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Wednesday, March 23, 2016

Mad Professor Stone Grey Distortion

Here's the Stone Grey Distortion from Mad Professor. It's reminiscent of the Distortion +/OD250 circuit, but with a hex inverter stuck after the opamp. It also uses 2 JFETs in the feedback loop of the opamp for clipping. Original op amp is the TL051, but other single opamps can be used (Tl061, 71, etc). Should be an easy fit in a 1590B. Mind the jumper under the CB4069UBE.



16 comments:

  1. Built this today with a TL071 and 2N3819 and it sounds great. I tired my Jazzmaster on it and my SG. I doubt I have to say it but this thing loves the burst buckers. The SG got some great crunch sounds and with drop D tuning it was instant Soundgarden sound. Outshined!

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    1. Hey. I have also build it, but have some issues with the signal. It is a little bit noisy and I think that the distortion knob is doing nothing... Any ideas?

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  2. cody, have you tried using tl072?

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    1. The TL072 won't work in this as it's a dual op amp. This effect uses a single op amp. Other options would include TL061, NE5534, or LF351. A LM741 would also work in a pinch, but probably wouldn't sound as good.

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  3. suhr riot pcb please brother!!!

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  4. do you have a pdf file of this pedal? is it 1590b size? thanks

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    1. It's in the Transfer Image Library tab at the top of the page. Yes, it'll fit in a 1590B.

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  5. any substitute components for 2N3819??

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  6. I was looking at the schematic to this one ( this http://3.bp.blogspot.com/-P2RCqMsl__A/TxLM0MEtCJI/AAAAAAAAAio/rVtTwB3v83g/s1600/Mad+Prof+stone+grey+schem.gif ), and i found an error in your layout. The 4.7uF capacitor should connect to the 10k resistor by the negative side and to the CD4069 by the positive side.

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  7. Awsome Awsome Distortion!!!
    Built it on Perf, sounds great
    Thank you very much

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  8. This comment has been removed by the author.

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  9. Is there any other JFET that can be used in lieu of 2N3819?
    Thanks in advance, and Happy New Year!

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    1. They're being used as clipping diodes, so you can use diodes or even a pair of MOSFETs like 2N7000 or BS170s

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  10. Built this yesterday with 2N7000 and TL061 and it sounds wicked.

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  11. Anyother pots that can be used intead of A1M ???

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