A monophonic analog synthesizer produced by Octave Electronics from about 1975 to 1982. This was Octave's first product and, at a price lower than the Odyssey, it sold well. This article from Gforce's Web site says that there were a number of semi-official factory customizations and options available, which was not the case for the Cat's competitors. Octave usually spelled the name in all upper case: the CAT. Three versions were produced: the original, the SRM I, and the SRM II.
Cats are moderately sought out on the collector market. The SRM I seems to be the preferred model. Many techs will not work on an SRM II because no schematics or service manuals are known to have survived, and the circuitry is quite different from the older models.
The Original CATEdit
The original version was fairly similar to the ARP Odyssey (enough so that ARP sued, unsuccessfully, for patent infringement). It had two VCOs (with suboscillators), a VCF, a VCA, two envelope generators, and an LFO. It had a duophonic keyboard capability, where the keyboard could produce two control voltages, one of which would be routed to VCO 1 and the second to VCO 2 when the "dual" mode was selected. It had a three octave keyboard and no other performance controls; in particular, there was no pitch wheel, although there was a non-sprung slider on the panel that allowed pitch to be varied.
In 1977 Octave upgraded the Cat to the "SRM" model. This added several requested improvements, including a turn-on delay to the LFO and a pedal input jack for offsetting the VCO1 frequency, but the main improvement was not visible from the panel: the keyboard interface circuitry was revised to include sample and hold circuits for both of the control voltages generated by the keyboard. On most duophonic synths of the era, there was only one sample and hold dedicated to the keyboard, so when playing duophonically, when the keys were released, the secondary control voltage would jump to the primary voltage, meaning that it was impossible to get duophonic notes in the envelope release phase. The Cat SRM, on the other hand, would hold both control voltages, so a two-note chord would continue to sound as a chord through the release phase. This was an unusual feature for an analog duophonic keyboard.
An SRM I or II can be distinguished from the original model by the pilot light next to the power switch, and a light next to the LFO FREQ control which flashes in synchronization with the LFO.
The SRM II replaced the older model in 1979 or 1980. The improvements were all under the hood: the discrete VCO circuits used in the earlier models were replaced by a Curtis 3340; the analog keyboard was replaced by a digital scanning keyboard (which retained the duophonic capability), and most of the internal switching circuitry was replaced by CMOS logic ICs. Since these changes had no direct benefit to performers, they were likely done to reduce manufacturing costs; they may also have been done to gain experience with technologies that Octave would later employ in the Voyetra 8.
This was a cut-down version of the Cat, with one VCO and one envelope generator, but otherwise similar. It was introduced in 1977.