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Noisy SVT4-PRO

Discussion in 'Amps and Cabs [BG]' started by barnezy33, Feb 14, 2006.


  1. barnezy33

    barnezy33

    Feb 14, 2006
    Shropshire UK
    Hi all. After owning a used SVT4-PRO for a couple of months
    it has just started to get noisy when I first switch it on. After a short while it goes away and the amp is fine after that even when cranked up. Do the pre-amp valves need replacing? And if so do the need biasing? Any advice/ideas anybody?:help:
     
  2. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    What sort of noise?

    Do you mean that when you turn it on it makes a sort of "rushing" noise and then is quiet?

    If so, it may be a loose solder connection in the preamp. Possibly at a resistor to ground between tube stages.

    That sort of noise is typical of an "inter-stage" capacitor charging up. Once charged, no more noise. The question is why it doesn't charge up quietly, and the answer may be in a loose solder connection.
     
  3. Ncognito

    Ncognito Banned Commercial User

    Jan 8, 2002
    Hoffman Estates, Illinois
    Owner, Xsonics Bass Cabinets
    I've got 3 Ampeg SVT-4Pro's. All 3 are noisy upon start up. Kinda sounds like bacon frying in the pan, then it goes away and everything is fine. Seems to be normal as all 3 do it.
     
  4. syciprider

    syciprider Banned

    May 27, 2005
    Inland Empire
    So that's why I feel like a BLT after playing.
     
  5. barnezy33

    barnezy33

    Feb 14, 2006
    Shropshire UK
    Hi Jerrold. Its not easy to decribe what comes through the speakers. Its not a definate buzz/crackle but a 'windy' kind of noise with a bit of crackle and hiss. I dont have a cab at home to try and its a bit hard to describe without being infront of it! Thanks for getting back.
     
  6. barnezy33

    barnezy33

    Feb 14, 2006
    Shropshire UK
    Hi Ncognito. 3 amps - wow! The one ive got is an old one with the SVT IV pro in blue letters. I dont know how old but i hope its not knackerd! Have you had any problems with these in the past? Thanks
     
  7. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    I haven't noticed that particularly, but......

    Some variation in noise as the various tube stages warm up is normal.

    I sort of assumed you had a pretty loud noise......... and since it suddenly appeared that means either you just noticed, or it just showed up.

    If you don't hear any noise in use, you may not want to get excited about it.

    That sort of thing is not one that most techs are particularly good at finding. Why pay a bench fee for no result?
     
  8. Ncognito

    Ncognito Banned Commercial User

    Jan 8, 2002
    Hoffman Estates, Illinois
    Owner, Xsonics Bass Cabinets
    I have one of the blue faced SVT-4Pros, and 2 of the black faced ones. I think they are identical in design, just the graphics are different. Great amplifier. They all 3 do make some "sizzling" sounds while warming up.