This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, February 29, 2016

Xotic BB Preamp

Got a request for the BB Preamp, but not the current version. The earlier version uses a dual-gang pot for the Level control and apparently more bass response. Like many of Xotic's offerings the BB owes a lot to the classic Tube Screamer. Schematic can be found here.



If you'd prefer to build the newer version without the dual-gang Level pot, you can use the same board. Just remove the 1µ capacitor and the 1k and 47k resistors in the bottom right side of the board and replace with a jumper like this:

30 comments:

  1. In the newer version, where does level 1/2 go?

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    1. You won't use the Level A connections. In the original version the Level pot was dual gang. The newer version just uses a regular single gang pot, which are the same as the Level B connections in the layout (top of the board).

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    3. Ok pal I get it.
      I got a BB preamp made by a friend using different schematic, but it is now broken. I'll rebuild it later using its components base on your layout after finishing my demo tape fuzz. Thanks man
      Awe

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  2. oh David, you always beat me
    just made layout for friend, Andy Timmons die hard fans in perf with onboard pots wannabe
    but worse, cause have 6 jumper! :( hehe

    @berkicau = maybe this scheme help you build two version
    https://1.bp.blogspot.com/-JNsyPpyyt7U/VtRuHepg5II/AAAAAAAAAOA/Ux3Fre0_7uo/s1600/bbprea.png
    put inside big box to small box. or thrash the big box! hehe

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    1. On board pots are always a good thing though. 6 jumpers with on board pots is ok in my book. If you don't mind sharing, send it over and maybe I can make a PCB version too and post our combined work if you're cool with that.

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    2. I have a BB +. I recently played the BB comp and LOVED the setting with no compression. Can anyone tell me how to mod my Plus to have no compression instead of "hard/soft". Ideal world the switch would be "off/soft." Any tips?

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  3. wow!!!
    if possible, can you make the layout of BB +. maybe it would be a good idea to separate the sides. I am very interested in the B side, which is like a drive and has much more gain.

    here the link: http://freestompboxes.org/viewtopic.php?f=7&t=19528&p=248830&hilit=bb+preamp#p248830

    Brejna made a layout but I have not the schematic to be corrected if it does not work.

    the schematic according Brejna, is from Darmstat

    *** Sorry if this is not the place to do this, but I did not find your email as previously

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    1. Francisco, the schematic is gone in fsb thread. Can you upload?
      honestly, i have bb+ and early bb, but in sprint and double side. so, i never built that
      please a look http://www.mediafire.com/download/gldlcoxeupw1bfy
      my eyes is trouble see the B side in there
      sorry forgot where i get that

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    2. that's the schematic!!!
      It was the same earlier drawing. It was the same that was in the tread that I put up.

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  4. i asked for it, you made it !! YOU ARE SO GREAT DUDE !!
    Rafik

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  5. you can check this, VERIFIED !!!
    but i found some little problems: https://goo.gl/photos/H5kfuspXjYZZ8CEt7
    And the Gain pot is more useful with a Log pot --> A1M

    sounds great thanks !!
    Great site by the way !
    cheers from Chile !

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    1. That for catching those and thanks for verifying!

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  6. I have a BB +. I recently played the BB comp and LOVED the setting with no compression. Can anyone tell me how to mod my Plus to have no compression instead of "hard/soft". Ideal world the switch would be "off/soft." Any tips?

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    Replies
    1. Hi Jp, if you want no compression, just remove the 4148 diodes, or add a switch for more versatility (see the link here: http://tagboardeffects.blogspot.fr/2012/10/xotic-bb-preamp.html).

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  7. Can I replace the 2SC1815 transistor to BC517?

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    1. You could try it, but it's probably overkill as the BC517 is a darlington. A BC550 would be better suited. Just mind the pinout.

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    2. I use 2N5088, working fine to me.

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  8. What does the yellow trace stand for?

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  9. Can 1N5818 replace with 1N5819?

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  10. This comment has been removed by the author.

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