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Bartolini 59J hum

Discussion in 'Pickups & Electronics [BG]' started by typ, Apr 7, 2005.

  1. typ


    Apr 7, 2005
    Hi all, first-time poster on talkbass.

    I recently installed a Bartolini 59J-L1/LN1 pickup set and NTBT preamp on my Carvin BB75. I like the sound of the pickups and preamp - pickups are slightly warmer and fuller on the low end and the low B seems to be stronger. However, I have noticed a small amount of hum when either the bridge or neck pickup is soloed (not present with both pickups on full). It is significantly less than single-coil hum, but still noticeable. I don't remember the stock Carvin H50N pickups humming like this.

    I know the 59Js have humbucking coils in a side-by-side configuration, as opposed to stacked configuration like the H50Ns. My theory is that since they are 5-string pickups, one coil is longer than the other (meaning, one coil handles 3 strings and the other handles 2) so that the two coils are partially - but not completely - humcancelling. Anybody else run into this or have any feedback/comments?
  2. Dr. PhunkyPants

    Dr. PhunkyPants Guest

    Aug 11, 2002
    Welcome to TB!

    Kind of hard to say at this point what the problem is (or really, whether there IS a problem, as opposed to being unhappy with the normal functioning of the pups).

    I think we're going to have to ask you questions and you may need to do some "systematic" work ruling out various issues. So, I guess I'll lead off:

    1. Were the items (pup and pre) purchased new or used. if the later, can you contact the prior owner?

    2. What sort of experience do you have working with instrument electronics and, as a result, how confident that you have a.) configured the components correctly and b.) connected/soldered the components cleanly?

    3. Are you using the bass in the same room, with the same gear, as before when you weren't having a problem?

    4. Can you remove the current pups and reconnect the originals to confirm that the problem is not originating with the preamp, versus the pups? And vice versa, can you connect the current pups to the original passive electronics and re-create the sound?

    5. If the pickups are, in fact, generating the problem, have you tried shielding the surrounding cavity?

    6. Have you discussed (and maybe this should come first!) your issues with the pickup manufacturer (Bartolini) to see if the complaint you have is a.) routine or unique b.) grounds for a replacement or c.) correctable.

    This is just a start, but seems to me the challenge is to:

    1. Identify the problem component
    2. Determine whether the component is functioning as intended
    3. Identify the countermeasure that will result in you being satisfied with your tone once again...

    Good luck. And feel free to post pics of your work.
  3. typ


    Apr 7, 2005
    Hey Dr.

    Thanks for the very thorough reply!

    I probably should have said first off that I don't believe this to really be a problem, but am just curious if anyone else noticed the same thing.

    But I will try to answer all of your questions to avoid redundant replies from other helpful members like yourself.

    1. Bought new (which rules out talking to the previous owner)
    2. I have extensive electronics/soldering experience and have done numerous other pickup installs, so I'm very confident it was done correctly.
    3. Yes, I am using the bass in the same room, with the same amp, etc., etc.
    4. I have not tried replacing with the original pups, although I COULD. I have pretty much ruled out the preamp because the hum becomes less and less noticeable as the blend pot is turned back towards the center, and disappears completely when the blend pot is in the middle. In other words, the symptom is IDENTICAL to single coil hum, except the overall level of the hum is MUCH lower (I compared to my fretless, which has a passive single coil J pup in the bridge position).
    5. I did NOT shield the pup cavities, mainly because in my experience this has been unnecessary with humbuckers (control cavity, yes, pup cavities no). But I am considering doing this, because it is pretty simple to do, and it certainly can't hurt.
    6. I did send a fax to Bartolini several days ago, and haven't received a response (believe it or not, the only way I could find to contact them is via fax - they currently have NO phone number listed on their web site and NO e-mail address, which I find unbelievable for the year 2005!).

    The more I think about it, the more I lean towards my theory of the coil lengths being different. It would explain why the 4-string version of the pickups, the 9J are "dead quiet" when soloed (according to an old BP review of the Mike Lull Vintage Jazz bass I found online). It would also explain why the hum is much quieter than a single coil pup, where you have NO humbucking when pickups are soloed.

    If anybody has the 59J pups installed, and wouldn't mind running a 5 minute test sometime, I would REALLY be curious if you ran into the same thing.

    Anyway, back to #5, I think I am going to shield the cavities. As I mentioned, it certainly can't hurt.
  4. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    Humbuckers still need shielding. That said all barts are supposed to be fully shielded inside the epoxy case. The wires that come from the pickup can be exposed and a possible source of noise. If they came with a 4 conducter cable with a shield make sure that cable is grounded and you might solve the problem.

    Good luck.
  5. Dr. PhunkyPants

    Dr. PhunkyPants Guest

    Aug 11, 2002
    Your point about the leads is a very good one.
  6. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    Why thank you :)

    Since it's just a tiny bit of noise it may actually be the right answer.
  7. typ


    Apr 7, 2005
    Thanks guys.

    I've got my copper tape. Tonight I'm going to try and do the deed. Will report results. And I do plan on soldering a ground wire to each control cavities' shield and then soldering this to the copper shield in the main control cavity. Which brings up another subject.....

    Bass and guitar circuits usually have ground loops galore. For example, pots are grounded to control plate due to their physical mounting and also typically have cases jumpered together, for example. What do you fellows think about these being a significant source of noise? I have always tended to view them as insignificant, due to the very short runs of wire involved. But then again, the voltages involved are pretty low too, so maybe these loops do have some affect.

    Thanks for all the great feedback!
  8. Dr. PhunkyPants

    Dr. PhunkyPants Guest

    Aug 11, 2002
    It's hard to talk specifics without knowing the environment the instrument is in. The same bass will hum differently in your house, versus the corner bar, versus my house. Give the shielding a try. You're also probably right that pickups with uneven pole lengths will interact less cleanly than something more balanced like a p-pup.

    In fact, if you care about coil hum, why are you playing a jazz bass in the first place?
  9. typ


    Apr 7, 2005

    In answer to your question about playing a jazz style bass, I think I'm just spoiled because the EMG JV's in my Fender Jazz are SICKENINGLY quiet. And they sound great too, as a sidenote. But it's an unfair comparison, of course - from a noise standpoint, using a true active pup like an EMG is a lot different than using passive pups with an onboard preamp because of the signal level/coil resistance considerations.

    Which of course reminds me of something else, somewhat related. With the old Carvin preamp and with my EMG-equipped Jazz Bass I usually just plug straight into the 1/4" (low Z) inputs on my recording console. I found out that with the NTBT preamp I can no longer do this, at least if I plan on using the volume pot. The reason (which dawned on me about 20 seconds after I noticed the logarithmic, as opposed to linear, effect of the volume pot, despite the fact that it's an audio taper pot) is that my NTBT conifguration has the active/passive switch, which means that the volume pot is 250K. This appears to be so it will work correctly in passive mode. But in active mode it adds a high impedance to the circuit. Not a big deal, of course. I have a direct box. But worth noting. Anyhway, I'm happyh with the preamp - I'll gladly trade the low Z output for having the flexibility of an active/passive switch.

    Anyway, thanks again for the suggestions. I will report back with whatever I find out.

    I will try the shielding though. I'm also going to post in the Carvin forum too. A lot of the guys on there have replaced the stock Carvin pups with Barts. I'm really just curious if anybody else has noticed this.