Electro-Harmonix Stereo Clone Theory, Stereo Pulsar, & Stereo Polyphase

The Stereo Clone Theory, Stereo Pulsar, and Stereo Polyphase are essentially more compact, stereo versions of already existing mono effects pedals. All three feature true-bypass switching, and are fitted with industry standard 2.5mm barrel-style power-supply jacks, instead of the mini-plugs found on many older EH pedals. The Stereo Clone Theory and Stereo Pulsar accept standard 9-volt/100mA power supplies (such as the optional US96DC-200BI), though you still have to remove four screws on the bottom of the units to replace their single 9-volt batteries. The Stereo Polyphase uses a provided 24-volt/100mA power supply, and it cannot be powered by batteries. The pedals also feature sturdy die-cast housings, rather than the relatively unsubstantial sheet-metal enclosures of their larger forebears.
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Stereo Clone Theory
Chorus Vibrato

Poised mid way between the large Clone Theory and the one-knob Small Clone, the Stereo Clone Theory ($159 retail/$118 street) has Depth and Rate controls, along with a switch for selecting Chorus 1, Chorus 2, or Vibrato. The Rate control covers a generous range—from ultra slow to reasonably rapid—and the speed remains the same when you switch between effect types (if you match the tempo of a song while using one effect, it will remain locked in when you switch to another). The Depth control provides subtle to sub-aquatic levels of modulation.
Chorus 1 produces a sweet, shimmering, slightly metallic sound that is quite musical. Depth is preset to what EH considers “optimal” (the Depth control is inactive), and adjusting the Rate control affects both modulation frequency and delay time, yielding comb-filter and flanger-type sounds in the first half of its range, and wider, more traditional chorus effects in the second half.
Chorus 2 produces a considerably more delayed and therefore wider effect, which can get seriously syrupy as you increase the Depth (I got a “Wild Honey Pie”-like warble with Rate at two o’clock and Depth maxed). The Vibrato is functional, if relatively unexciting, and it lacks stereo separation.
The Stereo Clone Theory is a nice-sounding chorus pedal with its own distinct personality. Chorus 1 is the most generally useful setting, though Chorus 2 offers some hip specialty sounds, and, ironically, a more convincing “vibrato” than Vibrato. My only real beefs are that Vibrato doesn’t operate in stereo, and that the pedal generates audible hiss.

Stereo Pulsar Variable Shape Tremolo

You might think that a pedal with three knobs—two of which are labeled Rate and Depth—would be pretty straightforward. However, in the case of the Pulsar ($110 retail/$82 street), the Rate control begins at medium-slow speed and exceeds recognizable “tremolo” velocity well before reaching the halfway point. Even better, the Depth control’s usable range lies between ten o’clock—when it kicks in—and two o’clock, beyond which it begins to “warp by modulating between positive and negative phase,” resulting in ring-mod-like weirdness.
Things get even more interesting when you factor in the Shape controls: a Shape switch that toggles between Triangle (smooth) and Square (staccato) waveform modulation, and a Shape knob that alters the way in which the waveforms rise, peak, and fall. With the Shape switch set to Triangle, the Shape knob goes from rising sawtooth, to triangle, to falling sawtooth. When the Shape switch is set to Square, the Shape knob goes from rising small pulse-width, to square, to falling large pulse-width. All this flexibility results in myriad sonic possibilities, including modern and vintage tremolo effects, jumpy rhythmic modulations, strange stuttering sounds, and radical panning effects. The controls are also highly interactive, and even slight adjustments made to one can affect the response of another.
Eccentric controls and extensive wave-shaping power notwithstanding, it is actually quite easy to dial in great straight-ahead tremolo sounds, and the wackier stuff is there should you wish to access it. All that—and the fact that the Pulsar is dead quiet—makes for one outstanding tremolo pedal.

Stereo Polyphase

As suggested by its name, the Stereo Polyphase ($278 retail/$208 street) offers several types of phase-shifting effects in one package. You get conventional phasing using the onboard LFO to set the rate (LFO mode), phasing that responds to your playing dynamics using an envelope-follower (ENV mode), and phasing controlled with an optional expression pedal (EXP mode).
One of the Polyphase’s coolest features is its ability to define the range and direction of the modulation sweep using the Start and Stop controls. This is particularly useful for fine-tuning the attack and release characteristics of the envelope while in ENV mode—that is, sculpting the way in which the formants “speak” (think auto-wah). Another key feature is a mini-toggle that switches between Triangle and Square waveforms in LFO mode, and Slow and Fast response in ENV mode, to give you lots of additional creative options. The Rate control adjusts the modulation speed when in LFO mode, and the Gain control adjusts the input sensitivity of the envelope follower when in ENV mode. The Feedback control determines how pronounced the phasing effect is, and it emphasizes the vowel-like qualities on some settings.
In LFO mode, the Polyphase delivers loads of lush, but not overly dense sounds, from subtle to super-swooshy, and smooth (Triangle) to choppy (Square) at speeds ranging from zero to extremely fast. One of my favorites was a sort of sibilant-tremolo-pulse effect that I got by setting the waveform to Square and maxing out the Feedback control. ENV mode dishes up some extremely funky filter effects with the switch set to Fast, and some only slightly less funky, vowel-like sounds with the switch set to Slow. On one setting, I got a fantastic envelope-modulated synth filter effect that fluttered, and then faded out, after strumming a chord and letting it ring.
Connecting an expression pedal in EXP mode lets you sweep the filter across the range defined by the Stop and Start controls, but as there is still a good bit of dry signal present, the effect isn’t as pronounced as it would be with an actual wah pedal. The expression pedal also functions while in LFO and ENV modes, adjusting the dry/effect ratio—though it is at maximum in the toe-up position!
The Polyphase is exceptionally quiet, and its optical circuitry contributes to its transparent and spacious sound. It won’t give you the grittier feel of some vintage phasers, but it is otherwise very versatile. For my money, the envelope-filter sounds alone are worth the price of admission.