From cadsi.com!kent@elvis.cadsi.comFri Jun 23 23:38:52 1995 Date: Sat, 24 Jun 1995 00:33:07 -0500 From: Kent Williams Reply to: cadsi.com!kent.williams@cadsi.com To: Tosh , AH Subject: Re: Whats this button do? (JX-3P) On Jun 24, 12:10am, Tosh wrote: > Subject: Whats this button do? (JX-3P) > I'm dumb. > Well dumb as in I have no clue what most of the knobs on my PG-200 > actually do to my 3P. Well, dumb as I am, I get really excited when someone asks a question here I actually know something about! > Whats a: Cross Mod, and Freq Mod do pointing to an LFO and ENV > knobs, which are poited to by a (I assume) polarity switch. Cross Modulation is the relationship between the two oscillators. If it's off, the frequency of the two are completely independent. If it's set to 'SYNC' then OSC 2 is synced to OSC 1. What this means is kind of complicated, but it boils down to OSC-2 being constrained to being tuned to OSC-1, but when you change the tuning it will change the harmonic content. The effect (at least on the 3P) is similar to a flanging or chorusing sound. If it's set to 'Metal' it's some goofy-ass thing that almost but doesn't quite sound like a ring modulator. No one has ever adequately explained what goes on with this setting. The switches below the waveform knob control whether or not the LFO and Envelope control the pitch of the oscillator. The interesting timbres on the 3P come from using 'sync' mode, but modulating the frequency of OSC2 with the LFO and/or Envelope. That's the first thing to try. The knobs under oscillators labeled LFO and ENV control the depth of pitch modulation. > (What does polarity do anyways?) It inverts the effect of the envelope on either the DCO (pitch) or the DCF (filter cutoff). If the switch is in the normal setting then the pitch (or cutoff) goes up as the envelope level rises and goes down as it falls. If you inverted, then when the envelope level goes up the pitch (or cutoff) goes down. > Then there's the thing at the top, the HPF, whassat? High pass filter. Rolls off frequency below a cutoff point. > Then under the VCF is more LFO Mod, and ENV Mod things, with the ENV Mod > pointed to by another polarity switch, and then whats Pitch Follow do? Pitch follow determines the relationship between the key played and the filter cutoff. If it's cranked full left, then the filter cutoff knob is absolute -- if you play a note whose root frequency is higher than the cutoff, you won't hear the note. If it's cranked right, then the cutoff is relative to the key played -- as you play higher notes, the cutoff changes to preserve a fixed ratio between the note played and the cutoff. There's this odd recipe for doing pulse width modulation. 1. Set Cross Mod to 'Sync'. 2. Set Both Oscillators to Pulse wave i.e. the one that looks like this: __ || | ||___| 3. Crank the Source mix knob hard right. Now the tuning knobs control the pulse width of DCO2. As do the ENV and LFO if you turn them on. Or so the manual says; at another point it says that if you set cross mod to sync, OSC2 is always a sawtooth wave. -- "This unit might get hot while operating, but there is nothing to worry about it." -- Chapter 1, Verse 10, the book of MKS30. -- kent.williams@cadsi.com [Kent Williams/CADSI/2651 Crosspark Rd/Coralville IA 52241/(319)626-6700]