The "right way" to modulate filter cut off with ADSR
  • Hey guys, I'm new to audulus. I'm not new to synthesis, and I've a got a real modular system... Have been reading the forums and watching the videos, trying to understand audulus workflow, I'm starting to get it, but there are stuff that maybe have the most effective way of doing.

    Basically I'm fooling around with MIDI triggers and the value meter, trying to understand how the nodes work, what values they output, etc...

    I've put together a very simple patch, I wanted to modulate the filter cutoff of the LP filter, and since the envelope node outputs a max value of 0.5, I had to multiply it by 2, and then multiply the result (1) by 18000 (which is the full spectrum of the LP filter), is that right?

    Ok, now to be able to modulate the ammount of modulation (what a sentence!) I had to use a level node. It works, but I think it must be a better way of doing this that I haven't "seen" in my mind yet.

    I'll attach the patch here.

    Thanks for your help!
  • @AlbertGauer, many of us use the Crossfade node to do this. I have to admit, it's one of the most clever bits of gimickry I've seen in Audulus. I've attached an image with an example.

    Basic idea is that the ADSR's env goes from 0 to 1. The Crossfade node's knob goes from 0 to 1. So you can "crossfade" between your low and high cutoff values by modulating the crossfade's knob.
    filtercutoffenvmod.audulus 2015-03-05 08-19-09.png
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  • @jjthrash, thank you so much!

    Wow that´s way simpler, clever indeed!! You can restrict the frequency band that you want the filter to operate in, nice! :D

    Two things I didn´t think about, now learned! Starting to love more and more Audulus...

    One question:

    If I stick the value meter node on the ADSR´s env output I only get 0.5 tops, from where did you get the 1 value? I tried but couldn´t set up max or min values for the ADSR output...

  • @AlbertGauer, interesting. I just hooked up the Value on the Env output and saw it go up to 1. It did quickly move away from the 1, though, as it decayed. Try hooking the waveform node to the output. It should give you a better picture of what's going on.

    Are you still using the Trigger into the Gate? The ADSR will scale based on the gate value, so if you're using a Keyboard with velocity, and you have a velocity of 0.5, the env will only go up to 0.5.
  • @jjthrash, my bad!!! I was getting 0.5 because I didn't have a full sustain...

    Thanks for helping me out!! :D
  • Albert - what kinda synth modules do you have? I've been drooling over Verbos Electronics' Harmonic Oscillator.
  • So here's a simple moog bass, getting the hang of it slowly!!

    You definetely need the level node after the crossfade so you can dose the depth of modulation :D
  • @biminiroad hi mate! have been checking your audulus patches too, all you guys are amazing.

    I have a mix of DIY stuff with some manufactured too, here's a list of what I have (more or less):

    3 x Living VCO's (Jurgen Haible's) DIY
    Bubblesound VCO
    Waverider (Frequency Central)
    FMVDO (Modcan)
    A DIY Dual Digital Oscillator
    The Buchla 258J Oscillator Clone
    Jupiter 8 LPF (AMSynths)
    Buchla 291 Filter Clone
    Moog Ladder LPF DIY (the one from bridechamber)
    The Buchla Dual Function Generator Clone
    4ms PEG
    A couple of ADSR modules
    Some multiples
    uScale 2 (Intelligel)
    Some wave multipliers and distortion modules
    Wave animator
    A couple of ring modulators
    A couple of LFOs
    Pamela's Workout (master clock)
    Expert Sleepers ES-4
    A good MIDI2CV (DIY)
    Some drum modules (909 and 808 clones, all DIY)
    A couple of noise generators, S&H

    There's a lot of unfinished DIY stuff, a pile of PCBs and stuff... Got lazy the last couple of months, I was crazy with this DIY thing and I was only buying parts and building, and no music making!! Kind of get bored of having to setting up everything, nowadays I just want to sit and play, and I getting back to digital slowly (ITB)... I will keep the modular for audio processing, though.

    Even though I'm kind of fed up of DIY, I couldn't resist the group buy going on right now at muffs for the mutable instruments Clouds module PCB, this one sounds very interesting.
  • The only thing that get's me bored is having to set up all the cables again, having to take pictures of patches, etc...

    With a virtual modular you can simply save the patch and recall whenever you want, you will have that same sound, always... Perhaps change it a bit and save a new patch, and so on... so practical
  • Very cool! I have a Paia synth in a half built state (something went wrong on my midi module and I haven't had the patience to track it down.
  • @biminiroad oh yeah, I feel you... Debugging is terrible when you don't know what to do or look for (which is 99% of the time lol)

  • Yeah I tend to treat electronics projects as all-or-nothing (ie stick it in the back of the closet and occasionally kick myself for not being smart enough to debug.
  • @jjthrash, do you ever use a exp function to scale your filter cutoff control? I recently mapped a fader to a constant controlling the cutoff and it was real jumpy in the lower frequencies.
  • @ceilidhshipley, I don't, but that's a great idea. If you haven't figured it out, something like the attached should work. You can play with the max and min of the constant knob, but I have it 0-14.135, which translates to 1Hz-about 18000Hz.
    Untitled 2015-03-07 10-36-02.png
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  • @jjtrash

    Oh this simple example would be great to explain what's going on the math node! (I really suck at math... (Gonna have to review some stuff long forgotten)