Alfa Rpar AS3394 Synth voice-on-a-chip

The ALFA RPAR AS3394 is a complete analog music synthesizer "voice" on a single chip designed for computer interfacing for software-based control. Requiring a bare minimum of other external components, the AS3394 is ideal for low cost polyphonic or polytimbric musical instruments featuring rich, analog sound.

Included inside the compact 24 pin package is fully temperature compensated, wide range, voltage controlled oscillator providing sub-oscillator, triangle, saw-tooth, and pulse waveforms; a voltage controlled mixer for adjusting the balance between the internally generated VCO waveforms and any external signal; a dedicated four-pole low-pass voltage controlled filter with voltage controlled resonance; a modulation VCA for modulating the filter frequency by the triangle waveform output of the VCO; and a final VCA for allowing the output to be enveloped. Envelope control for both the VCF and final VCA may be provided by either a hardware envelope generator such as the AS3310 or through software.

All eight control inputs are provided with internal very high input impedance, low bias current buffers. Thus interface to a microprocessor system may be accomplished simply with a single DAC, 4051-type CMOS multiplexer, and 8 hold capacitors.

Features

• Sample & hold buffers on-chip for easy interface to a microprocessor
• Fully temperature compensated VCO
• Independently selectable VCO waveforms
• Sub-oscillator output
• Separate saw-tooth output
• Separate VCO and filter sections allowing design flexibility
• Constant loudness vs resonance VCF
• Filter FM routing for more timbres
• Low noise, low feedthrough VCA
• +5V, −6.5V power supply

Product Replacements

This device is electrically compatible with original chips used in the following products. Note however that this device has 4 more pins than the original and thus cannot be used directly as a replacement.

• Akai AX60 (Qty 6)
• Akai AX73 (Qty 6)
• Akai VX90 (Qty 6)
• Doepfer A-111-5 Mini Synthesizer Voice (Qty 1)
• Doepfer Dark Energy, Monophonic Synthesizer (orig model only) (Qty 1)
• Sequential Circuits / Dave Smith Instruments Six-Trax (Qty 6)
• Sequential Circuits / Dave Smith Instruments Multi-Trak (Qyt 6)
• Sequential Circuits / Dave Smith Instruments MAX (Qty 6)
• Sequential Circuits / Dave Smith Instruments Split8 (Qty 8)
• Simmons Drums SDS9/SDS1000 (Qty 3)
• Simmons Drums SDS200 (Qty 2)
• Simmons Drums SDS400/SDS800 (Qty 4)

Package: DIL-24