Can someone explain filter envelopes for me?

Trying to get my head around modulation in general. I understand, for instance in the case of an LFO that you can modulate filter frequency with the LFO. So one thing has a constantly changing impact on another feature of a sound.

I understand ADSR with regards to a volume envelope and when I change these settings in an envelope I can hear the difference made...when I actually trigger a sound that is.

I understand how filters work but what impact does each part (ADSR) of a filter envelope have on the filtered sound? Is it basically setting the time required to hear the impact of the filter on the sound?

Sorry I'm tired and there are times when I feel like I need to learn so much more. Electronic music production will most likely be a struggle for the first few years right...worth it though.

It controls filter cutoff over time. Think of yourself twisting the cutoff knob over time. For a stereotypical ADSR envelope, this would be analogous to you twisting clockwise quickly then anti clockwise, then stop and pause and then twist anti-clockwise back to starting position.

well an envelope (for example ADSR) is a type of modulation that you can apply to virtually every parameter of the sound you could think about. As you understood, this modulation happens when you trigger it, commonly when you play a key on your keyboard (or when the synth receives a MIDI note).

The most common way envelopes are used is for amplitude modulation, which allows to control the "shape" of a sound across the time (with a simple AD envelope : A = how long it takes for the sound to go to its maximum amplitude once you played the key / D = how long it takes to revert back to silent). It's also very common to use an envelope on the frequency cutoff of a filter. In this case, the modulation will add to the actual value of the filter cutoff control. Let's say your filter cutoff is at 150 Hz and the modulation you apply has a range of 200 Hz. With the same AD envelope : A = the time it will take to the cutoff to go from 150 to 350 Hz / D = the time it will take for it to revert back to 150 Hz. Now this modulation doesn't have to be 200 Hz : you can control the amount of modulation you want with a parameter commonly named "envelope amount".

AD is a very simple type of envelope but there are a lot of more complex ones (which imply more stages). you can find good readings on internet on that kind of matter anyway, which are written by people who explain better than me for sure. of course having a little substractive synth like you're looking for is best for practical work! good luck

edit: wow kakapo explained it better than me but with two lines, pretty cool. time to go to bed i guess

or a quick diagram

Apologies for the rather rudimentary paint graph attached, and just to elaborate on what's been said already, but an 'easy' wait to consider the effect any envelope will have is that basically time goes along the x axis (so how long each element of ADSR takes) and on the y axis you have X. X being the thing that is being altered/enveloped, and by how much.

When dealing with an envelope applied to a filter, X is the cut off frequency, and the minimum value (i.e. the base of the graph) becomes the value of the filter cut off (say 300Hz). The max value available tends to increase the more you send through the envelope to the filter.

Let's say you have an envelope controlling something a bit more obscure.... I'll randomly say LFO speed. The X is essentially showing the range of speeds the LFO can go through. And again the minimum value/base of the graph is determined by value of the parameter being altered. So if the speed is set to 1/4, that is the minimum value. As the envelope goes through each segment it will increase that value (1/8, 1/16, 1/32 etc etc). And again the max value available increases the more you send the envelope to its destination.

It's somewhat akin to automation, or moving the value (be it filter cut off, LFO speed, amplitude etc etc etc) yourself over time, only the envelope does it for you.

I hope that makes sense.

EDIT: heh, probably could have found a nice one on the internet like Modey!

  On 5/12/2015 at 1:18 AM, b born droid said:

EDIT: heh, probably could have found a nice one on the internet like Modey!

haha, the benefit of being a technical illustrator meant I could draw it at work and nobody would question it

in addition to the very nice explanations posted above a good way of grasping that stuff imo is simply to twiddle the knobs and see what it does to your sound while you're pressing a key on your keyboard

As with the LFO, it's in many ways the same thing as a filter envelope. Both have a 'pattern' which you set, and is modulated over time. Except with the envelope you usually have one with an attack, decay, sustain, release. There's no REAL difference between LFO/Envelope/Manual automation. IT's all just automation by different means.

Think about what's being modulated first, then think about the pattern(LFO/Envelope/Manual automation). Whether you're using an envelope or LFO or manual automation, and try to use something like this signal analyzer: http://www.kvraudio.com/product/signal_analyzer_by_rs_metto then coorelate what you're hearing, and seeing in the signal analyzer, with your knowledge. So you can gain an intuition of what's going on so you can learn to identify what you're hearing (an lfo, envelope, manual automation) by hearing it or seeing it, so you can become better :)

THANKS A LOT FOR ALL OF THESE RESPONSES YOU LOVELY PEOPLE.

I'll work my way through them later. Knackered right now. I get hung up on stuff sometimes and all I need is a few lines of info to spur me on :)

It's great to find a place to ask questions like this and you guys get back to me. Really appreciated.

cheers

easy way to think about it is that the oscillator is a noise behind a sound proofed door. it's a constant sound but you can't here it. when you press a key, the door opens wide instantly and when you let go it slams shut. the vca envelope lets you open it more slowly, leave it open for a duration then close it gradually. The filter is like a curtain screen behind the door and the filter envelope lets you do the same with that as the envelope does to the main door.

I dunno maybe that's more confusing haha

it makes it go wwwwwwwwiiiioooowwwwww or brooooooooowwwwww or dug or wuuuuuuuurrrm

hey guys i just realized that you have to turn this thing up to make the filter envelope actually work in operator

this concludes another protip from noresults

if you think of envelopes like paper envelopes that you deliver mail in, except in the case of audio, envelopes are usually the same exact size of what they contain. so if you have a fish shaped envelope, the audio will sound more or less like a fish.