EOWAVE Persephone

Apr 1, 2007 12:00 PM, By Gino Robair

           

The Persephone puts a monophonic analog synth under the control of a ribbon strip.

Although ribbon controllers have been incorporated into a variety of instruments over the years, Eowave's Persephone is one of the few instruments to make the ribbon its primary interface. The Persephone has a single synth voice featuring an analog oscillator with a 10-octave range, a 1-pole (6 dB per octave) lowpass filter, and an LFO (with a range of approximately 1 to 20 Hz) for modulation.

The instrument is available in desktop ($1,099) and suitcase versions ($1,299). The suitcase model, reviewed here, includes a handle, a removable lid, and Tolex covering (available in three colors). Four rubber feet keep the instrument from slipping as you play.

Horizontal Boogie

The ribbon's rubberized playing surface is very responsive and has a nice feel. It's roughly 19.25 inches long and 0.7 inch wide, and the entire instrument is the size of a small mono synth.

To the left of the ribbon is a wooden expression key that is automatically mapped to control amplitude, modulation amount, or filter cutoff frequency, depending on the performance mode. The expression key, modeled after a similar control on the Ondes Martenot, uses an optical sensor, making it musically useful (see Web Clip 1).

Despite being an analog instrument, the Persephone has eight digital controls on the front panel. The Mode knob sets the behavior of the ribbon, the expression key, and the CV expression pedal. The 4-position Scale knob sets the oscillator's range on the ribbon at one, two, five, and ten octaves, minus the last note at the highest position on the ribbon. (By tweaking an internal trim pot, you can adjust the ribbon scaling to complete the top octave and get scale ranges other than the factory presets.)

The Tune and Finetune knobs set the instrument's base pitch. Set it too high, and the upper portion of the 10-octave scaling goes out of the audio range. For pitch accuracy while playing, I taped scale steps for each of the octave scalings above the ribbon. (A removable template marked with pitches would be a nice add-on feature.) The oscillator is very stable and the instrument will stay in tune for hours.

The output waveform is continuously variable between triangle and sawtooth using the Wave knob. The Filter Frequency control determines the filter cutoff point, and the Modulation control sets how much further the filter opens as the expression key or ribbon is pressed. When fully open, the filter control lowers the pitch slightly.

The instrument has an unbalanced ¼-inch output, MIDI I/O, an expression pedal input, a CV output, and an internal power supply. The CV output accepts a standard Y-cable with a TRS plug at one end, so you can send control voltages corresponding to ribbon pressure (ring) and horizontal position (tip) from one jack. An expression pedal is a must: without it, the LFO speed remains constant.

la Mode

The four performance modes (A to D) determine how the ribbon, expression key, and expression pedal are mapped to the audio parameters as well as the pressure CV output. Mode doesn't affect the MIDI mappings. Horizontal finger position on the ribbon always controls pitch.

In mode A, ribbon pressure controls the filter's cutoff frequency, the expression key is used to swell the note in and out, and the expression pedal acts as the master volume. Once you touch the ribbon in this mode, the Persephone remembers the pitch, even if you remove your finger. In mode B, ribbon pressure and the expression pedal control amplitude, and the expression key controls the filter cutoff frequency. Unfortunately, you can hear stepping in the volume level when the expression pedal moves through its lowest range in these two modes.

In mode C — tremolo mode — ribbon pressure controls volume, the expression key sets the modulation depth, and the pedal controls the tremolo (LFO) speed. Mode D works similarly except that the type of modulation controlled is vibrato.

Note that as the scaling is increased from one to ten octaves, the base pitch rises slightly (see Web Clip 2), so you will have to adjust the tuning when you change ranges. Also, as you increase the number of octaves on the ribbon, intermodulation distortion adds buzziness to the tone.

Outward Control

The MIDI I/O and a CV output on the Persephone are a welcome addition, though somewhat problematic. Although the pitch CV response is smooth, the pressure response is a little trickier to use, and the harder you press on the ribbon, the more noise you get in the pitch CV. Also, the pitch CV is scaled only to the 5-octave range. It would be more useful if it changed with the position of the range knob.

The MIDI implementation is basic. The ribbon senses horizontal position before sending a Note On, giving you a stable pitch right away. It sends Note On (Velocity 127) and Note Off (Velocity 0) when your finger touches and leaves the ribbon, respectively, and it sends Pitch Bend messages from C3 (MIDI Note Number 60) depending on finger position. The expression key sends Volume data using CC 7, while the expression pedal sends data using CC 2 (Breath Controller).

Unfortunately, you will need a computer and MIDI interface to send the instrument Program Change messages to switch MIDI Local on and off, as well as to use the half- and whole-step quantization modes. On an instrument with digital controls designed for live use, these should be accessible with an onboard switch or key combination.

Back to the Future

I applaud Eowave for offering a pro-level ribbon-controlled analog synth built by hand in a world of cheaply mass-produced me-too instruments. Although its MIDI and CV implementation needs some tweaking, as an instrument on its own, the Persephone allows for sophisticated music making and is a joy to use.

Value (1 through 5): 3
Eowave/Analogue Haven (distributor)
www.analoguehaven.com