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Amp modulation with LFO. Only some waveforms work?

Amp modulation with LFO. Only some waveforms work?
« on: March 05, 2017, 07:42:51 AM »
It looks like saw, rev and square of the LFO have no influence on amplitude modulation. The triangle and random waveforms do work.

That seems really weird. Especially since square would be a much more useful modulation for amplitude then random IMO.

Re: Amp modulation with LFO. Only some waveforms work?
« Reply #1 on: March 05, 2017, 07:59:15 AM »
It looks like saw, rev and square of the LFO have no influence on amplitude modulation. The triangle and random waveforms do work.

That seems really weird. Especially since square would be a much more useful modulation for amplitude then random IMO.

I'm too un-tech to understand/explain why/what, but try turning the Env Amount down to zero on the Amp Env. Then try each wave shape in the LFO.

Re: Amp modulation with LFO. Only some waveforms work?
« Reply #2 on: March 06, 2017, 03:18:46 AM »
Hah I can't seem to replicate it now exactly, since all waveforms seem to work, but yeah I guess you are right about the envelope setting.

I'm guessing the modulation is added to the envelope level, and in case it's already maxed out and the modulation signal is unipolar it doesn't have an audible effect. Maybe some waveforms are unipolar and some bipolar.

Thanks!

Re: Amp modulation with LFO. Only some waveforms work?
« Reply #3 on: March 07, 2017, 03:59:58 AM »
It looks like saw, rev and square of the LFO have no influence on amplitude modulation. The triangle and random waveforms do work.

That seems really weird. Especially since square would be a much more useful modulation for amplitude then random IMO.

When you modulate filters or amps with LFOs or Envelopes, you have to imagine the filter or amp having a MAXIMUM value. If you start the modulation near that maximum value and move upward, you won't get much change.
Another example is adjusting Cutoff and Envelope amount. Depending on the Cutoff level and initial Envelope amount, you may not hear any change at all. You will have bring the Env amount down a bit and adjust the Cutoff before you can hear what the Env is doing.

However, when you modulate pitch with LFO or envelope you have a much wider range and you wont find yourself hearing no change like the example above.

All Analog synths do this to some degree, digital synths compensate with software since the sound is 100% software anyway.


Re: Amp modulation with LFO. Only some waveforms work?
« Reply #4 on: March 07, 2017, 07:28:57 PM »
It looks like saw, rev and square of the LFO have no influence on amplitude modulation. The triangle and random waveforms do work.

That seems really weird. Especially since square would be a much more useful modulation for amplitude then random IMO.

To understand this behaviour, I recommend you to read pg. 31 of the manual.  But the most important thing you have to know to understand it is that "Triangle and Random waves are bipolar."...."The square wave, sawtooth, and reverse sawtooth generate only positive values".

If you use the Env Amount up to 10, positive values of LFO won´t affect the signal.

Hope it helps.