MXR Model 126 Flanger Doubler

Curating the Cabinet can be quite an exhaustive effort. Among the scads of pedals two rows deep sits a myriad of gear, and with the strength of the front row, sometimes we never reach the back. Today’s pull says that we should reach further much more often. For at the bottom, in the back row, sits a unit I forgot I owned, not to mention existed: the MXR Model 126 Flanger Doubler.

If you need a moment to collect yourself and realize that MXR made a piece of rack equipment, take as much time as you need. Then take as many as you need when you find out they made eight (not counting equalizers). If you didn’t know MXR also made drum machines, pour yourself a drink, it’s going to be a long read.

As celebrated and ubiquitous as MXR’s pedal offerings are, it’s sometimes tough to remember that it wasn’t always singularly colored boxes with the infamous block (or script) logo front-and-center. Several other lines were released, including the Commande series and the 2000 series And as much ado has been made about the stompboxes, the rack equipment was universally celebrated by gear aficionados everywhere, yet today’s players have mostly forgotten about them. Did you know MXR also made a Pitch Transposer back in the ‘70s?

That and the Model 126 were the breakout pieces of the rack series. You could find them in studios across every nook and cranny of the world, and many of them are still in use. The “doubler” effect involves a slight delay, and its usage in a piece of studio equipment is no accident. Doubling was, after all, invented in a studio.

The actual practice of vocal doubling was discovered in the ‘50s, and wasn’t automated until 1966. The effect itself involves recording an instrument exactly, be it vocals or guitar, that when combined delivered a much richer rendition of the original. While performing an exact copy of a track on guitar or drums wasn’t so difficult, vocals were another story. Performing this way in a studio was a real headache, until Ken Townshend of Abbey Road studios was spurred into action by John Lennon on the recording of Revolver.

Using bucket-brigade chips, engineers were able to simulate this technique by slightly delaying the input signal, then playing it back in concert with the original. It’s a simple enough task, but the implementation requires a deft hand and plenty of processing. The 126 uses two BBD devices, the well-trodden Reticon SAD1024 and the much more mysterious Reticon R5101 chip, for which no datasheet seems to exist. It is the mystique of this chip that makes modern reproduction of the juicy Doubler circuit impossible. That hasn’t stifled demand for the old units, however. And because automatic doubling is such a studio life raft, MXR’s 126 saw plenty of use on everything from drum tracks to synthesizers, and still does.

As for the Flanger side, the 126’s architecture has much more room for precise bipolar bias voltages, and MXR’s crew had much more real estate to make a superior flanger to the 117 that already existed in stompbox format. While the controls are nearly identical, the flanging itself was extremely juicy and may be one of the finest examples of the effect that has ever been released.

This is responsible for the high prices of the unit—that and the host of famous players that have made use of them over the years, including Eric Johnson, Zakk Wylde and Eddie Van Halen. While those two players made great use of the Flanger side, it was Dimebag Darrell that sent prices shooting up even more. He put the 126 into Doubler mode and never turned it off. Ever.

For as little mention as this unit gets, UAD still makes a fully-licensed precisely-engineered plugin version of the 126. And as far as technology has come since 1978, “bucket-brigade” is splashed about the product copy with wanton abandon; there are some things that raw binary processing power just can’t improve upon.