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anyone have this problem

Discussion in 'Amps and Cabs [BG]' started by tramp, Jul 12, 2005.


  1. tramp

    tramp

    Mar 5, 2004
    South Louisiana
    I have a fender bassman 150. This is a good amp. I played a gig this weekend. I was lined out and the sound man for the club (a kid in his early 20's)puts his earphones to set the bass and tells me that is a loud buzz in the phones. He could not set the bass in the mains. It as distorted and a terrible sound to boot. The monitor sound was ok. There was no buzz coming out of the mains or the monitors. I turned down my output for the lineout, flipped the gound switch and still had the buzz. I pulled the cable out of the lineout and used a mike and the buzzing went away. Than trying to set sound for the horns, he says that there is something wrong with the pa system. We have not had any problems with the system until this gig. I might add that on all previous gigs, I had no problem lineing out with my amp. This weekend, we are playing at a casino and we will line out to their pa system. I will see than if it is the amp lineout or the soundman at the club.
    Tramp
     
  2. Funkengrooven

    Funkengrooven Turn it down? You gotta be nuts!!

    The line out buzz problem can come from a number of sources.
    1, Bad Cable is the simplest and most obvious.
    2, Bad power is the next most likely (inherent in the club)
    3, Having the pa powered on the same circuit as the light dimmers and/or neon beer signs ( those neon signs are the most annoying noise because the operate on a high frequency that is not filtered by most amps)
    4, the pa is not properly grounded or shielded in the first place.
    5, The soundman is clueless
     
  3. Eric Moesle

    Eric Moesle Supporting Member

    Sep 21, 2001
    Columbus OH
    Also consider phantom power, perhaps it fried your DI.

    Anyone try a ground lift on the line? Did you try a regular DI on that line?

    C'mon, if this was a "sound man" and not a "kid tinkering", all of these things and those posted above could have been examined within a minute and a half . . .
     
  4. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Did the mixer have separate inputs for line-level signals? Or maybe pads for line levels?

    Your description screams out "line level into a mic-level input."
     
  5. tramp

    tramp

    Mar 5, 2004
    South Louisiana
    The cable I used for the mike was the same cable that was in my line out. I had a direct box with me and never thought to try it. I plug the line out cable in the snake. Like I said, there was no buzz period in the monitors or the speakers for the mains. Only when he put his earphones on. He had to take the earphones off because the buzzing was hurting his ears. I think this was a kid tinkering. Before we started playing, the monitors quit working and the "soundman" couldn't fix that. We went 3/4 of the night with no monitors.The was no problem with the gig we played 2 day earlier.
     
  6. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    clueless soundman sounds about right. also, the fact that the buzz was only audible thru the headphones makes me wonder if instead of describing 60 cycle hum, he was instead describing distortion/overexcursion of the headphone "speakers" themselves, which often happens when running bass guitar thru them unless it's compressed to heck. ;)
     
  7. thedoctor

    thedoctor

    Jun 20, 2005
    Is it possible that the PA was plugged into a differnet phase of 3-phase? This would only happen in a large venue like a BIG school, church or civic center. If your power is 120 degrees out-of-phase with his, problems arise. You would think that all the DC filtering and such in most equip. would filter this out but it is something to look at.
     
  8. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    That wouldn't cause a problem.
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    I also would wonder about the headphones/amp. A mixer is lucky to have more than maybe a tenth of a watt available on the headphone out, not enough to handle much volume, especially with bass. A groundloop would be heard systemwide.
     
  10. tramp

    tramp

    Mar 5, 2004
    South Louisiana
    Yep, it was a kid tinkering. I played at the casino this past weekend, lined out and had no problems. Ofcourse, we had a professional soundman. :bassist:

    Tramp