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Hi there, welcome to my blog - La Revolution Deux. It's an odd name - but I like it! Here you will find all the info on my various DIY Guitar effects builds, amplifiers and guitars. Everything from a humble Ibanez tubescreamer to the holiest KLON Overdrive.

You may also find a few effects builds that I am looking to move on - usually in exchange for other effects/gear/cash. You can always check my ebay account to see what I've got up for grabs.

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Friday, 6 July 2012

Vox - Clyde McCoy Wah

Jimi Hendrix's Clyde McCoy Wah which sold for over $11,000 at a recent auction.
Who is Clyde McCoy and why is this Wah pedal so sought after?

Good old wikipedia provides this info;

"Clyde McCoy was a jazz Trumpet player ... who developed a signature "wah-wah" sound in the late 1920s by fluttering a Harmon mute in the bell of his trumpet. In 1967, this distinctive sound was replicated for electric guitar with the introduction of the Vox Clyde McCoy Wah-Wah Pedal, the most significant guitar effect of its time. The Wah-wah pedal was invented by a young engineer named Brad Plunkett, who worked for the Thomas Organ Company, Vox/JMI’s U.S. counterpart. The wah circuit basically sprang from the 3-position midrange voicing function used on the Vox Super Beatle amplifier.

Vox cleverly packaged the circuit into an enclosure with a rocker pedal attached to the pot (which controlled the frequency of the resonant peak) and named the new device after Clyde McCoy. Early versions of the Clyde McCoy pedal featured an image of McCoy on the bottom panel, which soon gave way to his signature only before Thomas Organ changed the name of the pedal to Cry Baby. Thomas Organ’s failure to trademark the Cry Baby name soon led to the market being flooded with Cry Baby imitations from various parts of the world, including Italy, where the McCoy pedals were originally made."

Ok, so they were the first wah-wah pedals ever made but that doesn't explain why everyone wants one. Well, Jimi Hendrix, the man who is probably most associated with a wah pedal, used one - that's why everyone wants one.

The insides of the Clyde McCoy Wah.
Here's Hendrix on his Wah playing Voodoo Chile live at the Royal Albert Hall, probably one of the songs most associated with the use of a wah pedal and the reason the effect became so popular;

So, let's check out the schematic of the original Vox Clyde McCoy and compare it to the standard Cry Baby model (although it's noted as a Jimi Hendrix model it's just the same as a standard Cry Baby model) wah;

Ok, so there's not that much difference but it's a small circuit so small differences in components add up to make a large difference in sound. Firstly the transistors are BC109, these have a much lower HFE (gain) than the MPSA18 darlington type transistors used in the standard Cry Baby, this lower transistor gain leads to the wah having a much nicer and rounder bass response. The wah pot has an "ICAR" taper, these are vintage specs and replicas can be bought from various sources. The ICAR taper alters the feel of the wah and, as I find, gives you more quack on the toe end of the travel. Add together the other small differences in component values and you have the changes that make the McCoy wah unique.

Going back to the gutshot of the Clyde McCoy wah there are a few further things we need to take note of before we look to construct a replica;

  • The capacitors are old "tropical fish" style caps, many people believe these caps have their own sound and contribute to the character of the original Vox Clyde McCoy.
  • The wah inductor - it's known as a "Halo" style inductor (due to it's ring type shape). There are many people who build replicas of these inductors, one of the best comes from arteffect in Israel.
So, we want to build one now, you've got your old Cry Baby shell gutted and you're ready to build up the circuit. Here's what you need - a great vero layout from Sinner of turretboard.org;

1 comment:

  1. Just finished this Wah, but when playing it feels somewhat uncomfortable, because it's too much low frequencies at half of full way, and then highs suddenly appears at the end of the way, much louder. Is it ICAR pot responsible? And maybe that's how it suppose to work?


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