3 comments


  • Hi Rob,

    One thought after reading through your article: Could the reference voltage input be the level at which the Attack/Decay comparator switches?
    If the envelope always charged towards +15V, but allowed you to alter the level at which it switched, you’d have some degree of control over the straightness/curviness of the attack curve. However, such a scheme would probably alter the maximum level of the output, and also requires explanation of how the sustain CV remains at 0-10V rather than 0-Vref.
    Perhaps it works the other way around and the comparator always switches at the same level, but you can alter the level it charges towards as you suggested. This also provides some degree of control over the curve, and maybe causes less other issues?

    May 10, 2019
  • René

    Thank you for the article, well done.

    While your reasoning behind the IR being a CV-to-Pulse-to-CV converter, because of the traits left by the JP4/Promars is indeed a strong option, I think it’d be a very convoluted way to do what it’s doing.

    That’d mean the design (i.e. JP8) would be A/D’ing the panel values, then D/A’ing them, passing thru the MPX to send to the boards, then again doing A/D/A inside each IR of each voice. I would think it would’ve been easier/cheaper just to distribute pulses as in the JP4 (which is extremely elegant imho).

    I don’t see what would´ve been the economic or technical benefit of crafting a custom IC ($) to do it. Unless they OEM’ed something already out there.

    I think the “old fashion” (should I say old^2?) of using a monostable would make for a simpler chip as well.

    Cheers!

    June 21, 2019
    • amsynths

      Thanks for the post and I do tend to agree, why make a complex chip and could it be made anyway? A monostable design would need the ADR sliders to be log which is how they are set up in the JP8, with the modulation waveform altering the timing of the monostable. I guess we will never know the exact details..Rob

      June 30, 2019

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