DEFX Cosmo King - The Guillotine wah/ring mod.

[Stickman393]

Build Rating

3.00 star(s)

Boy howdy. This one has caused me a ton of problems.

So: this is my second attempt. First attempt was an absolute failure. It's part of why I switched back to leaded solder: the unleaded stuff is unforgiving, and de-soldering is liable to lift a pad.

So, I bought another board and gave it another go. I got the thing together and...well...

Ringmod was fine. I'm not crazy about how untweakable the ring mod is, especially because of all the offboard wiring that one has to do.

Jfet selection will determine the amount of drive the ringmod section gets. Lower IDSS values tend to correlate to lower gain.

Tone knob? If I had to do it over again I'd leave this one out. Volume - same. No reason for it. It's cool, but I don't particularly see it displacing my current wah pedal.

The wah portion caused me some headaches. It's quiet as all hell. Ya really see a *huge* dropout in volume when it's engaged.

I addressed this two ways: first, the input impedance is *super* low, so I added a simple opamp buffer to drive the front end. This also is active in bypass, so it makes for a decent first pedal on a board.

The second mod was to swap out Q1 with an MPSA18 instead of a 2n5089. The higher gain Darlington transistor helped increase the volume of the wah a fair amount. Its not *entirely* there yet. I might come back to it later.

Anywho, this is the "Cosmo King", based off the "Royal Cosmo Wah". And if there is one thing to know about stickman, it is that he doesn't particularly care for royalty. So, random word association yeilds this.

I tried painting and...I'm not good at paint. Too much paitence required. I'm also not good at keeping things clean and perfect. So, I went the opposite direction here, and I kinda love how it came out.

Ta da!

 

[Feral Feline]

I abso-freq'n'-lutely LOVE the aesthetic of this thing!

If I were you and really not liking/using this down the road I would SSSOHHHHHHhhhhhh swap in a PCB-wahble-board I did like and this hell-torn treadle-shell would be permanently affixed to my main pedalboard. So F$%^&* MEAN!






Ahem, one small note: MPSA18 is NOT a Darly, it's just a regular BJT, albeit a high-gainer.
I know, it's weird 'cause every other MPSAxx is a Darlington...

 

[Stickman393]

So it is! Huh. Yeah, I had kinda assumed that it was a Darlington. The one I put in there was like 1k.


I'm planning on doing a few more like this: I have another two shells that need the distressing treatment. My current wah is a RMC wizard II...I'd really like to make more of my board DIY.

Wahs are tricky. Need to do a bit more reading and experiment a bit.

 

[Feral Feline]

I always thought it was a Darlington, too, and quite surprised to discover it's not.

Have you got an inkling of which wah-circuit you'd like to do next?

 

[Stickman393]

I always thought it was a Darlington, too, and quite surprised to discover it's not.

Have you got an inkling of which wah-circuit you'd like to do next?

I've been looking into that...

I mean, a wah is a pretty simple circuit. I'd love to de-goop my wizard and see how that circuit compares to the "standard" vox/crybaby.

Mines an early model, before the redesign. Before that I was using a Clyde deluxe.

Ideally, I'd love to have something for a "main" wah pedal that has the extended treadle range of the redesigned RMCs or the fulltone, just a wee bit more range on the rack and pinion, so I could use more of the sweep of the potentiometer. I've never been a whaka-shaka-whaka-shaka-whaka-shaka kinda guy. I'm the dude that uses slow, drawn out sweeps that getcha checking your watch and saying "lil' self indulgent there bro. Pick it up".

Which would mean either gutting a modern passive volume/expression pedal, or bending and welding together my own design out of sheet aluminum and self-machined parts. Which is a little beyond my skill levels at the moment, though it's something I'd love to do some day.

Shoot. I could even carve out a piece of 8/4 and 4/4 lumber into the basic parts of an enclosure. Something like that would need to be made out of a *very* hard wood and reinforced/sheilded on the inside. To make it last it'd need to be stabilized via vacuum resin impregnation too. But damn that would be slick. I've actually got a bit of quartersawn 8/4 wenge that would be great for that.

The actual circuit? Can't say. Simplicity is key for me in a wah pedal: I want something that I step on and go wheedly wheedly wheedly wahhhhhh. And then look at stickwife and say

"yeah, I wrote that. It's called 'I wanna rock your body'. And then in parenthesis (until the break of dawn)"

And then have her say

"That's beautiful, it's like poetry"

You know. Like, normal stuff.

 

[Feral Feline]

As I started reading "or bending and welding together my own desi..." I knew/know you'll do that, before I even finished the sentence, before "some day". You rock man, I'm sure "some day" is right around the corner and sooner than you think; I mean "poetry", right?