Shannon Phaser


  • Volume
    controls the output volume of the effect
  • Speed
    controls the speed/rate of the LFO wave that controls the effect
  • Color
    sets the amount of effected signal fed back into the effect (for a stronger effect)


Shannon (2004-2005)

The Shannon Phaser offers the classic sound of the old script logo version of the MXR Phase 90, but doesn't stop there. Both a depth and a volume control have been added. The depth knob lets you go from a subtle, mellow shimmer to all out thick, warm swoosh. The volume control allows you to dial in unity gain, but can give you a slight boost if needed. To achieve such a great sound, great care is taken by hand sorting the JFET transistors one at a time for matching to within 0.1%. This precise matching gives you some of the most even, lush phasing you'll ever hear.


  • LEVEL, SPEED, DEPTH controls
  • TL072 opamps (socketed)
  • Hand-sorted, precision matched JFET transistors
  • Metal film resistors, metal film capacitors for higher fidelity and lower noise
  • True Bypass switch with Blue LED on/off indicator
  • Red powder coated die-cast aluminum enclosure with silk screened label
  • Operates using a 9V battery or standard 9V negative tip barrel plug
  • Hand-made, durable, clean construction that includes interconnected full-size potentiometers, heavy duty nylon jacks, 3PDT switch, and double-sided plated through hole circuit boards with ground plane
  • 2-year warranty

Shannon (2006)

The Shannon Phaser is a four-stage phaser based on the old script logo version of the MXR Phase 90. This version is considered by many to be the best phase effect around. Imagine improving upon this sound by using high quality components and giving it more versatility. This is what the Shannon Phaser offers.

Along with the standard Speed knob, both Volume and Color controls have been added.

The Volume knob is useful for allowing you to dial in unity gain. No more worrying about a volume drop/boost when engaging the effect. Plus it has enough volume to boost your signal if you want for lead work.

The Color knob opens up an array of phase tones from this classic effect. Previously labeled "Depth", it lets you go from subtle, mellow shimmer to all out thick, warm swoosh to biting swirl.


  • Volume Control
    Adjusts the output level of the effect. Enough volume is on tap to provide a boost if necessary. Most importantly, it allows you to match the volume of the effect to your bypassed signal. No need to worry about a boost or cut in siganl level when engaging the effect.

  • Speed Control
    Varies the rate of modulation of the effect. It's wired so that the speed increases when turned counter-clockwise. This is done because an audio taper potentiometer is used in order to step through the faster speeds more evenly.

  • Color Control
    The control acts like a tone knob for the phase effect. It was previously labeled "Depth", but renamed "Color" to more accurately describe its function. It sets the center frequency of the phase sweep, which determines the balance of the frequency sweep. Similar to the trimpot you'd find on the inside of a Phase 90. However, the entire range of the Color knob covers all posible settings of this trimpot.

    This control is calibrated so that when fully counter-clockwise, the effect is subtle and most noticle at faster speeds.. The first portion of the knob produces more mellow, bass heavy phase tones. As you turn the knob towards the center position, the frequency sweep becomes more balanced. This is where you get the really deep, classic swooshy effect that is signature of the Phase 90. The slowest speed settings tend work best in this range. Then, as you move towards the clockwise end, the frequency balance shifts toward the treble end producing a phase tone with a nice bite to it.

    Dial this knob in to produce various flavors of classic phase bliss. You'll find many sweet spots at various combinations of Color and Speed settings.

  • True-Bypass Switching
    Uses the reliable "blue taiwan" 3PDT footswitch for true-bypass switching in order to preserve your signal when the effect is off. The effect input in grounded when bypassed.

  • On/Off LED
    A bright white LED indicates when the effect is engaged. This high efficiency LED minimizes current draw to help extend battery life.

  • Custom Enclosure
    Durable two-piece 16-gauge steel casing features top side mounted jack for convenient pedal board layout. 15 degree angled face allows for easy footswitch engagement and gives the pedal a unique wedge shape. Finished in a durable red powder coating with permanent white silk screen graphics.

    Enclosure has a footprint (width x length) that measures 3.7 x 4.5 inches (94 x 114 mm). This is just slightly smaller footprint than a Hammond BB size box. The height is approximately 1.125 in. (29mm) at the front edge and 2.25 in. (57mm) at the back edge.

  • Power
    Operates on a 9V battery(included) or standard 9V DC negative tip power supply with a 2.1mm barrel. The battery is mounted to the lower portion of the enclosure using a battery clip.


The Shannon Phaser uses all high quality components. TL072 opamps, metal film resistors and metallized polyester film capacitors are used throughout the signal path. This gives it lower noise and better fidelity than you'd find in any Phase 90. The original script versions used ceramic capacitors in the phase stages. Ceramic capacitors are known to be a bit harsh sounding. Also, the 1% tolerance of metal film resistors work well in this circuit near the output to more accurately mix the wet (phased shifted) signal and dry signal to get the phasing effect. The better the signals are mixed, the more true the phase effect.

JFET Matching

Why is this important? The Phase 90 circuit uses 4 JFET transistors (one for each stage) to act as variable resistors within the phase stages to create the phasing effect. However, these transistors need to be matched so that they all turn on at the same point when connected to the LFO (low frequency oscillator) of the circuit.

I hand sort large batches of JFETs one at a time and record their values using my matching fixture. Once sorted, I match them up in sets of 4 that have a VGS (turn-on voltage) within 0.001 volts of each other. That's as accurate as my multimeter will let me. A typical set would be matched at values of -1.902V, -1.902V, -1.903V, -1.903V. That's roughly within 0.05%! You won't find that accuracy in any Phase 90 in existence!

Precise matching of the JFETs in the circuit is critical to getting the most even, smooth phasing effect.


myFXDB user reviews

1 review, average score of 9 / 10

2014-01-29Matt Golgotha9/10  ......

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