Just.Another.Wah

[Kipper4]

Just Another Wah
Kipper@DIYSB.COM

Credits to
Duck Arse @ DIYSB.com

My brief was to devise an envelope filter using common pedal builder parts that would fit into a 1590B enclosure.
After much trial and error. I settled on the Coloursound Inductorless filter. You may find it a bit peaky in the highs.

A true bypass envelope filter
How it works.
The guitar signal is split after the anti pop resistor R1 and input capacitor C1.
The side chain signal is then buffered (IC1-A) sent to the amp (IC1-B) where the gain is set via a 25K Linear trimmer. This is used to set the input sensitivity depending on your guitar pick up.
The AC signal is then rectified by D1,D2. producing a half wave DC signal to drive the led found in the negative feedback loop of IC1-C.
The Brightness of the led can be varied using R Brite.
The led is part of a home rolled vactrol, the other Part is the Light dependant resistor (KE17020).
For the Led I used a green 5mm diffuse dull (100mcd)

The other half of the spit guitar signal is sent to the twin t filter.This is the bit that goes wah.
The vactrol controls the variable resistance seen at the node C5,C6.
The output of the filter is then sent to IC1-D a gain stage used to set the level at the pedal output.


Mods
You could use TL072 for the input buffer (IC1-A) and output gain stage (IC1-D)

You could use LM358 for the side chain (IC1-B and IC1-C)

This design should also work well with an NSL32 vactrol
Alternative LDR is GL5516.



https://imageshack.com/i/p4j09O38j

theres a layout for it on my imageshack too

[Ben N]

Cool, thanks. I look forward to giving this a go after my next parts order.

[mth5044]

I'm not sure what image you posted, but it isn't working, and your schematic is much too small to read on your imageshack!

[Kipper4]

Thanks Matt
I will update it ASAP

[duck_arse]

hey rich, youse gots to go on the middle right on the imageshack (blecch! so much junk code) page, where it says "get links/ image size". then you can pick a smaller size, on the right, and it will provide you a link looking VERY much like this:

Code Select Expand

[img]http://imageshack.com/a/img540/1802/50RT2f.jpg[/img]

then we can all see wot it is.

[Kipper4]

There we go fellas
If you need it bigger just hollow

[Kipper4]

Side note the GL5506 LDR works good too in the roll your own vactrol.

[deadastronaut]

cool...clips?..

[mac]

Cool! The Colorsound Inductorless Wah as the filter stage. IMHO it's better than the MFBF, ie, Bass Ball and others.

Any chance of a bigger schem. My eyes are not very good these days

mac

[Kipper4]

I'll do a clip soon Dead Astro. As soon as I can
Mac I tried sevral filters including some MFBF and your SVF and some more and your SVF too. Schematic sent btw. Check your inbox.
It was a lot of fun creating this. You guys where a lot of help too. Its much appreciated.
It's not the best envelope filter but I learned a lot from this little project.
I just hope I learned enough to field any questions.

[bool]

But you could re-mix the concept a little and replace the LDR sidechain with the Dr.Q sidechain, no?

[mac]

I have to simulate the CIW with a buffer after it, like in your schematic.

mac

[deadastronaut]

@rich: hows the envelope detect part on that?.

is it subtle to full on, nice attack/decay etc..

[mac]

Rich,
I remembered to have played with the CIW as the filter without the input and output opamps.
If the detector steals some signal the 330k can be reduced.
If a FF works fine without the output opamp you can simplify things a bit.
Just a thought

mac

[Kipper4]

The envelope detector is just fine Rob. I cant take credit for it. D.A designed it and I tweeked it for my needs.
Adjusting the decay Attack and R Brite will get you a few differant sounds.
May I suggest you bread board the envelope detector maybe with an LM358.

I did mess with the 330k Mac and It did make up the lose some.
I guess it could be made simpler. I had the extra op amp so Ithought I'd make use of it.
Yall know what its like with mission creep.

I didnt try the Dr Q detector maybe I should have Bool. I was dead set on making an EF with the nsl32 and of course learning the ins and outs of it.

[duck_arse]

The envelope detector is just fine Rob. I cant take credit for it. D.A Kipper4 designed it, DA shifted some parts around, and I tweeked it for my needs.
Adjusting the decay Attack and R Brite will get you a few differant sounds.
May I suggest you bread board the envelope detector maybe with an LM358.

I did mess with the 330k Mac and It did make up the lose some.
I guess it could be made simpler. I had the extra op amp so Ithought I'd make use of it.
Yall know what its like with mission creep.

I didnt try the Dr Q detector maybe I should have Bool. I was dead set on making an EF with the nsl32 and of course learning the ins and outs of it.

there ya go rich, I fixed it for ya.

[Kipper4]

Cheers Mate