Vox - Wah Wah Distortion  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Rocket Roll
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Post by Rocket Roll »

VOX Wah-Wah Distortion on DiscoFreq: http://www.effectsdatabase.com/model/vo ... distortion

Any idea which kind of inductor, what pots, what kind of integrated fuzz and where it was built?

Transistors: 2xBC209C and 2xFMPS5172.
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Post by Rocket Roll »

Some more gutshots:
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Post by Rocket Roll »

...and some more:
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Post by Paul Marossy »

Huh, I've never seen one of those. The inductor doesn't look like any I've seen before.

Can you draw up a schematic for it? That's probably the only way anyone is going to determine what the fuzz section looks like, and if it is original or a derivative of something else.
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Post by lolbou »

I guess it's a fairly basic inductor with a green plastic cover on it. I guess that removing the nut on top of it would let the green plastic come free, and it would look like this (on the right):
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Post by Paul Marossy »

Yeah, I doubt that the inductor is anything special.
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Post by ik6gpy »

That is probably an italian pedal. I had a Moreschi Wah-Fuzz (nothing special) that had the same enclosure and the same inductor of your Vox. Bc209's are european trannies, so my guess is probably right.

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Post by Paul Marossy »

ik6gpy wrote:That is probably an italian pedal. I had a Moreschi Wah-Fuzz (nothing special) that had the same enclosure and the same inductor of your Vox. Bc209's are european trannies, so my guess is probably right.
My first thought was that it is a Italian Jen made product. But on regular wah pedals, that is usually clearly marked... :hmmm:
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Post by Rocket Roll »

I found that it looks surprisingly similar to Silversound SE-20 Whau-Whau Distortion - same type of build, I'd say even the same factory.

Here's the schematics and some pics of the SE-20: http://www.fetishguitars.com/mrt/silversound/jean.html

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Post by Paul Marossy »

Rocket Roll wrote:I found that it looks surprisingly similar to Silversound SE-20 Whau-Whau Distortion - same type of build, I'd say even the same factory.

Here's the schematics and some pics of the SE-20: http://www.fetishguitars.com/mrt/silversound/jean.html
Yeah, the two look very similar.
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Post by ik6gpy »

Here it is: http://www.effectsdatabase.com/model/cosmosound/cse3
It was made by the old italian Cosmosound factory. It's exactly the same pedal of yours.

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Post by Paul Marossy »

ik6gpy wrote:Here it is: http://www.effectsdatabase.com/model/cosmosound/cse3
It was made by the old italian Cosmosound factory. It's exactly the same pedal of yours.
Looks like a dead ringer!
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Post by Rocket Roll »

Yep, that's the one!

Do you think it's possible for it to be a... what's the word... a forgery? "Vintage fogery", but still a forgery? Not an official VOX product? Something that was made with a VOX logo in order to boost the sales?

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Post by DiscoFreq »

I have 2 of these: 1 Vox, 1 Cosmosound :D
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Post by noelyoung »

I have a Silversound SE-20, and it's the same pedal, like this Vox and Cosmosound. Can someone tell me the taper of the original pot? I have to replace because it's scratchy. Thanks

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Post by Rocket Roll »

I have another one in front of me. Since they're so few and far between in our parts, a few more photos, including the PCB traces:
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Post by Rocket Roll »

...more elements...
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Post by Rocket Roll »

...and PCB.

I like this fuzz. For me, the best vintage Si Fuzz Face that I have ever tried. Cleans very well (extremely well for a Si FF), has a great wall of thick but very musical fuzz, "sharpens" the guitar nicely when you roll off the pickup volume.

As far as I can tell, the fuzz part uses two MPS5172 transistors, and the wah uses two BC209C transistors. It stands to reason, since MPS5172's should have lower hFE (from 150 upwards). However, not a lot of silicone Fuzz Faces use them.

The only problem? A decent amount of hiss. Wouldn't know if that has something to do with the layout, this particular unit or a part that has "drifted".
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Post by Rocket Roll »

So, here we have the fuzz part of the circuit (minus Volume and Fuzz pots and 10uF capacitor mounted on the Fuzz pot), and the schematic. I have modified the Cosmosound Distortion Whau Repeat schematic that you can find on the Effectsdatabase (http://files.effectsdatabase.com/docs/s ... ematic.gif). The values are mostly OK, but the author of that one had a different unit or made a mistake: R2 is 27K and R5 is 2K7 in the VOX, as all of the pictures clearly show.

I cannot check the potentiometers' value, but I expect no problems there.

So, not your typical silicone Fuzz Face, but a variant.
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Post by ljn »

Wow! That's an awesome looking pedal. As for the scratchy pot, have you tried some contact cleaner?
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