EHX POG - Expression pedal?

[azrael]

In an issue of GuitarWorld, they showed a fairly recent picture (Last year or two) of Joe Perry's pedalboard.

On it, he had numerous pedals, a couple of fuzzes and delays - and an EHX POG. Not really crazy on its own, but in the blurb about the pedal, he mentioned that the POG had a "secret modification" done to it. And sure enough, there was an expression pedal plugged into the POG, into a jack that had been modified in.
Do I know that it was an used expression pedal, like in the HOG? No, not really.

But it was definitely hooked up to it.
I don't recall which issue of GW it was, though...

But anyone have any ideas on this?

Or how well would a blend pedal (Like several of the DIY projects here) work with a POG?

I ask because I would love to have the HOG's expression pedal ability, but man, the HOG is freakin' expensive!!

[drewl]

I fixed one a few months ago and was impressed by the sound and tracking.
My guess would be a blend control like you said.
No bending over to adjust the level just add as much as you want with a pedal.
Sounds like a great idea.

[azrael]

Yeah, something like this:
http://aronnelson.com/gallery/main.php/v/BarcodeVeroLayouts/album120/MiniBlenderPCBLayout.gif.html
or this
http://aronnelson.com/gallery/main.php/v/ANY-machines/album47/

[sockeye]

Having a pedal do the work of the LP filter slider on a POG would sound really cool -- like a wah but with octave effects.

I had a POG for awhile and thought about doing just that but ended up selling it -- I mostly just wanted octave down and I'm going to build an Anderton Rocktave which I'm hoping will give me a less synthy-sounding octave down.

[Processaurus]

Hi, I bet it is an expression pedal for the LP filter, I had one for a minute and sweeping the lowpass filter is a great effect.  Easy to implement if you're confident hacking a $250 pedal.  The Pog's pots are just control voltages being sent to a microprocessor, so no audio goes through them.

you need a stereo jack with normaled connections, so that the pedal will work right without an expression pedal plugged in.  That way the slide pot on the pedal's CV to the processor gets routed through the jack and back to the processor when nothing's plugged in.

You'd just cut the trace connecting the wiper of the lp filter pot to the processor, send that to the expression pedal's stereo jack's ring (put a 220 ohm resistor in series so the pedals power supply won't be destroyed when someone plugs a mono cable in), then the tip to where the wiper was originally going on the Pog's PCB.  Ground to the sleeve (naturally).  The trick is to connect the normally closed tip connection on the jack to the ring, so that when nothing is plugged in, it's like the expression pedal is all the way toe down.


to be super tricky you could eliminate the 220 ohm idiot resistor from the path through the jack when nothing is plugged in, by hooking the slide pot's wiper directly to the normally closed connection on the ring rather than the normal ring connection, and put the 220 ohm resistor between those two connections.  We still connect the ring to the normally closed tip connection.That way when nothing is plugged in, the resistor is being shorted out by the jack, but when something is plugged in, boom, it's in the circuit.  The small advantage of this is that you avoid the small voltage drop of the 220 resistor with no exp. pedal plugged in, allowing you to get every last bit of the filter (though it probably won't be that big of a difference.

Hear is a schematic and write up for like minded modders of how I did this with a different digital pedal, same idea though

http://www.diystompboxes.com/smfforum/index.php?topic=45777.0

[azrael]

Hey, just in case anyone wanted to know, I found a site detailing this mod:
http://www.ehx.com/forums/viewthread/319/P15/

the EHX site itself!