Envelope follower
 

Hi ..
could someone please explain what an envelope follower is and how to use it??
maybe some examples too....

thanks

Hi...does anybody know about this?? could you please explain..what is and how do i use the input follower ??

thanks

Anyone feel free to correct me if I'm wrong, but an envelope follower as I understand it will take the levels of an input signal and use those levels to generate a control signal.

So if you had the output of an EF connected to a filter cutoff, as the input signal got louder, the EF would open the filter more. As the signal falls off, it closes the filter.

Hi..thanks Maelstrom..
any idea on how to achieve this on the virus snow??

thanks

:)

Well, I own a TI keyboard, so I'm not really familiar with actual menu navigation on the Snow. On the TI keyboard you hit the Edit button twice on the lower FX section and it opens up the menu where you can access the "other" effects options like the Input Follower and the Vocoder.

Inside of VC however, it is in the FX1 tab on the lower left. Basicly select the input you want to use, Level adjusts the level of the incoming signal, and the Attack and Release knobs function much in the same way as they would on a compressor...pretty much allowing you to adjust how tight or loose the control signal output mimics the input signal.

For the control signal output, it is important to note that it replaces the filter envelope. As such, in the Mod Matrix section you select the Filter Envelope as the Mod Source and then apply it to whatever control destination you like.

I hope that helps.

Just saw this...Thanks for the help

:)

In synthesis, Envelopes are events that happen over time, have a particular shape of intensity over time, and can be triggered by other events.

The are usually triggered by note-on events, but on modular synths you can triggers envelopes from other events and modulators like sequencers, LFOs, etc.

An Envelope follower is an Envelope that is triggered by an incoming audio signal. In dedicated modular Envelope Followers you can set the threshold, that is, the volume level at which the Envelope will be triggered. You cannot set this threshold on the Virus.

The vast majority of DSP Envelope Followers are hard wired to control the volume (amplitude) and brightness (LPF) of the incoming signal.

In real modular synthesis you set an envelope to control anything even non-audio signals, and be triggered by anything even non-audio signals.

Thanks Narcissus...
very helpful explanation ..

Hey again. I was trying to use the analog inputs on the snow, so decided to try the envelope follower, so I did a google search for it, and the result that popped up was this page :) ..a question I myself had asked a little while ago.
Anyway..I re-read it, and this time understood a little better, since recently I learned about envelope followers in FL studio, using something called a Peak Controller. The same way a bassline is sidechained, the peak controller can be linked to any destination or parameter in the DAW. I had been sidechaining bass for a while before, but only realized the potential of the peak controller/ env follower, recently after reading about it online. Great little technique. I enjoyed using it on a distortion plugin, so as the bass got louder it distorted more.
Although I have grasped the concept of env followers, quite well, I am still having a hard time implementing it on the Virus.
I am not sure how to set it up and use it. For example,on the input mode patch, FX page - activate input- static input, and then activate the Env follower from input. WHat is the env follower affecting in this case ? is it acting on the input signal itself or can I play the synth oscillators and stuff at the same time as input ? will the env follower affect the oscillators internally ? can it modulate anythig apart from volume and filter cutoff ?also does each of the 4 parts on My snow have an individual env follower or can one stereo analog input affect the env follower on all 4 parts.
I wasn't really able to figure it out. something did happen, but I couldn't figure out what exactly was happening.

Thanks :D

Not to hijack here, but will an envelope follower allow for treating the incoming signal unaltered? As in if I was to send it an external LFO or envelope signal, would the envelope follower alter the envelope or LFO wave no matter its settings, or could it, with the right settings, just echo the wave as it was originally?

If so, will any of the viruses allow this?

the signal can pass untouched, yes. you can use just the fx or filters on it without the envelope follower, therefore preserving the signal as is.

No I meant as a modulation source. I might have misunderstood something though. What I'd like to be able to do is to put a line level modulation wave in there, say to modulate filter frequency, without the envelope follower changing the shape of the signal wave, like rounding off the edges etc. But is this at all how it works, and is it possible to do this with one of the viruses?

what the envelope follower does is replace the filter envelope.

you can use it as a modulation source in the mod matrix, by choosing "filtenv" source. so if you were to put this volume modulated wave in there to modulate the filter frequency, it would instantly work like that. you'd use the env amount knob to control how much it affects the filter, and the attack and decay knobs are usable to, as well as the sustain knob that acts like an input knob for the incoming signal.

Wow that's nice to know! So if attack is set to 0, decay to 64(?), sustain to 127 (for unattenuated input level(?)) and release to 0, then the filter frequency is modulated by the original, unaltered wave, and modulation depth is then controlled with the env ammount knob, is that correct?

I don't think you can bypass the envelope's settings. but the thing is, an envelope in standard operation (as in a note being triggered by either midi from the daw or a key press on some controller or keyboard) has the "note in" and "note off" thing, in this case this is triggered by the volume in the signal - any kind of volume since there's no threshold setting.

Thanks, TweakHead! I'm a bit less confused now. The Virus B manual is also helping a bit. :D

Sorry about the hijack, nutrinoland. I've pasted your last post below. I don't have the snow, but I'll try to answer some of it anyway. Someone with a better understanding of this should jump in here, and also correct me if what I tell you is wrong.

It's still unclear to me whether the envelope follower is able to pass the signal untouched, but it seems to me that the way to make it change the signal as little as possible is to set attack, decay and release to zero, and the sustain knob to max, but I'm not really sure. It's all in the Virus B manual however, which is good for explaining a few things, as the TI manual is such a sad excuse of a cheap joke. Look up Envelope follower in the tricks & tips section. I'm unable to copy text from the PDF file I found. Just remember there are some differences between the B and the TI.

Anyways, the manual actually seems to suggest that you can have the clean input signal modulate whatever you want, without the envelope follower changing that signal at all. I guess you still just use the filter envelope as source in the mod matrix, but I'm not sure. I'll try experimenting with this later.

Oh, and I don't think the input signal will blend with the synth sound unless you use it to modulate something or activate it to be treated as audio.

Hope that was of some help

but why would you want to use this untouched signal in the first place? when you can send the Virus a costumized midi message that would do what you want?

not sure I know what you'd like to do ;)

Who, me? I'd like to be able to use an external LFO with the virus. A real LFO that can swap between waveshapes and time signatures and do other neat things a MIDI message wont deliver. Besides, I'd like to avoid clogging the MIDI flow to prevent sluggish timing. It also could be interesting to try out audio range modulation, although I suspect the Virus has some hidden self destruct function that would activete by the sight of a modulation wave faster than 20Hz.. What do you think?

I've thought about using the control pedal input, and I'm looking into CV to resistance convertion, but that looks pretty complicated, and I suppose I'll have a hard time finding a suiting expression pedal with input for CV control.

I love the virus sound and the free updates and all, but the LFO section is pretty limited, and the lack of any audio rate modulation source is frustrating to put it mildly. No sequencer and no repeating envelopes doesn't help either.

It's almous like Access went out of their way to make sure to keep it boring. I know DSP power isn't handed out for free, but neither is the TI. It's actually quite expensive for a VA with the mentioned limitations if you ask me. Nevertheless, I'm not looking for a replacement. I have other synths, and will keep the virus, but if it's possible to have an external LFO working with the virus, then it's something that I'd like to make sure I know about.

A MIDI message will deliver! If you draw the automation (in your daw with the pencil tool and curve edditing...) and assign it to the parameters you want to control, then the Virus can perform just like Massive or any of the most reveered for their modulation options synths.

Of course you'll need to familiarize yourself with your host's automation tools a lot, but you can surely build an automation curve that goes beyond 20Hz. Just don't expect it to perform aliasing free, since most DSP instruments are thought out to not exibit aliasing on their most extreme settings of modulation, and that doesn't account for using external modulation inputs.

Simple test: just extend the range of your pitch bend wheel first. Then draw some crazy curves on your daw for it. Draw some very short cycles 20Hz or more and play it. It does respond as it should. And you have a ton of other CC's to use, assignable in the mod matrix, plus you have the midi cc map to assign parameters directly if you want.

Even if you have some fancy modular LFO in there, and perhaps some warp modules and modifiers of sorts, it would still send a CV message, not audio, and therefore how would you even expect to use that in a DSP based synthesizer? CV>MIDI converter would enable you to use it on any MIDI capable machine though, you could store this midi message on your daw and then assign some cc, like cc#3 to this and assign cc#3 on the Virus to handle pitch or filt cuttof or something, and there you go!

but the LFOs on the Virus are far from being limited. I mean, where else do you have 64 waves to choose from besides the regular "analogue" shapes? And what about the contour settings? Fade in and out on 3rd LFO? Being able to use recursive modulation to have one modulating the rate of the other, while the other's rate is modulating itself, plus the amount that the former is modulating the rate of this one? That's a wacky modulation input that can sound as weird and organic as some weird euro rack module.

ok, so just build yourself a nice collection of automation drawings and have some fun!

If I could manage to convert CV to resistance, I'd have a realtime tweakable LFO to use with the expression pedal input of the virus. However, it doesn't seem likely at the moment.

The virus LFO's are OK, but they have a limited range, as mentioned, and I'd like to be able to trig them independent of key press.

Thanks for the pep talk. I'll check out how far I can push it with MIDI automation, but as you said, it's tedious work, it's not very realtime, and as I usually run at fairly high tempos(150ish+ BPM), I fear the timing will go south when sending MIDI sequences to the virus at the same time as complex CC patterns. You seem to have some experience with this. Did you notice any sluggish behaviour?

I work with fast bpm many times to. automation works fine for me with the Virus C, so I presume will work just as well with the ti/snow. I didn't go into audio range kind of modulation, but there's a way to make the automation points smaller in logic (similar to time stretch but with the automation points), then just repeat those little steps, then a group of them, and you'd be 20Hz or more in next to no time. you could save a whole bank of those to call back to them when you need them. you can also use Reaktor to create or assemble something that would suit your needs, and then send the signal to the Virus, could even be activated with the pedal or anything else, easily. don't know how the Virus would cope with a cc#3>pitch assignment and the midi message telling it to go faster then 20Hz, would presumably sound similar to fm but maybe with a ton of aliasing on tops? damn, will have to try this myself to... just to see what happens!

and about the audio rate modulation. if one piece of equipment doesn't do it, don't blame it. just add something that does that to your setup, like the Blofeld - and explore the sounds you can do with it that you can't on the Virus and vice-versa. any machine will have it's own set of limitations, despite of price, what would you say of a 3k moog with just low pass filter? it's good doing what it does and that's good, right?

fm is a kind of audio rate mod, and the virus excels in it's fm sound (can't get enough of the positive tri mode myself). would also like to see them make this lfos the "classic", and then present us with some more that could go into insanely fast rates, like 2Khz, and selectable as fm sources. filter fm would also be cool of course, same goes for am sounds. it's been said many times over here, willing to bet someone at Access has already read some of it! but on the other hand I don't see how they could implement every known feature of every synthesizer in there and still call it Virus. user drawable waves for both OSC and LFO's (along with multi-stage EG) wouldn't hurt coupled with complete range lfos (which would of course double as oscillators when not modulating anything, and hence the non practicallity of this demand, since they'd more then likely would have to multiply the current dsp used by 10..)

but it wouldn't be fair, as they'd totally kill every single VA on the market by doing so. and they could start making some analogue monster of a synth in the spare time (more then 10 years with the ti, this new one would continue to sell for a century for sure).

Been making some effect chains in my snow and started to toy around with the env follower, which I have yet to get my head around since I cannot really hear it do anything apart from attenuating the volume when bringing in the "level". Regardless of how my modmatrix looks (as the env follower is replacing the filter env as far as I can tell - I was expecting things to happen when I was routing that to affect various stuff). Did anyone get it to work?

Also, is there a way to map the three Env follower parameters: "level", "attack" and "release" to either the softknobs, mod matrix or to control it with external midi somehow? Can't find the names listed in there, but maybe I overlooked something.