DOD - 250 Overdrive Preamp [model comparision]  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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roseblood11
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Post by roseblood11 »

I´ve seen different photos of grey versions on the net that had a 10µF electrolytic coupling cap after the IC... (C5?)

But who really cares?

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drbob1
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Post by drbob1 »

I have what looks like a late 81 model (with the feedback cap) that's using a TL081CP op amp. There's another on Ebay right now with the same op amp. The spec sheet looks pretty similar to the 741 to my eyes but I know very little about these. Is there going to be a big difference in sound compared to the 741? Also, I'm assuming the feedback cap is acting like a high pass filter in the feedback loop reducing high end gain? What's interesting is that my 75 script logo D+ has WAY more bass than the DOD...

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sinner
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Post by sinner »

Grey coming first. More, in a bit

I think you can fit it into "A" enclosure, but "B" is what I was thinking to use, so this is what it shows

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beedotman
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Post by beedotman »

Good shit! :thumbsup :blackeye

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sinner
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Post by sinner »

Actually, I'm getting confused with 250's

There is at least 5 different versions, and different sources give different info. When I think I have the correct schematic another one pops up and screw me in my brain... Fucking DOD bastards, why didn't they just stay with one schemo?

Also big middle finger up to ProCo

It's the same story with ProCo Rats - this is the reason why Rat is still absent on T.org

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Seiche
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Post by Seiche »

what's different? Values? Just post all the versions :mrgreen:

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sinner
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Post by sinner »

As soon as I find some logical order, honey

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LooseCannon
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Post by LooseCannon »

Hey guys,

I've seen different layouts with a different order of the .047uf cap and 1M resistor, and the 4.7uf cap and the 10k resistor, on some of them the cap is first and on some the resistor is first.

Does it make a difference if the cap is before the resistor and vice versa?

Thanks

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LooseCannon
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Post by LooseCannon »

Correction- the .047uf cap and 4.7k resistor. How do you edit posts? :)

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snmavronis
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Post by snmavronis »

I don't think the order makes a difference. It's more of a design and layout preference but I could be wrong. Here is an official company schematic for the DOD Overdrive Preamp 250. See my attachment upload. This appears to be post grey era but has all the elements of both versions. Thanks to Tom Cram of DigiTech for graciously providing this to me and giving permission to post it. I always find it interesting to see how official effects pedal company schematics are drawn up.
DOD Overdrive Preamp 250 Official Schematic
DOD Overdrive Preamp 250 Official Schematic
Guitar > Boss NS2 Noise Suppressor > NS2 Send > MXR Custom Comp > Neo-Classic 741 Overdrive > NS2 Return/Output > VHT Special 6 Ultra Amp Input > Amp Send > MXR Carbon Copy Analog Delay > Boss RC3 Loop Station > Amp Return

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LooseCannon
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Post by LooseCannon »

Thanks snmavronis!

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_Solderman_
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