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SVT 3 Pro "shhh" and crackle, time to change tubes?

Discussion in 'Amps and Cabs [BG]' started by bassman_al, Mar 29, 2009.


  1. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    SVT 3 Pro settings, as recommended by many:
    EQ to taste, other knobs and settings to taste as well. Dime the volume knob and use the Gain knob as master volume. Works nicely overall, get plenty of volume and good tone.

    Problem is that the amp has a "shhh" sound and occasional crackles. I figure that is a sign that I need to replace the tubes, since a similar problem in a Hartke head I had was greatly reduced when I replaced the tubes.

    Diagnosis anyone, before I send tubedepot about $55 of hard earned coin? Thanks!
     
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Chances are it's only one bad tube. No need to buy all 5. Get a 12AX7 and a 12AU7.
     
  3. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    Thanks Jimmy!
     
  4. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    what is the best type to get? JJ audio ok? tubedepot.com has a lot of different kinds.
     
  5. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    JJ's are fine tubes.
     
  6. dmrogers

    dmrogers Supporting Member

    Jan 26, 2005
    Eastman, GA
    My 3 Pro does the same thing. Figured it was one of the tubes. Haven't tried to fix it yet since I'm not playing out right now. I have some old tubes, I should open it up and try to find the culprit.

    Good luck.
     
  7. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    +1 on trying the preamp tubes first.
     
  8. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    New update: last night I turned on the amp with the bass plugged in, but didn't play it. The guitar volume was turned down all the way. I wanted to listen more closely to exactly the type of noise the amp was making.

    For the first 10 or so minutes the noise and crackle continued, then it stopped altogehter. I then played the bass for a few minutes, then sat it down again. Still no noise. The weirdest thing. :eyebrow:

    Is this due to the tubes needing to warm up for a certain amount of time before the noises "burn off?" Anyone experience this? Maybe there is a ghost haunting my machine...:meh:

    I'll try the same thing tonight to see if I get the same results.
     
  9. meatwad

    meatwad

    Apr 9, 2008
    Smallville, USA
    Could be a tube simply needing reseated/dirty socket, could actually be a bad tube. Mine made noises kinda like yours, turned out to be a dirty FX loop jack... A little contact cleaner and plugging in a cable a few times fixed it.
     
  10. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    2 questions: where do you get contact cleaner, and is it possible that a dirty jack can be the problem even if the jack is not getting used? Thanks!
     
  11. meatwad

    meatwad

    Apr 9, 2008
    Smallville, USA
    1. contact cleaner can be found at radio shack

    2. mine was. after unplugging my compressor from the fx loop, mine got instant noise. some contact cleaner fixed it right up. always use the stuff with lube for pots. non-lube for tube sockets, jacks, ect...
     
  12. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    thanks!
     
  13. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    also, how would I go about cleaning a dirty socket? Compressed air can, a couple blasts?
     
  14. bassman251

    bassman251

    Jan 30, 2007
    Some of it may be normal. All amps have a certain amount of noise that is going to be amplified, especially if you crank the volume all the way up. If it is excessive noise then maybe a problem. Not sure about the crackling noise. Could be dirty pots if you are adjusting the volume.

    When I got my SVT3Pro I put all brand new JJ tubes in them & they still have a little bit of noise.

    I use to put the master all the way up and used the gain as a volume control. That is when I noticed a lot more noise.

    So I went back to putting gain on full & use the master as a volume control so the noise is less noticeable.

    You could still get new tubes to see if that helps the problem & use the old ones as a backup.
     
  15. meatwad

    meatwad

    Apr 9, 2008
    Smallville, USA

    Now that you mention it, i used non-lube contact cleaner on my tube sockets followed by compressed air. It worked for me and my III.
     
  16. bassman251

    bassman251

    Jan 30, 2007
    Good idea, it would be better to try that first.
     
  17. bassman_al

    bassman_al Supporting Member

    Apr 16, 2008
    Fairfax, VA USA
    after several repeats of my experiment ("Volume" at full, "Gain" at 9:00) I get the same results. Initially, that shh and crackling noise, followed by quiet. Its gotta be a tube or tubes! I think I'll go with Jimmy's advice to try one at a time.
     

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