Ultimate Guide to Phaser Pedals

Since its appearance on the scene in the '60s, the Phaser has become one of the most recognisable guitar effects available on the market.


Pioneered by the likes of Hendrix and Van Halen, this simple pedal has the capacity to warp your tone beyond recognition. Read on for the full lowdown on how to find the perfect Phaser for you!


Set To Stun: An Introduction To Phasers

The term 'Phaser' was originally used in some cases to refer to the popular tape flanging effect, whereby two reels of tape played the same signal but one was slightly slowed down by regular intervals. This created a slow 'whooshing' effect that we know now as the Flanger.


It was in the late '60s, however, that the Phaser came into its own. The Uni Vibe effects pedal from Japanese manufacturer Shin-ei pioneered the phase-shift sound via an up-and-coming guitarist called Jimi Hendrix. By the early '70s, the Phaser had become a readily available portable guitar effect - and the rest is history!


In this guide, we’ll explore the Phaser effect’s unique qualities, the big names in the category, and how you can incorporate it into your sound, taking you one step closer to finding the pedal that’s right for you!

The Phaser Effect

Before we begin, let's have a listen. Eddie Van Halen is known for his love of Phaser effects, among other things. Check out the intro to 'Atomic Punk':

Notice that the Phaser has an almost speech-like quality, as if your amp has a mouth that opens and closes. Although this iconic tone summarises the effect rather nicely, a Phaser can be tweaked to attain many weird and wonderful sounds!

How Does A Phaser Work?

A 'phase' is a position on a frequency spectrum - when you see a waveform, you're seeing numerous phases beginning and ending as they hit the zero degree axis.


The Phase-shift sound is achieved by mixing two identical signals together; one signal is the dry input signal, but the other has multiple peaks and troughs applied to its frequency spectrum - this is called an all-pass filter, meaning any frequency can be cut or boosted. The position of this filter can be gradually moved around using an LFO, and this altered signal is then combined with the original.


Because of the movement caused by the LFO, your guitar goes in and out of phase - the frequency spectrums of the two signals match, then unmatch, then match, and so on...and this, folks, is how you create a swirling Phaser effect!

Phasers often use multiple all-pass filters in a chain - this is why some Phasers have multiple 'stages', creating more complex overtones. In some cases, the output can also be partially fed back into the input, generating feedback that adds another dimension to the sound. Here's a nice diagram that'll do a way better job of explaining:

How do I use a Phaser?

There are several things to consider when using a Phaser. As you've heard with our Van Halen example, it's an extremely obvious, in-your-face effect! But in order to make the most of its boldness, you'll need a little bit of extra knowhow!


These are the most common controls that you’ll encounter on a Phaser. Let’s take a closer look at what they do:


  • Speed / Rate – you may have already guessed that this controls the speed of the LFO that controls the position of the Phaser's all-pass filters. A low rate gives you a slow-burning 'open & close' effect, but when you increase it, your tone will reach new levels of swirling sci-fi glory!


  • Level – sometimes called ‘mix’ or ‘wet/dry’, this controls the amount of the effect applied vs. the dry input signal. With the depth set to minimum, you’ll only get a faint suggestion of movement, but set it to full and your guitar will be virtually unrecognisable.


  • Depth – this controls the size of the peaks and troughs in the all-pass filter. The bigger they are, the more warped your guitar will sound!


  • Feedback – this controls the amount of output signal that’s fed back into the input. It’s in the term ‘feedback’; similar to when you hold a microphone next to a speaker, the signal snowballs into a wash of noisy overtones. This can sometimes be used to dramatic effect, giving your sound an otherworldly distorted quality.

Signal chain

As with most modulation effects, Phaser traditionally sits towards the back end of your pedal chain, after everything except ambient effects like reverb and delay.


This means the effect will apply to everything in your chain so far, including distortion, EQ, filters and more. You can play around with this order to create more abstract sounds; it's worth noting that some prefer to put modulation pedals in the effects loop of their amp, if they have one. This ensures that the effect applies only to the cleanest version of your signal - but it's all down to preference!

Phaser vs. Flanger vs. Chorus

These three modulation effects work in very similar ways. They all mix your dry signal with a filtered/detuned signal to create an abstract sound. Because of this, it can be easy to get them mixed up! Each one creates a modulated effect using an LFO, but tweaked slightly differently - so what is the difference between flanger, phaser and chorus? Here's a quick breakdown:


The phase of your signal's waveform is adjusted by an LFO, then mixed with the dry signal. The frequencies that are out of phase cancel eachother out, causing a warped, wavy sound.


With flanger, the dry signal is mixed with a delayed signal swaying between 5-25ms The delayed signal is then fed back into the chain creating harmonic feedback.


And with chorus, your dry signal is mixed with a slightly detuned and delayed signal. The LFO controls the pitch of the delayed signal, and the further you push the pitch, the more wobbly the effect.


IN SUMMARY: A phaser uses an LFO to adjust the phase of your waveform, a flanger uses an LFO the adjust the delay of the signal, and chorus uses an LFO to adjust the pitch!

Popular Models

Next up, we're going to take a look at some of the big names in the Phaser category. These pedals have helped define the effect itself, so chances are you may well recognise some of them.


This small selection is made up of just a few of our favourites, containing both vintage and abstract sounds and will fit neatly onto your board. Let's take a look:


  • Electro Harmonix Bad Stone Analog Phaser - EHX originally released the Bad Stone in the '70s, and it very quickly became a pedalboard staple. This updated & ultra-affordable version features a slower minimum rate, plus the super-useful manual shift control. This lets you cut the LFO movement out of the equation, giving you a static parked-wah phase sound!


  • MXR Phase 90 - arguably the most recognisable of the bunch, the Phase 90 brought the phase-shift effect to the masses. With a single control (speed), this pedal does the rest of the work for you. Eddie Van Halen loved it so much, MXR made him his own signature version!


  • Boss PH-3 - Boss's take on the Phaser offers far more flexibility for a little extra cash. It allows you to choose the number of all-pass stages to your phase sound, choose the sweeping direction (up or down, shepard tone-style), hard-edged step phasing for robotic sounds, and has a tap-tempo footswitch option! Killer!


  • Empress Effects Phaser - this is the all-singing, all-dancing powerhouse! Offering unparalleled tweakability, expression pedal connectivity, 8 unique phase-shift modes, built-in signal boost and much, much more, the Empress Effects Phaser is the ultimate toolkit for guitarists who like their tone modulated!


Although most multi-fx units feature a wide range of sounds, there are some that specialise in modulation. Here are some key players:


  • Strymon Mobius - 12 different modulation types including a spacey Phaser effect. The usual controls apply but you're able to store your own presets - 200 to be precise! Other neat features include manual tempo input, formidable processing power and full MIDI implementation.


  • Boss MD-500 - similarly to the Mobius, the MD-500 features MIDI in/out and user preset banks that can be easily toggled to and fro. However, this incredible all-in-one features 28 modulation types across 12 modes and studio-level 32-bit sound with a 96 kHz sampling rate. Blissful.


  • Line 6 MM4 Modulation Modeller - for a long time, the MM4 was the go-to multi-modulation pedal. The benefits include an intuitive and easy-on-the-eye interface, versatile selection of sounds and simple stomp-able presets. You'll have all of the killer modulation sounds you need but for a fraction of the price of some units!


You may have heard swirling, manic guitar effects on your favourite albums and wondered 'what effect is that?' In theory, you'll now be able to tell the difference!


The idea of a Phaser pedal in your setup should now seem like more of a reality - ask yourself: are you looking to add a throbbing, headachey quality to your riffage, a little extra colour to your plucked cleans, or just warped abstract tones to hypnotise your audience? Each of the pedals we've discussed has its own character and special feature - which one would sit best in your sound? If you get a chance, spend some time trying some effects out, and experiment with some of the example settings above to find the right tone for you!


That's all for now, folks! Don't forget to check out the rest of our buyer's guides while you're at it!