Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

bartolini preamp woes...

Discussion in 'Pickups & Electronics [BG]' started by gumwr, Dec 17, 2002.


  1. gumwr

    gumwr

    Jun 3, 2002
    Harrisonburg, Va
    hey guys,
    i've installed a bartolini ntbt 2 band 9v or 18v preamp in my bass. i got wiring diagrams from the website and installed it just as it specified. i also included a passive/active switch (on/on switch i got from radio shack...). finished the project today and plugged it in for its first run. on the passive side, it sounds good, not any different than it had before, only the volume is very low, not inaudible, just pretty low (much lower than the previous passive system). in addition, when i switch to active, the sound almost disappears! its so low you almost cant hear it! i dont know what i've done wrong. the conections look good, and everything is in its correct place. please help. offer suggestions if you have had problems like this before or if you know much about electronics and know what this may be. thanks in advance
    william gum
    ps. check out the wiring diagram here: http://www.bartolini.net/1_wirngs/ntbt_2.gif
    check out the passive/active switch diagram here:
    http://www.bartolini.net/1_wirngs/ppapsw_n.htm
     
  2. DigMe

    DigMe

    Aug 10, 2002
    Waco, TX
    Ok you can file this under "Stupid Questions" if you want but have you tried with both 9 and 18volts? If you've only tried it with 9 I'd try it with 18 and see what happens.

    brad cook
     
  3. gumwr

    gumwr

    Jun 3, 2002
    Harrisonburg, Va
    brad,
    i have tried it both ways.... same results. thanks for the input though
    william
     
  4. hujo

    hujo

    Apr 18, 2001
    Stockholm, Sweden
    I think Bartolinis have a gain-adjuster.. Should be a little lever somewhere, might be that.
     
  5. gumwr

    gumwr

    Jun 3, 2002
    Harrisonburg, Va
    i tried it with the gain all the way up, and all the way down (clockwise and counterclockwise respectively). no difference. thanks for the idea.
    william
     
  6. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    This would be so hard to troubleshoot over a forum. The passive sound should be the same either way. It sounds like a miswired install, if it's new. If it's used it could be defective but IME when I run into an install problem like this it's usually something I've done.
     
  7. Rock City

    Rock City

    Apr 8, 2001
    Boston,Ma
    gumwr,
    It sounds to me like you have the wrong switch type (DPDT/SPDT? I didn't look at the diagram!), or you've got something wired incorrectly. If the switch type and wiring are correct, it should sound EXACTLY as it did before in passive mode. Because you have a problem in activeand passive, I'd rule out the preamp.
    GEEK
     
  8. gumwr

    gumwr

    Jun 3, 2002
    Harrisonburg, Va
    guys,
    thanks so much for your input so far. i am begining to believe that something is wired wrong etc. i'll take a very thorough look at the wiring tomorrow to try and find out what is fouling things up. could it be as simple as a bad solder somewhere? how about a ground that doesnt need to be there... i'm not sure. also, the diagram called for a dpdt switch which is what i used. it obviously switches something, so i think that its ok. the passive side is REALLY low and the active side is slightly low so it feels as if some of the signal is bleeding off somewhere. any ideas on this theory? thanks for the help
    william
     
  9. notduane

    notduane

    Nov 24, 2000
    Location
    ummm...off to Pickups?
     
  10. Rock City

    Rock City

    Apr 8, 2001
    Boston,Ma
    It sounds as if you've got the pickup being sent partially to ground somewhere. The "low volume" passive mode kinda points to that. Dig in deeper tomorrow, and I bet you'll find it! I've been repairing and building guitars professionally for almost 20 years, and every now and then one "gets" me! Don't panic.
    GEEK
     
  11. gumwr

    gumwr

    Jun 3, 2002
    Harrisonburg, Va
    GEEK,
    thanks for the idea. i've tried many other things so far, but to no avail. when you say that the pup signal is bleeding off to ground do you mean that some of the signal coming from the interior core of the wire (the actual pup wire not the ground) is being grounded (ie, the terminal it is connected to is somehow grounded)? if this is so, how do you suggest that i ground the braided insulator part of the wire? i've got them connected to a blend pot... i couldnt run the ground from the body of the ground because the bottom of it spins with the pot shaft. so, what i did was connect the braided ground portion of the wire to the terminals on the blend pot that are to the left or right of the respective pup wire terminal (which is center on the pot). is this a bad way of doing it? lemme know what you think and any suggestions. thanks
    william
     
  12. Rock City

    Rock City

    Apr 8, 2001
    Boston,Ma
    gumwr,
    I'm not sure exactly where you're at ,but...... the ground(shield) should be attached to a common ground lug in a shielded cavity(usually best) or to the back(case) of the pot. Can you email me close ups of what you've done?
    GEEK
     
  13. FalsehoodBass

    FalsehoodBass

    Jul 22, 2001
    Denver, CO
    make sure that the pickups aren't wired backwards and are cancelling each other. I've heard of people doing that.
     
  14. JOME77

    JOME77 Supporting Member

    Aug 18, 2002
    Georgia
    gumwr,
    I'd by-pass the DPDT Passive/Active switch first. Simplify the circuit as much as possible to trouble shoot where your problem is. You also may want to check the wiring of the pre-amp GND on the input jack. The pre-amp should get GND when you plug in the jack. It sounds like your pre-amp isn't getting power. Also check and make sure the pre-amp HOT is connected correctly (to Battery) and check the battery connector. I had a strange problem with some jazz stacked Bart's this morning. I just installed a Moses Graphite neck on a Warmoth Jazz deluxe 5 body and my "G" string sounded like it had a chorus on it! After trying just about everything I knew to do, I adjusted the "G" string (side-to-side) so it was closer the edge of the P/U. Amazingly the strange thin/chorus sound went away! I've never seen this on any P/U's except P/U's with pole pieces. Stange. If you can take a close up picture of the wiring, someone may be able to help easier (providing you can see the connections). Good luck!
    :)
     
  15. Bazzist

    Bazzist

    Dec 7, 2002
    Nova Scotia
    I think i have the answer to your problem most bartolini preampso have a system gain so raise your system gain so yur immiting normal decibal levels n whiel raising system gain leave eq flat and max out yur volume control on the preamp
     
  16. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    LOL. Here's an individual who buys arguably the best preamp in the world, then uses Radio Shack components in the installation. Anyway, what kind of pickups are you using? Not Radio Shack, I hope.
     
  17. :help: I just bought a new 5 string and I purchased some bart 5J's and a HR-3.3AP/918 from bestbassgear.com. It comes with as follows:

    Jack- 1
    Vol w/ Active/ Passive switch- 1
    Blend Pot- 1
    Treble/ Bass cut/ boost- 1
    NTBT-918 preamp- 1

    I installed everything according to the instructions and diagrams.* When I plugged it in, the passive mode worked fine (no treble/ bass control), but the active did not. I remove the active/ passive and just went with one of the volume pots that came with the bass. No effect. I'm coming pretty close to shooting another bass so any assistance would be greatly appreciated.

    *I used the flush mount jack that came with the bass instead of the one included with the kit.
     
  18. Rodent

    Rodent Supporting Member Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Regenerate Guitar Works
    I had a problem with a NTMB this past week. After all was done I got zero sound. Well, after close (like in third time around checking) I notice that I have a break in ground at the jack. Once this was resolved ... BINGO! volume that will overdive most amplifiers.

    All of the preamps from Best Bass Gear come pre-wired. These are tested to be working properly before they are shipped out. If something ain't working, it's usually one of two things: a bad connection some place, or one of the pots got fried due to overheating while you were doing your installation. If you're pretty sure you didn't cook a pot while soldering a ground to it, then it's gotta be a bad connection some place.

    A couple of questions:

    * how did you shield the cavity - are all of the copper tape sections soldered together along at least one seam?

    * are all of your grounding leads connected together to a common ground?

    * have you verified all your grounds with a multi tester?

    R
     
  19. :hyper: Fixed it. The problem was that my dumbass didn't ground the harness to the jack. So the jack was grounded, but nothing else.

    What have we learned?

    If your Active/ Passive system only works in the passive mode, it's probably grounding problem.

    Have a good day.
     
  20. Rodent

    Rodent Supporting Member Commercial User

    Dec 20, 2004
    Upper Left Corner (Seattle)
    Player-Builder-Founder: Regenerate Guitar Works
    Congratulations!!!! :hyper:

    R