Wah-wah-yaow-moe-pedal question. I mean, auto-wah.

[JimRayden]

I'm finally starting to tinker on the multi-wah-setting I was discussing on this forum a while back. You know, to gain wovels.

What do you think, what would an envelope-controlled wah and a time-controlled wah in parallel give me? I'm guessing it would be pretty interesting. What about series?

If anyone who has both kinds of pedals (or could quickly breadboard a few) could try it out, I'd be superhappy.

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Jimbo

[puretube]

no comment...

[JimRayden]

Uh, well thank you, puretube. You've been most of help.

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Jimbo

[puretube]

youknowiknowwhentoshutup - don`tcha?  :wink:

[JimRayden]

[nonsense]
YesIdo.... Yesido... Mr. Yesido Kukusaki. I am the great cornholio!
[/nonsense]

Alright, can anyone say something that would actually be helpful? Read the post number one.

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Jimbo

[Jaicen_solo]

Hmm, thinking in terms of frequency response, series would probably not sound good. You'd be sweeping through ranges where there's no output, as the bandpass filters are not aligned.
In parallel, you could get some interesting interactions, when the notches are coincident, they may resonate like a synth filter.
One idea is to use a bandpass and a notch filter together. This will produce some very interesting filtering as the center frequencies begin to cross. If one filter had a very wide Q, you could get interesting humps and bumps in the frequency response too.
FWIW, I believe that effects like the bassballs sweeps two bandpass filters which are a constant distance apart, hence the particular sound. this could possibly be imitated using a phase network, where you can sweep the notches, rather than peaks.

*b

[JimRayden]

Also, what would be better in parallel with a manual wah-pedal? Envelope or time controlled autowah?

Hmm, what about having one autowah with a possibility to switch between the two modes. Any current DIY-projects capable of that? What circuit is the easier to mod to do that?

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Jimbo

[Paul Perry (Frostwave)]

I expect that two parallel filters would be best (this is closest to the natural twin peak of humans, to whihc out brain is wired to respond).
But, a cheaper & possibly interestign option would be to add the filter control voltages together, that is to have the wah or envelope-derived or LFO control voltages summed and then used to control the single voltage controlled filter.
As for whetehr filters in series would be OK, well if you had a low pass and a high pass in series, and made sure that they didn't overlap so that nothing went thru, and you added resonance to each, you would have somethign that sounded like a.... MS20 filter (the whole thing, not one section).

[Mark Hammer]

Also, what would be better in parallel with a manual wah-pedal? Envelope or time controlled autowah?

Hmm, what about having one autowah with a possibility to switch between the two modes. Any current DIY-projects capable of that? What circuit is the easier to mod to do that?

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Jimbo

There is actually a *somewhat* easier way of doing things (and I say that with reservations), and that is a dual-channel auto-wah with discrepant time constants (sweeps).

Here's the suggested scenario...

Perf yourself a Dr. Quack, leaving lots of space, say about 60% more than the DQ itself requires.  You can find the schematic at www.muzique.com.   I *suppose* you might sonsider making a board, but let's keep it simple for the moment.

Make the filter caps 8200pf to 12nf instead of the 4700-5000pf shown.  Replace the 100R resistor between the LED and 1N914 with 47R and a 500R to 1k pot, wired as variable resistor.  The 10uf cap *might* be changed for 22uf at some later point, but we'll leave it at 10uf for now.  Instead of the 470k terminating resistor on the output, make that a 100k log pot, wired as volume pot.

The mode switch is simply going to complicate matters, so we'll skip it and go for the most conventional mode of the two.  Personally, I find its sweep more serviceable anyways.  The 47k resistor that goes from the filter caps and transistor collector to the common of the switch will now go directly to ground, without any switch present (this resistor provides a resistance parallel to the tranny to adjust sweep range). The audio signal from the FET and 10uf cap is now going to come in on the 470k resistor to the "-" pin.  Because we're skipping the filter mode switch, the .01uf cap and 47k resistor to ground are unnecesary.  The 470k resistor goes directly to the 10uf cap output.  There, that's channel 1.

Get yourself a second dual op-amp (although a quad would be sufficient for the entire project).   Wire up one of the additional op-amps as a filter, identical to the initial one.  Everything about it will be just about the same, with the following changes.  First, change the 4700-5000pf caps to something between 2200 and 3300pf.  Second, I don't think you'll need a second bias circuit, so just run the + input of the additional op-amp filter to the Vref point at the junction of the two 47k resistors and 10uf cap.  Third, we'll want a little more resonance on the filter, so change the 470k feedback resistor for 560k or perhaps 680k.

Like the first channel, the second one is going to have a 100k output level pot.  The outputs (wipers) of those two filters are going to go through 10k resistors to the "-" input of a mixer stage.  Give the mixer a 12k feedback resistor to add a little gain, just for the hell of it, and a 1000pf feedback cap to keep any acquired hiss a little lower.  Take the output through a 1uf cap and 100k resistor to ground.  As before, run the + input pin to the Vref point.

The gain stage for the envelope follower is going to have two outputs.  Just for insurance, we're going to up the feedback resistor from 2.2meg to 2.7meg.  From the output of the gain stage, duplicate everything you see - LED, diode, cap to ground, series resistance, trimpot and transistor.  Make the cap to ground 22uf, though, to add a little time to its decay.  

There, you now have two staggered parallel envelope controlled filters.  The trimpots can tune the filter sections, but also adjust the amouint of sweep.  The different time constant caps in the individual rectifier sections will yield different decay times and the 1k pots can be used to adjust the attack/onset time, so that one filter can begin its sweep faster than the other.  The output pots from each filter section can help adjust both the overall output level of the circuit and the balance between higher and lower filters.

The E-H Baseballs is also a dual-filter auto-wah - essentially a dual Dr. Q - with a very vocal-like quality.  It also uses the same filter mode I've selected, and a roughly similar stagger between filters, although the range would seem to be a little lower than I've adopted.  Moving the dual trimpots up to be chassis-mount pots adds a great deal to the ability to achieve different sounds and characters.  What the Baseballs LACKS, however, is any means for altering the relative balance between filters and any means for achieving different "movement" of the filters.  A simple read through the phonology chapter of any introductory linguistics textbook will show you that the formants of human speech "move" at different speeds.  Consequently, I've included some means - albeit probably too simple - to derive different amounts/rates of movement from the two filters.  My instinct tells me that having one of the filters possess a little more resonance might also allow for achieving a greater variety of vocal-like sounds.  The BB uses identical resonance for each filter section, and as good as it is, the two filter sections can sound remarkably similar.  That's not really what we want.

I hope somebody builds this.  I'm curious to find out whether it sounds more vocal-like.  Sometimes theory yields accurate predictions, and sometimes not.

[JimRayden]

Wow. Now that's the kind of help I need. Thanks, I'll try it out!

Though, with two envelope controlled wahs, wouldn't two identical string pickings sound similiar? I'm looking for maybe a bit more "chaos" in that. So it wouldn't "say" the same things, so I could have a sensless talking-singing effect. The envelope-wah gives the talking a little interactivity with the playing and I though maybe a time-based wah would give me the chaosness. Or to have a manual wah pedal with the envelop controlled one.

And I just realised I recently found an old-old wah pedal wich I could use for that project.

Would a three-peak effect sound too messy?

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Jimbo

[sean k]

http://photobucket.com/albums/y115/quickkiwi/?action=view&current=DRQx2.jpg

[DiyFreaque]

I suppose this question is a little on-topic for this thread (well if you stretch it a bit).  When I was a young lad, back in the mid to late 70's, I could swear that I saw an EH catalogue or brochure that had a pedal called the 'AEIOU' pedal or something like that.  In other words, instead of going 'Waaahhhh' when you rocked the pedal, it would go through the vowel formants.  Did I dream this or was there such a thing?

I've been wondering that for a long time now......

Cheers,
Scott

[puretube]

E-H "TALKING PEDAL"...

>Bernie Worrell< of the P-Funk Allstars is a master on it:

>(with glasses  )<

[DiyFreaque]

Thanks, Ton!  What a relief.  I'm not crazy (or senile)!

I recall back in the day, an  EH catalog was just so cool to paw through.....

That and PAiA.

Cheers,
Scott

[puretube]

somewhere on the web, there are soundclips... ( :?: )

[Mark Hammer]

http://photobucket.com/albums/y115/quickkiwi/?action=view&current=DRQx2.jpg

Wow!!  Now that's the kind of help *I* need.      Did you just whip that up, or was it sitting around undiscovered?

[JimRayden]

Is that the circuit you were referring to, Mark?

And yea, I've heard the EH pedal. And to me, it didn't sound too much different from a regular wah. Well, you could notice the speech characteristics but it didn't sound too versatile to me.

I think I'll go with a manu.wah+env.wah setting for now because I need to get the thing ready for a gig. The circuit is so huge it seems to take forever to troubleshoot. I'll build it afterwards though.

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Jimbo

[JimRayden]

And I think I'll build the Nurse Quacky circuit since I've built it before and it's more familiar to me.

Anyone know how to add the "down" switch on the nurse?

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Jimbo

[sean k]

Yup Mark,I just whipped it up,so I'm glad I could be of service,I liked how you mentioned the TL074 and upon drawing up the schematic realised ther were two mirrored circuits and that sooo suits the 74.Not too mention all those non inverting inputs sitting straight on V bias it seemed too good an opportunity not to tunnel straight up the middle of the 74.On an area like that I'll just black out,I draw onto copper with solvent markers,all the underneath of the 74 and then scrape out channels for the etchchant to get in with the end of a knife.Great opportunity to do so...so thankyou!

[Mark Hammer]

Well Thank YOU, sir.  This is inter-NET-ional cooperation at its finest.  Problem gets posted in one country in the afternoon, mulled over by someone in another country, and within 24hrs worked out and turned into a viable design/board in yet another country.  Amazing.  You young tykes have no idea how completely foreign and mind-boggling this is to us old farts who would check the pages of Guitar Player and the display cases of the 2 or 3 music stores in town regularly back in the day, in the hopes of finding MAYBE a half dozen new pedals per year.

Just in case it isn't clear to some folks from the schem drawn, there are essentially 7 pots to toy with: attack, tune/range, and level for each filter section, as well as a master sensitivity section.

The thing with many of the envelope controlled things is that if the attack time is brief enough, relative to the decay, it starts to SOUND like the drive is downward.  The Baseballs is your standard sweep-up-before-down design, but if you bop over to the E-H site and listen to the sampes it sounds as IF it has a downward drive.

As for moving more in the direction of vocoder-like control, I suspect that, yes, a manually swept device would yield more control than anything envelope-controlled.  Should one want to spend a little less time thinking about foot movements, and a little bit jore time thinking about note choices, though, withing the context of an "automatic" device, the dual filter thing, as I laid out with Sean's help, can yield some really interesting possibilities.  It may not sound like one is "talking", but it will permit one to sound like the filtering sounds produced are similar to those made by the vocal cavity, as if you could automate a cheek-sucking filter sweep from a "talkbox".  Of course, that may be less than you were aiming for.