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  • "Cubic_Spline" started this thread

Posts: 7

Location: Grenoble / France

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1

Thursday, November 3rd 2011, 4:11pm

Audio Rate LFO

Hello guys ! :)

One feature i'm definitively looking for is audio rate LFOs ! (and/or oscillators available as mod sources in the matrix).

One way to implement this and keep the compatibility with older patches would be an option in the LFO section : "Range : Normal / Wide" with the first one beeing like it was always, and the second one beeing LFO rate from slow to 1-5 Khz ! It would allow some crazy stuff, AM modulations ... !

Thanks for reading ;)

Clément

This post has been edited 1 times, last edit by "Cubic_Spline" (Nov 3rd 2011, 6:00pm)


MaF

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Saturday, November 5th 2011, 5:34pm

Someone correct me if I'm wrong but I'm afraid, the Virus would run out of DSP power quite fast, wouldn't it? That's also why its envelopes have rather slow attack phases compared to e.g. Zebra.

AtonyB

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3

Sunday, November 6th 2011, 12:46am

I'm not sure I agree that the envelope attacks are slow... I'd say the opposite, actually, as the variation in the last few points (125-127) have a very large range of variation, of course you expect that something to infinity step, but sometimes you really cant get a long enough attack on the envelopes.

Bear in mind that a lot of what you could do that would be useful with audio range LFOs is already available such as FM, RM (AM) and the modulation on the delay effect - I cant think of anything that wouldn't come out as garbage being modulated at audio frequencies with the LFOs. I'm certain that it's a complexity thing, though, as the mod matrix may not be 'polled' fast enough and you would get terrible aliasing, and increasing the polling rate may compromise the overall performance...

dark_fader

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4

Monday, November 7th 2011, 5:39pm

If it's possible (and the existence of the 'FM' knob would suggest that it is), it would be nice and useful for creating interesting sonic textures. I can immediately imagine a situation where a siren type sound slowly sped up to become its own rising metallic texture. Build-up heaven. Unfortunately at the moment FM can either be carried out at LFO frequencies or audio frequencies, but not both from the same modulation source.

Making it available to all modulation destinations would be a natural 'why the hell not?' next step.

AtonyB

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5

Monday, November 7th 2011, 8:34pm

FM is internal to the oscillator 'structure' in the software - instead of grabbing osc2 value, grab it times osc1 value - synchronising the mod matrix is a much lower frequency process as there would be a lot more going on buffering variables or using semaphores to ensure there isnt inconsistent update of variables, etc.

In other words, the delay effect, for example, may only have its delay time variable updated at, like, 20Hz or something, so if you try to modulate it with a signal going at, say, 1kHz, you would get epic aliasing. Changing the virus OS to support this would be somewhere between sacrificing a lot of voices and a complete rewrite of the OS.

dark_fader

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6

Monday, November 7th 2011, 10:49pm

If that's true then it's a bit of a shame. But I can see the logic in it.

Looking at it the other way round, perhaps an interesting feature to add would be a toggle to allow one of the oscillators to go down to LFO frequencies.

Edited to add: Ooh, looks like you can. :)

This post has been edited 1 times, last edit by "dark_fader" (Nov 7th 2011, 11:22pm)


AtonyB

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7

Tuesday, November 8th 2011, 8:13pm

They go pretty low.

dark_fader

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8

Wednesday, November 9th 2011, 12:34am

Dunno how smooth I can make it with the octave shifts... :)

9

Wednesday, November 9th 2011, 8:17am

I'm tempted to try and make this "LFO becoming FM" patch myself

dark_fader

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Wednesday, November 9th 2011, 10:46am

http://www.youtube.com/watch?v=0rD1gQHzc10

Listen from 1:58 to 2:44.

Although I think there's some cheating going on... ;)