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Trying to install a Bart NTMB HR-4.6 3 band and I need some help....

Discussion in 'Pickups & Electronics [BG]' started by Philthy, Oct 22, 2004.


  1. Philthy

    Philthy Supporting Member

    Jun 12, 2001
    Wallington, NJ
    I'm trying to install a Bartolini NTMB hr-4.6 preamp/harness into my bass and, I can't for the life of me, get it to work correctly. I'm pretty good with soldering and electronics and I've installed preamps before with no problem but I can't get this one to work. For some reason, I can't get sound out of the bridge pickup. I know everything is wired correctly according to directions. All the wires are in tact but the bridge pickup just won't work. I've been spending all night on it and I can't get it too work. And just when I think it works and I get sound, I install the blend pot and nothing. I know it's a long shot but any ideas out there? It's driving me crazy.

    Thanks,!!!
     
  2. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    The bridge pickup was working fine before? You didn't pull the wires loose at all when doing the work? Just wondering, I've done that before.

    First thing I'd try is to wire the bridge hot to where the neck hot is going and vice versa and see if the problem is in the pickup wiring or the blend pot.
     
  3. Philthy

    Philthy Supporting Member

    Jun 12, 2001
    Wallington, NJ
    Ok, there is definitely not a problem with the pickups. I tested both of them and they're in perfect working order. I believe the problem was with the blend pot. It might have gotten over heated when trying to solder. So, I bought a new blend pot and now a new problem arose. I get sound when I pan to bridge pickup alone and neck pickup alone but when I put the knob center, no sound at all. Maybe it's a grounding problem. I don't know.
     
  4. Schwinn

    Schwinn

    Dec 4, 2002
    Sarasota, FL
    After reading your first post I was going to say it was the blend pot. I had one that did something like that. About your second problem, try looking for a way to "switch" one of the hot wires with the other wire of one pickup. May be out of phase. I have a problem similar to yours on a bass, but only half of the strings sound out of phase and I as far as I remember, switching wires on the MM bridge only made it worse. Maybe I have another bad pot, don't know what's going on with that.

    Anyway, switch the wires if you can and give it a shot.
     
  5. Philthy

    Philthy Supporting Member

    Jun 12, 2001
    Wallington, NJ
    ok, I think I finally figured it out and got it to work. First of all, I definitely cooked or had a faulty pot. So, I bought a new one. I was only getting sound when I panned to each pickup individually. When I had the pot in the middle....nothing. So, I decided...out of curiousity....to try a blend pot off of the original preamp that was in this bass. It worked!!! After further analyzing the pots; the one I bought was a 250k blend pot where as the one on the old preamp was a 500k blend pot. Now, according to the bartolini preamp diagram, the blend pot is 250k for the NTMB preamp harness. Yet, the actual pot that came with the Bart didn't have any markings on it so I don't know what the value was. Does this make sense to anyone? I don't understand much about pot values so does this sound correct that the 500k pot should be the right pot?

    Thanks!!!!

    Also, maybe it's just me being very anal and noticing everything, but is the bridge pickup on a bass with soapbars considerably lower in volume vs. the neck pickup when each is played alone?
     
  6. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    the pot value won't make that difference. Was it the same brand of pot? I've seen different brands of blend pot wired differently. I think it was more than likely that.
     
  7. Philthy

    Philthy Supporting Member

    Jun 12, 2001
    Wallington, NJ
    No it wasn't the same brand of pot. The original pot was obviously a Bartolini. The other 250K pot I tried was from Allparts and the one that finally worked (500K) was from the original Ibanez preamp. But either way, it seems to work fine.

    But now there is one other very small annoyance. There seems to be a electronic buzzing coming from the bridge pickup. Almost like a ground buzz. It doesn't go away when I touch the strings, however, I noticed that when I face the amp at a specific way it will go away a bit. If I turn a little bit to the left or right or move to a different spot, the buzz is back. Any idea?
     
  8. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    Not that it matters really, but Bartolini don't make their own pots - I think they use Alpha or Noble.
     
  9. Philthy

    Philthy Supporting Member

    Jun 12, 2001
    Wallington, NJ
    Sorry about that. Then I think it's Alpha.

    Any idea about my bridge pickup buzzing? Thanks for all your help.
     
  10. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    Do you have a cold solder joint at the connection to the blend pot or ground?
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    the description sounds like a 60 cycle hum which normally is just something you have to deal with with some singles. But Bart pups and preamps don't hum.

    Typcially, if a bass with singles is properly grounded, you can touch the magnets and hum will decrease since the slugs are usually grounded. If it increases, then you've got a ground issue and sometimes reversing the pup wires will resolve that. I've also found if the bass is grounded from the bridge, if properly grounded, touching the strings will decrease the hum and if not it increases. A 60 cycle hum will only decrease by changing position - as you mentioned.

    But there should be no hum with Bart pups or a preamp if all components are in good working order, compatable, and properly installed. This doesn't sound like a distortion issue but the Bart has an internal gain control and I would alter that to it rule out just the same.