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Copyright Kevin Lightner,
used with permission. |
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 Manuals
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 * Audity Brochure 1980
188 KB
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 * Audity Voice
Architecture 1.2 MB
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Audity Zero Project
Overview E-mu Systems created the ultimate analog synthesizer - the Audity System in 1980. By using the new SSM analog synthesizer chips they were able to create a multi-timbral
programmable synthesizer with 8 - 64 voices. Whilst some of the voice architecture was similar to the contemporary Prophet 5, the Emuons added their own ideas with 3 filters (low pass, high pass
and resonant) and an extensive set of modulation busses. This is the largest analog sunthesizer ever envisaged, although only the original prototype with 8 voices has ever been heard. The Audity
Microprocessor can command 64 individual voices, each one on a separate card.
Cloned The Audity Zero is a clone of just one voice of the original, using the original design
and schematics. Additional voices would be too expensive and the SSM chips are too rare. Full programmability will be included and the voice architecture will fully replicate the original
with just a few simple additions may be added - such as:
- A random waveshape has been added to the LFO, created by an E-mu S+H
- A second LFO has been added
- MIDI with aftertouch, velocity and modulation busses will be implemented
Key Features
The Auidty Zero is a MIDI controlled fully analog monophonic synthesizer, with a fixed but flexible internal architecture, that uses a switched routing scheme to interconnect modules. It contains the following analog circuits:
- 2 VCO's with Sine, Triangle, Ramp and Square waveforms
- A Noise Source with White, Pink and Red outputs
- 2 LFO's with Sine, Triangle, Ramp, Square and Random waveforms
- An audio mixer for the VCO's and Noise Source
- A High Pass 24dB Filter
- A Low Pass 24dB Filter, which can be in parallel or in series with the HPF
- Resonant Filter, with HP, BP, LP at 12dB
- 4 ADSR envelope generators, one for each filter, the VCA and FM of the VCO's
- A 5 bus modulation routing scheme (MOD, FM, PWM, VELOCITY, AFTERTOUCH)
- Standard conductive plastic rotary pots, not rotary encoders
- Original E-mu control knobs (new)
- New switches with blue rockers and blue LED's
- Accurate coloured front panel and wooden console (like a Voyager)
- 2 x 40 blue LCD (VFD)
- 5-octave MIDI keyboard with velocity (re-using an Emax keyboard)
- I may embed a Roland MC500 as the sequencer, with its own blue LCD
Project Status
The project started in September 2002 with some initial design ideas, and we don't expect to complete the Audity Zero until 2004/2005. This is a big project!
- 11/02 -a set of SSM chips have been procurred, for use in the Audity Zero, extra SSM2020's are needed in the Resonant Filter and VCA's.
- 01/03 - the Voice Card schematics arrive from E-mu Systems (thanks Riley!). I already have an AES paper by Dave Rossum that provides a good technical overview of the
Audity System.
- 07/03 - A review of the schematics is complete and the analog design can be replicated.
- Next Step is to build a VCO using analog controls.
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