Ploytec PL2 Reviewed: Synth in a Cube

MIDI in, RCA audio out.
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Snap Judgment

Super-compact, MIDI-powered. Unique sound. Speech synthesis. All parameters are CC-controllable.

No wheel-controlled vibrato. Pitch-bend is always one octave. No dedicated filter envelope. No legato envelope triggering.

Bottom Line
Compact size, tiny price, huge personality . . . for sound, innovation and affordability, the PL2 is a must-have.
$129 list | $99 street

MIDI in, RCA audio out. The PL2 also has a micro-USB jack so you can use it with MIDI controllers that don’t provide enough power. The USB jack carries only power, not data. The straightforward Mac/Windows editor sends tweaks to the PL2 in real time as MIDI CC messages. Click the Random button for inspiration.

A $99 synth that’s powered by a MIDI cable and small enough to fit in your mouth? That would be enough to put the Ploytec Pi L Squared (PL2 for short from here on) in the running for musical gadget of the year, but this tiny instrument, less than two inches on a side, also pumps out unique new sounds. Ploytec is a German company best known for developing USB audio drivers for dozens of manufacturers ranging from Apogee to Yamaha. Playfully, they introduced the PL2 by claiming, “No other synth on the market has more aliasing and quantization noise.” The PL2 is based around an eight-bit microcontroller for raspy, cutting timbres. However, it can also produce softer, warmer sounds thanks to its analog filter.

My first move was to plug the PL2 into my original Novation Bass Station, a monophonic analog synth. (The Ploytec website lists controllers reported to work with the PL2; see Fig. 1.) Realization 1: The two-voice polyphony on the PL2 opens a lot of performance possibilities. Realization 2: To play the PL2 expressively, you need to use multiple MIDI continuous controller messages. My old Bass Station wasn’t up to the task. Ploytec offers hardware controller templates online, as well as a Native Instruments Reaktor ensemble that lets you tweak the PL2 from a DAW.

Every synthesis parameter on the PL2 is mapped to a MIDI CC. To change envelope attack time, for example, you adjust CC 17. The free software editor (see Fig. 2) simply transmits CCs, turning editing into performance and performance into presets.

You can save your patches into 32 user program slots, though the saving process is unintuitive: Call up a program between 33 and 64 (the user bank), make your edits with the editor or external controllers, and then send another program change from an external MIDI source. When you switch back to that program, your new patch will be there. Settings interact in unexpected ways, so check the PL2 manual for tips. For example, setting “Digital Cutoff” to 0 maps velocity to filter frequency.

Square Wave Synthesis
Every boutique synth needs a novel technology; the PL2’s is called square wave synthesis. Two digital oscillators produce pulse waveforms. Using two pulse-width modulation (PWM) controls, you can vary the width of alternate cycles independently, producing a rich, animated sound. Firmware version 2.0 offers seven pulse variations plus a combo bass drum/noise wave that’s split across the keyboard. The drum follows MIDI notes, so with a touch of filter distortion, you can create a cool bass and snare duo.

Waveform 1 is warm and buzzy; varying the pulse width modulation adds a sub-octave. Waveform 2 mixes two pulses an octave apart for metallic or organ sounds. Waveform 3 has a more chorused timbre than number 1. Waveform 4 sounds clearer than number 3. The others add unusual harmonics and detuning. There’s a lot of potential in square waves! You can also configure the oscillators in monophonic, polyphonic, unison-detune, or octave mode to make massive basses and leads.

Next up is the resonant digital filter, with highpass, lowpass, and bandpass modes. It’s not as juicy as an analog filter, but you can get grinding distortion by cranking the DC Offset (CC 22). Your snarling sound then passes through an analog filter and saturation stage, which rounds off the digital edge. The non-resonant analog filter is designed to dial in warmth; sweeping it produces glitches.

On the modulation side, a lone ADSR envelope handles both the amp and digital filter. Unfortunately, there’s no legato retriggering mode for bass slides. More strangely, the mod wheel doesn’t offer vibrato, and pitch-bend is pinned to an octave.

A New Voice
Firmware version 2.56 converts the PL2 into a speech synthesizer inspired by the 1980s General Instrument SP0256 chip. (Imagine a Speak & Spell with velocity sensitivity and pitch-bend.) You can trigger notes from the keyboard while selecting speech fragments from the mod wheel, or vice-versa. It’s rough, percussive, and full of personality.

Updating the firmware with a MIDI sys-ex dump took less than five seconds after I found a compatible MIDI interface, a KMI MIDI Expander. (The first two interfaces I tried didn’t work.) You can switch back to version 2.0 just as fast, making the PL2 a true chameleon. Ploytec hints at more updates, including waveforms from the SID chip made famous in the Commodore 64 computer. They’re also designing a PL2 with USB in and MIDI out.


Smaller than your cell phone charger and packed with personality, the Ploytec PL2 brings a big new sound for a tiny price. It’s a definite Key Buy.

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