How to use an envelope to overcome the LFO rate limit, an old trick

I stumbled upon this concept by accident, even if you don’t get a real and versatile FM it’s interesting to experiment with.
There are obvious limitations but perhaps it is just a matter of concept and technique.

Instead of using the traditional LFO as a modulator, I used an envelope with time synchronization and a very short loop of 20 milliseconds that correspond to 50 Hz.
You can modify loop size from 10 millisecond (equivalent to 100 Hz) to more than 16 seconds.

There are many improvements to be made and parameters with which to experiment, envelope shape and pitch range are the two most obvious.
FM.xrni (9.5 KB)

I hope it will be stimulating and fun

This trick was already known by @gentleclockdivider and others. I apologize for having proposed it again.


Fuck yeah, dude! This is great! Not sure that it’s “true” FM, but there’s a ton of potential here! More complex modulation waves are also possible at short time-scales using the envelope generator. Will definitely be messing around with this concept…
First “granular,” now “FM” in the same week! Awesome :crazy_face:

…Just added a second looping pitch envelop with an operand multiplier for more complexity :metal: Great technique!

It sounds more like complex ring modulation to me than “real” FM, but it’s still a great sound!

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I’m happy, it’s a great week after all!
If I hadn’t messed with the Granular technique I wouldn’t have discovered this one. Amazing that it has always been before our eyes.

Well FM it’s simple on its concept but if you go to fast I think (not sure) will be ring modulation or maybe sound like.
Quoting Wikipedia

In essence, the amplitude and frequency of one waveform modulates the frequency of another waveform producing a resultant waveform that can be periodic or non-periodic depending upon the ratio of the two frequencies.

John Chowning discovered FM by rising the frequency of Vibrato; anyway its a new concept to explore and open up new sound palette.


For sure. I suppose I meant that it might not be “real” FM, because most FM synths are modulating the phase to produce FM-like sounds. Perhaps this is “true” FM in its pure sense :slight_smile:

Whatever it is, I like it! Big ups for cracking the nut!!!

I rendered out some waves… looks like FM to me.
Screen Shot 2021-10-19 at 12.42.18 PM


Me too, but I will make a proof of concept setup.
I’m really trilled, we have two new technique two explore :crazy_face:

Ok sample recorded
Schermata del 2021-10-19 19-58-01

And Setup with Sinewave
FM_basic.xrni (5.4 KB)

The timbre is mainly due to the waveform of the modulator, just vary it a little to get a different timbre.
From Wikipedia


Dude, this is fucking awesome! :metal: :alien: :metal:

Check this patch. just two sine waves native fx and a little modulation:
bloop generator 1.xrni (8.2 KB)

super cheap on cpu as well :+1:


What an interesting find! Is it also ‘variable’? Say I’d like to have it modulated with another envelope for timbral change?

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You can modulate the pitch envelope input amount and/or an operand modulator to scale the effect. So, you could set up an lfo as an envelope in the instrument effects section to modulate the amount over time by tying pitch input to a macro and using the lfo to modulate that parameter, then tie the lfo to a key tracker controlling lfo reset to have a consistent envelope with each key press, if that’s what you’re after… You do need to have set up and saved a doofer with instrument macros in it beforehand from the mixer section - which you can then access in the instrument effects section. Here’s a simple example:
FM envelope control.xrni (3.9 KB)
The limitation being that it is a “monophonic” envelope that is reset with each keypress.

I’m also modulating additional high rate pitch envelopes’ on/off switches to create more complex timbral variation with @Same_Freaky_Sound’s technique
See the “bloop generator” patch above for an example of this :slight_smile:

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Excellent- I’m thinking how some FM/PM synthesis works by a timbral shift caused by envelope control - like an electric piano gets duller the longer the note is held - sounds possible! Cool!

Ya, definitely possible to modulate it!

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Also, what happens to the sound when the amplitude is modulated via an envelope? That’s kind of a ‘filter/tone” method (the louder it gets, the more aggressive the sound, softer volume modulation gets the less waveform modulation).

Oh I’m just so excited!

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Yes, interesting possibilities, for sure. I just tried this method on the filter section, and there’s definitely some potential there as well, especially with the AM filters. LP was pretty cool, too. Of course, you can always combine high-rate modulation across volume, pitch, filter, etc… Good things

Great! Yeah this is funky patch :badteethslayer:


Actually we have a limitation on loop size, we can just set it but not modulate start and end of the loop. Maybe in the future versione of Renoise :pray:

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Maybe this can help?

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Well this can handle sample loop and its great, I need to control envelope loop and if I’m right it can’t be done actually.
Thanks for looking for a solution, any suggestion is welcome.

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That would be fantastic to be able to control envelope loop length for this technique!

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Thank you for idea and inspiration!

my short demo


Funny why ya’ll jumping on this , you’ve all been living under a rock ?
I’ve been doing this since 3.0 was capable of (relatively ) fast envelopes and immediatly asked for finer loop resolution
It 's not FM (linear frequency modulation ) , and certainly not phase modulation ( YAMAH FM ) ,
It’s just exponential PITCH modulation that is still flawed by renoise TPL based envelopes
Sorry to be the party pooper ,sure it’s still cool as an effect
… to end this on a positive note :slight_smile:

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The envelope can NOT loop at 1ms , ( 1000 HZ ) , the engine is not capable of that
It’s not because the display shows you 1ms that it’s actually capable of doing so

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