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"J20" (K-20X Preamp, only OD and with 071 instead of 072)

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joecool85:
Does this look like it would work?  I would like to take just the OD circuit from the Dean Markley K-20X (as seen here: http://deanmarkley.com/Info/LegacyAmps/Schematics/D1515.pdf ).  Will this work?

J M Fahey:
Yes it will. It needs +/-15V (down to +/-9V).
It's practically an MXR Distortion+ with a slight buzz filtering (which you may easily add).
I'd just build the Dist+, which also has a board and layout already solved , and has higher input impedance (this one is low and will load your pickup somewhat)
Or you can build a simplified Turbo-RAT, the one with LEDs.
Are you going to drive a TDA something with this preamp?

joecool85:

--- Quote from: J M Fahey on December 03, 2010, 12:40:49 AM ---Yes it will. It needs +/-15V (down to +/-9V).
It's practically an MXR Distortion+ with a slight buzz filtering (which you may easily add).
I'd just build the Dist+, which also has a board and layout already solved , and has higher input impedance (this one is low and will load your pickup somewhat)
Or you can build a simplified Turbo-RAT, the one with LEDs.
Are you going to drive a TDA something with this preamp?

--- End quote ---

I was thinking I'd use it more like a pedal than a preamp, run it in front of an amplifier.

On the original dean markley version I'm not sure how the preamp works.  I was thinking that the TL072 hook ups on the left of the schematic were for "clean" and the ones on the right for overdrive.  But it looks like it always runs through the left portion and maybe for clean it skips the right portion?  Am I right in my thinking?

I really like the Dean's OD circuit.  Maybe I will take a look at the MXR Distortion Plus and make some tweaks to make it "more dean".

J M Fahey:
Then use the MXR Dist+ as a base pedal, leave the "gain", bias, etc original, specially because it's already meant to be used with single +9Volts, but modify the clipping and post clipping "tuning" at will.
Dean Markleys sound *good*, even the cheapes ones, the guy obviously has ears.
I specially like the simplest one, the K15.
Driving a 10"/12" speaker and powered with a TDA2050 with +/-22 or +/-25V  it becomes loud and club capable in a very simple package.

joecool85:

--- Quote from: J M Fahey on December 03, 2010, 10:54:34 AM ---Then use the MXR Dist+ as a base pedal, leave the "gain", bias, etc original, specially because it's already meant to be used with single +9Volts, but modify the clipping and post clipping "tuning" at will.
Dean Markleys sound *good*, even the cheapes ones, the guy obviously has ears.
I specially like the simplest one, the K15.
Driving a 10"/12" speaker and powered with a TDA2050 with +/-22 or +/-25V  it becomes loud and club capable in a very simple package.

--- End quote ---

Sounds like a plan.  Now, post clipping I assume you're referring to the LEDs etc at the end of the circuit, correct?  As for "regular" clipping, are you referring to the gain?  If I'm correct that is the resistor between the inverted input and the output.

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