1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Ampeg SVT-cl problems

Discussion in 'Amps and Cabs [BG]' started by iannaconej1, Mar 29, 2014.

  1. iannaconej1


    Mar 29, 2014
    Hey guys today i been having some problems with my SVT. Its one of the newer cls and its having some crackling issues. It use to happen every once and awhile but its getting more and more common. It almost sounds like there is dust between the tube and the connecter and its burning it off.(i know its not that but just trying to describe it) it can happen with no signal going into amp if its just on idle off of standby and it also happens when i play. I've read that the 12AU7 could possibly be the problem but would love to have another opinion

    Thanks in advance c:
  2. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    It probably is a tube. If you have one of each kind that's in it that you know works, you can replace each tube one at a time till you find a culprit. Or you can take a light wood stick like a chopstick or butt end of a wooden spoon and tap each tube lightly while it's on and turned up a little to see if any of your tubes do weird stuff. Don't use anything metal for obvious reasons.
  3. iannaconej1


    Mar 29, 2014
    okay ill try this out tomorrow and let you know if it works (PRAYING IT DOES)
  4. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Well bear in mind I'm no tech ;) I could be wrong.
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Jimmy is on the right track.

    The first thing to do is to see if the crackling can be isolated as coming from the preamp or the power amp. If you know that, you can narrow down the area to search. On the back of the amp there is a pre out and a power amp in (check the manual if you don't know where these are). Plug your instrument into the power amp in and listen for the crackling. If you can, take the pre out and feed that into another amp, listen.

    Next step. There are a number of possibilities but the easiest first thing to do is to check out the tubes. Even if your amp is fairly new, a tube that shouldn't have could have got through quality control.

    The small signal tubes like the 12AX7 and 12AT7 are the easiest to look at. Buy a known good spare of each and substitute them in one at a time and see if it resolves the crackling. It is easiest to start with the power amp small tubes.

    But there are also tubes in the preamp. To get access to them you will need to remove the preamp which is the part in the top of the cabinet. There is some danger in opening up the amp. Even if the amp is unplugged you can get a shock if you tough the wrong thing.

    Here are some guidelines for when it is time to look at your tubes.

    If this doesn't resolve the crackling, time to have it seen by a tech. The first thing that they should do is clean the jacks and tube sockets with a product such as Deoxit. The crackling could also be caused by a loose connection, bad component, solder joint so those things would have to be looked at.
  6. Laurent

    Laurent Supporting Member

    May 21, 2008
    Napa, California
    Yes tube problem. Classic symptom.
    I suspect power tube section is the culprit.