This module is a variation on the 1973 Classic Serge Triple Wave Shaper module.
To quote the 1982 catalog: The Triple Wave Shaper (TWS) is a non-linear modifier which can transform a sawtooth wave into a sine wave. This module incorporates three independent wave shapers for modifying synthesizer waveforms or for processing signals from preamplified instruments. Although originally designed as a wave shaper for our early oscillators, this module has been found to be a excellent modifier of electronic and acoustic sounds, and is highly recommended for subtle timbrel modifications beyond the range of simple oscillator/filter patches.
Of course, it's uses go beyond this. When used in series, they can be used to add folds to the wave shape. Each extra wave shaper you put in series adds a fold to the waveform. As such, quite a lot of tonal variety/harmonic enrichment can be achieve.
A little on how it works:
The schematic of Triple Wave Shaper module. All sections are identical.
On the 1973 version of the Tripe Wave Shaper, all of the input pull down resistors were 22k, not 100k as shown in this schematic, and the components for the AC coupled outputs were mounted on the back of the jacks themselves. By around 1975, these AC coupled outputs were dropped, and both output jacks were simply linked. The output is usually in the 0-5V region. The AC coupled output "centers" it around 0V, an apparent offset varying with wave shape. 25k pots were used for the input level controls. Later two-column panel designs dropped the second outputs altogether, and added a Join switch that coupled the three shapers together. The pots were moved from the PCBs to the panel, but the PCB remained essentially unchanged.
On the schematic for the CGS85 version shown here, additional 220k input resistors have been added, allowing for a Join switch while preserving the individual inputs, unlike the original, which disconnects them. The new Join switch wiring connects all three wave shapers in series, but allows input and output connections to each shaper. If using this Join switch wiring option, the input pots for the second and third shapers are bypassed, and have no effect on the signal coming from the previous shaper. They do, however, allow mixing in an additional signal connected to the corresponding shaper input. If you still wish to use the "classic" joining of the modules, it can easily be arranged by leaving the Join switch off, and using patch cords between the three shapers. 100k pots have been used, bringing the input impedance up to the modern standard of 100k.
Specs & Downloads
Specs & Downloads
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