Lazy Super Reverb owner

Discussion in 'Amp Central Station' started by Crazy neddie, Jun 2, 2015.

  1. Crazy neddie

    Crazy neddie Tele-Meister

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    Well I was playing my 68 super yesterday. I recently had the good fortune to pick up a Gibson R8 which is something I have wanted for many years. Anyway this guitar sounds so good though my super that I have been cranking it up with just the guitar and amp. Around half way it just sings and crunches, and you can roll the volumes back to clean it up and it sounds beautiful. But I blew a tube last night, a pre amp tube I think? I have heard the sounds of distant lightning crashes every now and then through this amp for a couple of weeks, but then it just started to make that sound full time. So I have a few questions.
    Anyway do I just start at V1 and start replacing tubes one at a time?
    Do I have to shut the amp off to change each tube or just put it in standby?
    Could it be the rectifier tube? I do have all the tubes I need to replace any of the tubes in this amp but I was hoping for some troubleshooting logic.
     
  2. String Tree

    String Tree Doctor of Teleocity Ad Free Member

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    More often than not, Tubes go bad because certain components in your Amp are Fried.

    With the Power Off, make sure all the tubes are nice and tight in their sockets.
    Same goes for Input Jacks and Speaker Jacks. Loose wires can cause problems too.
    Turn the amp on and the lights down low, look back there and make sure all of the tubes are glowing the same.
     
  3. clintj

    clintj Friend of Leo's

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    Try new power tubes first. They have the shortest lifespan. After that, start rolling in new tubes starting with the 12AT7 in V6, and the 12AX7 in V4. Those two handle both channels. If you lost V5 or V3 you'd have no reverb and tremolo. V1 and V2 handle the Normal and Vibrato channels respectively, and you'd have no sound on just one channel.
     
  4. Crazy neddie

    Crazy neddie Tele-Meister

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    Awesome avatar string tree! As you can see I'm a foghorn leghorn fan myself.
     
  5. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    Has the amp had the electrolytic capacitors replaced?
    They make loud crackling noises when bad... among other issues.
     
  6. String Tree

    String Tree Doctor of Teleocity Ad Free Member

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    Yeah, he's my, I SAY he's my hero!
     
  7. clintj

    clintj Friend of Leo's

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    ^^ A very good point.

    As far as swapping, go ahead and power down. It doesn't take that long to warm up again, and the power tubes are hot enough to give you a nasty burn if you grab an operating one. The power tubes should be run as a pair, too.
     
  8. Johnny Cache

    Johnny Cache Former Member

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    It sounds like you were having arching in one of your tubes. This happens usually in power tubes but can happen in preamp tubes. Did you blow a fuse? If so them there may be other issues. I would think about replacing both power tubes first and see if that solves the problem. Do you know how old your tubes are? It might be best to replace them as a set. I always test the tubes in my amps before replacing them and then test any new tubes I plan to use. I keep track of their strength and condition. If you don't have a tube tester and are going on the faith of others good luck. In which case your better off to buy a full set of good branded tubes and hope for the best.

    Of course it could be the filter caps but I would suspect it's the tubes. Filter caps are pretty easy to change and if the amp is 10-15 years old it may be ready for them to be upgraded. However I've seen Fender amps with 30+ year old filter caps that worked without any issues.
     
  9. jaycoyoyo

    jaycoyoyo Tele-Meister

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    Unfortunately I can't comment on how to fix the amp, but I can't resist to ask how you tolerate a "cranked" Super? Wowza...that must be loud
     
  10. muchxs

    muchxs Doctor of Teleocity

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    I'm thinkin' tech time.

    Murphy's First Law of Vintage Amps:

    If you speak the same language as your amp you know an amp makin' funny noises is beggin' for service.

    Murphy's Second Law of Vintage Amps:

    An amp begging for service will start to beg louder. In other words if it's makin' funny noises it will eventually make loud funny noises.

    Murphy's Third Law of Vintage Amps:

    An amp subjected to deplorable working conditions will eventually go on strike.

    An amp that's takin' a break is still preferable to a broken amp.
     
  11. clintj

    clintj Friend of Leo's

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    ^^^

    I may just print that out and stick it above my bench. :D
     
  12. Paul in Colorado

    Paul in Colorado Telefied Ad Free Member

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    I can't help you with the repairs, but a Les Paul and a cranked Super Reverb is a beautiful thing.
     
  13. Wally

    Wally Telefied Ad Free Member

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    A nice Les Paul and a cranked SR that is in good operating condition can be a beautiful thing. However, cranking an amp that has started making noises...as described : " I have heard the sounds of distant lightning crashes every now and then through this amp for a couple of weeks, but then it just started to make that sound full time.".....is asking for that 3rd law listed above.
    therefor, I am much in agreement with muchxs on his first statement: "I'm thinkin' tech time." With all due respect, Crazyneddie, but imho... ignoring those noises and meantime cranking the amp is evidence that the experience to deal with this amp's problem lies in a tech. Or not....it is your amp.... Hopefully, the OT is still good to go. More than likely it is, but that would be the worst case scenario. Hence the need not to ignore those types of noises.
     
  14. Crazy neddie

    Crazy neddie Tele-Meister

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    Thanks for the words of wisdom all. I do have a good tech and he changed out the caps a few years ago. These tubes are TAD's and its my first go around with them. I do have a few other sets of tubes including the ones I replaced with the TAD's I can try. I have a bias probe and multimeter, etc and I have biased plenty of amps. I think I should be biasing this amp around 35 MV correct?
     
  15. clintj

    clintj Friend of Leo's

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    Depends on your power tube plate voltage and personal taste. For a typical voltage of 470, 35mA is a nice middle of the road. You can go colder, down to 55-60% and see what you hear, or up to close to 70%. I eventually settled on 65% plate dissipation being what I like best. Fender traditionally biased cold for longer tube life.
     
  16. aaronftnm

    aaronftnm TDPRI Member

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    A friend of mine was having a similar problem with a Twin Reverb, and it turned out that the tube sockets and the small thing that holds the tube on both needed to be re-tensioned. Any time you would walk past the amp it would start to crackle and pop super loud. Maybe cranking the amp rattled a tube loose.
     
  17. Crazy neddie

    Crazy neddie Tele-Meister

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    Well I did want to get the original speakers back in this amp so I suppose a trip to the tech is in the forecast.
     
  18. Wally

    Wally Telefied Ad Free Member

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    +1 with ClintJ.
    I just finished setting up a March, 1966 BFDR. IT had already been recapped...although I did remove the 2 x 47mfds in the first stage for more appropriate capacitance. Who wants to take out a vintage 5AR4/GZ34, right?
    The amp came to the present owner with Sylvania GTA's......biased at 102% of max plate dissipation. (8^O .....no redplating, though. It is now biased at about 67%...sounds good and lively. The bias voltage is at -32.5v. The schematic calls for -35v...so Fender voltages would cool the tubes down a bit as far a plate dissipation. It would increase the B+ a bit, too. I am probably going to suggest to the owner to run a 5R4 rectifier to bring the voltages on down closer to the schematic....although these aren't bad....420's at different adjustment points up in the 60-70% range. Surprisingly, the wall voltage has been 117-119VAC here lately.

    useless question of the day.....what would you give for a stable 120VAC at the wall at all places at all times?!? eeeeehaw....
     
  19. clintj

    clintj Friend of Leo's

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    Neil Young runs a Variac on his tweed Deluxe to get constant voltage to it - he's that picky on his tone.

    That AC variance is why I seldom bias to a full 70% - wall voltage creeps up and suddenly you're flirting with red plate territory on these high plate voltage amps.
     
  20. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    +2 with clintj -

    And why would you think that? You mention "biasing plenty of amps" but aren't sure how to begin checking tubes...IF tubes are the problem at all?

    I think you have either been reading the wrong or some very limited tech material.

    There is no number you can pull out of the air for biasing. As previously mentioned, once you know the plate voltage you can figure out a general *starting* point. But the actual bias setting depends on the tubes, plate voltage, speakers (because tight speakers may sound awful with a cold setting) and getting the best sound FOR YOU within a safe zone. ma settings (large manufacturers simply set them by negative bias voltage) are used ONLY as a starting point. There is NO specific setting rule, no matter what you may have read. Even charts showing plate voltage and "proper bias settings" are BS. They only give guidelines, not specifics.

    As far as isolating the problem in your amp - FIRST determine if the same problem is in both the normal and vibrato channel. If it's in only ONE, then the problem is related to the preamp for that channel only.

    If it's in both, then the preamp sections are not the problem - it's in the phase inverter or power section (or components leading into the phase inverter or the power supply circuit for those sections).

    When you get noises like that the first thing you do is isolate the problem. Otherwise you are chasing your tail - if the problem is in the vibrato channel, changing the first preamp tube is irrelevant; if it's in the normal channel, changing the second (or the reverb/trem tubes) is also a waste of time. And if it's in the power section, you can leave the preamp tubes alone.

    Honestly, (and I mean this in kindness) you need to take the amp to your tech. You are in over your head. And I would suggest not biasing any more amps either until you understand the parameters.

    Good luck -
     
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