Akai AX73 (1986)
6-voice analog synthesizer with velocity-sensitive 73-key keyboard and built-in chorus, released in 1986.
Overview
The Akai AX73 is a 6-voice analog synthesizer and master keyboard released in 1986. It features a 73-note velocity-sensitive keyboard and combines the sound engine of the AX-60 with expanded modulation routing and MIDI split capability. The AX73 shares identical sound-generating circuitry with the VX90 rack module and is part of Akai’s AX series of analog synths, which includes the AX60 and AX80.
Specifications
| Production Year | 1986 |
| Polyphony | 6 voices |
| Oscillators | 1 VCO per voice |
| VCO Waveforms | Triangle, sawtooth, variable pulse (with PWM), composite saw + triangle |
| VCF | 24dB/octave resonant lowpass filter with non-time-variable highpass in series |
| Envelopes | 2 analog ADSR generators per voice |
| LFO | Global; waveforms: triangle, saw, pulse, random (sample & hold) |
| Effects | Built-in chorus (MN3009/MN3101) |
| MIDI | MIDI IN, MIDI OUT, keyboard split with adjustable split point |
| Keyboard | 73 keys, velocity sensitive |
| Display | 15-letter backlit LCD |
| Programming | Step programming with data entry slider |
| Sound Chip | Curtis CEM3394 |
| Power Supply Voltages | ±5V, ±15V |
| Dimensions | 1152 mm x 364 mm x 110 mm |
| Weight | 15 kg |
| Manufactured in | Japan |
| MSRP | $1,199.00 USD |
Design
The AX73 uses a digitally controlled analog subtractive architecture centered on the Curtis CEM3394 "synth-on-a-chip," with socketed voice chips and analog ADSR envelopes. It features a 24dB/octave resonant lowpass filter that self-oscillates cleanly, paired with a fixed highpass filter. The VCO can modulate the VCF, and both envelopes can modulate VCF, VCA, or VCO pitch. The keyboard supports poly, dual, and unison modes, with 1, 3, or 6 oscillators per note. The power supply board contains 22µF, 100µF, and 220µF capacitors prone to high ESR over time. The unit is described as "built like a Sherman Tank" with a construction style resembling Akai’s S900 sampler.
Context
The AX73 is essentially an AX-60 with velocity sensitivity, a 73-key keyboard, and added modulation routings, sharing the same sound engine as the VX90 rack module. It can interface with Akai S612, S900, and S950 samplers via a special cable, allowing external audio to be processed through its analog filters. Despite its analog nature, its minimalist front panel often leads to it being mistaken for a digital instrument, contributing to its underappreciation.
Market
Current market prices range from $900 to $1,400. Common issues include stiff or unresponsive buttons, cracked front boards, and loose screw posts connecting the button PCB to the panel—often repaired with epoxy. The power supply is susceptible to capacitor failure, particularly the 22µF, 100µF, and 220µF units. Battery replacement is a known service fix, and a service manual was listed for $25 on eBay. Recapping the power supply is recommended as preventative maintenance.
eBay Listings
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