Digitech - Screamin Blues  [schematic]

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

regards, kusi
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DigiTech_ScreaminBlues.JPG

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bajaman
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Post by bajaman »

Thanks Kusi and Happy New Year to you :applause:
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WhiteKeyHole
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Post by WhiteKeyHole »

Nice. Blues Driver clone.

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HENK
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Post by HENK »

DANKESCHÖN!

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nooneknows
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Post by nooneknows »

thank you Kusi!

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Dirk_Hendrik
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Post by Dirk_Hendrik »

Thanks!
Sorry. Plain out of planes.

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nooneknows
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Post by nooneknows »

from the schematics it seems there's a sort of marshall/fender like tonestack after Q14 with fixed value...
since this pedal lacks some mids I think this could be an interesting place for some mod, I have to think about it.

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Dirk_Hendrik
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Post by Dirk_Hendrik »

Same thing happens after Q18. In the BD2 schem it's drawn even clearer. It's the first thing that struck me when I saw the BD2 schem for the first time.

I happen to like these arrangements. When one looks up the ibanez FZ7 there's a similar case where clearly an EQ was incorporated, set to taste, and then made fixed. It's a simple but very quick and effective approach to tuning soundwise.
Sorry. Plain out of planes.

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george giblet
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Post by george giblet »

Thanks!

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Silent Fly
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Post by Silent Fly »

Thanks Kusi!

Do you have the Bad Monkey schematics as well by any chance? :wink:
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kusi
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Post by kusi »

you`re welcome guy`s! ;) sorry, no monkey-schem...

regards, kusi

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Post by TubeDude22 »

Is something wrong with the link? I can't download or see the attachment.

TD

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Post by Dirk_Hendrik »

Works over here :scratch:
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Post by TubeDude22 »

Weird. It won't work for me with FireFox 3.0.5 but works with IE7. I'll check my settings.

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nooneknows
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Post by nooneknows »

Hi, I've just made a simulation of the 'virtual' tone stack after Q18 with Duncan Tone stack Simulator, the result is what I'm attaching over here, do you believe it's correct? If so it could be an interesting point to mod...
thank you
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tscscreaminblues.jpg

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pjgmusic
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Post by pjgmusic »

kusi wrote:regards, kusi
Any suggestions for an easy solution such as cap swap to tame that ridiculous high end on this pedal and maybe increase lows? Right now, the pedal is pretty responsive and dynamic, better than I expected. But the bottom drops even with the low knob all the way up and the highs are piercing even with the treble knob all the way down. Ironically, the mids are not bad which is usually the prob with most of the TS variants or so I've heard. :wink:

I'm very new to this, but I managed to swap out the op amp, some capacitors and diodes in my DOD 250 to make it more like a gray version, so I can handle something basic like swapping one component for another if that is possible.

The best way for me is to have a pic of the PCB with notes as to which component to swap as in this mod for the Bad Monkey: http://profile.ultimate-guitar.com/Iban ... log/53932/

If there is a way to mod the SB the same way as this person did with the BM, except reduce highs rather than mids, that would be awesome. Otherwise, I'll ditch this one, get a BM and perform that mod.

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fransvanhelvoort
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Post by fransvanhelvoort »

Sorry but this is not! the screamin Blues schematic! This is a Boss bd2 schematic. See the tone stack. Only one
toneknob!

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Jan1966
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Post by Jan1966 »

fransvanhelvoort wrote:Sorry but this is not! the screamin Blues schematic! This is a Boss bd2 schematic. See the tone stack. Only one
toneknob!
Calm down. Necro thread.

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Post by fransvanhelvoort »

Alltough this is an old thread here some comments. Pjgmusic wanted to hear a solution for the idiot high fizzle in this stompbox. According to the schematic the most simple way is a cap parallel to C10. I placed a cap of 10nF there and the result was not a single effect. 10nF in that place must kill all the high frequenties and the sound had to be overbassy. So my conclusion on that was the schematic is not the correct one. I tried some other places with the 10 nF again what in the schematic should be very effect full. Nothing. So the last attempt was to put the cap from the middle lug of the high pot to earth. Hoppa that works. I put there a cap of 470pF and the ear piercing high freq. are gone. Perfect for my Strat and Fender solidstate amp. Very dumble like I think.

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