Basic questions re/ Diva modulation controls

[lillloyd]

After many years of relying solely on presets (or "preset tweaking"), I've finally begun in earnest to really learn how to program sounds. I'm using Diva for this purpose, along with as many books (synth cookbook, gorges' wizoo book, steal this sound) and online tutorials as I can find.

But I'm having trouble wrapping my head around how the modulation controls work within Diva. I understand the basic signal flow and ADS envelope concepts but don't quite understand the interrelationship between the Cutoff filter knob, the Env2 knob (that modulates the filter), and the actual Env2 controls.

• Assuming that the cutoff filter knob is set to anything but a max level, and the Env 2 knob is set to a *positive* value, is it accurate to say that the cutoff filter knob value controls the *starting* tone/freq of the sound (i.e. the tone at the very beginning of the attack phase?)
  
  if the Env 2 sustain level is set to a non-zero value, does the sound still eventually "return" to the value set by the cutoff filter? Or does the sound "stop" at a freq above the cutoff filter value? (Maybe not articulating this well--I guess I'm asking if the cutoff filter knob sort of sets the "baseline" freq for the sound, and any non-zero setting on the Sustain level will make the sound "return" to a higher frequency than the one set by the Cutoff filter knob, after the Decay is complete).
  
  If the cutoff filter knob is set to the maximum, and the Env2 knob is set to a positive value, I can see that the ADS Env 2 controls don't have any effect on the sound...but I don't understand why(?)
  
  Finally, I can't figure out exactly what happens when I set the Env 2 knob to a *negative* value. If I set the Cutoff knob to halfway (90), and set the Env 2 knob to full negative, it seems like the sound changes so that the Attack is always immediate, and the actual Attack knob controls the Decay, while the Decay and Sustain knobs don't do anything.

Sorry for the lengthy post, and thanks in advance to anyone who takes a bit of time to shed some light on these questions!

lillloyd

[Sendy]

Cutoff frequency defines the theoretical start and end frequency, or the base frequency of the filter. With positive amounts of envelope modulation, the attack stage will rise, the decay will fall until the sustain level is reached, then at key off release is the time it takes for the filter to return to it's cutoff setting.

With negative amounts of envelope, the opposite happens, attacks push downward and the decay rises up to the mirror image of where the positive sustain level was.

Maximum cutoff value and positive envelope modulation produces no result because the filter can't move higher than it's maximum, and the envelope will only try to do this.

A good "one size fits all" setting is to have the cutoff on a low value and have a fair amount of positive envelope modulation. Playing with the ADSR controls will yeild the vast majority of classic analog sounds that way.

[lillloyd]

Thank you Sendy for the detailed reply!

So if I understand you correctly, in both cases--whether the Env2 control is set to a positive or negative value--the attack will push *away* from the "baseline frequency" (the frequency set by the cutoff knob), towards one extreme or the other of the frequency range. If the Env2 is a positive value, the attack setting is the time it takes for the filter to fully open; if Env2 is negative, the attack setting is the time it takes for the filter to fully close.

So in both instances then the decay should be the amount of time it takes to return the filter from the extreme open/close position, to the frequency level set by the Sustain level setting. If the Sustain is 0, the frequency returns to the baseline frequency when the decay is done; if the Sustain is a non-zero setting, the frequency returns to a level above the baseline frequency (if env2 is positive) or below it (if Env2 is negative).

Does that sound about right?


One other question: when I'm trying to mimic a sound and it ends up too dark or bright, tweaking either the Env2 amount knob OR the Cutoff Frequency seems to adjust the overall tone...is there a better or worse way to do this?

[EvilDragon]

If the Env2 is a positive value, the attack setting is the time it takes for the filter to fully open; if Env2 is negative, the attack setting is the time it takes for the filter to fully close.

"Fully" depends on modulation amount, of course.