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PCBs for DIY clone 2-band Preamps

Discussion in 'TalkBass Bazaar: Effects & Electronics' started by UncleFluffy, Feb 1, 2011.


  1. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
  2. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    Been a little behind due to family issues. Made it to the post office yesterday, 18 Boards shipped. Everyone who's paypal-ed should have a PM.
     
  3. Hi all,

    I'm just a little confused on the off-board connections. Is there a layout available for the board?

    Thanks!
     
  4. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    All the build info is currently scattered randomly throughout the original thread. This is the key post that has the schematic and wiring info:

    http://www.talkbass.com/forum/f38/stingray-aftermarket-2-band-pre-614382/index7.html#post8783810

    BajaMusicmanStingrayBasspreamp.

    NOTE: For the details, check the big thread but the schematic has a small error - the output cap is shown as 1u when it should be 10u. The layout diagram is correct.
     
  5. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    Shipped off this week's batch, 15 boards in the capable hands of the US Postal Service.

    Everyone who sent $ as of yesterday should have a PM and/or a board by now.

    I'm a little worried by the lack of build photos in the other thread - has anyone built a working preamp from this batch yet? Anyone encountered weird/unsolvable problems?
     
  6. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    i haven't built up one of the newest boards yet, but i think the printing on the top for the 1uf tantalum (or electrolytic) that goes "in from pickup" (furthest left cap on the schematic) has the polarity printed in reverse on your new pcbs. not a problem at all though, just flip the cap 180 degrees.
     
  7. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    Thanks for spotting that. I'll make a note in both threads.
     
  8. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    As johnk_10 pointed out, there's an error in the screen print on these boards.

    DSCN1789.

    The capacitor marked with the red * is printed the wrong way around. The + should be on the left (closer to the big holes).

    As far as I know there's nothing wrong electrically and the boards should still be completely usable. I'm still very sorry about this error and any confusion caused, and will cheerfully give a refund to anyone who PMs me asking for one.
     
  9. TDR1138

    TDR1138

    Apr 11, 2007
    Section 204
    Putting my Mouser shopping cart together... Anyone know what pots to use for a rear-mount cavity?
     
  10. BassLife77

    BassLife77

    Nov 13, 2009
    San Diego
    I don't think Mouser sells the pots with the long bushings you need. the volume and bass pots are easy to find
    http://www.gpdusa.com/25K_Pots-25K_Pot_Linear_Taper.html
    http://www.gpdusa.com/100K_Pots-100K_Pot_Audio_Taper.html

    When I was building my preamps I couldn't find the C1M reverse log treble pot with a long bushing. The ones they sell at Mouser only has a 5mm bushing (threaded part). I lucked out and never needed one. you will need a 16mm or 20mm pot and the threaded part has to be at least 10mm long
     
  11. praisegig

    praisegig Supporting Member

    Jul 7, 2008
    Stephenville, TX
    I ordered my parts from Mouser, but I'm having problems with the 120pf cap and the 220k resistor. The leads on both are .030 and the hole in the PCB are .020. Has anyone else come across this problem and have a fix?
     
  12. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    I've got some that fit. If you can't persuade the ones you have to fit let me know and I'll drop a set in the mail.

    (edit: I just checked the proofs from the board house and the small holes are 0.032.)

    edit2: here's the drill size map

    Untitled.
     
  13. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    Well, I just hand-checked one of the boards and the holes do seem a little snug. I can push the blunt end of a 1/32" (0.031) drill bit through the "0.032" holes but it needs some force. Probably just under 0.030.

    Anyone who has already bought components that should fit, but don't, let me know and I'll send some in the mail. I'd hate to see anyone get all fired up to build a preamp and get caught out by something this simple.

    Not going to be an issue for most people. Most parts should fit, you will only see problems when the leads are a bit chubby and the hole is a bit snug.
     
  14. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Did the first test build today, using an LT 1351 opamp and a few mild component deviations. I used non-polarized electrolytics in the signal path, plan to try 1uF mylars or polypros the next time. I had to reverse wire the treble pot since I haven't sourced the reverse taper one yet. Frankly, I may not bother, works fine for me the way it is.

    Anyhow, the preamp sounds absolutely great, just what I wanted for my ancient Travis Bean fretless, which is a very aggressive sounding fretless by nature. Primus City if I want it...:bassist: Thanks again Derek!
     
  15. BassLife77

    BassLife77

    Nov 13, 2009
    San Diego
    I was wondering when you used a regular 1M pot did you just switch the wires going to lugs 1 & 3? is the tapering correct, you get more treble as you turn clockwise? If so it will be easier to source those pots for replacements and future builds.
     
  16. TDR1138

    TDR1138

    Apr 11, 2007
    Section 204
    Thanks... I'm dropping it in a G&L, which I think uses a 1M reverse log, so I might just be able to use that one...
     
  17. UncleFluffy

    UncleFluffy

    Mar 8, 2009
    California
    Head Tinkerer, The Flufflab
    Guys ...

    Just dropped the Paypal balance from these into the Tsunami relief fund. I think they can use it more than I can use the beers.

    Thankyou all for this, and next time you play your homebrew-pre-equipped bass, you can tell yourself that it's not only sounding good but it's helping some folks who really need a hand right now.

    (edit: and that'll be true for the rest of the boards from this batch, as long as it lasts)
     
    Kubicki Fan likes this.
  18. praisegig

    praisegig Supporting Member

    Jul 7, 2008
    Stephenville, TX
    May God bless you for this act of kindness and meeting a need.
     
  19. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    No such luck. The tapering is good with 1 & 3 reversed on an A taper pot, but full clockwise is then full treble cut.

    I think I would be perfectly happy with a bit less adjustment range on the treble control, so I'll experiment with using a 1 meg linear pot and a few resistors to mimic a C taper pot.
     
  20. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Your tone was killin' out in the house last evening. I'm pretty sure that Nemesis wasn't helping any ...
     

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