Maxon PH350 Rotary Phaser - Better Guitar 2004


Maxon PH350 Rotary Phaser Review

Phasers were one of the "standard" effects of the late 60's and throughout the 70's. That swooshy sound can be heard on countless recordings of that era. Thirty years later, Phasers appear to be making a comeback. The Maxon Rotary Phaser (PH-350) is part of Maxon's Vintage Series of effects. I put the Rotary Phaser to the test to see if it captured that classic sound of the 70's.

Controls, Features, and Construction

Most Phasers of the 70's were simple affairs. In fact, one of the most popular models had only one control (speed.) The Maxon Rotary Phaser has quite few controls. In addition to the standard SPEED and DEPTH controls, there is a FEEDBACK control and a MODE control. The FEEDBACK control is quite unusual. It allows you to select either positive-phase or negative-phase feedback. While hard to explain, it allows you to get either a scooped tone effect or a more pronounced vocal-like effect. The MODE control offers three stages of phase shifting for subtle, normal, or pronounced phasing. The Rotary Phaser is solid metal and a little larger than most single effect stompboxes. It has a metal effect switch (mechanical - not true bypass), solid plastic control knobs, and an LED effect indicator. It has one input jack and two output jacks (A and B) to achieve a stereo effect when used with two amps. It comes with a rubber pad that you can attach to the bottom of the unit to keep it from sliding around. Or you can leave it bare if you are using Velcro to attach it to a pedalboard. It requires an AC adapter to run. There is no option for using it with a battery.

The Effect

Having used a 70's model MXR Phase 110 for many years, I was surprised at the sound of the Rotary Phaser the first time I plugged in. My old MXR had a fat and pronounced phase effect, the Rotary Phaser was cleaner and more subtle. After reading the manual, I realized this was due to the fact that the Rotary Phaser is really a stereo effects pedal. When using two amps, the phaser effect comes out the A jack, and the B jack outputs the dry signal. When using the Rotary Phaser with a single amp, the pedal sends a mix of both the dry and effected signals through the A jack. Since both signals are present, the effect is more subtle. Unfortunately, there is no knob for controlling the mix of the effected signal and the dry signal when using a single amp. Dual amp users can emphasize the phase effect by turning up the volume on the amp receiving the effected signal (jack A.)

Audio Magic

I wondered why Maxon chose this dry/effect signal routing scheme until I plugged the Rotary Phaser into two amps. Then the "Rotary" label became obvious. I won't pretend to understand the audio science behind it, but the combination of using an amp with a dry signal and an amp with an effected signal, gave the illusion of the "swooshing" effect bouncing (or panning) between the two amps. This was quite magical, and a pretty good simulation of what a rotary speaker playing a phase effect might sound like. Obviously, there is no way you can get this effect with a single amp, but those with two-amp setups are sure to love this bit of ear candy.

More Surprises

Another aural surprise was the vocal-like quality of the phasing when using the FEEDBACK control. It sounded like a mix of a wah and synth filter. When I inquired about the unique tone, Kevin Bolembach of Godlyke (Maxon's US distributor) replied:

    "The cause of the "vocal/wah" type sound of the PH350 comes from the fact that it uses photocouplers instead of FET's to create the phasing effect. Photocouplers are well known for their vocal-like audio quality, and they were used in all the original Mutron products as well as the original Univibe. Barely anyone designs around them anymore for several reasons - 1) They are expensive 2) They are hard to find 3) They are temperamental and have wide tolerance ranges so they generally must be matched for optimum sound quality. This is the reason the PH350 is somewhat expensive compared to other phasers."

This vocal quality is unique among phasers I have tried, and may be just the thing for those looking for a "different" sound.


The Maxon Rotary Phaser is a not your typical Phaser. It is capable of a wide variety of phasing effects (including flanging and vibrato) from classic to extreme, and has a unique vocal quality to it. When used with two amps, it is capable of producing some very cool panning effects. However, when used with a single amp, its effect is more subtle. Some will like this subtleness, other may not. It requires an AC adapter (included) so you will need an available plug to use it. It is expensive. Still, if you are interested in Phasers, you owe it to yourself to check one out (preferably with two amps.)