Autowah and Envelope Filter differences

Discussion in 'Effects, Pedals, Strings & Things' started by stuey222, Feb 3, 2008.


  1. stuey222

    stuey222 Member

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    I'm looking for a quick explaination of autowah and envelope filters. I know they're similar and both produce a wah like effect, but I'm pretty sure they're different in some ways and would appreciate some help.
     
  2. Bryan T

    Bryan T Guitar Owner Silver Supporting Member

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    An envelope filter uses the volume of the signal (the envelope) to control the behavior of a filter, usually the cutoff or center frequency depending on the filter. It can be any type of filter, though you typically see low-pass or band-pass filters used. An autowah would be a an envelope controlled bandpass filter. The Moog Low Pas Filter is an example of an envelope controlled low pass filter.

    Hope that helps,
    Bryan
     
  3. stuey222

    stuey222 Member

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    So the envelope filter would activate the effect when the volume reaches a certain point, and an autowah would have the effect going as soon as you turn it on? Does the intensity of an envelope filter increase when you increase volume?

    Also, what are song songs/players that use each?
     
  4. Laxrappa11

    Laxrappa11 Member

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    from what i understand, an autowah is controlled by pots, for example you control the overall sound by changing the depth, sweep, and rate of the wah sound, etc. with an envelope filter you also control the sound of the wah, but trigger the effect with your picking dynamics. jerry garcia used a mutron, which is the quintessential "envelope filter" sound as far as i know. i own a pigtronix EP-1 which is an absolutely wonderful envelope filter with a built in phaser. really cant go wrong with that pedal
     
  5. stuey222

    stuey222 Member

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    Thanks, that helped clarify everything!
     
  6. Lolaviola

    Lolaviola Supporting Member

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    An autowah literally immitates rocking a wah-wah back and forth in time. The time (fast slow) is what is controlled by the pot.
     
  7. Bryan T

    Bryan T Guitar Owner Silver Supporting Member

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    Maybe I'm confused (and adding to the confusion). I didn't realize that an autowah had an LFO built-in. I thought it was a type of envelope follower.

    Bryan
     
  8. DiscoFreq

    DiscoFreq Member

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    Most effects with "auto wah" in their name are envelope filters, I suppose the name auto wah just means that the filter moves automatically without specifying how (lfo/envelope/sample-hold/...).

    Here's a list of effects with "auto wah" in their name:

    envelope:
    ===========
    Aria AWH-1 Auto Wah
    Danelectro DJ-24 French Fries Auto Wah
    Do-In AWA-1 Auto Wah
    Guyatone PS-104 Cross Over Box Auto Wah
    Ibanez AW5 Auto Wah
    Ibanez AW7 Autowah
    IMG Stage Line MWH-22 Auto Wah
    Ken Multi MWH-7 Auto Wah
    Monarch MWH-22 Auto Wah
    Roadrunner Flexitone Auto Wah-Dist


    LFO:
    =====
    Park Auto-Wah
    Memphis Auto Wah


    combinations of LFO & envelope:
    ================================
    Boss AW-2 Auto Wah
    Jacques Trinity - Filter, Classic & Auto Wah
    Guyatone GST-U05 Ultron Optical Auto Wah




    For a list of these and other envelope filters (235 of them ;)):
    http://filters.muziq.be/type/filter/envelope
     
  9. Zillie

    Zillie Member

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  10. DiscoFreq

    DiscoFreq Member

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    The HT is already tagged as lfo-controlled and envelope-controlled, but the list above was only of models with "auto wah" in their name :)
     
  11. stuey222

    stuey222 Member

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    Ok, so envelope is once the trigger is reached, the effect activates, right? What does LFO do?
     
  12. DiscoFreq

    DiscoFreq Member

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    An envelope filter is not the same as a triggered filter: a triggered filter starts a predefined sweep once it's triggered (by a certain input level), with an envelope filter the filter sweeps the same way as the volume of the input signal sweeps.

    LFO = low frequency oscillator, a generator of waves (sine, square,...). In an LFO-controlled filter such waves control the filter frequency.
     
  13. stuey222

    stuey222 Member

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    ok, so to get the wah to basically wah with how hard I pick, I want an envelope filter? Can you explain the LFO a little more, I still don't understand it. Sorry if I'm being a pain, but I want to wrap my mind around this.
     
  14. DiscoFreq

    DiscoFreq Member

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    Yes :)

    It's a wave with a constant speed and depth set by some knobs, other pedals using an lfo:

    tremolo (volume)
    flanger (delay)
    chorus (delay)
    vibrato (pitch)
    phaser (phase shift)
     
  15. stuey222

    stuey222 Member

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    So I want a non-LFO envelope filter then? Or do I want LFO? Or does it matter?
     
  16. DiscoFreq

    DiscoFreq Member

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    if you want a filter that moves like phaser or flanger then you want an LFO, if you want a filter that responds to the way you play (as you said a few posts ago) then you want an envelope filter, not an LFO filter.
     
  17. stuey222

    stuey222 Member

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    cool, that's what I want. So what is the Q-tron line?
     
  18. Laxrappa11

    Laxrappa11 Member

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    stuey- sorry if my comment before was confusing, but the Pigtronix EP-1 is an Envelope Phaser. Its circuitry contains an Envelope Follower AND a seperate LFO that gives awesome rotary phase shifting sounds. New they are only 220, plus you can get it from analogman with some really awesome mods.

    [​IMG]
     
  19. stuey222

    stuey222 Member

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    No problem, I understand it all now. But that's cool, thanks!
     
  20. Lolaviola

    Lolaviola Supporting Member

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    DiscoFreq you rule, OK!?!
     

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