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Vox V847 Wah Pedal


NY3

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Has anyone reading this purchased the latest model Vox V847 Wah pedal and performed mods to the circuit? I just bought one to customize and was surprised when I took the back off to find a more complex circuit than the ones I've seen published on the web for earlier model wah pedals. This model is the one Vox claim is "built to the exact specifications of the original VOX wah-wah pedal". If anyone can tell me about the technical aspects of this model I'd be grateful. My intent is to tweak some of the components to get a sound I like, but at the moment I'm having difficulty relating the rather high-tech looking dual-layer physical circuit board to the simple circuit schematics I've seen published on the web.

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I've started a mod page on my site for the V847-A (click the "power list" link in my sig, and you'll find it in the DIY section). So far it's mostly about modifying to true bypass, but eventually I'll have other mods up there as well.

 

Don't expect it to be anywhere near as mod-able as the old V847 - many of the components are the tiny surface-mounted variety, and messing with those should only be done by people with serious soldering skills.

 

/Andreas

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I've started a mod page on my site for the V847-A (click the "power list" link in my sig, and you'll find it in the DIY section). So far it's mostly about modifying to true bypass, but eventually I'll have other mods up there as well.


Don't expect it to be anywhere near as mod-able as the old V847 - many of the components are the tiny surface-mounted variety, and messing with those should only be done by people with serious soldering skills.


/Andreas

 

 

What about the 848 (Clyde McCoy)? Do they have surface-mount stuff, too, or is it just the 847A? I'll probably wind up with one of those today, or soon, anyway.

 

The old 847 is really easy to mod. I thought the 847A was the same thing, but with an added power jack. Go figure.

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The V848 should be easier to work with. I haven't been in one of those myself, and have seen pics of two different circuit board layouts. One seemed quite closely related to the GCB-95 (complete with input buffer stage, multi-connector and all) and another that looked more like a hand-wired older Crybaby or Vox. Both had full-size components, and modding them would therefore be a lot more viable.

 

/Andreas

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I've started a mod page on my site for the V847-A (click the "power list" link in my sig, and you'll find it in the DIY section). So far it's mostly about modifying to true bypass, but eventually I'll have other mods up there as well.

/Andreas

 

 

Great work, Andreas. I look forward to you posting more details of the mods. The mod I'm most interested in (apart from true bypass which you have described) is the lowering the sweep range. You say on your page this is likely to be doable because the 0.01uF "sweep cap" is still a full-size component. I'm guessing that in the photo on your page that's the green cap closest to the inductor (the only 0.01uF full-size capacitor?).

 

BTW I'm game to solder/desolder surface-mounted components if necessary for the vocal and midrange mods.

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Yah the new ones are exact spec...which is cool....just think...thats what jimi use lol...but in all seriousnous:

 

I bought a v847 with intent to mod it to tb...but i found that i really liked the way it effected my tone in bypass...like....i play a fender...so it reallly makes it even out as far as harsh trebles go...you still get harsh trebles...which i love...but you can feel like..the weight of the bypass in the osund

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Yah the new ones are exact spec...which is cool....just think...thats what jimi use lol...but in all seriousnous:


I bought a v847 with intent to mod it to tb...but i found that i really liked the way it effected my tone in bypass...like....i play a fender...so it reallly makes it even out as far as harsh trebles go...you still get harsh trebles...which i love...but you can feel like..the weight of the bypass in the osund

Well, as I always say: if it works for you, it works. Don't mess with it - count yourself lucky, and rock on. :thu:

 

/Andreas

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Actually, there should be two 0.01uF caps in there. The most likely one is the one you mention, closest to the inductor. But there's also a 0.01uF input cap after the 68K input resistor (keep in mind that this is the "input" to the actual wah circuit - after the buffer stage, thus). Again, the first one I'd try is the one closest to the inductor, as the other one seems to sit just right to be the input cap (quite close to the buffer transistor).


Well, desoldering is one thing, if the components can be scrapped afterwards, and if no new components are to go in those positions. Soldering in a new resistor or capacitor to those tiny contact points is a
very
different matter... So taking the buffer stage out will probably be doable for most people, but I'd be hesitant to write up an info page detailing mods that require soldering skills most people (I'm not even sure about myself there) don't have. I already get enough e-mails from people who managed to botch their pedals as it is...
:eek:

Well, as I always say: if it works for you, it works. Don't mess with it - count yourself lucky, and rock on.
:thu:

/Andreas

 

 

I think I've used mods from your page quite a bit...I just kind of use them as a guide to experiment with...I rarely use the exact suggested values, at the end of the day, but it's some good {censored} to learn by.

 

Either way, anybody that could botch a pedal trying them has no business boiling water.

 

SMT stuff is a different beast, but the old ones?:freak:

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