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I think I blew a tube

Discussion in 'Amps and Cabs [BG]' started by dirtrider, May 24, 2005.


  1. So I flip on the power on my DB 359, flip the standby swith start playing and then...sound goes dead, power is off and tubes start "tinkling." I look at the back of the amp and over the vent where one tube is, it's really warm.

    After a minute of disbelief, I open up the case and remove all 4 tubes. The tube that was in the area of the warmth has some blackish discoloration on it. It's not too bad, but none of the others have anything like that. I can't see anything busted in there, but I'm pretty much convinced that I blew this tube. Can anyone confirm and if so, point me in the right direction to replace it/them for as cheaply as possible?

    Thanks.
     
  2. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Try tapping the tube and see if it sounds like the others.
     
  3. Sounds pretty similar. Doesn't sound like anything is rattling around in there.
     
  4. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Remember to tap it all the way around. Tap at the midsection and turn it as you do to check it thoroughly. It will change in sound when you come onto a certian area if it is a bad tube.
     
  5. Well, it seems like when I tap, I can hear the filaments, then at one point, I don't seem to hear anything. What am I listening for?

    Thanks for your help, btw.
     
  6. Anyone else have any input?
     
  7. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    If it sounds at all different from another good tube then you know its gone bad. Try tapping 2 more and see if they sound the same. In my experience, when I hear the fillaments doing their kinda metalic sound then they seem to be bad.
     
  8. Arent they meant to "tinkle" when the powers turned off as its just the glass cooling ???
     
  9. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Mine do that when they power up, but I've never listened as I turned it off...
     
  10. Daytona955i

    Daytona955i

    Feb 17, 2005
    Albany, NY
    can you put two tubes back in and play?
     
  11. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    You can, but you have to do it in the right way. If you don't you are risking your whole amp. So I don't even mess with stuff like that.
     
  12. This would be incredibly funny if you weren't serious! :eek:

    There are two ways to test tubes: in a tester or in an amp. There are no rattles or any kind of physical noises from a "dead" tubes that aren't present in a good one. The ONLY physical indicator that a tube would be "dead" short of a shattered envelope, is when the tube loses vaccum and oxidizes the getter, turning the inside of the glass milky white.

    It sounds like one of your tubes shorted or 'lost" its bias current and WAY overdrew the mains voltage. You probably( should have, BTW) lost the mains fuse, but short of a tester or amp tech checking the amp you have no way of knowing. If it's new, send it back to Aguilar, if not, find a good tech.
     
  13. I wrote Aguilar and the CTO asked if the amp would power up with the tubes removed. I removed them and it didn't power up. Since he asked, something tells me the amp should power up. I looked at the fuses and they look like they are intact. If the fuse(s) are blown, I know the amp won't power up. (At least my SVT 3 wouldn't) I guess I should try replacing the fuses and see if the amp powers up without the tubes.

    Stay tuned.