DIY wah wah pedal suggestions wanted?

[Robmosis]

Hey guys, I have been learning all I can about tube amp circuitry and how it all fits together.
I want to do an amp project one day, but figure I will start pretty small.
I need some recommendations on a DIY wah wah pedal kit.
Something along the lines of a vox or crybaby would be nice, but doesn't necessarily have to be.
I have a Dunlop Mr Crybaby super now that works fine but there is just to much on it.(Volume pedal, boost, no true bypass)
I want to use that chassis but I want to build the guts from a kit.
I have good soldering skills, and some knowledge so I feel pretty comfortable in the project.
I would like just a nice wah with true bypass.
Any suggestions on where to look would be greatly appreciated.
Thanks
Robmosis

[Robert M. Martinelli]

Hi Rob,
Well, a wah is pretty simple from an "electronic" point of view, being basically a preamplifier with a variable RLC filter, so I won't go any deeper on this.

I prefer to give you some general guidelines that I hope to be helpful.

Usually the wah is placed at the beginning of the FX chain, so my advice would be to use low noise BJTs. I have achieved very good results with Japanese 2SC1815s, but AFAIK 2N4104s and 2N5210s have a very low noise figure too.

To keep noise as low as possible, you should also consider using metal film resistors. They're more expensive, but in a wah pedal there are only a few, so the overall cost will not be much higher.

One last advice about the pedal-operated variable resistor ( that's the way the pot in wired in a Dunlop and many other wahs ) - consider implementing an optical emitter/receiver device ( LED+LDR ). This will give free you from having to periodically clean the pot ( if it's the cheap "open" type ) or replace it when worn out ( if it's the expensive "sealed" type ). This "contact-less" solution will have an indefinite life cycle, it will be absolutely noise/scratch proof and it will also give you the possibility to fine tune the pedal taper by shaping the black moving mask between the LED and the LDR according to your taste.

Hope this helps

Best regards

Bob

[Robmosis]

Thanks voxrules for the advice. I appreciate it and will use your suggestions.
I understand that a wah is a fairly simple form of electronics but at this point I still don't understand enough to just build one without some sort of kit, or instructions.
I know I could get the parts but how do I put them in a working order?
If you know of a kit that would be very helpful.
Like I said I have the chassis of the mr crybaby that I will gut and use. And I will probably be able to use some parts off of it also.
Pedals interest me and I like love tone (Hence I own a vox ac30cc2)and I really love tayloring my tone to myself. So what better than building pedals and learning how each piece effects the sound.

[Bloodbath]

Romosis,

PM'd you.

[alfonso]

There are some Cry Baby mods that seem to be very nice....why don't you start with that?

You'll find useful infos on that and more here:
http://www.wah-wah.co.uk/index.html

[Robmosis]

I have looked at all the mods but none will work with the mr crybaby super since the electonics are much more complicated than the normal wah.
thanks for the advice though.
Rob

[Robert M. Martinelli]

Hi again Rob,
I know of a German site selling pedal kits, it's fairly cheap too, but that wouldn't probably be good if you're living outside the EU because adding the shipping costs, import taxes and fees you'd probably end up spending more on taxes and fees than on the kit itself.

I think it's good for you to take a look though, because they have published the schematics, PCBs and layouts on their site, so you'd be able to get an idea on "how to put things in working order" as per your statement.

They also sell parts individually ( inductors, Germanium BJTs etc. )

Here' the link to their main page, then click on the "kits" section.

http://www.musikding.de

Hope this helps

Best regards

Bob

[noelgrassy]

Robmosis,
You need to start from scratch and neatly set that shitty circuit in a box. By a Whipple inductor and simply lay all the common wah parts on a perf board and wire them to your jax and pot.
Here's a dandy chart of the wah's construction at least the most popular models. This comes from RG Keen's site and I hope he doesn't mind me sharing it. The components are identified with their interelation and function.
http://music-electronics-forum.com/t13171/#post109575
Hope this clears things up foryou,

NG.