Unipolar vs Bipolar

    Hi,


    I noticed when selecting LFO's in the Matrix that we now have two selections of LFO's, the Unipolar and Bipolar. I understand the definition of them, however i don't understand the effect or how they interact with modulation routing, like what is the advantage or application for choosing one or the other. Can someone shed some light on this?


    Thanks again.

    Fairly easy:



    Since you understand the definition of unipolar vs. bipolar, try some simple experiments to see what it can do:



    -Set up a simple sawtooh patch and put filter 1 cutoff in the middle (=64). Also add some resonace. Now go for the modulation matrix and let lfo 1 modulate the filter 1 cutoff bipolar. Keep it simple and predictable so set lfo 1 waveform to sine or triangle. Play and hold a note and now you should hear the filter open and close fully. That is: it moves filter cutoff from fully closed (0) to fully opened (128). Once you put the modulation in unipolar, the negative part of the lfo cycle is inverted and therefore also positive. Result: the filter doesn' t close anymore. Instead it moves from 64 to 128 twice in one cycle which allows for a different rhythmic structure.



    -A practical, little more complicated example and walkthrough:



    Start from an init patch and set the following parameters:


    -set both oscillators to sinewave
    -Set fm type to wave
    -Raise oscillator 1 pitch with two octaves
    -Set oscillator balance to 128, so you only hear the right oscillator.
    -Set oscillator phase to 1
    -Set detuning of oscillator 2 to 0 (=no detuning)


    -Play a couple of low notes and twist a little with the env->fm amount. That parameter controls how much the filter envelope injects fm into oscillator 2.


    -Experiment with env->fm amount, fm amount and the filter envelope parameters until you obtain a classic fm bass sound.


    -Turn on the arpeggiator and configure the arp so that it generates a nice arp.



    -Time for some modulation:


    -Move into the modulation matrix and and let lfo 1 modulate env->fm amount or fm amount or both.
    -Set lfo 1 to tempo synced and choose a speed that is rhythmic, for example 1/2, 1/4, 1/8 or something.
    -experiment with different lfo waveforms, the shape parameter and unipolar vs. bipolar modulation.


    Once you play and hold a few notes, the arp keeps repeating those notes and the tempo synced lfo injects various amounts of fm into the signal. Since the lfo is tempo synced, this should sound fairly rhythmic and changing from uni to bipolar gives different variations.



    If you are still reading, enhance this patch a little further:


    -set lfo 2 to a tempo of 1/6 or 1/3 or something like that.
    -in the modulation matrix let lfo 2 modulate the depth of modulation of lfo 1. You do that by selecting the correct slot destination.


    Now lfo 1 directly modulates fm amount, but at the same time lfo 2 controls how much lfo 1 affects the signal. Since lfo 2 and lfo 1 have different speeds, you have two "rhythms" in one signal. Again create variations by changing uni and bipolar modulation, tempo, lfo waveforms, shapes, etc...



    A final further enhancement to top it off:


    -Let lfo 1 modulate lfo 2 depth. Meaning: lfo 1 modulates lfo 2 which modulates lfo 1 which modulates fm.
    -Let lfo 2 or 1 or both modulate oscillator 1 pitch. This gives wild results with a lot of harmonics. If it gets too wild, use the filter to keep it under control.


    -There happens to be a third lfo...



    Greetz,



    M.

    Ummm, Merlin, that is incorrect. Unipolar does not have an inverted half-cycle, it's applied as an offset.


    mclifton, imagine it like this: let's say you want to use a square LFO to modify pitch. With bipolar, you'd be setting the pitch of your oscillators, and then applying the modulation, which would result in your patch having two pitches: one below the pitch you initially set (for the lower part of the LFO cycle), and one above it (for the upper part).


    With unipolar, you're only pushing the pitch in the direction of your modulation amount. You still get two pitches, but if you're using positive modulation, you're getting the original pitch you set, and a higher pitch - never a lower one.


    This makes it a bit easier to control some modulations - like in the above example, you might want one of the pitches to always be the actual note you're playing on the keyboard. With bipolar modulation that's much trickier to do.


    This might make it easier than the wordy method above:


    If you set LFO 1 Bipolar to modulate Oscillator 1's pitch with a modulation amount of 12, and hold down C3, the notes you hear are C2 and C4 (again, with a square wave because it's easier to hear).


    If you do the same thing Unipolar, you get C3 and C5. So you see it's still jumping two octaves, but the lower note is the key you're holding, and the entire offset is upwards, instead of the first case where the offset is above and below the note on the keyboard you're holding. I hope that's clear?

    Hello,


    I was just going through this exciting Bootcamp #10 and noticed I don't have LFO unipolar or bipolar showing up in the matrix sections. Only Lfo 1, 2, 3 I'm updated to version 4.1.1.5. Do I need the new public beta for this bootcamp or...?


    Thank you for your help!


    Best regards,
    Martin

    [quote='Merlin',index.php?page=Thread&postID=15577#post15577]Yes, a.f.a.I.k. the unipolar entries in the modulation matrix only show up in the public beta version of the virus o.s.



    Perfect and much thanks! Can't wait to get it loaded!!


    Cheers and best,
    Martin