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Reply To: Oscillator and LFO waveforms.

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Hello DaveFX!

thanks for the informative post!


All Eventides that run VSIG have sawtooth waveforms!  You can insert an audio rate OSCILLATOR or a mod rate LFO, set the waveform to a ?triangle?, and change the duty cycle from the default value (0.5) to the min or max (0 or 1).  This will make a sawtooth waveform on any Eventide that runs VSIG, from the original DSP4000 up through the present flagship H8000FW.

To be honest, I have thought about the triangular waveform with the duty cycle set to 0 or 1 might produce a down or up saw, respectively, but silly me never tried it! It's nice to know that the sawtooth is there!


For a barberpole effect, you can use the newer SLFO module (on the operating systems that have SLFO).  To modulate a frequency with a sawtooth: Set an SLFO waveform to ?triangle? and change the duty cycle from the default value (0.5) to the min or max (0 or 1).  To modulate an amplitude with a ramp up and down: Set an SLFO waveform to ?triangle? with the symmetric duty cycle (0.5) and select ?unipolar? (output values between 0 and 1).  With the settings I just recommended, one cycle of a master SLFO will take your slave SLFOs through one cycle of sawtooth upsweep (for frequency) and one cycle of ramp up and down (for amplitude).

You can check everything I wrote here by making little test programs that bridge the oscillator outputs to monitor modules.  HMONITOR is my favorite because I can fit eight on one screen, which would be trippy to watch with your 8 waveforms at 0, 45, 90, 135, 180, 225, 270, and 315 degrees!  You?ll see Eight Fingers of Love!

This is cool, but does the SLFO has provision to modulate it's phase? The H-3000OSC has such an input and I am using eight of these H-3000OSC modules that output 8 triangle waves (waveform = 1), and these are spaced apart by 45 degrees. These are routed to 8 slew limiters, with rise time being a 1/f, thus I can have a single LFO sweeping both the H-3000OSC modules directly and the slew limiters by a simple math manipulation. In the slew limiter, when rise = 1/f (f being the master LFO frequency) and fall = 0, it will lag the input as long as the signal rises (the ramp up of the tri) and then when the signal falls (down ramp) it will output a 0, thus a saw. The nice thing with the slew limiters is that, if rise = 0 and fall = 1/f, then I can create an ever falling Barberpole phaser (as opposed the classic ever-rising) and with a simple switch (shown as text in the LCD) I can select between the two!

Anyway, here's a jpeg of it, I was too tired to finish it yesterday. Tell me what you think!


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Again, thanks for your input!

Regards, Yannis.

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