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Amp noise - take off!

Discussion in 'Amps and Cabs [BG]' started by drd07, Nov 11, 2003.


  1. drd07

    drd07

    Jan 19, 2003
    Hola,
    I was at rehearsal last night and I got this annoying distortion sound from my cab. My setup is a bassman 300 with 2 210 avatar cabs. I previously had a vibrating noise from the cabs before, and I just had to screw down the speakers. Problem solved.

    My band plays really loud and we were paying by the hour, so I went through practice and played it out. I tested it out today to find out what the problem might be on both cabs. Heres what happens:

    On either cab, I get this hissing noise when I play at louder volumes - that almost sounds like a "plane taking off". It happens the same on both cabs, so I don't think that it is the cabs. Could it be the capicitors? The power tubes look fine. Should I take this amp in to a tech? Any advice?
     
  2. Boozy

    Boozy

    Apr 29, 2002
    Kelowna BC, Canada
    Do your cabs contain tweeters? Tweeters hiss... I have to turn my treble down when I use a cab with a tweeter, or it hisses and annoys me.
     
  3. drd07

    drd07

    Jan 19, 2003
    Yeah, the cabs have tweeters. I don't think it's the tweeters though. Do you think it could be anything else?
     
  4. Stephen Soto

    Stephen Soto

    Oct 12, 2003
    Or try turning the treble down and tweeter off :confused: ;)
     
  5. Boozy

    Boozy

    Apr 29, 2002
    Kelowna BC, Canada
    ummm.... I dunno really..

    It should be easy to tell if it is the tweeters causing the hiss:

    Do you have an attenuator knob or an on off switch for your tweeter? If so, turn them off, if the hiss goes away, walla.

    If you can't turn them off, do this:

    Say your tweeter is located roughly like this: O*O (O=speakers *=tweeter)
    Cover the grill where the tweeter is located with your hand, did the hiss just about go away? then it is the tweeter.

    I just turn my treble down to compinsate for my tweeter cause I cant turn them off. Many people just disconnect them.
     
  6. 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
    Tweeters don't cause hiss; they just reproduce it. The hiss is coming from somewhere upstream. It could typically be caused by faulty (or poorly designed) circuitry or by less-than-optimal gain structure.
     
  7. drd07

    drd07

    Jan 19, 2003
    Dudes,
    Problem solved. However, it wasn't the tweeter. I ended up disconnecting the tweeter and the problem persisted. I left my amp alone for a couple of minutes. When I came back, the problem was gone!?!

    I think that I didn't let my amp warm up enough - Doh! Have you guys ever had a similar problem with tube amps?

    Thanks for all your help!
     
  8. Boozy

    Boozy

    Apr 29, 2002
    Kelowna BC, Canada
    Yeah, tube amps need to be warmed up.

    If tweeters dont cause hiss, then why does my tweeter hiss? When I turn down the treble on my amp the hissing goes away. Probably just crappy power amp? or crappy tweeter/cab?

    I don't really care, just curious, (thnx Bob.)

    I run MM StingRay > Sansamp RBI > Fender BXR 300C Preamp in (bypassing the BXR's preamp) > 15" EV & MM EB HD-210... Monster instrument cable, and Monster Speaker cable going to the HD-210 (with tweeter that hisses.)

    Bebop.
     
  9. drd07

    drd07

    Jan 19, 2003
    I think that all tweeters hiss. I usually leave mine turned all the way down or just a tad on.
     
  10. 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
    Does a faucet cause water?

    Does a tailpipe cause exhaust?

    Nope. In either case, that is just where it comes out. Same thing with a tweeter.

    If the tweeter caused hiss, turning the treble down on the amp wouldn't do anything. And if the tweeter caused hiss, the hiss would be there even if you unplugged the speaker.

    The hiss is high-frequency noise coming from either your amp, your preamp, your active bass (if you have one), effects, et al, or any combination of them.
     
  11. Hmmm, guess that means the treble knob on my bass doesn't cause that string noise. [​IMG]
     
  12. Stephen Soto

    Stephen Soto

    Oct 12, 2003
    :eek:







    :rolleyes: