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Lowrey Cotillion formant filter schematic

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  • Lowrey Cotillion formant filter schematic

    Hiya,
    I am trying to build a eurorack module that approximates the Choir function on the cotillion D-575. I'm digging through patents etc. right now, but i was wondering if anyone had a cotillion schematic, or knew when that function first appeared in lowrey organs. I imagine its just some kind of poly formant filter, but being an early 80s thing, im not sure if theres a basic little processor in there with code or if its done with some CEM or SSM chips.
    So really any information about the early 80s Lowrey choir effect would be great! thanks so much to anyone who takes the time to respond.

  • #2
    Here's the filter schematic.

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    • #3
      WOW thank you so much! I can't believe it. Thank you, Thank you!

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      • #4
        At the risk of sounding like an Ingrate, do by chance also have the parts list so i can figure out those op amps?

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        • #5
          If you're just looking for analogue vocal sounds like OOH and AAH, it might also be worthwhile considering the electronics from the Kawai DX900 as well as the Cotillion.

          I remember our engineer at Kawai taking a brass sound from a Kawai E550 and filtering it into AAH. Not sure how he got the OOH, but he predated the Cotillion and DX900 by a year or two. Alas I have no idea exactly how he did it!

          The Cotillion's trick was to cycle through the various vocal sounds it could produce with each key press. Fun for five minutes but became irritating when you only wanted one sound to stick!
          It's not what you play. It's not how you play. It's the fact that you're playing that counts.

          New website now live - www.andrew-gilbert.com

          Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha PSR-S970, Kawai K1m
          Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
          Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
          Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1

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          • #6
            andyg Thanks! I will check out that kawai. The Cotillion trick is really what im interested in. because i would like to
            A: do as you suggest and allow it settle on one sound
            B: give manual controls for the filter itself
            C: add a control voltage input so that the adjustments can be modulated by an external lfo

            Im not sure what the base oscillator for the choir sound is. Whether its just cycling through various states of the 3 filters @TusconDave posted in the schematic, or if there is some kind of a rom holding the various voice waveforms. It seems like everything between 1979 and 1985 was a hybrid of everything.

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            • #7
              The Cotillion was maybe a little to far ahead of its time - with the result that it gained a reputation for unreliability. I don't think we're into sampled sounds here, AFAIK it's all done with filtering.
              It's not what you play. It's not how you play. It's the fact that you're playing that counts.

              New website now live - www.andrew-gilbert.com

              Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha PSR-S970, Kawai K1m
              Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
              Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
              Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1

              Comment


              • #8
                Here's the parts list.
                Operation in a nutshell:
                Audio in is a sawtooth wave from the keyers. Voltage controlled filters are varied by the voltage divider consisting of the resistors to 14 volt supply and the resistors that are connected to the PIC chips which connects them to ground as needed.

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