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Please help me

Discussion in 'Amps and Cabs [BG]' started by Melvin7822, Jun 10, 2004.


  1. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    My setup consists of a MIA Fender Jazz with Dimarzio Ultra Jazz pups (not an active bass), an Alembic F1-X, a Stewart World 2.1, and an Acme Low B-2.

    My problem is that whenever I turn the Alembic up past 4, I get distortion and I'm not clipping. I'm only pushing 650 watts into a 4 ohm Acme. I tried plugging my bass into the -6dB input on the Alembic and still the same thing. I tried turning down the power amp and it only made the distortion worse. Is the Alembic a bad match for the Stewart or is the problem somewhere else? Please help.
     
  2. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    The Alembic should be a lovely match for the Stewart.

    How are you wiring the amp to the cabinet? Is it possible that the bridge/stereo switch is in the wrong position?

    If you're using both red terminals, the switch should be set to "bridge". If you are using a red terminal and a black terminal, then the switch should be set to "stereo".

    If your speaker connector is a Speakon, make sure it is wired correctly.
     
  3. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    I'm just running one channel of the Stewart with the Acme. The switch is set to stereo. The speaker cable I use is a Pro Co Fat Max Banana to Speakon. I know for a fact that I don't have the phase reversed on the wrong end. But would incorrect wiring on the Speakon end really account for distortion when the preamp is set higher?

    I've had the Acme for several months now, and it is properly broken in. I broke it in with a sine wave generator. All my cables are in excellent condition. I would think if pickup height were the problem that the distortion would be present at all volume levels and that also wouldn't explain why the distortion gets worse when the pre is past 5 and I turn down the gain on the Stewart.

    Anyone else have any ideas?
     
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Tubes?

    Lonnybass uses the F1-X/World 2.1 with a pair of 4 ohm B2s and he's more than happy.

    Have you tried another preamp in for Alembic's place?
     
  5. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    The preamp is brand new, so I hope it wouldn't be the tubes. Back when I had a Bass PODxt Pro as a preamp, I had no problem cranking that all the way.
     
  6. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    A speakon connector has four possibilities, so if yours is wired, say, 1+ and 2+ instead of 1+ and 1-, then that could cause distortion. Let me put it this way: I was once experimenting with different wiring out of my 2.1 and set the stereo/bridge switch wrong. I got distortion such as you described... I was afraid I'd broken something, but after shutting down and setting the switch properly everything worked fine.

    Then again: you say the distortion problem didn't begin until you acquired to the Alembic? Strange. I suppose it's possible you have a defective pre... damaged in shipping? Loose tube? The only time I had a problem running my Alembic F2B into my Stewart World 2.1 was when the Alembic developed a loose solder joint... that's the only problem I've had with that pre in 20 years.
     
  7. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    I used another cable without a Speakon and the issue was the same. I'm now wondering if it is the tube. I guess that would kinda make sense that when I turn the volume on the preamp past 4 and distortion is apparent even though I'm not clipping maybe it might mean the tube is shorting out or something. Also, last I recalled I used it through an Ampeg 8x10 at my rehearsal space and had it cranked to six, and didn't notice the distortion.
     
  8. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
  9. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
  10. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Since the preamp is brand new, I'm wondering whether its a tube issue or perhaps a bad capacitor.

    If it was my preamp, I'd contact Alembic, describe the problem and ask them what they want me to do. I presume that it's still under warranty and I'm sure that they'll take good care of you.

    Good luck and please keep us up to date.
     
  11. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    I also suspect that my rack is acting up because a very poor ground in my house. I don't recall having this problem at my rehearsal space. But I will ascertain this tomorrow.
     
  12. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
  13. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    Well... as BillyB mentioned above, replace the Alembic with another preamp and see what happens. If the distortion goes away your preamp is probably defective, so you should have it repaired.
     
  14. Melvin7822

    Melvin7822 Supporting Member

    May 11, 2004
    Broomfield, CO
    Honestly, I'm suspecting it to be something with the improper ground in my house because that last time I had it at rehearsal I don't recall having this problem.