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Analog Synthesizer Module

Other names for this product: ASM1, ASM 1,
Courtesy/Thanks to: Gene Stopp

Description: Please Observe! The ASM-1 PCB is discontinued and is replaced by the ASM-2 PCB.

The ASM-1 is a DIY analog synthesiser created by Gene Stopp and was derived from
a number of Electronotes projects submitted by Terry Mikulic and Bernie Hitchins.
The ASM-1 design brings together the basic modules for a classically
configured synthesiser on a single pcb.
Although on a single pcb, each module is fully self-contained with only the power rails common to all modules. This allows the user the freedom to use the ASM-1* in any type of design desired, from a small pre-patched unit to a fully modular system.
(words by Laurie Biddulph who runs a DIY site in Australia and also sells premade PCB's for the ASM-1 and ASM-2 Synthesizers).

The ASM-1 Analog Synthesizer Module was created for a few reasons:

  1. I wanted to build a manually-patched polyphonic analog music synthesizer for

    my own use, having given up hope of finding an old Oberheim 8-voice for a couple

    of hundred bucks. Making a circuit board for each voice is only marginally

    crazzy - making the whole thing on vectorboards would be totally crazy. I'm only

    marginally crazy.

  2. If i did make a circuit board, I could make extra ones and sell them to

    synthesizer builders, to help pay for the rather expensive PCB setup costs at

    the local shops.

  3. I like to design circuit boards.
The ASM-1 contains a fairly

standard arrangment of traditional analog synthesizer modules, in what can be

considered a compromise between simplivity and usefulness. The circuit sections


2 Voltage Controlled Oscillators (VCO's)

Sawtooth and variable rectangular outputs

1 Voltage Controlled State Variable Filter (VCF)

Lowpass, bandpass, highpass and notch outputs

2 Voltage Controlled Amplifiers (VCA's)

Linear response

2 ADSR Envelope Generators

Exponential curves

1 Low Frequency Oscillator (LFO)

Triangle and square outputs

1 Noise Source

White, pink and random outputs

1 CV Glide Buffer

Linear or exponential glide

These circuit sections can be considered "modules" in the

modular synthesizer sence, since they are not interconnected in any way on the

circuit board other than by power and ground busses. Therefore the builder has

the freedom to use the ASM-1 in any type of design desired, from a small

pre-patched expander module to a fully patchable semi-modular system.


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   asm 1 noise source schematics
   The ASM-1 pages at Elby Designs
   ASM1 Style State Variable Filter
   ASM-1 Homepage
   Papareil' ASM-1 X
   Elby Designs - Home of the ASM-2 PCB, EDP WASP clone and SimpleSizer
Gene Stopp
   The creator of the now worldknown ASM-1
Other versions/mods
   Semi pre-patched ASM-1 synthesiser
   Semi pre-patched ASM-1 synthesiser
   Analog synthesizer Developed around the ASM-1
Parts used
   2MHz, Operational Transconductance Amplifier (OTA)
   PNP switching transistor
   NPN switching transistor
   JFet-input Operational Amplifier
HCC 4002
   Dual 4 input NOR gate
Related Products
   Semi-modular synthesizer
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