Dean Markley - Overlord 1 Tube Drive - power transformer  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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Duckman
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Post by Duckman »

Well, an old unit is in the bench right now, so I traced (the switch just give up)
Is fully checked, but some values doesn't match with that old drawing we all know :shock: :D
Take a look and if in doubt, I can make some clarifying pics.
Rgds
Pato

Corrected schematic: https://www.freestompboxes.org/viewtopic ... 01#p276681

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Duckman
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Post by Duckman »

I spotted a little mistake today: that point -V2 in between R23 and the (-) pin of C18 IT'S WRONG. Must be -V1. :slap:

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Duckman
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Post by Duckman »

Today repairing another unit, spotted another minor error in that schemo: R14 = 24k, not 47k... sorry :slap:

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Duckman
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Post by Duckman »

Corrected schemo
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OVERLORD (corrected).bmp
OVERLORD (corrected).bmp (499.36 KiB) Viewed 2031 times

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ppluis0
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Post by ppluis0 »

Duckman wrote:Today repairing another unit...:
Hola Pato,

If you still have the unit on your bench, try to swap the tube for a 12AU7 (ECC82) and tell us what you hear after do that.

There are several reports from tube driver users indicating this stompbox suits better those lower gain tubes.

Greetings from Argentina !!!
José

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Duckman
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Post by Duckman »

(José, maestrazo! Brava la cosa por ahí, no? Animo que han salido de peores!! :hug:)

In fact, this particular unit has a 12AU7 but sadly, I don´t have a 12AX7 to make a personal test. Any way, the owner said that a pleasant change happened, kinda "clean the thing out", but... and correct me please if I'm wrong: how many gain is the tube providing in that particular configuration? Tubes are not my expertise, so it will be interesting to know. I'm planning to do some test bypassing the tube section and have a clue of what is the opamp really giving, in terms of sound. The eq section is awful, to say the least, so I'll run some changes in a breadboard to bypass the original without mayor changes and see what can be improved.
We'll see...

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