BFDR help....again

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by wleeds, Dec 18, 2009.

  1. wleeds

    wleeds Member

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    I have a 66 BFDR with a C-Rex. I just put the C-Rex in a few weeks ago and have been playing the hell out of it while my DRRI is in the shop.
    The amp was running beautilful cleans up to around 6 1/2 before any slight breakup. All of a sudden there is a lot of breakup with the volume at 5. I notice that the power tubes and rectifier tube are loose.
    Can this cause the sudden change?

    I'm not an amp guy at all. Can I open it up and tighten the sockets withour discharging the caps?
     
  2. phsyconoodler

    phsyconoodler Member

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    The sockets are tightened from the outside,but you should be aware of voltages.To drain the caps enough to do the job,play the amp and turn the power switch off while playing and keep playing til there is no sound.That will sufficiently drain the caps so you can do the job.
    I would think however,that you have a bad power tube.
     
  3. wleeds

    wleeds Member

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    now it's really wierd. I popped ths tubes out The socket screws are tight but the actual tube socket, where the pins go in is loose. I haven't opened up the amp. I put the tubes back in and now it's back to being clean. I assume there is some connection coming loose somewhere. I also noticed, and this probably has nothing to do with anything, that both 6V6's are MESA's, same number on the tube but one is slightly shorter than the other. The rectifier is a Mullard.

    THis amp has been very frustrating. I want to be able to rely on it for gigs, it blows the drri away...when it works.
     
  4. mbratch

    mbratch Member

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    I assume you mean that the "plastic" (brown) part of the tube socket is tight as well and the pin receptacles themselves are loose? It is normal for there to be a wee bit of "play" in the socket "receptors" in the holes. But way too much play and/or bad contact with the tube pins could be an issue. They might just need tightening. Or, if they're severly worn out enough, you might even need new sockets. It shouldn't take much to make the amp reliable for you.
     
  5. phsyconoodler

    phsyconoodler Member

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    Fender sockets are notoriously loose feeling.The metal contacts are indeed flopping around as the socket itself is rigid.
    Also the tube pins don't go all the way into the socket.I've changed many Fender sockets because of this over the years.
     
  6. wleeds

    wleeds Member

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    The part thats loose, or has a lot of play is the pin (black) socket. The rectifier and the tube beside it have a lot of play compared to my drri that has none.
    When its working right it really is amazing. You already knew that:facepalm
     
  7. mbratch

    mbratch Member

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    The black part shouldn't be loose. In theory, as long as the tube is holding securely in the socket by the pins and wiggling the socket doesn't cause a short, it should work fine. However, the vibration of the amp may cause an issue with the tube and could work the tube loose while playing (potentially). I would probably replace the sockets.
     
  8. tubetwang

    tubetwang Member

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    i would change those for phenolic sockets.

    you want a tight fit on them tubes.
     
  9. wleeds

    wleeds Member

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    It just went on the fritz again.
    This time I noticed that one of the output tubes seems warmer than the other and the rectifier isn't as warm as the power tubes. This is after the amp being on and playing for around 15 minutes. It started out clean and got dirty after a bit.
     
  10. slider313

    slider313 Silver Supporting Member

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    Are you using JJ 6V6's? The reason I ask is that the pins on the JJ's are slightly smaller in circumference than most and can cause contact issues.
     
  11. wleeds

    wleeds Member

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    They are MESA 6V6-GTA STR-417.
     
  12. slider313

    slider313 Silver Supporting Member

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    Try another set of 6V6's. Also, has the amp ever been serviced?
     
  13. wleeds

    wleeds Member

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    seems better with a set of jj's from another amp.
    Now the question is what alternatives are there to the JJ's?

    The amp has been serviced about a year ago. Apparently the caps were fine and the tubes at the time.
     
  14. davemccarthy707

    davemccarthy707 Member

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  15. slider313

    slider313 Silver Supporting Member

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    You probably have a bad tube in the Mesa set. Get a set of the new Tung Sol 6V6's.
     
  16. wleeds

    wleeds Member

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    When the MESA's were working they had a full sound to them. THere didn't seem to be a frequency more dominant than any other. The JJ's seem to have a little more lower(?) mids. How do the JAN Philips sound?
     
  17. Lonesomedave

    Lonesomedave Member

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    I've heard good things about the new Tung Sol 6V6's as well...
     
  18. wleeds

    wleeds Member

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    Any thoughts on the MESA's?
     
  19. zzmoore

    zzmoore Member

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    We have had good results in a Fargen and a Fender with these tubes; both tone and longevity.
    Good Luck
     

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