Blues Driver

by gaussmarkov

Stobiepole and I are putting this out for comment. This is a Boss BD-2 clone in two versions. Both versions are verified. The schematic source was

We used the J201 for the N-channel JFETs and 2N3904 and 2N3906 for the bipolar BJTs and that worked fine.  Neither are original in the Boss box.

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20 Responses to “Blues Driver”

  1. Fullback said:

    what are the code of the transistor.

    Posted 17.08.2007 at 2:01 am

  2. gaussmarkov said:

    I was hoping that some people would try various transistors and report what they found on Aron’s forum. This is why the transistors are listed as types.

    We used J201 for n-jfet (Q1, Q2, Q4, and Q5), 2N3906 for pnp-bjt (Q3 and Q6), and 2N3904 for npn-bjt (Q7). These work very well.

    I hope this is the answer to your question.

    Posted 17.08.2007 at 7:03 am

  3. ROCKEY said:

    I wanna to know where can we find the transistor refrence
    please guid me to find the equivalent that can we use insted of above.
    Thank you.

    Posted 20.08.2007 at 2:00 pm

  4. gaussmarkov said:

    Hi Rockey,

    That’s a good question for a DIY forum like Aron’s at

    All the best!

    Posted 20.08.2007 at 2:57 pm

  5. Chris Daudet said:


    I was wondering if there are any sounding or performance differences between the circuit with the Opamp Vr supply and the one without it.


    Posted 16.09.2007 at 1:45 am

  6. gaussmarkov said:

    Hi Chris,

    I have played through both and found no discernible difference. But there are probably times when it matters. I didn’t do a really careful study. 😉

    FWIW, I have redesigned this circuit with an input buffer (like the original) that raises the input impedance from approximately 200K up to around 700K. That does make a difference for my setup. I will post the modified layout soon.

    But if you have a low impedance source (like another stompbox), then it won’t matter much.

    All the best, gm

    Posted 16.09.2007 at 10:42 am

  7. ray said:

    hey gm, why not just drop the buffers and make a stripped down version and drop out the one diode for a bit less fizz?

    Posted 12.11.2007 at 4:01 pm

  8. gaussmarkov said:

    Hi ray,

    That’s a fine idea. And it’s one of the things that I was hoping people would do: take the circuit and experiment. Your suggestion for less (and asymetrical) clipping is just the thing.

    I hope you will try it and report back what you think. Maybe socket the diodes and try various setups?

    Cheers, gm

    Posted 12.11.2007 at 5:02 pm

  9. sebastian said:

    hi, i’m trying to “debug” my circuit, and i really need some help, i have already check the voltage of all transistors (jfet 2n5457; 2n3904; and 2n3906) and it looks good, but the volume in the out is lower than the input, even with gain and level at max.

    thank and sorry for my english (im from argentina)

    Posted 12.11.2007 at 8:33 pm

  10. gaussmarkov said:

    Hi sebastion,

    I am happy to help with debugging. The best place I know for doing that is on Aron’s forum. Send me a personal message there and I (and others) will try to help. Be sure to follow the on-line instructions about the information that you should provide (e.g., voltage readings).

    Cheers, gm

    Posted 13.11.2007 at 8:45 am

  11. cris said:

    you have a great review of op amps. Do you know where I can by an adopter to go from a straight pin configuration to a typical 4×4? Mone Allum,coom has them for 6.49 USD each and I want to buy in bulk. This could help you also.

    Posted 10.05.2008 at 4:41 pm

  12. njkmonty said:

    ive heard that the Keeley modded version of this is great. Ive built by self a ts808 clone with his mods. Is it worth doing this pedal if i already have a tubescreamer, and if so does anyone know the keeley mods?
    ps which is the recommende version?

    Posted 04.06.2009 at 6:35 am

  13. Fernando (Argentina) said:

    Just build it, it works fine, and i didn´t have trouble with that fx pedal. I used J201 fets and 2n3906 and 2n3904 Bipolar transistors. Thanks for that beautiful project!

    Posted 22.09.2009 at 10:34 pm

  14. Pointer Men’s Basketball said:

    Maybe you should edit the page name gaussmarkov: diy fx » Blues Driver to something more catching for your content you make. I enjoyed the post withal.

    Posted 29.10.2010 at 7:11 pm

  15. mikro said:

    thanks for great documentation!
    could it be possible to use a SPST switch+4013 dual flip-flop+4066 quad bilateral switch serving as a truebypass/effect switch? this way a LED could be toggled as well showing bypass/no bypass…
    what do you think?

    Posted 01.12.2011 at 8:16 am

  16. Walter said:

    is the dual gain potentiometer log or lin?

    Thank you!

    Posted 09.09.2012 at 9:54 am

  17. gm said:

    Hi Walter,

    It’s log (or audio). The A after 250K on the schematic refers to an audio taper.

    All the best!

    Posted 12.09.2012 at 7:34 am

  18. darpi said:

    Hi GM
    Did you measured voltages such as voltage before clipping stage?

    Posted 08.12.2013 at 2:07 pm

  19. mikro said:


    I made a mod as found on web anywhere: with a switch I can change one pair of clipping diodes to a pair of 3mm green LEDs. Result:
    no change in its character at all, swithced or not.
    LEDs should glow with signal don’t they? They just don’t do. polarity checked, LEDs checked. what’s wrong?


    Posted 24.01.2014 at 4:37 pm

  20. Hong said:

    Hello guya,

    I need some help with my stomp box,
    I built the no verf version of the BD-2,
    I use 1n4148 instead of 1n914 for the diodes, and use 4.7n capacitor instead of 5.6n as I can’t found these parts. The circuit can make some sound, however, it becomes a clear booster, no drive with Max Gain. Tone and Volume works. Anyone can offer some help.


    Posted 22.09.2014 at 7:35 pm