Filter Boards - What to chose?
  • I’m looking to buy a Shruthi-1 kit from tubeohm, and they have the option to order with either a 4PM,SMR4, or Shruthacon filterboard. Can someone explain to me the differences between the different filterboards, and what differences in sound and features each one has?

  • From Mutable’s website :

    “ SMR4mkII: 4-pole OTA-integrator LPF
    [...] 4-Pole Mission: A clean 4-pole based on the high quality SSM2164, from which are derived 15 different filter responses (LP, HP, notch, allpass…) according to a technique popularized on the Oberheim Xpander. Additional circuitry provides 4 different “flavours” of the resonance self-oscillation, from pure and liquid to chaotic and distorted

    Basically, the SMR is the standard Shruthi Filter, with a very nice Roland-ish low pass filter.
    The 4PM is a bit more versatile and the Shruthacon is based around the Synthacon filter, which is known for being nasty, see demos here

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