The Crumar Spirit stands as one of the most complex and powerful analog monophonic synthesizers ever produced, yet it remains obscure due to Crumar's reputation for budget instruments. Released in 1983 and designed by legendary figures Bob Moog, Jim Scott, and Tom Rhea, the Spirit represents the pinnacle of Italian synthesizer manufacturing from the Castelfidardo region.

Design Philosophy & Heritage

The Spirit emerged from Crumar's evolution beyond cheap electric pianos and string machines. Founded by Mario Crucianelli, Crumar had established itself in the affordable keyboard market but struggled to shake its budget image despite increasingly innovative designs. The Spirit was their answer to creating a world-class monosynth, incorporating design input from Minimoog co-designer Jim Scott, Moog employee and manual writer Tom Rhea, and Bob Moog himself.

Sound Architecture

Built around premium components including dual CEM3340 oscillators, dual CEM3350 filters, and six CEM3360 VCAs — the same chips found in legendary instruments like the Memorymoog, Prophet 5, Oberheim OB series, and Rhodes Chroma — the Spirit delivers exceptional sonic quality. While not as immediately warm as a three-oscillator Minimoog, it offers considerably more flexibility and complexity.

The Spirit features two voltage-controlled oscillators with complementary waveform selections. Oscillator A provides triangle, square (with 30%, 15%, and 5% pulse widths), and sawtooth waves across a 32' to 4' octave range. Oscillator B offers triangle, various pulse widths (40%, 20%, 10%, and 3%), and sawtooth, with four octave ranges relative to Oscillator A and a detune control spanning ±8 semitones. Critically, Oscillator B can be set to Bass mode (30Hz-300Hz) or Wide mode (2Hz-10kHz), disconnecting it from keyboard tracking to function as a modulation source or drone, enabling unique sync sounds where Oscillator A tracks the keyboard while B remains at fixed frequencies.

Dual Filter Architecture

The filter section represents one of the Spirit's most distinctive features. Rather than a simple low-pass design, it employs two independently configurable filters named U (Upper) and L (Lower) based on their panel positions. Filter U is a traditional resonant low-pass filter with switchable 12dB/octave or 24dB/octave slopes, variable keyboard tracking (0-110%), and a dedicated ADSR envelope with variable depth and polarity inversion. The resonance can be set to fixed low (Q≈0.5) or variable.

Filter L operates in four modes: Out (bypassed), Overdrive (adds distortion and functions as parametric EQ with frequency boost), Band-pass (parametric EQ without distortion), and High-pass. A Dynamic/Formant switch allows Filter L to be disconnected from keyboard tracking and filter CVs, creating a fixed formant filter effect. The Filter L cutoff control operates relative to Filter U rather than as an absolute value, allowing the two filters to be offset or aligned. When self-oscillating filters are offset slightly, this creates ghostly timbres unique to the Spirit. One filter can track pitch while the other remains stationary, causing filter characteristics to change across the keyboard.

Signal Paths

The Spirit employs two parallel signal paths. The primary Filter/ADSR path routes oscillators through the dual filters and a VCA controlled by a dedicated ADSR envelope. The secondary Shaper Y path processes all sound sources (including a ring modulator) through a 6dB/octave low-pass filter and a VCA shaped by the Shaper Y modulator. These paths can be mixed in the Mixer section, where tiny phase shifts introduced by the filters create significant fattening when combining the same sources from both paths.

Modulation System: Mod X & Shaper Y

The Spirit's most powerful and complex feature is its dual modulation system with interlinked capabilities. Mod X offers six modulation sources: triangle wave, square wave, sample & hold, Shaper Y, red noise, and Oscillator B. It includes a dedicated LFO that doubles as the S&H clock. Mod X can be routed via a dedicated wheel to five destinations: pitches of both oscillators; Oscillator A pitch alone; Oscillator A pulse width; both filter cutoffs; or Filter U cutoff alone.

Shaper Y provides a triangular LFO whose waveform can be varied from sawtooth through triangle to ramp using the Shape control. Its Mode control offers four options: Free (simple LFO centered on 0V for vibrato/tremolo), KB Hold (gated ASR contour), Reset (AD contour that resets when retriggered), and Run (unconditional AD contour that completes regardless of keyboard input). Shaper Y routes through its own wheel to destinations including: both oscillator pitches; Oscillator B pitch alone; Oscillator B pulse width; Mod X LFO frequency; and Filter L cutoff alone.

The system becomes extraordinarily complex because Mod X can use Shaper Y as a modulation source, while simultaneously Shaper Y can modulate the Mod X LFO frequency. Additionally, a Wheel Destinations switch allows Shaper Y to modulate the output from Mod X, creating intricate modulation matrices impossible to replicate without extensive modular patching.

Arpeggiator

The built-in arpeggiator offers three unique modes at LFO-controlled rates: Ripple (plays held notes upward), Arpeggio (repeats notes at the played octave, one above, and one below in three-octave patterns), and Leap (plays first note at source octave, second at +1 octave, third at -1 octave). The Leap mode creates complex patterns, particularly when holding multiple notes—four held notes generate 12-note cycles that can be altered in real-time by changing held notes.

Keyboard & Performance Features

The 37-note keyboard lacks velocity sensitivity and aftertouch but implements an intelligent keying system. It uses primarily last-note priority while remembering the first note played. When releasing subsequent notes while holding the first, pitch returns to the initial note without retriggering — forgiving accidental note brushes and making the Spirit ideal for lead lines and phrases with root drones.

The VCA envelope can be gated from four sources: keyboard (with Single or Multiple triggering), X, Y, or External. Portamento offers two modes: standard On mode for continuous glide, and Auto mode that only glides when holding the first key while playing the second, allowing technique-based portamento control.

Three performance wheels provide pitch bend, Mod X amount, and Shaper Y amount. Combined with the arpeggiator and extensive modulation routing, these enable highly expressive and complex performances.

Connectivity & Integration

Despite its integrated appearance, the Spirit functions excellently in modular setups. The rear panel provides individual outputs for the Filter/ADSR and Shaper Y paths, allowing separate processing of the two timbres. An audio input replaces the internal noise source, enabling external signals to be processed through the Spirit's filters and modulators.

Voltage control inputs include: Filter Pedal (controls Lower and/or Upper filter cutoffs), Osc B (controls Oscillator B pitch, ideal for sync sounds), plus conventional CV and Gate inputs and outputs. These can serve as general CV inputs beyond their labeled functions. The rear panel features a MIDI hole covered by a grommet, but no internal MIDI electronics were ever installed, and no retrofit interface was developed.

Playing Character

The Spirit demands patience and understanding rather than offering the Minimoog's immediate gratification. It rewards deep knowledge of its architecture with access to virtually any classic analog timbre plus sounds unique to its architecture. Simple patches using one oscillator, basic filtering, and appropriate envelopes deliver superb lead tones with character and depth. Adding the second filter in Band-pass or Overdrive mode enters expensive sonic territory. Incorporating the second oscillator, extensive modulation options, and the Shaper Y path unlocks the Spirit's full potential.

The dual signal paths, offset filter configurations, formant filtering, complex modulation routings, and oscillator sync capabilities create timbres impossible on simpler architectures. Phase shifts from mixing both signal paths fatten sounds considerably. The intelligent keying system prevents performance errors while enabling sophisticated playing techniques.

Historical Context & Legacy

The Spirit arrived at an unfortunate moment. Released in 1983 when MIDI was just emerging and the Yamaha DX7 was revolutionizing synthesis with digital FM, analog monosynths were falling from favor. Crumar's budget reputation meant few took notice despite the impressive design pedigree. The Spirit became Crumar's final monosynth before the company shifted to the Bit series of analog polysynths and ultimately ceased trading in 1987.

Two cosmetic versions exist: early units in dark wood finish and later "blonde" models in lighter colored cases. Production numbers were minimal—documented serial numbers suggest extremely limited manufacturing. The Spirit remains one of the rarest professional synthesizers, with almost no market presence when new and minimal awareness even in vintage synth circles.

Assessment

The Spirit ranks alongside the Minimoog as a performance instrument, though with different character. Where the Minimoog offers immediate sonic satisfaction, the Spirit demands investment in learning its complex architecture. It stands as perhaps the most sophisticated integrated monosynth ever produced, with modulation and filtering capabilities requiring extensive modular systems to replicate. For those willing to master its intricacies, it delivers unparalleled flexibility and sonic possibilities. A polyphonic Spirit could have rivaled any analog polysynth in history, but it remained a magnificent monosynth — obscure, eccentric, powerful, and ultimately Crumar's swan song.

Technical Specifications

Synthesis Architecture

• Type: Analog monophonic synthesizer
• Signal Paths: Dual independent paths (Filter/ADSR and Shaper Y)
• Polyphony: Monophonic with intelligent last-note priority (remembers first note)

Oscillators

• Oscillator A:
  • Waveforms: Triangle, Square, Pulse (30%, 15%, 5%), Sawtooth
  • Octave Range: 32', 16', 8', 4' (four octaves)
  • Master tuning control
• Oscillator B:
  • Waveforms: Triangle, Pulse (40%, 20%, 10%, 3%), Sawtooth
  • Ranges: -1 octave, Unison, +1 octave, +2 octave (relative to Osc A)
  • Detune: ±8 semitones
  • Special Modes: Bass (30Hz-300Hz), Wide (2Hz-10kHz) with keyboard disconnect
• Oscillator Sync: Oscillator B can sync to Oscillator A
• Noise: White and Pink noise generators (plus Red noise in Mod X)

Filters

• Filter U (Upper):
  • Type: Resonant low-pass
  • Slopes: Switchable 12dB/octave or 24dB/octave
  • Cutoff: Master cutoff frequency control
  • Keyboard Tracking: Variable 0% to ~110%
  • Resonance: Switchable Low (fixed Q≈0.5) or Variable
  • Envelope: Dedicated ADSR with variable depth and polarity (normal/inverted)
• Filter L (Lower):
  • Modes: Out (bypass), Overdrive (distortion + parametric EQ), Band-pass (parametric without distortion), High-pass
  • Cutoff: Relative control (adjusts Filter L relative to Filter U cutoff)
  • Resonance: Dedicated control for parametric boost or high-pass resonance
  • Dynamic/Formant Switch: Disconnects Filter L from keyboard tracking and CVs for fixed formant filtering
• Self-Oscillation: Both filters capable of self-oscillation

Voltage Controlled Amplifiers

• Filter/ADSR Path VCA:
  • ADSR Envelope with bypass switch
  • Gate Sources: Keyboard (Single/Multiple trigger), X, Y, External
• Shaper Y Path VCA:
  • Gain controlled by Shaper Y modulator
  • Simple 6dB/octave low-pass filter in path

Modulation Sources

Mod X

• Sources: Triangle wave, Square wave, Sample & Hold, Shaper Y, Red noise, Oscillator B
• LFO: Dedicated rate control, doubles as S&H clock
• Routing: Via dedicated Mod X wheel
• Destinations:
  • Oscillators A & B pitch
  • Oscillator A pitch alone
  • Oscillator A pulse width
  • Filters U & L cutoff
  • Filter U cutoff alone

Shaper Y

• Waveform: Variable from Sawtooth through Triangle to Ramp
• LFO: Dedicated rate and shape controls
• Modes:
  • Free: Simple LFO centered on 0V
  • KB Hold: Gated ASR contour
  • Reset: AD contour (resets when retriggered)
  • Run: Unconditional AD contour (completes cycle regardless of keyboard)
• Routing: Via dedicated Shaper Y wheel
• Destinations:
  • Oscillators A & B pitch
  • Oscillator B pitch alone
  • Oscillator B pulse width
  • Mod X LFO rate
  • Filter L cutoff alone
• Cross-Modulation: Shape X with Y switch allows Shaper Y to modulate Mod X output

Arpeggiator

• Modes:
  • Ripple: Up/Down pattern
  • Arpeggio: Plays notes at played octave, +1 octave, -1 octave (three-octave patterns)
  • Leap: First note at source octave, second at +1 octave, third at -1 octave
• Clocking: Linked to LFO rate
• Complexity: Multi-note chords create extended pattern sequences

Additional Processing

• Ring Modulator: Built-in, routable in Shaper Y path
• Mixer: Independent level controls for:
  • Filter/ADSR path: Oscillator A, Oscillator B, Noise
  • Shaper Y path: Oscillator A, Oscillator B, Ring Mod, Noise
• External Audio Input: Replaces internal noise source, processes external signals through filters and modulators

Portamento/Glide

• Modes:
  • On: Standard continuous glide
  • Auto: Glides only when holding first key while playing second (technique-dependent)
• Control: Glide rate knob

Keyboard

• Keys: 37 notes, 3 octaves
• Velocity Sensitivity: None
• Aftertouch: None
• Priority: Last-note with first-note memory
• Triggering: Single or Multiple

Performance Controls

• Wheels: Three total
  • Pitch Bend wheel
  • Mod X wheel (controls modulation amount)
  • Shaper Y wheel (controls modulation amount)
• Front Panel: 24 knobs, 10 switches, 15 sliders

Connectivity (Rear Panel)

• Audio Outputs:
  • Filter/ADSR path output
  • Shaper Y path output
• Audio Input: External signal input (replaces internal noise)
• Control Inputs:
  • CV Input
  • Gate Input
  • Filter Pedal Input (controls filter cutoffs)
  • Osc B Input (controls Oscillator B pitch)
• Control Outputs:
  • CV Output
  • Gate Output
• MIDI: Hole present but no electronics installed (never implemented)

Internal Components

• Oscillators: 2× CEM3340 VCO chips
• Filters: 2× CEM3350 Dual VCF chips
• VCAs: 6× CEM3360 Dual VCA chips
• Digital Components: Decoders, scanners, adders, flip-flops, shift registers, D-A converter (for pitch CV), computer connector (diagnostic purposes)
• Signal Path: Fully analog (digital components only for keyboard scanning and CV generation)

Memory

• Patch Storage: None (all settings manual)

Physical Specifications

• Finish: Two versions
  • Early models: Dark wood finish
  • Later models: Light "blonde" wood finish
• Construction: Standard keyboard housing with extensive control panel

Production&Historical Notes

• Final monosynth produced by Crumar
• Released: 1983. Sales finished in 1987. Extremely rare with minimal original market penetration
• Designed by: Bob Moog, Jim Scott, Tom Rhea
• Manufacturer: Crumar (Castelfidardo, Italy)
• Production Run: Very limited (low serial numbers documented)
• Shares chip architecture with Memorymoog, Prophet 5/10, Oberheim OBXa/OBSX/OB8, Rhodes Chroma, Roland Jupiter 6, and other legendary synthesizers