|
 SSM Analog Synthesizer Chips
Overview
Dave Rossum's first silicon chip design achievements came in the analog arena rather than in the digital domain. Whilst Scott Wedge was programming the Eµ4060 Z80 software in 1976,
Dave co-developed the first ever range of analog synthesizer chips with Ron Dow. The chips were manufactured by a local Silicon Valley foundry – Solid State Music (SSM). This range of
SSM chips achieved considerable fame as the basis for a wide range of ground breaking synthesizers over the next few years, including the Prophet 5.
First Attempts In 1975 Ron called by the E-mu Systems office
(house) in Santa Cruz and discussed a new VCA custom chip he was planning to manufacture, which had the potential of being utilised in E-mu's modular synthesizers. He was keen to get E-mu
to buy in (literally), as he wanted them to stump up the US$1000 to integrate it! The idea was initially interesting until Ron explained that chips would work with power rails up to +/-12V.
Since the E-mu modular systems were based on +/-15V this was a non-starter and Ron was shown the door!
Improved Designs A year later and Ron was back with an improved VCA design which had +/-15V power rails. This time
Dave became interested! A loose co-development partnership developed over the next few years, with Dave contributing design ideas and providing Ron with lab equipment to perfect the
design of the SSM2010 (low distortion VCA), SSM2020 (VCA) and SSM2030 (VCO). The SSM2030 was a lengthy year long and difficult project. It was followed by the SSM2040 (VCF) and SSM2050 (Transient Generator) which were largely Dave's
designs. These innovative chips were all available by the early summer of 1977, making a new generation of synthesizers feasible in 1978.
Fathers of the Polyphonic Synth The range of SSM chips that
Dave Rossum designed with Ron made polyphonic synthesizers possible. The availability of each analog building block on a single chip meant that multi-voice synthesizers were economical to
build, and could be manufactured so that each voice sounded nearly the same. This was a big step forward from the expensive and huge Yamaha CS80 and Oberheim 8-voice of 1976.
The chips achieved considerable fame as the basis for a wide range of ground breaking polyphonic synthesizers including the Prophet 5 Revision 1, the PPG Wave 2.2 and the Korg PolySix.
Emulator Core
E-mu Systems based a number of analog synthesizers of the late 1970's on the SSM chips, including the Audity, Galanti and Blue Box. They sold both individual chips and complete voice cards up until 1980/81. Later SSM chips featured
in the warm analog VCF's of the early E-mu digital samplers and all the drum machines.
- SSM2020 (Dual VCA) - Audity, Blue Box, Voice Card
- SSM2030 (VCO) - Audity LFO, Blue Box, Voice Card
- SSM2040 (VCF) - Audity, Blue Box, Voice Card
- SSM2044 (LPF VCF) -Emulator, Drumulator, SP-12, SP1200
- SSM2045 (VCF/VCA) - Emulator II
- SSM2047 (VCF/VCA) - Emax
- SSM2050 (TG) - Audity, Blue Box, Voice Card
Most of the analog modules in the Modular were switched over to
using SSM chips from 1977 - 1979. If you want more information on how these chips were used in the Modular click on the more.
- Resonant Filter - SSM2020 more »
- High Pass Filter - SSM2040
- Transient Generator - SM2050, SSM2055 more »
- VCA and Dual VCA - SM2010, SSM2020 more »
E-mu Systems finally stopped using the SSM designs when
supplies of the SSM2044 ran out in the late 90's, and they had to replicate the chip with discrete logic in the final run of SP1200's.
Competition The chips proved very popular from 1977 - 1985,
with the only competition coming from Curtis Electromusic Specialities (CEM) based in Santa Clara, who began manufacturing a range of analog synthesizer chips in 1979. These proved to be rather more stable in design, but they did not have
the warmth of the SSM designs. The Emulator III was the only E-mu design to use CEM chips (the CEM 3387).
Today The SSM analog synthesizer chips are now out of
production and quite hard to locate new. The SSM2044 was manufactured up until the late 90's, but many others are over 20 years old. Some chips turn up as old synthesizers are broken for
spares. The original chip designs are apparently lost, although it may be possible to reverse engineer them as they use a standard transistor base. SSM were taken over by Analog Devices, and
some SSM designs are still in production including dual transistors and VCA's.
Some designers have started to duplicate some of these classic designs. At E-mu Systems Gary Hull replicated the SSM2044 for
the last SP1200's in the late 90's, and there is a complete replication of the famed SSM2040 VCF in discrete transistor logic in a contemporary modular system.
|
Site Options
Product Spec
* The first analog synthesizer
* The catalyst for numerous
* E-mu Systems built a few 
* SSM2010 - VCA
* SSM2020 - Dual VCA
* SSM2030 - VCO
* SSM2055 - TG
* SSM2010 - VCA
* SSM2033 - VCO
* SSM2044 - VCF/VCA