sLFOw - ways to make slow LFOs with timers
  • Tim from Discchord ( http://www.discchord.com ; Twitter: @discchord ) pointed out that the Osc node doesn't play nice with very slow LFO times. Good thing is there are better solutions than using the Osc node. The Osc node is anti-aliased, and uses a lot more resource than it needs to for an LFO. I'm waiting to hear back from @Taylor on whether this inability to run slowly is a bug or an artifact of the anti-aliasing, but either way, it's really beside the point - you should be using either phasors or these "cheater" ways to make slow LFOs.

    Here are some really resource-cheap ways of making slow LFOs out of timers. The basic idea is to have a feedback loop with a logic trigger. When the timer gets to X seconds, it pulses and resets the timer. So a feedback loop between a timer node and an expression node with "x==1" will give you a saw wave with a frequency of 1Hz.

    The slowest LFO with this technique has a ~64 year period.

    You can also use the spline node to fake other curvy waveshapes - basically, in a all but the most finicky calculative situations, no one will be able to perceive the difference between a sine wave and a faked sine wave on a spline node like the one in this patch.

    The Longest Time LFO doesn't work like it should right now, but I'm going to fix that in the new library. I think I'll make it go to some absurd number - will reach for a googol years, or about 2.8^90 times the age of the universe.
    sLFOw.audulus
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  • I was talking with taylor the other day and if I remember correctly the Oscillator node uses two different wave tables, one for slower audio rate and one for signals pushing harmonics into the nyquist, so that it band limits the harmonics that would have folded back upon breaching the nyquist. Also it would take some nice table interpolation to allow that same oscillator to to go into super slow lfo rate at a smoothness you are desiring. Having said that I haven't yet noticed any issues in practice, but in general I've been moving toward using the phaser for deeper flexibility/possibility. I also am enjoying combining the timer with the break point node in different ways, very useful combo.
  • Which is "the break point node"?
  • @JDRaoul - that's what he calls the spline node :) Thanks for the insight Nico - this came up because @discchord needed slow, accurate LFOs for this patch he was making
  • Voila. Thanks.