Sunday, 2 May 2021

Mad Professor Blueberry Bass Overdrive

 This is basically a higher gain version of BJFE Blueberry Bass OD since it has an added pre amp stage (Q1). Note that originals had the now obsolete BF244A transistors with DGS pinouts. I changed the pinouts for more accesible transistors. 2N5457s should bias up fine and sound good.





14 comments:

  1. This comment has been removed by the author.

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  2. I can still buy BF244As, unlike the 2N5457s,

    so, I'd like to modify this layout for DGS pinout, if you were so kind as to share the DIYLC file...

    of course, if you could make that version, it would only be better... :)

    But anyway, the reason why I'm asking is because I really like this layout, 19 cols wide !!! so cool...
    much better than the "original" BBOD with red LEDs and without the preamplification stage, being 22 cols in width :)

    I mean, this should be "it" :)
    but I'd love to build the BF244A version...

    this is day 2 for be browsing this site...
    congrats!

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    1. I'll try to tweak the layout for DGS pinouts but it will take few days until I'm back home.

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  3. No sound. Looks to be missing 47pf cap from 1M resistor to Q1 drain?

    Comparing to this:
    http://tagboardeffects.blogspot.com/2012/06/mad-professor-blueberry.html


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    1. Hi there.
      Yes I missed the 47pF cap. It is now added. I also spotted another small mistake. The 14,7k resistor at the top left corner had it top leg in the wrong spot. It needs to be moved down one row (it is now a 3 row resitor...). The layout is updated reflecting both of these changes.

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  4. Hi I built this layout and it works great. It sounds as good as the original one. I tried UA741 and TL071 and they work well too. Thanks.

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  5. Any way we could get a layout for BF244A transistors?

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  6. It looks like the original jfet specified is a DGS pin out, so in lieu of a total redraw, you would just need to move the jumper that connects to "G" down one row, and move the legs of the 2k6 resistor and the 220nF cap up one row to connect to the "S" - essentially swapping their positions. And also make sure that you have the jfet facing to that is goes S-G-D from top to bottom. Not the most elegant solution but it should work. Since it looks like those components are the only ones that connect to those pins of the transistor. Good luck!

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    1. Based on the datasheet I found online, it looks like the shape of the BF244A means that you would have it facing the same way that the jfet is on this layout. Of course, having a semiconductor tester for this stuff never hurts just to make sure you've got it right. https://www.digikey.com/en/products/detail/peak-electronic-design-limited/DCA55/9687218

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  7. or just twist the legs(use sockets)

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    1. I just thought that it might make the layout a little smaller so I could get it in a 1590b.

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    2. Dunno if I can speak to Anders being THE best at drawing layouts, but when it comes to economizing space and getting all the components in as tight as they can be, I don't know of anyone who does it better. Unfortunately, it looks like this one can't really be shrunk down too much smaller.

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  8. true , even in perf it would not be much smaller https://effectslayouts.blogspot.com/2015/02/bearfoot-fx-blueberry-bass-overdrive.html

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