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Ampeg SVT II (non pro) 1991

Discussion in 'Amps and Cabs [BG]' started by GeezerB, Jan 22, 2014.

  1. GeezerB


    Nov 5, 2013
    Hi, i just bought it and when i power it i let it warmed about 5 minutes and open it it works well for about 10 minutes and shut off, what is the problem, a fuse or power tubes?
  2. jmpiwonka


    Jun 11, 2002
    could be many things

    try the simple stuff first
    stick a patch cable in the preamp out/amp in jacks
    try cleaning them with contact cleaner maybe

    this amp doesn't have any protection so it's probably not actually shutting down? you just losing signal?

    try plugging your bass into the amp in jack in the back when the amp start acting up...this will tell you if the problem is in the preamp or power amp section

    does it play fine after you turn it off then turn it back on or flip it to standby?

    two other things that caused this problem for my svtII (the jacks in the back were once) was a bad preamp tube and then the connector that plugs in to one of the boards coming from the preamp board. the plug had to be re-worked.

    btw i could always get sound from the power section when it was acting up so i knew it was something related to the preamp or signal from the preamp...
  3. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Might be a tube, might not be. There are ways of checking your tubes, such as subbing out a known working tube of the same type until you find a culprit, but if it works 5 minutes and stops, I'd suspect something else. Best to always take a tube amp into your local tech when you buy one used anyway, just to give it a bill of health.
  4. GeezerB


    Nov 5, 2013
    Hi, tanks, i just send the amp at the music store yesterday and the problem is 2 bad power tubes and a bad fuse, now it works good, but i want to know what is the best power tubes for this amp. Thanks.
  5. catgut


    Jan 15, 2014
    Seattle, WA
    There are no 'best'. There is best to you and best to me, etc… How about some Sovtek's or JJ's or Tun-Sol's? Fun thing about tube amps is that you can experiment and in doing so alter your sound slightly and in some cases greatly. A side note, I have always found Groove-tubes a bit too hot with their 6550 sets (overdrive at 3!). GEs would be and have been great when I had my 72' SVT but they seem super expensive nowadays. I used GE's back in 1991.
  6. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I'm not disliking the JJ's in my Heritage.