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a technical envelope filter question

Discussion in 'Effects [BG]' started by jimbodapunkbass, Aug 16, 2007.

  1. jimbodapunkbass


    Aug 16, 2007
    i am trying to find an effect sound that i dont really know if it exists. basically i want it to sound like a resonance filter sweep as found on a synthesizer which activates when you play each note... so its an envelope filter... but all the envelope filters i've heard sound more like auto-wahs. i dont necesarily want a funky sound, i want more of a phaser-ish sounding filter sweep. does anyone know of an effect like this? i dont know if the technical jargon i'm using is correct but if anyone has an idea what i'm getting at, i'd love to know what you know about it.

    one example might be like the synthesizer intro on tom sawyer by rush, the way the filter sweeps on the keyboard note, and doesnt sound like a wah. an effect that could do similiar things to a bass.
  2. bongomania

    bongomania Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    The Moog MF101 should work for you, as should any low-pass filter which has control over the envelope (e.g. the attack and decay of the sweep). None of the options I can think of are cheap, though... the "usual suspects" among envelope filters don't have much control over the envelope. Your best bet might be one like the Moog or the Frostwave which can be controlled by an expression pedal.
  3. You want an oscillator controlled filter, but instead of the oscillator controlling the filter frequency you want it controlling the resonance, right? Trouble is, I can hear what you want, but can't think of any auto wahs that have a resonance control, let alone one that's oscillator controlled.

    BTW, my definition of "auto wah" is an oscillator controlled filter but I have a feeling your definition is what I would call an "envelope filter" ie; the filter is controlled by the amplitude of the input signal.
  4. hoerni


    Jun 4, 2007
    The Ibanez Bass Synth pedal can do some sounds like that. It has a filter whose level is amplitude Dependant. Alot of other env-filters will use the input level to trigger the circuit, but use another circuit to actually sweep the filter afterward. The Ibanez doesn't completely work like this (although I think there is some circuitry to slow things down if you do want to use it like that)

    I think you want something a bit more flexible. The resonance control that someone mentioned is good, That will turn the peaky bandpass filter from most auto-wahs into a smoother filter that shouldn't sound quite so funky.

    You might also look for something that does sounds other than bandpass. My favorite is the Korg PME Dist-wah, but they are super rare, expensive (and they require the base module). Also I think it is more of a trigger and sweep system as apposed to the amplitude dependent type you want.
  5. sonicvi


    Jun 10, 2005
    Houston, TX
    The EHX Bass Micro Synthesizer does the Tom sawyer synth thing really well. It's envelope is not based on the strength of the input signal like most auto-wahs or envelope filters so you're not stuck with just the funky kinda sound. You set the start and stop frequencies of the sweep and the rate of sweep between them.
  6. Jazz Ad

    Jazz Ad Mi la ré sol

    It's a fix wah.
    So either a wah pedal that you don't move when you found the sound you're after, or a dedicated pedal.
    A Boss AW-3 or a Jacques Trinity will do this.
    I do it with my Korg Ax-1B.
  7. JanusZarate

    JanusZarate Low End Avenger

    Feb 21, 2006
    Petaluma, CA, USA

    The BMS' filter sweeps in one direction (up or down, depending on how you set the Start or Stop frequencies) and is highly tweakable. You can narrow it down to one frequency for a fixed-wah sort of effect, and dial in the Resonance and Rate as desired for the filter effect you're looking for. It's distinctly NOT your typical filter or wah sound - it's more true to what you'd find with keyboard synthesizers.

    Plus, with a bit of the Attack Delay dialed in, you can remove some of the attack of your plucked note so it's more keyboard-like, or you can dial it higher to get volume swells like what you'd get from the old Boss Slow Gear.

    Not to mention, it has a great voicing section with sub-octave, octave-up, dry signal, and fuzz sliders for your enjoyment. This section runs into the filter section, in case you were curious about the order.

    It's definitely worth a try, at the very least!

    There's also a big Synthesizer Pedal Review thread that Markjazzbassist and I started - I recommend checking it out!
  8. jimbodapunkbass


    Aug 16, 2007
    thanks a bunch, this is helpful information.
  9. Vic Winters

    Vic Winters Supporting Member

    Apr 20, 2006
    Western NY
    BSW has a few settings that sound like what you described.

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