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

Distortion in Brtolini Pickups - help plse

Discussion in 'Pickups & Electronics [BG]' started by Maurice Carr, Oct 11, 2004.


  1. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    The bartolini pickups in my BTB1005 seem to be distorting.
    The pu's are passive with 18v EQ system.
    The batteries are completely fresh ( both checked with volt meter just in case ) Energiser Titanium E2s.
    I get distortion when I turn the volume knob on the bass anywhere from 2/3 to full vol. If I pluck the strings gently, no distortion, but with any forceful plucking the distortion begins.
    I have tried keeping the guitar volume down, using my BDDI as a means to boost the signal to the amp, still distorts when I pluck with any force ( not much causes distortion )
    I have a BTB405 as well, passive + 18V EQ fitted with the Ibanez pick-ups and I don't get the same problem. The BT1005 is a far better bass though apart from this distortion problem which just seems to be getting worse.
    Another weird thing is when using the octaver on the Digitech BNX3, the octave up notes fade in and on ONLY on the D strings between 3rd and 9th fret, like some part of the signal isn't getting trhough, is weak or whatever - but only on D string - on each or both pickups. This doesn't happen on the BTB 405.
    Bartolini's web site has problems so I can't email them about it. The local agents are reknowned for not being much help.
    Does anyone know of any way to thoroughly test the output of the pickups to determine if their is a deteriorated signal and help find out what is wrong? - say an oscilliscope method in which case what does one look for.
    How do you determine if it's the pick-ups or the electronics?


    Any help would be appreciated.

    Thanks - Maurice
     
  2. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    re: the distortion
    Did you check the input gain trim knob on the preamp? It's a little trim pot on the main preamp unit. Turn it down to minimum, make sure you don't get distortion, then you can turn it up until you find the point where you get most input gain without distortion.
     
  3. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    Thanks - no I haven't tried that yet. Haven't opened up the main electronics cavity so I assume you are meaning I'll find it in there. Will explore and post result - again many thanks David.
    Maurice
     
  4. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    David, OK found the trim pot, positioned at a bout 12:00 and pushing out up to 16 volt when the string was plucked hard. Wave on scope showed lots of distortion and you could hear that thru phones. Knocked it back to 10:00, average output up to 2 volts, lots better according to the scope etc.

    Wound back to 7:00 the pre-amp was too quiet but it certainly knocked back he distortion more ( up to 1volt output ).

    Tried at practice last night and there was some improvement but still distorted when sting plucked with reasonable force.

    Will carry our more extensive rig tests tonight but I'm still a bit unhappy overall.

    Maurice
     
  5. It sounds to me as if the problem is with the preamp, not with the pickups. If it were the pickups, they'd be distorting no matter what the volume or internal gain settings were, as long as you were hitting the strings with the same force.

    Looks as if the BTB1005 uses a Bart EQ as well as pickups. Does it have an active/passive switch, as well? A typical Bart wiring harness would do this by pulling up the volume control, but the wiring diagram on the Ibanez site doesn't indicate anything like that.

    Mike
     
  6. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    I've gotten disortion with hi ouput pups that are too close too the strings but have never got that response from Barts and would almost definetly rule that out but it's best not to assume anything in trouble-shooting. You want to know and the only way do that is to vary one thing at a time holding all else constant, taking it one step at a time taking the quickest, easiest, cheapest fist. Like isolating it to the bass for starters.

    Don't know about the Titanium batteries but I'd try a set of alkalines just to be sure cuase those are what are typically recommended.

    I'd say it's highly unlikely there's anything wrong with the pups themselves but you can find out by wiring them direct to the jack. And if you get the distortion I'd drop them down from the strings for sure and check the results.

    The only time I've got distortion with Bart rigging is when I plunked a Bart TCT preamp (no gain pot) out of a Tobias in with a set of Bart M34C's - and I got what basically sounds like what you're describing. That preamp had a Bart DAT1.3 buffer and I yanked it and that resolved the problem.

    I also wouldn't rule out a bad ground and I'd recheck all of your wiring. I don't see where you said anything about having the original pups and whether there was a problem then or not. If not, swapping another set of pups into the bass is the only way I know of checking the preamp out in general. Jacks themselves are a frequent source of problem and I wouldn't rule out a pot if those items haven't been confirmed good.

    It took me many hours and swapping stuff around to isolate that buffer issue. No fun. Good luck.
     
  7. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    Thanks Mike - no the bass does not have an active/passive switch. My gut feeling is that it's the pre-amp as I get the weird effect on the D string with the BNX no matter whcih pick-up I use - would be very unsusual for both pick-ups to die.

    Maurice
     
  8. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    luknfur - thanks for that. I'll try your suggestion of std alkalines, but i've got titanium e2 in my btb405 and there's no problem there.

    These are the original pups supplied with the bass and the bass has had no mods.

    I've tried manipulating all pots to try and isolate any offender but no difference in the distortion, is this the way to test pots or is there a more scientific way?

    Appreciate your interest to help me.

    Maurice
     
  9. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    If you're getting it with all pots the chance of there being a problem is remote. The battery thing I only mention cause I have no familiarity with Titaniums and it's a cheap, quick check. The chance of it being a pup is also remote but in wiring them direct to the jacks you'll know. Preamps do go bad sometimes but that's also a long shot - but it happens. Likelyhood is more in a connection.
     
  10. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    This DAT 1.3 buffer - where would I find that, ( it is positioned at a special place in the circuit no doubt ) and what does it look like? The BTB bart electronics are a special manufacture made for Ibanez only and getting any info apart from the schematic on the Ibanez site is nigh impossible. If necessary I could take a photo and post it .

    Also you suggested wiring the pick-ups direct to the jack, this sounds major work or is it an easy task - I have a son who is an ex air-force avionics tech and has his own business building electronic circuit boards for industry - he's a wizz at soldering obviously.

    Thanks for the suggestion of changing the Titaniums, I tried std Energiser Alkalines today, no difference - worth the try though, at least that's one more thing eliminated.

    Really appreciate the help bro.

    Maurice
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    --------------------------------------------------------
     
  12. Maurice Carr

    Maurice Carr

    Aug 7, 2004
    Mt Wellington, Auckland, NZ
    Authorised BFM and fEARful cab builder: New Zealand
    Luknfur - many thanks for that - That gives me heaps to do in the coming weekend - I'll let you know how we got on.

    Maurice