What it is: The Phaser is a modulation effect. The Phaser is an effect which produces a characteristic whooshing, or sweeping sound when applied to a signal. It was originally an effect pedal before the age of computers, and thusly used mainly on guitars. Since then, however, it has found its way into the plugin toolbox of every DAW out there. It can be used to give a rather psychedelic modulating effect, formant and resonance rich, providing a useful coating to just about anything, though it sounds particularly good on things with higher range frequency content. As its name suggests, it effects the Phase of the incoming signal, however, it does so in an interesting fashion…

Diagram A.

How it works: There are two methods by which a phaser plugin works, and they both accomplish the exact same thing(thats a lie, but you cant tell, so bugger off). The first(see Diagram A), and most common, is by sending the signal through a series of all pass filters that change the phase of the frequencies they cover. The phase shifting of the filters is modulated by a Low Frequency Oscillator. This is mixed with the original signal to create the phasing effect. Because the two signals are out of phase, notches and peaks across the frequency spectrum are created due to the occurrence of some frequencies canceling(notches), and some frequencies adding up(peaks). The sweeping effect is caused by the LFO moving the filtering around.

Diagram B.

Now, the reason I say there are two different methods of creating a phaser effect is because Apple Logic’s phaser does the same thing, without a series of all pass filters(see diagram B). See? Instead of using all pass filters to create the phasing, it mixes the original signal with one that is slightly out of phase, and modulates with an LFO. I don’t know if any other phasers do this, but it would make sense if they did, considering that this method produces the exact same effect. I got this information from Logic’s description of their product: https://documentation.apple.com/en/logicstudio/effects/index.html#chapter=9%26section=6%26tasks=true

In addition to this basic function, many phasers have a feedback function, which allows the signal to be fed back through the series, increasing the resonance on the peaks and notches for an even more interesting sound. Also, the amount of all pass filters increases the number of notches and peaks, also leading to a more interesting effect. Some phasers can have as many as thirty all pass filters in series. The number of all pass filters it has determines how many stages it has, so 4 all pass filters=4stage phaser.

Important notes:

By its definition, the phaser effect causes phase discrepancies in a signal, using it with a slower setting on the LFO allows for the phase changing to be overlooked, and instead a really cool effect is achieved.

Many times a Phaser is confused with a Flanger, they are not the same, although they utilize many of the same principles. See other Soundphysics Basics posts for more info.

Phaser Effects to look at:

(I am not being paid, nor asked to sponsor any of the products here, and I have personally tried every one)

https://www.audiodamage.com/collections/software/products/ad008-phase-two

A nice sounding, easy to use simulation of a vintage Bi-Phase phaser. It sounds good, the interface is quirky, and its versatile. It is essentially two six stage phasers that can be run in series or parallel. MSRP: $29.00US

https://www.audiothing.net/effects/phase-motion/

The Phase Motion calls itself an “advanced phaser”, and, well, it is. It offers up to 16 stages, 7 different waveforms for the LFO, and an absolutely amazing sound. MSRP $30.00US

http://www.vst4free.com/free_vst.php?id=492

Free isn’t always good, but this one is. From Kjaerhus Audio, this little vintage emulation phaser is amazing for being the freebie that it is. It offers up to 12 stages, and is incredibly simple and easy to use. This plugin is perfect for beginners due to its simplicity, and I suggest it to anyone who wants to learn to use a phaser. This was the first phaser plugin I ever used.