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 Model 35 - the original E-mu synthesizer is reborn!
Introduction
E-mu Systems created their first desktop analog synthesizers, the Model 25, in 1972. They sold two before moving on to building modular synthesizers - as they were more flexible (and profitable!). To celebrate the
30 year Anniversary of Scott and Dave founding their business I am building a new analog monophonic syntheszier - the model 35 - based on the original Model 25 idea but using the circuits from the E-mu Modular.
Voice Architecture
The Model 35 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:
- 3 VCO's with Sine, Triangle, Ramp and Square waveforms. Sync option.
- A Noise Source with White and Red outputs.
- A LFO with Sine, Triangle, Ramp, Square and Random waveforms.
- A Sample & Hold circuit.
- 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
- 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).
- VELOCITY destinations are HPF, LPF, VCA
- AFTERTOUCH destinations are LFO mod, HPF, LPF
The synthesizer also has an in-built MIDI controller. Some further features are being
considered:
Functional Design The Model 35 will use professionally manufactured PCB's, along with a high quality adonised aluminium front panel (in blue). It would be nice to fit the synth into a
3U 19" rack, but 6U is more likely! The power supply will be an off the shelf +/-15V module. Rotary controls will be used, unlike the sliders in the Model 25 or encoders in the Audity.
Switches will either be toggle or maybe Prophet 5 style buttons with blue LED's and analog switches controlling the circuit path.
Project Status The Model 35 project started in August 2002 and currently it is at Phase
1A/1B. I am trying to track down the Model 25 schematics - so the project is old hold until 2003.
- Phase 1A - Voice Architecture design
- Phase 1B - Front Panel layout design.
- Phase 1C - Functional design (case, front panel, power)
- Phase 2A - Locate E-mu schematics and transfer into CAD
- Phase 2B - Modernise E-mu schematics for modern parts, update CAD
- Phase 2C - PCB design
- Phase 2D - PCB order
- Phase 2C - Bill of Materials
- Phase 2D - Order parts
- Phase 3 - Build and test prototype 1
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