by Sam Chittenden
The Theremorph, a collaboration between Electro-Faustus and Delptronics, is a stand-alone synth featuring as its main attraction an optical sensor which controls its dedicated synth engine. Housed in a solid enclosure with a high-quality red [or black or white] finish, the Theremorph is essentially an optical Theremin coupled with an integrated LFO, a low pass filter and an AR type envelope–all with various dedicated controls. On its rear panel the Theremorph has a 1/4" mono out, four 3.5mm jacks for CV and Gate in and out, and 5-pin DIN MIDI in and out connections.
The Theremorph has an onboard digital oscillator and offers a selection of three waveforms: a nice buzzy saw wave, a mellow triangle, and a fat sounding square. There are dedicated knobs for the oscillator's minimum frequency [which is quantized in whole-note steps] and for modulating the square wave's pulse width. The oscillator is normalled through a transistor ladder low pass filter with controls for filter cutoff and resonance. The filter sweeps pretty smoothly and does its job well, rounding off some of the buzzy edges of the oscillator's waveforms if needed. With the resonance cranked up, the filter will oscillate with a kind of grainy whine and at less extreme settings gives some nice added higher harmonics to the Theremorph's basic waveforms. It’s a filter with some character, but not one that gets all that squelchy or has an overly aggressive resonance.
Moving rightwards along the control surface, there are four knobs for adjusting the modulation of the Theremorph's oscillator’s pitch and filter frequency, two for the LFO [pitch, filter] and two for the envelope [pitch, filter]. The LFO knobs increase the amount of modulation as the knob is rotated clockwise, while the envelope modulation knobs offer both normal and reversed response. Turning them clockwise from center [which equates to zero modulation] follows the rise and fall of the attack and decay slope, while rotating them counter-clockwise reverses this and modulates pitch or filter cutoff opposite of what the envelope is doing. This is an all manual affair as there are no inputs to modulate the LFO or envelope externally. While more options for control is something I like to see in any instrument, my enjoyment wasn’t hampered in any way by the lack of CV control. The Theremorph demands to be played. Fortunately, the controls are spaced nicely and are easily accessed with whichever hand is free from controlling the sensor. Its solid and sturdy enclosure has a durable heft which won’t skitter around even under the most fervent knob twisting. The LFO is triangle based and can be continuously morphed from ramp through triangle to sawtooth. I found the ramp wave [knob set hard left] to be particularly fun to mess with, giving a nice soft, yet chirpy pulse to the sound. There is also a dedicated rate control which sweeps through a frequency range from slow-morphing to rhythmic warbling. I would have liked to see a bit higher upper limit —maybe into low audio rates—which could really open up the sound sculpting possibilities a bit more. Nevertheless, the LFO is great for adding everything from a nice slow sweep, to a bit of tremolo, and up to more rhythmic treatments. There is no dedicated output for the Theremorph’s LFO, but modulating the Theremorph's pitch with the LFO will also affect the voltage present at the CV out and can be used as a way to utilize the LFO with external gear.
On the input side, the Theremorph will track an external CV and Gate sequence [or via its MIDI input] well and will take orders from your favorite sequencer with little complaint but with its own flavor and flair. There does seem to be a little "softness" to the attack of the Theremorph's envelope, especially when affecting pitch and the various envelope and lfo modulation settings will greatly affect the end result. The sensor on the Theremorph can be toggled between controlling the pitch of the onboard oscillator and only sending out MIDI information [the MIDI messages sent out can be configured via a web page]. The range of the Theremorph's optical sensor is adjustable from 1 octave to 8 and—similarly to the envelope modulation controls—can invert the control scheme depending on which way the sensor range knob is twisted. Clockwise will set the sensor to increase pitch the higher above the sensor your hand is and counter-clockwise the pitch will be lower the higher your hand is. This is a nice feature to have as each gestural direction may make sense depending on what you are controlling with the Theremorph.
The Theremorph will also output CV and gates. The CV generated follows the pitch information of the sensor and adheres to the sensor range control scheme [voltage output dependent on how high or low your hand is from the sensor]. A gate is generated if you "break the beam" within range or when your hand leaves the beam. Quick gate streams can be generated by cutting your hand back and forth quickly, while sustained gates are made by simply holding your hand steady [or while adjusting the pitch with up and down movements]. The pitch data output from the sensor is smooth while running through Theremorph's internal synth, but I did notice that quick, large range movements output a stepped pitch change to external oscillators, something I’m not a fan of. This was obvious when the Theremorph's sensor range was at its highest 8-octave setting and less so when in the one to two octave zone. While receiving pitch information from an external input, the Theremorph sensor will take precedence over the incoming CV, which leaves the door wide open for wild note manipulation mid-sequence [or the odd forehead-based transposition].
The Theremorph is an interesting beast. Anyone looking for an easy way to play specific melodies with the optical control will have their work cut out for them. While the synth engine sounds great and offers a respectable amount of modulation options and controls, if you are looking for a mono synth with a lot of modulation routing options or voltage control over all the things, you may want to keep looking. That being said, the Theremorph is a surprisingly fun and addictive synth to play. The optical sensor is a blast and creative possibilities abound for controlling external gear in interesting, unpredictable, and rewarding ways. Utilizing the CV out to control the frequency of a filter, stepping through an external sequence using the Gate out, or modulating the frequency of an external oscillator with the Theremorph's audio out are all fruitful ground for exploration. I had a fantastic time putting together various combinations of all three in different patches. At the very least, the Theremorph will lead you to break away from your normal methods of control. Taken on its own, the Theremorph offers a wide ranging palette of great sounds, from warbled, spacey madness to wild, sweeping screams, and is great fun. Straightforward and simple to use, the Theremorph will have you spinning off into sci-fi territory in no time, perhaps with a bit more of an aggressive sound than the ghostly wavering of a traditional Theremin. You may find yourself like I did, whiling away a few hours just waving one hand in the air above the Theremorph with a wide and steadily growing smile on your face.