Flanger and Phaser pedals can do great things for your sound, but there are a lot of things to think about before you go shopping for one. This guide explains flanging and phasing, and walks you through some of the big questions you should ask before you buy one.

What are phasing and flanging, and how do they differ?

Flanging and Phasing are similar effects produced in different ways. Both alter your sound by splitting the input source into two paths, an unaffected and an affected tone, and mixing them back together. This causes the waves of the two sounds to interfere with each other, producing the swoop or shimmer (or spooky space-age psychedelia!) we call flanging or phasing.

Flanging is produced by slightly slowing down and speeding up a tone that is then mixed with an unaffected “dry” tone. It originated as a tape effect produced by recording the same sound onto two different tape decks and mixing them together on a third tape while slightly slowing down and speeding up one of the machines. In most cases, flanging is now produced via analog or digital signal processing, and not tape. Phasing has always been a signal processing effect. It uses an “all pass filter” to force some frequencies of a signal out of phase with the dry signal. The two effects are in some ways quite similar, and the terms are occasionally used interchangeably.

Flanging is technically a kind of phasing. It occurs when frequencies in the affected and the dry signal go out of phase with one another and produce interference. The difference between flanging and phasing has to do with the way the phase cancellations are produced: a flanger delays the entire signal, thus sends all of the frequencies of the signal out of phase with the dry tone, while a phaser generally manipulates some number of specific frequencies in the signal. Subjectively, this gives flangers a pronounced and regular ‘whoosh’ sound and phasers a more space-y, random, or unsettling alteration to the sound.

Stereo phasers use two identical phaser circuits for the left and the right channel and put them out of phase with one another.

That’s really interesting, but which one should I buy, Mr. Smarty-Pants?

All this technical stuff is nice, but how should you pick one?

Well that depends on what you’re looking for. There are flangers and phasers that offer many ways of manipulating the sound, as well as ones that produce a specific effect without much variation: one knob and a switch or two. Some of these are really well known, like the ElectroHarmonix Small Stone and the MXR Phase 90. They sound like they sound, and lots of people think they sound really cool.

Two famous examples:

• The classic Eddie Van Halen sound from early Van Halen records was produced with a Phase 90 and an MXR M117R Flanger, and
• The late 70’s Rolling Stones sound on tunes like “Shattered” is all about the Small Stone.

That’s great, but which one should I buy?

Only you can decide what you want from your sound. But here are some questions you should ask yourself before you go shopping:

1. Am I looking for a pedal with a signature sound, or one that can do a bunch of different things?

Flanger pedals tend to have a wider range of control, because phaser pedals’ selling points tend to revolve more around a signature sound based on hardwired presets.

There are phasers with a wider range of control that edge into full Low Frequency Oscillator territory, and are like having little synthesizers at your feet. They can also set you back $300 or more.

So you should decide whether you want a specific kind of effect, like a Phase 90 or Small Stone, or a versatile box that can produce a wide range of effects, like the Moog Moogerfooger. If you’re looking for a box with a signature sound you can skip the next questions and go on to my final bit of advice.

If you’re looking for a versatile box, there are two more questions to ask:

1. How many parameters can I control?
2. How much control do I have over each parameter I can control?

Phasers and flangers both have controls for speed and depth, and often a “feedback” control (sometimes called something like “enhance” or “sensitivity”). Together these control how fast the effect is, how wide the effect is, and how prominent it is in your mix.

Flangers often also have a control called “delay time” or “manual” that determines the intensity of the effect. This is different than the effect’s prominence in your mix. It determines something more like how “off” or skewed the effected sound it, while the above effects have more to do with how the effected sound relates to the dry tone.

Some pedals allow you to control a wide range of parameters, some allow you a wide range of control over each of the parameters, and some offer both. Only you can decide whether you want to have a lot of versatility, the ability to make your sound crazy wild and over the top, or both. So:

A Final Bit of Advice:

Once you have an idea what you’re looking for, look at the range of pedals available on the website of an online music retailer. Search for “flanger” or “phaser” and browse the list of options that comes up. Then browse manufacturer websites or search on YouTube for demos. There are videos online for almost every kind of pedal available produced by the manufacturers themselves, as well as by music stores and private individuals that demonstrate the range of control each pedal offers, and its personality (or lack thereof). These demos can sometimes be even more valuable than trying out a pedal yourself, because they are produced by someone who has already spent a lot of time with the box, and who may be privy to the way it was constructed and designed.

Bruno Sturgess loves to help musicians get the most from their effects pedals.