WEM, Watkins, Rush - Pepbox, Rush Pep Box  [schematic]

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

And here's the silicon version:

Image

Note that the level pot's value is not confirmed. Later incarnations of the Pepbox (or Rush Pep Box) have a 50k log level pot, but no 56k resistor in parallel.
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Rush Pep Box Germanium WEM schematic
Rush Pep Box Germanium WEM schematic
Pep Rush Box Wem schematic silicon
Pep Rush Box Wem schematic silicon

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mictester
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Post by mictester »

Electric Warrior wrote:Whoops, here it is with really correct transistor symbols (PNP):

germaniumpepbox.png

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"Why is it humming?" "Because it doesn't know the words!"

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Electric Warrior
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Post by Electric Warrior »

Big OOOPS! Some friendly builder just pointed out to me that I had the wiring of the Effect pot wrong in both schematics and I forgot to remove the 820k from the silicon schematic :blackeye
Hope I have everything right now.

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Electric Warrior
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Post by Electric Warrior »

mictester wrote:
Electric Warrior wrote:Whoops, here it is with really correct transistor symbols (PNP):
You're too fast. It was wrong again for a couple of minutes :blackeye

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Post by sinner »

Here's old school Ge vero layout

The one on my website was wrong

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Post by drewl »

So which version do you guys think sounds the best?

I was thinking about building that Ge version above.

Thanks.

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Post by bhill »

Just looking at both your schematics above on this page, my first thought was that the paralleled 56k and the 500k output pot could be replaced with a 50k log pot. You seeing that in a later version just confirms that.

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Electric Warrior
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Post by Electric Warrior »

They copied that from the FZ-1.

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Post by sinner »

Request from my favorite beta tester :thumbsup

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Post by beedotman »

Nice and clean!

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Post by agoldoor »

sinner wrote:Request from my favorite beta tester :thumbsup
Just a heads up, here are my impressions from building this layout that I was emailing to sinner, and thought I'd CC it here.. Consider it verified except for my comments about the DC jack below:

So I've played a lot with the silicon pep box layout, and I wanted to give you what I found out.

First off, it's DEFINITELY a 100K trimpot there. I tried a 25k, a 10k and a 50k before finding the 100k. The 100k has a LOT of different sweet spots in it's sweep, it almost is cool enough that it might dictate being used as a SECOND tone knob. But I didn't do that, I just went with a 100k trimpot set to my liking.

Also, I noticed that on your layout, I don't know if it's just a different way of wiring or whatnot, but it looks to me like you laid out the DC jack and it's grounds like one would in a PNP circuit rather than NPN. So I didn't follow the layout in that part, also I didn't use an LED, so I left that out.

But otherwise, it worked great. Thanks again for your work! You're the man!

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Post by alexradium »

phibes wrote:To keep discussion rollin, here's how I see the studio 2. I'm not sure on the value of the cap running between collectors but it has to be higher than 5pf. My guess is 47pf-100pf. The 5 might of designated 50.
about JMI studio 2,schematic is ok in general,the one i have for repair has a 3300p in parallel with the 1M res,a 33p cap on Q2,10k trimmer in place of the fixed resistor,250kA level pot,1kB effect pot,47uF on +9V.

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Post by capricorn_1 »

The silicon version I do (big red slab version) has no 56k resistor, 50k level pot, 500k trimpot.
I actually have the PCBs on Ebay if you do a search! The PCB has the option of adding an output capacitor 'tone' control which is quite useful.

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Post by alexradium »

The original Pep box is quite different from the JMI,which in fact is a fuzz face,i don't know why they advertise its an exact replica,maybe there is a lot of people ready to spend 300 pounds and don't care what's inside....

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Post by capricorn_1 »

also forgot to say the one I traced had 12.5uf electrolytics, I use 12uf in my clone, I guess 10uf could be used as well.

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Post by Masuto »

Im going to plunge myself in this.. Its great to see how you managed to tackle it from legend and bay shots to a viable bunch of layouts! I am intrigued by this mytical charachter, Pepe Rush (Pepe is a spanish name btw, not italian), who apparently was an italian electronics engineer based in the London West End and who designed also amps.. Any more about him?

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Post by petey twofinger »

he was an amazing plumber .

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Post by Masuto »

petey twofinger wrote:he was an amazing plumber .
Yes, and he could do double jumps.

Wow razor sharp humor here! ;)

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Post by Rocket Roll »

I've tried to build the PNP Germanium version using a PCB from here: https://effectslayouts.blogspot.com/2015 ... p-box.html

However, even with multiple transistor changes (70-90 hFE works best), the unit sounds nice (for a raspy, bass-heavy fuzz), but pops obnoxiously when (dis)engaged and loses a lot of volume in front of VOX AC30's Top Boost channel. Also, you can hear in British Pedal Company's video that the volume pot riding functions normally on their reissue. With this layout, if you try to turn the volume down, the sound cuts in and out, which shows (at least) that British Pedal Company's (correct?) reissue and this layout are two different beasts.

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Post by bloom »

Hullo all, long time reader first time poster... :lol:

Has anyone around these parts built the Pep Box from this layout? https://tagboardeffects.blogspot.com/201 ... epbox.html

Only I've just had a pop at it and it just doesn't seem to want to bias up - the only changes I've made are to drop the electrolytics to 12uF as per the Ghost Effects/original version - but no matter what I do I get super low output and absurdly gated fuzz (almost anything below *smashing* the strings doesn't make any noise!) Any ideas what it could be?

(...and after all that I've just (carelessly) fried one of the transistors while fiddling about with it so time to call it a night :lol: )

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