Original Octave Cat after repair

This formerly sick Cat came in with a filter that was always open.  That is to say, broken.  Open as it was broken, it would pass audio and resonate supersonically but without the fun beeeeeyyaaaoooohhhh that we have come to know and love.  With the help a few new friends at Sprout‘s Synth Night, we found that the voltage to exponential current converter in the filter was trashed, and had a wrong transistor in there backwards.  Luckily Sprout being awesome as they are, had the transistor pair as well as an opamp that also seemed to have gone, all on hand.  Thanks!  With those parts replaced, the filter was up and running.  The old wiring was also coming apart, which was causing intermittent signal from the VCOs, which was easily fixed just by re-seating the friction connectors.  I also went through the whole thing and cleaned it up, cleaned all the connections, knob and slider controls, switches, etc.

This video is a short dive into just some of what the Cat can do after a full intonation and calibration was performed.  The modulation paths of the Cat are vast, with 2 modulation source controls for the pitch of both of the VCOs as well as the filter.  VCO1 can serve as a true modulation oscillator, although the triangle wave is too rich in harmonics to get that west coast sound, (and sadly lacking in VCO2).  It makes up for it with the legendary Cross-Mod btwn VCO 1&2.  Fantastic.

This is the original model of the Octave Cat.  This one has discrete filter and VCO topology.  Later models including the SRM had SSM chips.  Later models also offer a delay for the LFO as well as an LFO indicator light.  Since the Cat is a beast well-suited for noise, brash tones and self triggering, I don’t miss the LFO stuff on this one, and would prefer the circutry.  An oft overlooked gem, as long as you can find one in decent condition.  Octave was not known for high-quality construction (or circuit design, as some of the guys at Sprout found a few oddities in the circuit/PCB)

giorgio

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~ by ptvn on December 9, 2010.

One Response to “Original Octave Cat after repair”

  1. Does anyone know where to find the service manual and schematic for the SRM II model? Thanks!

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