Time to replace those tubes again

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by SteveOnSteve, Feb 23, 2012.

  1. SteveOnSteve

    SteveOnSteve Member

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    So, I'm currently playing through a Mesa Stiletto Trident Stage 1 and the other night my power tubes burned out on me. I've been using the JJ standard retube kit with E34Ls in the power section, ECC83S preamp section, and GZ34 rectifier replacement option.

    Basically, I'm just asking for any opinions on retubing preferences. I'm looking to stay around the same price range as JJs (about $200 for the whole set). So, unless somebody wants to give me some high quality NOS tubes for free, those seem to be out of the question..

    The only other tubes I've tried were the almost dead Mesa tubes that came with the amp in the trade (rectifiers included) and JJ KT77s in the power section.

    Any feedback is appreciated!

    Thanks guys!
     
  2. 900z1

    900z1 Member

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    Why replace the whole set ?
    Power tubes wear out the fastest, and it's a good idea to replace the phase inverter at the same time because it works hard also ( the tube beside the power tubes) but the other preamp tubes can last for years... so...
    why not get a nicer set of power tubes and keep the preamp tubes that are still good ?

    you can use lots of different tubes in your amp, but if you don't know how to bias the power tubes, you will need to take it to a Tech that knows what's up. Mesa says their amps don't need adjusting, but that's only if you use their colour coded tubes.

    you can use 6ca7's, jj makes a nice sounding 6ca7
    you can use new issue mullard EL34's, Winged C, New issue TungSol's or even splurge and get a set of NOS EL34's.

    the 6CA7's are the same pinout as the EL34's and sound like a cross between the EL34 and a 6L6.
    I have heard of others on this forum using KT77's but I have not, so ask others..
     
  3. SteveOnSteve

    SteveOnSteve Member

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    Ah, that's definitely good to hear that it's not necessary to replace all the tubes. My main reason for thinking about replacing the whole preamp section was that I had read on a few forums that it's usually good to replace them every other time you replace the power tubes. So thanks for clearing that up!

    I've read about the jj 6ca7s and they definitely sounded like something I'd like to try. Have you personally tried them out? Also, how do the Winged Cs compare to JJs, in general?
     
  4. GearHeadFred

    GearHeadFred Member

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    How old were your old tubes?
    Are you sure it's the tubes?

    Unless you bias them too hot or abusing them in some other way (amp dimed), output tubes should last a pretty long time.

    Preamp tubes should last a REEEEAL long time.
     
  5. RussB

    RussB low rent hobbyist Silver Supporting Member

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    The easy and cheap solution is to buy a set of Mesa branded power tubes.

    By getting your power tubes at random, you have no way of knowing if they are operating within safe parameters
     
  6. SteveOnSteve

    SteveOnSteve Member

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    I've actually only had the tubes for about a year (same with the last pair). We normally play twice a week and the volume is never past 4, 4 1/2, and I run the head into an older Soundcity cab, stereo at 8 ohms. While we were playing, the amp basically just started sounding bad - no low end, the mids were lacking, and the highs became distorted. The usual amount of gain was still there, so, as i'm finding out, I doubt it has anything to do with the preamp.

    The last time the power tubes went, there was a considerable volume drop. This time I didn't necessarily notice a drop in volume, but then again we all but stopped playing when there was a difference in tone (because it was that noticeable).

    Also, when I last replaced the tubes, I didn't have the amp biased. I confirmed with eurotubes both times I retubed my amp, and they said all the tubes were drop-in, no re- biassing needed for Mesa heads.

    Maybe it's time to have the head checked out.. or at least re-biassed?
     
  7. 900z1

    900z1 Member

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    I have a set of 6ca7's in my traynor yba1a. I noticed a difference in bass playing with them, but a real difference with guitar.

    I had Winged C EL34's in before the 6ca7's and I prefer the 6ca7's, but that's my preference, and may not be yours.

    In my personal opinion, you will be happy with having the power amp biased properly with a new set of tubes. different manufacturers need different settings to get the same dissipation or wattage, and even different batches of the same model tubes can be different. it's no big deal, it's just a few measurements and changing a resistor, but it can make a big difference in sound, and it opens up the selection of what you can use, ( no longer tied to only mesa tubes )

    I usually install an adjustable pot in my amps to make tube changes easier, if you are likely to go to the same tech again and again, you may want to get one installed in yours, it also aids in finer adjusting of the bias.

    different amp circuits respond differently to different tubes, and after a while, you may also want to get a few different 12ax7's and try them in different spots in the preamp - they can really change the sound..

    I have had good success with both the mullard reissue as a phase inverter and in v1, also TungSol reissues in my deluxe... also NOS 12ax7's can also change everything in some amps, not so much in others - my old amps like them.
    good luck with it.
     
  8. zenas

    zenas Member

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    Keep in mind preamp tubes are plug in and play so you can try all sorts of tubes there.
    Like the other guys said changing all the tubes is a wast of YOUR money. In fact it could be just a preamp tube getting weak. I've had that happen as much as power tubes.
    I also would do a bias pot mod if I had a Mesa.
     
  9. donnyjaguar

    donnyjaguar Member

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    Phase splitter working harder than the other tubes? How is that possible when it has the least amount of current across it? :) Reberb drivers see abusive service alright.
     
  10. 900z1

    900z1 Member

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    I have read in a few different places it is the hardest working preamp tube and should be replaced with the power tubes, however if I am wrong, thanks for the info. Can you explain basically ? is it that each triode sees half the signal ?

    steve
     
  11. SteveOnSteve

    SteveOnSteve Member

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    Zenas, if it was a preamp tube getting weak, wouldn't it be a gradual decrease in tonal quality, or would it be sudden? because this was almost out of nowhere. and the bias mod, is that something I could easily do myself with little experience? or is this for the experienced amp tech? any videos, forums, instructional sites, etc would be awesome if you know of any.

    also, thanks for all the input guys, everything's been helpful!
     
  12. zenas

    zenas Member

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    It may not be a preamp tube but thay are so easy to change why not try it? You should have spare tubes on hand with any tube amp.
    I put a bias pot in an old Hiwatt years ago. Went from a mod for a RI Bassman in a Gerald Weber book.
    Working on a Mesa is tricky with the PC boards if you have a good tech or some experience no biggy. But you can also do damage to yourself or the amp. You have to make that call.
    Almost (I said almost) any problem with a tube amp the first thing I do is swap preamp tubes. I use tubes pulled from organs and junk mostly. Good old tubes but you never know how much life thay have left. For the most part thay do last a long time.
     
  13. Davidg1974

    Davidg1974 Member

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    I would stick with JJs if u are thinking that there is a better tube in that price range because in my opinion there is not one even close and thats from personal experience. I also use eurotubes and have found them to be helpful even when I wasnt buying anything which means alot to me.And adding a bias pot correctly is not a project for a beginner IMHO-maybe on an old traynor but not that amp.Maybe u can do it but how much will it cost if u cant and mess up the board or worse? I know when I first started learning about amps there was a guy that i took my amps too that I paid extra if he let me watch and learn.Maybe u can find someone like that that doesnt care to pass it on down-just make it clear that it is because u want to learn and not because u dont trust his work.
     

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