Is Sidechain the same as using a Envelope Follower?
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crazyfiltertweaker crazyfiltertweaker https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=277536
- KVRian
- Topic Starter
- 918 posts since 25 Mar, 2012
When I control a parameter with a envelope follower ist this the same like controlling it with sidechain with the same source?
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- KVRAF
- 3080 posts since 17 Apr, 2005 from S.E. TN
I don't know the application context of your question.
For instance a compressor processes the audio into a control signal, which is the same basic process as an envelope follower circuit, then uses this envelope to modify the audio gain. If you send a different audio signal into the compressor's sidechain, then the envelope detection is derived from the sidechain audio and applied to the audio on the compressor's main inputs.
Compressors have many nuances of how the envelope is detected, depending on the compressor design. So in some cases the envelope following done inside the compressor might be fancier than a generic standalone envelope follower. But maybe there are standalone envelope followers with very fancy parameters as well.
Sidechain input would typically be audio. Envelope follower output is a smoothed control signal. Maybe with some plugins, the plugin would work just as good with either kind of sidechain input.
But many sidechains would not work right with the smoothed control signal of an envelope follower. For instance, vocoder or dynamic eq or ring modulator. Probably other classes of effect as well. If you don't send audio into those sidechains, the device probably will not give very useful results.
For instance a compressor processes the audio into a control signal, which is the same basic process as an envelope follower circuit, then uses this envelope to modify the audio gain. If you send a different audio signal into the compressor's sidechain, then the envelope detection is derived from the sidechain audio and applied to the audio on the compressor's main inputs.
Compressors have many nuances of how the envelope is detected, depending on the compressor design. So in some cases the envelope following done inside the compressor might be fancier than a generic standalone envelope follower. But maybe there are standalone envelope followers with very fancy parameters as well.
Sidechain input would typically be audio. Envelope follower output is a smoothed control signal. Maybe with some plugins, the plugin would work just as good with either kind of sidechain input.
But many sidechains would not work right with the smoothed control signal of an envelope follower. For instance, vocoder or dynamic eq or ring modulator. Probably other classes of effect as well. If you don't send audio into those sidechains, the device probably will not give very useful results.
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- KVRAF
- 1645 posts since 12 Dec, 2012 from Switzerland
I say nope, although I'm surely not the ultimate expert 
As far as I understood it, the main difference between compressor and enveloper are: Compressor are volume dependent, enveloper not. Compressors have two trigger points, enveloper only one. But both can be used to sharpen or smooth sounds.
The detector circuit of a compressor does not create an envelope (signal) in the classical way, although it seems so. It checks if the trigger signal (internal or external) is above the threshold. If yes, it will create a control signal depending on the ratio as fast as the attack time is set. As soon as the trigger signal drops below the threshold, the detector will "drive" back the control signal as fast as the release time is set.
So practically you have two trigger points. An enveloper has only one trigger point. The start of the signal (mostly a transient). From this point on, it will go thru the envelope, no matter how loud or how long the signal is. As soon as this trigger point arrives, the envelope starts. A compressor can't do that.
With a correctly designed sidechain signal you can get similar results with a compressor as with an enveloper. But the trigger signal should have a stable volume. So it will be a totally independent from another source.
The idea of the (external) sidechain is to have the possibility to create a independent and different control signal, that influences the original.
As far as I understood it, the main difference between compressor and enveloper are: Compressor are volume dependent, enveloper not. Compressors have two trigger points, enveloper only one. But both can be used to sharpen or smooth sounds.
The detector circuit of a compressor does not create an envelope (signal) in the classical way, although it seems so. It checks if the trigger signal (internal or external) is above the threshold. If yes, it will create a control signal depending on the ratio as fast as the attack time is set. As soon as the trigger signal drops below the threshold, the detector will "drive" back the control signal as fast as the release time is set.
So practically you have two trigger points. An enveloper has only one trigger point. The start of the signal (mostly a transient). From this point on, it will go thru the envelope, no matter how loud or how long the signal is. As soon as this trigger point arrives, the envelope starts. A compressor can't do that.
With a correctly designed sidechain signal you can get similar results with a compressor as with an enveloper. But the trigger signal should have a stable volume. So it will be a totally independent from another source.
The idea of the (external) sidechain is to have the possibility to create a independent and different control signal, that influences the original.
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- KVRAF
- 3080 posts since 17 Apr, 2005 from S.E. TN
It is a semantic problem. Envelope follower means different things. In the old days people would call the sub-circuit that converts audio to a control signal, an envelope follower. The equivalent software code is also called an envelope follower.
Compressors and other dynamics tools usually contain envelope followers or maybe called envelope detector. The details vary, because in attempt to make the processing sound good, the envelope followers in some compressors can be very fancy, much fancier than a generic envelope follower.
Then a class of stomp boxes became popular in the 1970's that would drive a filter from an envelope follower circuit, and those stomp boxes were called envelope followers.
Maybe there are additional modern uses of the term.
Compressors and other dynamics tools usually contain envelope followers or maybe called envelope detector. The details vary, because in attempt to make the processing sound good, the envelope followers in some compressors can be very fancy, much fancier than a generic envelope follower.
Then a class of stomp boxes became popular in the 1970's that would drive a filter from an envelope follower circuit, and those stomp boxes were called envelope followers.
Maybe there are additional modern uses of the term.
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- KVRer
- 25 posts since 6 Apr, 2010 from Vladivostok, Russia
"...like controlling it with sidechain with the same source..."
just call it samechain
just call it samechain
