Making an 18V circuit from a 9V plan

Discussion in 'Pickups & Electronics [BG]' started by Hclafkir, Apr 10, 2020.


  1. Hclafkir

    Hclafkir

    Apr 4, 2020
    Hi all, I’ve read this entire post and loved it along with all the comments;

    DIY Stingray 3EQ Preamp

    However, I would like to make that circuit be able to handle 18V to replace the PCB in the AMERICAN DELUXE PRECISION BASS® 2013 plan;

    019-407A_SISD.pdf

    First, is there a newer version of this plan for Fender?

    Second, where can I find instructions on converting Dominic DeCosa’s circuit to 18V?

    Thanks so much for your time everyone.
     
  2. Hclafkir

    Hclafkir

    Apr 4, 2020
    Sorry all, more specifically, how can it be modified to support a dual supply op amp?
     
  3. You don’t have to make any notifications other than adding the 2nd battery and battery clip. You’ll just have to make sure that the components are rated for more than 18V.

    Really the only thing to be careful with are the capacitors. (Standard voltage ratings for caps that you can use are: 25V, 35V, or 50V.) Anything higher is fine but they’ll usually be bigger in size.

    1/4W or 1/8W resistors are fine to use.

    The typical op-amps like TL06X or TL07X are able to handle the 18V. If you plan to use anything else, then read the data sheet to find the maximum supply they can handle.

    Hope that helps!
     
    Crater likes this.
  4. Hclafkir

    Hclafkir

    Apr 4, 2020
    Thanks AB. Sorry, I have worded this incorrectly. I am looking to run it at +/- 9V, not at 18V in series. I am really trying to duplicate the set-up that Fender uses in this plan;

    019-407A_SISD.pdf

    upload_2020-4-11_13-45-1.png

    I am looking to have added gain, not added voltage.

    Hopefully someone has seen a circuit layout here on TB in the past 7 years. Fingers crossed.
     
  5. gerryjazzman

    gerryjazzman

    Dec 31, 2006
    New Jersey
    Hi. I'm assuming this is the preamp schematic you're referencing. It's fairly straightforward to convert this to dual rail supply as I have shown by the modifications in red. I am assuming you already have this bass and just want to replace the preamp, since the wiring is already set up for +/- 9V. Otherwise you would need to replace the jack to switch both batteries.



    You could just use the existing layout with very minor modifications. Just eliminate the bias components in the lower left of the schematic (crossed out). Then the two bias points for each op amp unit would get tied to ground instead. Pin 4 of the dual op amp is tied to the -9v rail instead of ground. All this references the op amps to ground (i.e. 0V) so you can also eliminate the 10 uF output coupling cap by replacing it with a jumper. Should be fairly easy to do with the existing layout.
     
  6. Hclafkir

    Hclafkir

    Apr 4, 2020
    Thanks so much gerryjazzman! I have a bass, yes, but this is for making a bass from scratch.
     
    gerryjazzman likes this.
  7. gerryjazzman

    gerryjazzman

    Dec 31, 2006
    New Jersey
    You are most welcome!
     
  8. Hclafkir

    Hclafkir

    Apr 4, 2020
    gerryjazzman, I have redone the circuit board as per your updated schematic. Any chance I could ask you to take a look?
     
  9. gerryjazzman

    gerryjazzman

    Dec 31, 2006
    New Jersey
    Sure.
     
  10. Hclafkir

    Hclafkir

    Apr 4, 2020
    Sorry, not an electrical engineer. I tried to duplicate the form of the original design. I hope this is readable.
     

    Attached Files:

  11. gerryjazzman

    gerryjazzman

    Dec 31, 2006
    New Jersey
    Looks right to me. At least the changes required to use a bipolar supply. :thumbsup: BTW, what kind of jack are you using two switch both batteries? Standard stereo / TRS jack won't work in this situation.
     
  12. Doubling the supply voltage won't increase the gain, only the headroom before clipping. Most pickups don't exceed a volt or so, so a 9 volt supply with a fresh battery will allow for approximately a 4 volt peak signal before clipping.
     
  13. Hclafkir

    Hclafkir

    Apr 4, 2020
    Thanks again!

    Here is the jack I’ve got:

    Fender Jack Output Roland VG 0073618000 0073618049 007-3618-049
     
  14. Hclafkir

    Hclafkir

    Apr 4, 2020
    Yes, not trying to increase gain. Just the headroom. Looking for clean sound throughout the 9V range.
     
  15. Have you had instances of clipping your preamp? Often people go to great lengths to cure a problem where there isn't any.
     
    Passinwind and wcriley like this.
  16. Hclafkir

    Hclafkir

    Apr 4, 2020
    No. I’ve never had an active bass. I am making one as per Fender specs.
     
  17. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    "If it ain't broke, fix it anyway." Yel_wink.gif
     
    robert43 likes this.
  18. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Jun 14, 2021

Share This Page