Future Retro
XS Semi-modular Analog Synthesizer

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Item: N13-1798

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XS Semi-modular Analog Synthesizer
XS Semi-modular Analog Synthesizer XS Semi-modular Analog Synthesizer XS Semi-modular Analog Synthesizer XS Semi-modular Analog Synthesizer


The XS is a true semi-modular analog synthesizer with a universe of sonic possibilities just waiting to be discovered. Its versatile design allows it to be used as either a rackmount or desktop instrument, and its compact size makes it ideal for musicians on the go.

In its simplest form, the XS is an extremely powerful monophonic synthesizer including 46 controls with internal signal routings pre-wired to allow the unit to act similarly to traditional synthesizers. The unit also provides 7 inputs and 11 outputs that can be connected in various ways to override the pre-wired signal routings, interface the unit with other instruments in a modular fashion, and even process external audio.

The XS can be controlled by both MIDI and CV/Gate control signals simultaneously in a variety of ways. It can also act as a MIDI to CV/Gate converter with outputs, including CV/Gate/Mod Wheel/Velocity signals for controlling other analog instruments.

With a single unit you can easily create basslines, leads, drones, percussion, and sound effects. Connect multiple units together to form larger systems and the possibilities are endless.

The XS provides 2 ultra stable, wide range voltage-controlled oscillators, each capable of covering a range of 0.5 Hz to 100 kHz. Oscillator A generates saw and square waveforms. Oscillator B generates sine, triangle, saw, pulse width/square waveforms, and its own sub oscillator waveform, which can be 1/2, 1/4, or 1/8 the frequency of the main waveform. The pulse width shape of Oscillator B can be set manually or modulated with an internal or external control voltage, and Oscillator B can also sync its frequency to Oscillator A. Each oscillator can be frequency-modulated independently by both internal and external signals to create more complex waveforms. The XS also provides a white noise source and ring modulator that can be used on the internal oscillators or an external source. Dedicated outputs are provided for the waveform select controls A, B, and C.

A dedicated LFO generates triangle, saw, square, and random waveforms to modulate internal parameters, or external circuits as well with its dedicated output. The LFO can act in a free-running mode, or sync its rate to divisions of an external MIDI clock. When synced to an external MIDI clock, the LFO can be used to generate analog clock signals at various synced rates for stepping analog sequencers or arpeggiators in time with modern sequencers.

The mixer section sets the levels of the oscillator waveforms, sub oscillator waveforms, white noise source, ring modulator, or any external audio signal to be sent to the input of the filter.

The 2-pole multimode filter provides 4 filter types, including lowpass, bandpass, highpass, and notch settings, each capable of covering a range from 5 Hz to 18 kHz. With high resonance settings, the filter will self-oscillate, allowing it to act as an additional audio source. The cutoff frequency can be modulated by both internal and external signals, and the filter's input and output can be overdriven independently, giving it unique tone characteristics. A dedicated output for the filter is also provided.

The XS includes our unique Velocity-sensitive ADSR type envelope with additional attack and decay time settings for accented envelopes. It's like having two envelopes in one, and it's capable of some truly funky sounds. This is the main modulation envelope internally routed to the modify the oscillators and filter. The envelope can be triggered by internal or external logic signals. Both normal and inverted polarity envelopes are available at the output.

And finally, a voltage-controlled amplifier is provided to process the amplitude of signals. The amplifier normally affects the filter's output but it can also be used to process external audio signals. The amplifier has its own dedicated envelope with four selectable shapes, Velocity-sensitive amplitude, and independent accent times. The amplifier also has a volume control for attenuating signals sent to the main output.

A universal power supply is included, allowing the unit to be used in all countries.


  • Semi-modular MIDI controlled Analog Synthesizer 
  • Oscillator A: Saw, Square, White Noise, Ext. Audio
  • Oscillator B: Sine, Triangle, Saw, Square/Pulse
  • Wave C: 3 Suboscillator divisions, Ring Modulator, White Noise, Ext. Audio
  • Mixer mixes A/B/C sources, each capable of overdriving the filter
  • 12 dB Multimode Filter: Lowpass, Bandpass, Highpass, Notch modes
  • Filter resonance self-oscillates when cranked
  • Filter Overdrive
  • 2 Velocity Sensitive Envelopes with accent functionality
  • Main Envelope: ADSR with seperate attack and decay settings for accented envelopes
  • VCA Envelope: 4 selectable shapes
  • LFO with MIDI Sync: Triangle, Saw, Square, Random
  • MIDI Controlled
  • 17 patch points
  • See specs for more details
  • Many Oscillator and Filter modulation possibilties


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  • Channel: 1-16
  • MIDI Messages Recognized: Pitch C2 to C7, Note On/Off, Pitch Bend +/- 2 semitones, Velocity, Mod Wheel, MIDI Clock


  • Waveshapes: triangle, saw, square, random
  • Free-running Rate: (MIDI SYNC Off) 4 seconds to 18 Hz
  • MIDI Clock Divisions: (MIDI SYNC On) 8 bars, 4 bars, 2 bars, 1 bar; 1/2, 3/8, 1/3, 1/4, 3/16, 1/6, 1/8, 3/32, 1/12, 1/16, 1/24, 1/32

Oscillator A

  • Total Frequency Range: 0.5 Hz to 100 kHz
  • Octave Control Range: 6 octaves
  • Fine Tune Control Range: -6 to +6 cents (master fine tuning for both oscillators)
  • Waveforms: saw, square, white noise, external audio

Oscillator B

  • Total Frequency Range: 0.5 Hz to 100 kHz
  • Oscillator Sync: on/off (syncs to Oscillator A)
  • Octave Control Range: 12 octaves
  • Frequency Control Range: -9 to +9 semitones
  • Waveforms: sine, triangle, saw, square/pulse width
  • Pulse Width Modulation Amount: typically 50% to 3%
  • Pulse Width Modulation Sources: external source, LFO, Mod Wheel, manual adjust, Velocity, Envelope 1

Wave C

  • Waveforms: 1/8, 1/4, 1/2 Oscillator B sub oscillator divisions, ring modulator, white noise source, external audio

Oscillator Modulation

  • Modulation Sources for Oscillator A: external source, LFO, LFO controlled by Mod Wheel, Mod Wheel, Waveform B, Waveform B controlled by Envelope 1, Envelope 1 (positive and negative polarity)
  • Modulation Sources for Oscillator B: external source, LFO, LFO controlled by Mod Wheel, Mod Wheel, Velocity, Waveform A, Waveform A controlled by Envelope 1, Waveform C, and Envelope 1 positive polarity


  • Controls: level A, level B, level C (all capable of overdriving filter input)


  • Filter Types: (12 dB) lowpass, bandpass, highpass, notch
  • Filter Frequency Range: 5 Hz to 18 kHz
  • Resonance: 0 to self oscillation
  • Overdrive: clean to fully crunched

Filter Modulation

  • Key Follow: 0 to 100%
  • Velocity: amplitude sensitivity control for Envelope 1
  • Modulation Sources: external source, LFO, LFO controlled by Mod Wheel, Mod Wheel, Waveform B, Waveform B controlled by Mod Wheel, Waveform B controlled by Envelope 1, Waveform C
  • Envelope 1: negative and postive polarity covering 10 octaves


  • Sensitivity: 0 to +10 volts
  • Attack Time: 0.5 milliseconds to 4 seconds
  • Decay Time: 2 milliseconds to 10 seconds

Envelope 1

  • Key Sync: on/off (envelope retriggering)
  • Attack Time: 0.5 milliseconds to 4 seconds
  • Decay Time: 2 milliseconds to 10 seconds
  • Sustain Level: 0 to 100% (+10 volts max)
  • Release Time: 1 millisecond to 10 seconds

Envelope 2

  • Attack Time: 1 millisecond to 4 seconds
  • Decay Time: 3 milliseconds to 7 seconds
  • Sustain Level: 100%
  • Release Time: 3 milliseconds to 7 seconds


  • Velocity: 0 to 100%
  • Envelope Shapes for Control: attack/decay, attack/sustain/release, accented decay/sustain/release, accented decay/normal decay


  • Pitch CV In: 1 V/Oct standard, typically 0 to +5 volts (+15 volts max)
  • Pitch CV Out: 1 V/Oct standard, 0 to +5 volts
  • Mod Wheel Out: 0 to +10 volts
  • Velocity Out: 0 to +10 volts
  • LFO Out: -5 to +5 volts
  • Oscillator Modulation In: typically -10 to +10 volts (+/-15 volts max)
  • Waveform A: -5 to +5 volts
  • Waveform B: -5 to +5 volts
  • Waveform C: 0 to +15 volts (for sub oscillator waves), -5 to +5 volts (for ring modulator and white noise)
  • Audio In: accepts line-level audio signals
  • Filter Modulation In: typically -10 to +10 volts (+/-15 volts max)
  • Velocity In: typically 0 to +10 volts (+/-15 volts max)
  • Gate In: gate-on equals +1.5 volts or higher, gate-off equals 0 volts
  • Gate Out: 0 to +14 volts
  • Envelope 1 Out +/-: 0 to +10 volts
  • Filter Out/Amp In Range: -15 to +15 volts max
  • Main Out Range: 11 volts peak/peak max


  • Universal Power Supply: +15 and -15 volts DC, can be used with power main voltages ranging from 90-260 volts AC


  • Rackmount: 19" standard rack width, 4 vertical rack spaces, 2.75" deep
  • Desktop: 17.5" width, 7.5" depth, 3" height


  • 4 lbs.


  • The XS comes with a 1 year limited warranty covering any failure of components being electric or mechanical.
  • For your warranty to be effective, you must register your unit within 30 days of purchase.
  • Any modifications done to the XS automatically void the warranty!

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