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Bass Phaser/Phase Shifter

The phasing effect is fairly popular effect for bass. It is often confused with another popular effect called flanging which we will discuss in an upcoming article.

In this bass effects article I will explain what phase, phase-shifting, and the phasing effect are, and give you some demos of the effect.

What is Phase?

Waves in the ocean go up and down. Similarly, sound waves fluctuate up and down.

phase is where the wave is in its cycle.

Think of the phases of the moon. The moon constantly moves between the full moon phase and the new moon phase, and all of the phases in-between.

In-Phase and Out-of-Phase

When two identical sound waves are at the same points in their cycle, they are said to be in-phase. If two identical sound waves are at opposite points in their cycle, they are said to be out-of-phase.

When identical sounds are out-of-phase, something interesting occurs: the waves cancel each other out.

If you place two speakers next to each other playing the same audio and they are out-of-phase, you wouldn't hear anything. If you've ever accidentally reversed the speaker wires on one speaker of a pair, you probably wondered why there was little or no sound. By reversing the polarity of one speaker, one wave hit its top while the other hit its bottom. The opposing audio waves canceled each other out.

What is the Phasing Effect?

The phasing effect uses this in- and out-of-phase phenomenon where different parts of the sound get canceled out.

First, the audio signal is copied, and the original signal is left alone. The copied signal is then phase-shifted. That is, where the sound wave is in its cycle is moved forward or backward.

When the phase-shifted sound is combined with the original sound, different parts of the sound will cancel out.

To give this effect motion, an LFO is used to control the amount and rate of back-and-forth phase-shifting. This gives the phasing effect its sweeping, swooshing sound.

The phasing sound has a hollowness to it. Since it is canceling frequencies, it will sound empty at points.

Using a Phaser on Bass

Phasing doesn't alter the rhythm or pitch of the bassline. A phaser, therefore, won't get in the way of the bass guitar's traditional role supporting the rhythmic and harmonic foundations.

Phasing can suck the low-end out of the bass however. That's something to watch.

Listen to my bassline without any phasing:


Here's the same line with a little bit of phasing:


Here's the same bassline with more phasing:


As with all effects, a little goes a long way. Using an effect sparingly can make listeners look forward to it when it kicks in. If it's on all of the time, it can get boring.

Example Songs Using the Phaser Effect

Dancing in the Moonlight by Thin Lizzy

This is a great example of the phasing effect on bass. You can hear the phaser's swooshing sound from the very beginning of singer/bassist Phil Lynott's bassline.

Bridge of Sighs by Robin Trower

Phasing is very popular on guitar as heard throughout this Robin Trower track.

Bass Phaser/Phase-Shifter Settings

Phaser settings are easy. When using a phaser pedal, you generally have one setting you can adjust: Rate.

This is the rate of the LFO. Adjusting the phaser's rate will alter how fast or slow the phase is shifted.

You'll have to experiment to see what sound you like. There aren't too many tips to give you besides listen. What's new, huh?

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