Craig Anderton Envelope Controlled Super Tone Control (Auto-Wah)

[MAO]

Update 01/25/2016 - I tried both Tayda LDRs and 5516s, neither really cut it regardless of LED color/type. I don't think these LDR's light resistance is low enough.  

I suggest going with the NSL-32 (specs seem identical to the original CLM6000s that Craig had used)

Update 01/16/2016 - The resonance control seems backwards, I had assumed I wired it up wrong. Turns out it is wired according to the schematic but is in fact backwards (IMO). I'd much prefer to have the resonance increase as the control in turned CW, so I ended up tying lug 2 to lug 3 of the Resonance pot (rather than lug 2 to lug 1 as shown in the schematic)  Schematic (John Lyons' website)  I did this right on the pot itself, no need to make changes at the board connections.

Another classic combination from Craig's Electronic Projects for Musicians.

The Envelope Follower and Super Tone Control wired together giving an Auto-Wah option.

Updated to use TL074 and TC1044SCPA (or ICL7660SCPA).

The layout has a 4PDT switch to engage the Envelope Follower for the auto-way effect. I also included a toggle to remove the EF from the signal chain. If you are going to build this, I would suggest you check it out 1st before committing to either switch. You may prefer to wire it up as a permanent auto-wah and skip the switching altogether.

The 2 boards are connected together at the +9v In/Out, -9v In/Out and Ground In/Out connections.  

If you don't want the EF bypass toggle, then Sensitivity-3 goes to the 2nd Input pad on the STC. Disregard the EF Bypass switch connections.

If you want a permanent Auto-Wah, omit the switch and Frequency dual pot and connect AW SW-9 to AW SW-5, AW SW-10 to AW SW-6, AW SW-11 to AW SW-7 and AW SW-12 to AW SW-8. Disregard Freq A1 and Freq B1 connections.

As always thanks to Mark, I slightly tweaked his original STC layout for this one.
   
Verified by me


Sample layout showing the board & switch placements in a 1590BB

[notnews]

This is great. Awesome work!

I'm curious about the resonance control.. how crazy can this get? I'd love to hear a demo of these circuits if anyone has the time!

[heuermh]

I'm curious what is actually coming from the envelope follower, looks like four values across the autowah switch (9 - 12).  Are those like control voltages or is it seen more like variable resistance?

Such a board could be useful in a lot of places.  I suppose I could just go dig up my copy of the book ...

[MAO]

Variable resistances for the STC.

Variable voltage on the phase shifter (separate topic)

You can have either option from the original Envelope Follower circuit,
however I have stripped it down to just what's necessary for this pedal.
(And for the phase shifter)

I do have a layout for a stand alone Envelope Follower which would allow
for either option.

[Muadzin]

Any chance for a demo youtube vid or a soundcloud audio for this one and the envelope phase shifter? I'm really curious to their sounds. Also, can these three Craig Anderton layout of yours fit into a 1590BB with topmounted jacks?

[MAO]

Yes, sorry meant to do that before I left for vacation. I'll post something when I get back next week for sure.

Not sure on the top mounted jacks as I don't use them. How much room do they need for clearance?

[Muadzin]

It depends on what kind of jacks you use and how far down you can push the board to make room up top. Maybe a gut shot of your build could help me make an assessment?

[MAO]

Will do, in the meantime checkout the faceplate picture I posted, it shows the 2 boards actual size in a 1590BB.

[Muadzin]

I hadn't even noticed it. Awesome looking faceplate by the way.

[Muadzin]

Question, the effect input on the super tone control board, does that first go to sw-1 of the EF bypass switch and then linked through to the board, or is it taken from that little blue dot next to the 220n cap? Or does it not matter one bit either way?

[MAO]

If you are going to use the Envelope Follower bypass switch (EF BYP), then both the tip of the input jack and EF BYP switch lug 1 go to the same place on the board. The blue pad is there for convenience so you can run separate wires from both to the board. I connected the input jack "normally" and then the EF switch to the blue pad.

The only reason I added the switch is so the envelope follower could be completely bypassed when not used, not so sure it is necessary.

You could omit the EF bypass switch and connect sensitivity lug 3 directly to the blue pad. But then you would no longer have a true bypass for the EF, it would always be connected to the input jack. (Which was the original suggestion in the book)

In fact, I ended up wiring mine permanently and omitted the switch. I found some of the settings I liked with the autowah didn't sound so great when the autwah was bypassed and the super tone control was engaged, so the autowah stomp switch wasn't that useful. I used a 4PDT toggle instead to choose between STC and autowah. And for cosmetic reasons omitted the EF bypass switch.

I'll post some pictures and a sound clip as soon as I can, really sorry for the delay.

[Muadzin]

I built this thing yesterday and got to the troubleshooting today. I had to solve some oscillating issues but now I got it to sound like an autowah. I do run into the following issues.

-  Lo/Hi switch when I turn it on causes oscillation, until I turn the Resonance up to 15:00.
- EF bypass switch doesn't seem to affect the sound at all, neither does the Sensitivity and Calibrate pots.

I managed to build it by the way with top mounts.

[MAO]

Nice, looks sharp, like the shade of red.

Curious how you replicated the faceplate?

Are you able to ditch the vero boards on the face? I had superimposed them just to show how they were positioned in the enclosure, they weren't meant to show in the final design. :0)

Here's a pic without the veros and knobs if it helps.



The EF bypass switch should disable the autowah function completely(calibrate and sensitivity controls disabled), originally I was going to use it to insure a true bypass for the envelope follower when I was just using the Super Tone Control by itself.

BTW, the calibrate and sensitivity controls are only active when the Envelope Follower is engaged. So with your setup, you would have the autowah stomp switch on and the EF bypass off to activate those 2 controls.

I'll record a video this weekend showing how I adjust the calibrate and sensitivity controls.

And your drilling is spot on, nicely done!

[MAO]

Settings Demo - Video



I'll also record some sound clips (without any talking) demonstrating the auto-wah used with a distortion pedal.  

And I found these clips by John Lyons demonstrating the STC installed in a wah wah pedal.

STC - Clean Wah

STC Fuzz Wah

STC sweep range

[clockman]

Great video! thanks for all the work you've put into this. Just finished building it and fired up without a problem. not boxed yet... too much joy playing.
 Per your notes and suggestions I went with permanent autowah wiring, as I've already built the STC twice before (one as a stand alone filter pedal and the second stuffed into a gutted plastic wah shell) I was eager to hear the envelope section. what a treat it is... super sensitive and highly tweakable.

I did sub some parts
7660scpaz instead of 1044
tl074 in place of lf353
and used Tayda ldr with 5mm red diffused leds

which optos did you end up using? i'm probably ordering nsl-32 soon along with a couple other LDRs from small bear. (I'm on autowah kick right now and I need to stock up)

Again, Thanx!!!

[MAO]

Thanks clockman! Can't wait to see it.

Before you box it you may want to try different values for the 39u cap which sets the envelope's decay time. I like the stock decay, but a switch to choose a shorter and/or a longer decay may be worthwhile. I haven't tried it yet on this one, but had good results with the DOD 440.

I used NSL-32s mainly because I still had a bunch. If I'm homebound tomorrow I will sub in the Tayda and 5516 ldrs and let you know how they compare to the NSLs.

[clockman]

Aha. I was wondering about that 39uf cap (used a 33 and 4.7 in parallel, forgot to mention on my sub list)
 while we're on the subject, there are several socketed components on both boards, any other suggestions?
We've got some snow here in the northeast, sadly i must contend with that first. Insert standard crying wah sound. Wah wah wah

[MAO]

Good luck with the snow. I used to live in NJ, I know the pain. The socketed 220k resistors on the envelope board allow you to tweak the EFs response to your playing style. They should be adjusted if you have to have the sensitivity control near either extreme to work. If the sensitivity pot its barely turned cw to get the sweep you want, then the EF is to sensitive. Lower both resistors to 100k, be sure to keep both values the same. If you have to turn the sensitivity pot near full on, then try raising both resistors to 470k or even higher. (I've never had to do this with humbuckers and nsl-32s, but it only takes a few minutes to check them out just to be sure) The 33k resistor on the STC sets the overall gain. If you are using the added volume control you could probably bump it up some.

[clockman]

Actually we didn't get as much snow as predicted here in Rhode Island. Already done.
 My sensitivity control seems fine enough as is, so i shall stick to tinkering with that 39uf cap idea.
I was one 10k audio pot short of the three needed. Used a 10k linear on the hi pass and it is just not the right taper. More parts ordering... Ack this damn pedal building addiction. That being the case i'm not boxing it yet.

Gotta say this is really a good circuit. I'm eyeballing that envelope phase now too🤘

[MAO]

It hurts to admit I now spend more time building pedals then playing them...not sure how that happened...but I love the whole process.

There seems to be something not quite right with the EF controlled Phase Shifter I just built. This is one of my favorite effecs, but this one sounds more like a EF filter than a EF phaser. The phaser alone seems fine, but the EF control doesn't seem right.It should be controlling the range/speed of the phasing, but mine seems to be acting more like the STC.

Unfortunately I sold my original one to a guy in NJ, so I cant compare them.

I should get back to it next weekend though.