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Wah Effect Mystery Parameters

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Michael Trigoboff
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Topic starter
 

I have looked all over the place and can't find any descriptions for the various Wah effect parameters.

For instance in VCM Auto Wah, there's a Type parameter that can be one of: High, Mid, Low, Bass. I have no idea what's being chosen here. In the particular Performance that I'm currently working with, all four of the alternatives sound the same to me.

Here are the parameters that I would appreciate getting an explanation of:

  • VCM Auto Wah: Type, Resonance Ofs (presumably Offset), Overdrive
  • VCM Touch Wah: Sensitivity, Attack Offset, Type, Resonance Ofs, Overdrive, Direction
  • VCM Pedal Wah: Type, Resonance Ofs, Overdrive, Direction

Thanks.

 
Posted : 17/04/2017 9:23 pm
Joel
 Joel
Posts: 537
Honorable Member
 

Hi Michael, i have write this for Motif XF on Moessieurs.

The VCM Auto Wah settings:

Speed: This parameter set the LFO speed that modulates the wah effect.

Bottom: set the amount of low wah filter.

Top: set the amount of treeble wah filter.

Resonance Offset: set the resonance applied to Wah.

LFO Wave: Sin Trp: set the shape of the LFO that modulates the wah : sinusoidal or trapezoidal.

Type: High, Mid, Low Bass: set the part of the spectrum where we hear most Wah: high, medium or low.

Overdrive: set the amount of "distortion" effect applied to the wah.

Output: set the level of the output signal of the effect block.

The VCM Touch Wah settings:

Sensitivity: This parameter set the sensitivity of the wah in relation to your keyboard playing (velocity).

Bottom: set the amount of low wah filter

Top: set the amount of high wah filter

Resonance Offset: set the resonance applied to Wah.

Direction: up, down: set the direction of the modulation up or down.

Type: High, Mid, Low Bass: set the part of the spectrum where we hear most Wah: high, medium or low.

Overdrive: set the amount of "distortion" effect applied to the wah.

Output: set the level of the output signal of the effect block.

Attack Offset set the time that elapses between when you press the key and the start of the wah effect.

VCM Pedal Wah settings:

Pedal Control: This setting set the cutoff frequency wah over your "playing" on the pedal.

Bottom: set the amount of low wah filter.

Top: set the amount of high wah filter.

Resonance Offset: set the resonance applied to Wah.

Direction: up, down: set the direction of the modulation up or down.

Type: High, Mid, Low Bass: set the part of the spectrum where we hear most Wah: high, medium or low.

Overdrive: set the amount of "distortion" effect applied to the wah.

Output: set the level of the output signal of the effect block.

Attack Offset set the time that elapses between when you press the key and the start of the wah effect.

 
Posted : 17/04/2017 10:03 pm
Bad Mister
Posts: 12304
 

Just FYI: All the Effect parameters are defined in the "Synthesizer Parameter Manual" available for download on the Official Montage download page.

But the definitions are a bit cryptic if your not really clear on what's being talked about.

VCM (Virtual Circuitry Modeling) Auto, Touch and Pedal Wah
The Physical Model here is a recreation of several different Wah-Wah devices from the 70's. A Wah Pedal is a Filter... that is the type of device it is. This will give a clue as to what the terms "Resonance", "High", "Mid", and "Low" are doing here. It is an Envelope Filter as you can shape the Frequency response of the sound. So words like "Attack" deal with how quickly it initially responds.

A filter is a device that can be used to remove certain things and allow others to pass. So we are dealing with Frequency and the High-Mid-Low would refer to Frequency (as opposed to Output level, for example). When you hear no response it could be that your playing in the wrong range to hear the difference. The filter in a music synthesizer is responsible for timbre change. We know well the "pedal" version... the three Models here simply have a different "energizer"

The VCM Auto Wah combines a Envelope shaper and a Filter with an LFO. So the moving Cutoff Frequency is automatic following the speed as set for the LFO.
The VCM Touch Wah replaces the LFO with a Velocity sensitive responds so the dynamic velocity causes a deeper change in the Filter movement.
The VCM Pedal Wah replaces both of the above with the FC7 pedal and gives you a 1:1 (manual) experience with an actual Wah pedal; although no audio traverses the pedal.

"Resonance Ofs" (Offset) - when viewing a graphic of a Low Pass Filter, left-to-right is the Frequency scale, up-down is the amplitude (level) of the Frequencies. A "peak" is referred to as a resonant peak - a Frequency range that is louder that those on either side. This resonant peak at the Cutoff Frequency looks like a mountain peak and then drops off to zero Output level at a specific rate per octave, as defined by the Filter. The movement of the energizer (the physical movement) changes the Cutoff Frequency and therefore, moves that resonant peak Frequency higher and lower (left/right), changes the pitches allowed to pass). But when you "Offset" the Resonance you are basically shifting it above or below the initial stored value... increasing or decreasing its peak (up or down)

"Overdrive" is just what you think happens in analog circuits. This will change the character of the Effect. Gives it some "hair". An important part of the Physical Modeling here is the character of things like the Overdrive - by modeling the components that were used in these classic devices you get the same behavior under the given settings.

"Sensitivity" refers to the Velocity component added in the TOUCH (sensitive) WAH, this controls how much effort it will take to (energize) make the resonant peak, we identify as the "Wah", pop.

"Attack Offset" is an offset to the default Attack setting... like the OP AEG OFFSET, you are changing the shape of an envelope... this time, specifically the initial attack time response. This creates a slight lag in the timbre change and is totally a "feel" thing based on what type of phrase you are manipulating.

"Type" is giving a recommendation on where the Wah would work best. High, Mid, Low, Bass; Select "Bass" if using on a bass line...for example.

"Direction" has to do with the action of the pedal, you can reverse the toe down/heel down response.

You will see settings for 'Bottom' and 'Top' - the Data List warns: "When the value of Bottom is greater than Top, the sound will not be modulated and only the Bottom value is available." This sets the Frequency range of the filter.

Extra Credit: Look up classic 1970s stomp-box the "Mu-Tron III" which was an Envelope Filter (also referred to as an Envelope Following Filter) this was the ultimate Auto Wah... back-in-the-day! the character of the unit is righteously emulated (imho).

 
Posted : 17/04/2017 10:08 pm
Michael Trigoboff
Posts: 0
Honorable Member
Topic starter
 

This weekend, I finally got around to following Bad Mister's extra credit advice. I finally managed to wrap my mind around the effects structure of the Montage to the point where I was able to do some experimentation on the wah effect.

The result is this Performance:

Each Part is a separate experiment. They are:[list]

  • Part 1: Mod Wheel controls Control Filter Cutoff (Insertion A)
  • Part 2: Mod Wheel controls Element 1 Filter Cutoff
  • Part 3: Part's Envelope Follower controls Element 1 Filter Cutoff
  • Part 4: Touch Wah (Insertion A)

    They're all wah-ish, more or less. I don't think any of them are better than the built-in Touch Wah effect. But it was fun figuring out how to put these together. I'm hoping this will be useful to others, and I'll be happy to answer any questions about it.

    Scene buttons 1-4 are set up so you can play each Part individually by muting the other three.

    For some reason, the forum won't allow me to attach the .zip file containing the .X7B file of the performance. I'm going to attempt to attach that to the next message in this thread.

    Attached files

     
  • Posted : 06/02/2018 2:52 am
    Michael Trigoboff
    Posts: 0
    Honorable Member
    Topic starter
     

    Here's the .X7B file, he said hopefully…

    Attached files

    Wah_Experiments.zip (6.8 KB) 

     
    Posted : 06/02/2018 3:03 am
    Bad Mister
    Posts: 12304
     

    Nice! The “Control Filter” (and “Dynamic Filter”) found in the Effects are quite the Filters!

     
    Posted : 07/02/2018 12:42 pm
    Michael Trigoboff
    Posts: 0
    Honorable Member
    Topic starter
     

    I tried out Dynamic Filter, but there didn't seem to be a way to make it act like Touch Wah. Is that just not possible, or am I missing something? I tried it both with and without a Side Chain (the Side Chain I used was the Part itself).

    The closest I was able to get to Touch Wah was with the settings below, but it still wasn't anywhere close to being Touch Wah.

    Due to glitches in the forum software I had to upload the image in the two posts below so that I could then insert it here.

     
    Posted : 08/02/2018 2:48 am
    Michael Trigoboff
    Posts: 0
    Honorable Member
    Topic starter
     

    This post wouldn't take the image for some odd reason. I'll try again with the next post.

    Attached files

     
    Posted : 08/02/2018 2:52 am
    Michael Trigoboff
    Posts: 0
    Honorable Member
    Topic starter
     

    Third try at posting the image:

    Attached files

     
    Posted : 08/02/2018 2:56 am
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