Maxon PH-350 Rotary Phaser


  • Speed
    controls the speed/rate of the LFO wave that controls the effect
  • Depth
    controls the depth/amplitude of the modulation (the size of the range in which the effect sweeps).
  • Mode (4/6/10)
    switches between 4, 6 or 10 phase shift stages
  • Feedback
    sets the amount of effected signal fed back into the effect (for a stronger effect)



Like all the Maxon Vintage Series models, the PH-350 Rotary Phaser was designed to offer an extremely versatile effect unit that provides consistent, low-noise, transparent operation. The PH-350's features were selected after careful study of other phasing units in order to provide as varied and useful a tone palette as possible. Likewise, certain functions and features were disregarded in order to keep performance intuitive and trouble-free.

Like the CP101 and AF-9, the PH-350 circuit uses CdS Photocouplers to achieve its unique voice. While extremely popular in the 1970s, Photocoupler's have generally been abandoned in modern circuits due to their high cost, large size, and wide tolerance ranges. However, their resulting tone simply cannot be replicated using other components ­ a truly liquid, vowel-like, three-dimensional phasing effect that is only compounded by the PH-350's multiple control parameters. To maximize performance, the PH-350's Photocouplers are matched for the smoothest phase shifting possible.

In addition to the standard Rate and Depth controls to vary speed and intensity of the phasing effect, the PH-350 also features switchable four, six, and ten stage phasing. As the phasing stages increase, the effect becomes more dramatic as focus is placed on the upper register harmonics. By changing the amount of phasing stages the PH-350 can emulate a wide variety of phase shifters, from classic units of the 1970's all the way to modern-day models.

Like the CS-550, the PH-350's third rotary control is its secret weapon. The PH-350's Feedback control features a center-detent at 12 o'clock which allows for both positive-phase and negative-phase feedback. Positive-phase feedback works in the standard way to increase the peak points of the phase signal as the control is turned clockwise. Negative-phase feedback works by "breaking" the peak points of the phase signal and "dephasing" the original signal. The resulting reversed-phase signal is delayed slightly from the original, creating a dramatic "scooped" effect unique to the PH-350. The Feedback control is calibrated to reach self-oscillation at either extreme, yielding a further array of bizarre oscillation effects.

Lastly, the PH-350's stereo outputs allow panning of the effect between two amplifiers or channels. The PH-350's ultra-wide frequency response and low noise allow it to process line level signals as well as standard instrument signals.

Ideal for the studio, essential for live performance, the PH-350 Rotary Phaser supplies a virtually unlimited array of classic and modern phasing effects.

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  • Input Impedance
    500K Ohms
  • Output Impedance
    10K Ohms or less
  • Residual Noise
    -92 dB
  • Maximum Output Level
    +8 dB
  • LFO Speed
    0.06 Hz ­ 12 Hz
  • Power Supply
    Special AC adaptor
  • Power Voltage
    DC10 V (AC-adaptor)
  • Current Consumption
    41 mA (10 VDC)
  • Dimensions (whole)
    117 mm (W) x 150 mm (D) x 60 mm (H)
  • Weight
    530 g

Where to find one?

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