanger/Doubler (Model 126) has been heard on countless recordings over its 30-year legacy — from rock to pop to new wave and early techno. Through its signature flanging, doubling, and delay effects, this sleek blue box can put a unique stamp on guitars, bass, synths, drums or just about any source needing movement and depth.

In this article, we’ll show you some tips and tricks to get started with the MXR Flanger/Doubler Plug-In for UAD-2 (Available as part of the latest UAD software download). As always, be sure to read the UAD User Manual to get the full rundown.


Flanging emerged as a tape effect in the 1960s, with two tape machines playing two identical and synchronized signals, and one being gradually delayed to create unique comb filtering effects. In the late 1970s, MXR introduced the famed Flanger/Doubler rackmount unit which, unlike tape flanging, recreated this effect electronically via an analog “bucket brigade” design, which tends to color the signal with a unique “warm” and low-fi sound.

Learning the Controls

The Sweep section is a primary
control for the sound of flanging.

The MXR Flanger/Doubler plug-in is laid out in a similar fashion to the original hardware unit, though some extra buttons were created for special “plug-in only” features.

The Manual knob determines the delay time of the effect, and is modulated by the Sweep LFO whenever the Width value is higher than 0%. The Sweep section, which includes the Width and Speed knobs, controls the character of the LFO modulation — Width determining the amount of modulation, and Speed controlling the rate of modulation over time.

The Mix knob adjusts the blend between the original dry signal and the processed wet signal. When set to minimum, only the dry signal is heard (though it is still colored by the original electronics of the unit).

The Regeneration knob is a feedback control for the delay effect, and creates a more resonant signal as its value is increased. Unlike other delay-style effects, Regeneration for the MXR Flanger/Doubler has a limited range that prevents feedback runaway, even when set to the maximum value of 100%.

Maximizing the Flanger Effect

The Mix knob controls the
amount of flanging heard.

With the MXR Flanger/Doubler plug-in, you can dial in subtle flange and doubling effects, or you can tweak it for really dramatic results. For the most extreme flanging effects, set the Mix knob to a 50/50 blend and set the Sweep Width to 100% so the LFO is modulating at its maximum range.

Increasing the amount of Regeneration will create more resonance in the signal. Also, try experimenting with the Sweep Speed — a fast speed gives you a fast-moving, wobbly flange effect, while a slower speed creates smoother modulations.

Next, try the Invert switch, which will flip the wet signal’s polarity when combining it with the dry signal, resulting in a more “hollowed-out” sound.

Setting the Tempo Sync

Unlike the hardware, the MXR
Flanger/Doubler plug-in lets
you sync to tempo.

Unlike the original hardware, the MXR Flanger/Doubler plug-in allows you to lock your LFO Sweep Speed to a particular beat value based on your session’s tempo. To do this, engage the Sync button. The LFO Speed in the rate display window will change to note duration values and sync to the tempo of the host application using the displayed note value.

Setting up an LFO Reset

Click the LEDs above the
Manual knob will set the
sweep downward in pitch.

Normally the Sweep LFO is free-running. However, on some occasions, you may want to start it in precisely the same place, for bouncing or mixing.

The Sweep LEDs above the Manual knob are a hidden control that allows you to set the Sweep LFO so the sweep cycle can be consistently controlled. Clicking either LED under automation writing will set the sweep downwards in pitch and can be automated for mixing or bouncing.

Using the Flanger Effect in Stereo

The Single/Dual switch works
in stereo to dramatically
alter the effect.

While the original MXR Flanger/Doubler hardware was mono, CV controls in the rear of the unit allowed two units to operate in tandem. With the UAD-2 plug-in version, the MXR Flanger/Doubler operates in true stereo, allowing some unique effects.

Single mode is switched on by default, and the stereo effects are most audible when the source material has a lot of stereo panning involved. In Single mode, the left and right signals are processed identically, with the Sweep LFO for both channels in phase with each other.

When Dual mode is enabled, the processing is applied to both the left and right channels with a phase difference of 180° applied between the Sweep LFO of the two channels. In this case, a mono in, stereo out configuration will still give a dramatic left to right effect.

There is also a Mono switch that can be useful for checking phase relationships — or as a creative effect, such as adding stereo emphasis on a bridge. Engaging the Mono switch will sum the stereo output of the wet signals to mono.

Using in Doubler Mode

Easily double vocals, guitars
and more in Doubler mode.

The MXR Flanger/Doubler can produce great "lo-fi" doubling effects for vocals, guitars, keys and more. When in Doubler mode, all controls have the exact same functionality as in Flanger mode, with the only difference being that the delay times are longer, providing audible delays. The delayed signal produces a very short echo, and a “double” of the original signal is heard.

For a clean doubling signal, turn the Sweep and Regeneration controls off. You’ll hear a slight delay between the original signal and a doubled second signal, and you can use the Manual control to tune the amount of delay to your liking.

You can add more spice to the Doubler by upping the Regeneration controls slightly, creating a small repeat effect. You can also get some very far out, warped sounds by cranking up the Sweep Width and Speed.


Of course, the ultimate way to approach the MXR Flanger/Doubler plug-in is to experiment with your source material and the various controls (especially the Sweep and Regeneration) to dial in your own unique effects. As with many things, you’ll find that using your ears and natural creativity can take you a long way.

Products in this article: MXR® Flanger/Doubler Plug-In