Im haveing a bit of trouble understanding the sustain on the filter envelope… if I turn up the envelope amt on the filters to positive, and i want the filters wide open, I turn the sustain up to max… but the sustain knob on the filter envelope needs to be turned all the way to the left to hear it at full open, not turned to the right. Is this filter envelope sustain knob inverted?
What’s happening when it’s turned all the way to the right? Is this perhaps some kind of interaction with keyboard tracking or velocity?
Maybe it’s a quirk - my Prophet '08’s osc mix and noise knobs are functionally swapped. Have never been able to work out why 
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I’m used to the Matriarch myself, so maybe that’s why.
No velocity is enabled. But I have the envelope amount on the filter turned up and if the knob is to the right it sounds like the filter is closed.
Wait, let me make a post with examples.
Are you applying it to the high pass too? Is the cutoff turned all the way down?
That would mean with no sustain it remains ‘open’, and would close with a positive envelope applied - if you wanted both filters to open with the envelope you’d need the hp cutoff at max (closed) with negative eg (opening it), and the lowpass at minimum (closed) with positive (opening it).
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Hmm that may be it! It’s definitely a learning curve.
Let me take a pic and see
I am so confused!
Yes I am applying to the high pass too. And if I put the HP to neutral, I don’t hear much difference in sound.
But this is what I started with.
To try and visualise it:
This is a LP filter with its cutoff set to 50%, applying a positive EG would ‘open’ it
This is a HP filter with its cutoff set to 50%, applying a positive EG would ‘close’ it
In your photo you have the LP set to full, so a positive EG wouldn’t do anything to it, and the HP will be closing.
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Okay. Wow, thank you Nate.
So forget the LP, and focus on what’s happening with the HP.
Wait, I have to go over this a couple times to really understand it. You laid this out for me nicely. I just have a hard time absorbing info like this. It’s really simple, but technical.
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Yea it makes more sense when you’re picturing the curves in your mind I think - and making sure you treat the cutoff knob not as an ‘amount’ but as a frequency/position. This is something that isn’t intuitive I don’t think when you just have a few knobs.
Having the HP is really useful for shaving off the low end and scultping the sound.
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Wait, so for the high pass. It’s a freq knob. Okay.
So with it to the left, it is letting the entire freq through. But with positive freq envelope amount and the sustain applied it cuts it off?
I thought raising the sustain allowed the level to be high.
Oh, that’s me getting amp envelope confused.
So filter envelope is always cutting.
You know what. It’s just really confounding. It’s too many inversions of envelopes. I guess less is more, not trying to use the envelope for wide open, but to just let the filters be open.
I would start with the highpass envelope amount at 0. Not sure why you have it cranked.
The way I understand it in your 2nd photo is that you have 100% filter envelope due to the max sustain which results in the highpass cutting all frequencies, which is why you don’t hear anything.
Start with the highpass all the way down, both the frequency knob and the EG amount. Start with the lowpass frequency all the way down as well and turn up the EG. Then play around with different filter envelope sustain amounts to hear it in action. If you want to hear the full oscillator you can just have the lowpass frequency all the way open to the right.
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Thank you!
Yeah, I’m just doing this blindly. Still not understanding it, but at least I’m getting the behavior I’m expecting.
I think the important concepts to understand first are those illustrated in @natehorn’s post with the images of a lowpass and highpass filter.
On a lowpass filter the Cutoff knob all the way “closed” (i.e. to the left) is cutting all frequencies down to the lowest, and you won’t start to hear anything until you start turning it clockwise to let more and more high frequencies through. Once you’ve turned it all the way clockwise you will hear the full frequencies of the oscillators.
On a highpass filter the Cutoff knob is kind of an opposite concept. All the way counterclockwise means the filer is all the way open and you hear all frequencies of the oscillators. As you turn that cutoff clockwise it’s cutting more and more low frequencies. Once it’s all the way to the right (clockwise) you won’t hear anything since it’s filtered everything out.
Play with those two cutoffs one at a time, with no Env Amount applied, to get familiar with their functions.
Then understand how the filter envelope affects those cutoffs. It’s an invisible hand that will control those knobs. So full positive Env Amount and full Sustain will turn a Cutoff knob fully clockwise. So on a Lowpass filter this means all the way open (all frequencies heard), but on a Highpass it means it’s filtering all frequencies OUT, and you won’t hear anything.
I hope this is starting to help.
Next step - turn Sustain all the way down and see how different amounts of Filter Envelope Decay affect the filters.
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be aware that the envelope amounts are bipolar controls.
you have to set them to 12 o clock to be out of the game.
in the last picture you provided the envelope amount of the HP Filter is not set to 0 but to max
on the negative side…
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Good observation. However I guess in the end it had the same effect in that a negative fully sustained filter EG on a highpass filter would keep it fully open (I think).
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that’s right (as long nothing else is modulating the HP Filter), but its fundamental to know that some knobs are not working from 0 to max to understand the basic use of envelopes and there purpose, especially when you think your synth is faulty or behaving wrong or inverted
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