The world of effects is a vast and complex one, a world that remains a mystery to many but that we guitarists must master if we are to find our own sound. From wah to reverb, from flange to delay... the possibilities are endless, and this complexity is compounded with each additional link in the chain. Effects are available in many guises today, with rack-mounted devices and software on our computers; however, we will concentrate on good old fashioned pedals.
This time we'll look at phasers. Belonging to the modulation family of effects they tend to be used more sparingly than some of the more familiar suspects on a pedalboard, but their use is widespread and distinctive.
The Science
To create a phasing effect, the signal needs to be spilt into two paths. One path applies an all-pass filter, preserving the amplitude of the original signal but altering the phase. The amount of change in phase is dependent on the frequency of the signal. When the two signal paths are mixed again, the frequencies that are out of phase cancel each other out creating the characteristic notches of a phaser. The notches are inaudible because of the 2 signals cancelling each other out, what you hear is the peaks in between. Changing the mix ratio changes the depth of the notches; the deepest notches occur when the mix ratio is 50%. The effect is then modulated so it varies slightly over time, creating some movement in the effect.
In Use
Phasers are responsible for the other-worldly guitar tones we hear in many recordings, mostly in the rock genre. Flanging is a specific type of phase where the signal is split and then mixed with a delayed version of itself, creating the familiar jet-plane 'whoosh' effect that became popular in the late 1960's. Jimi Hendrix used a phased effect extensively with his Univibe pedal – although the Univibe achieves the effect in a very different way to modern pahsers. Brian May used a phaser to create the distinctive guitar tone of Bohemian Rhapsody and more recently Eddie Van Halen became a famous user of phasers, placing them after distortion in the signal chain to create sonic chaos. They remain popular, but as the effect becomes less subtle, its use becomes more sparing.
Products
As ever in the crowded effects market place, the choice of phaser pedals is almost overwhelming. The Ibanez PH-7 is a nice, robust entry level pedal with all the features you're going to need and enough scope for tweaking to integrate a phaser into your signal chain. A PH-7 could be yours for around $50 or £40 and would be my recommendation if you are new to this effect – you might hate it anway! BOSS are always a good yardstick and the current incarnation of their phaser, the PH-3 is also a good choice for starting out in this area. A little pricier at around $110 or £95, to my ear it has a more defined 'signature' sound in so far as it seems quite cold and clinical in use – at home in extreme use in a funk or disco kind of setting but it lacks the warm and subtlety of other pedals available. At the other end of the spectrum is the small stone – it also has a very definite sound, and one that is more spacey and harks back to the sound of the late 60s. Another one to try before you buy.
MXR also produce several phasers – the Phase 90, Phase 100 and variations on the theme. At the top end in terms of cost, the MXR pedals are my personal choice. I chose the EVH Phase 90 – Eddie Van Halen's signature pedal. It offers a 'modern' sound which has a little more bite and fits well with my aggressive style of playing, but also switches to the original 'script logo' tone for which the standard phase 90 is justly famous. It sports a wicked striped paintjob, and clashes wonderfully with my Jemini. The only downside is that it doesn't have true bypass, but it has never gotten in my way as it's nice and quiet – a quality product.
So that's phasers in a nutshell... the subtle flavours of phaser are quite distinct, so testing a number of pedals if recommended before you buy.
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