Which Power Tube ?

Discussion in 'Audio Hardware' started by iDigital, Apr 16, 2019.

  1. Salectric

    Salectric Forum Resident

    Location:
    Maryland
    It’s hard to separate the sound of the particular output tube from the sound of the amp in which it is being used. Also, the sound of a pentode or beam tetrode when used in a SE amp as opposed to push-pull. For my money I prefer PP over SE, and my favorite output tube in a PP circuit is the 6L6GC.

    I don’t know how anyone can describe the “sound” of a 6L6GC because different makes sound so different. I have 4 sets that I use—-RCA blackplates, GE grayplates, SED Winged C, and Tung Sol STR, and they sound wildly different from each other. Of these only the T-S is currently manufactured, but the good news is it sounds great. I would have no problem using the T-S exclusively.
     
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  2. russk

    russk Forum Resident

    Location:
    Syracuse NY
    This has been brought up before but I don’t think anyone is making a true pentode el34 or at least no one was a couple of years ago. Do you know if anyone actual making a true pentode el34?
     
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  3. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Not really, but it is something that I never paid any particular attention to, before this thread.

    I don't particularly care for modern production EL34's anyway, more linear, less magic. I far prefer KT77's or KT88's.

    Maybe that is one of the reasons that NOS EL4's sound so much better and have that magic midrange.

    With NOS KT88's being completely unaffordable, were basically stuck with modern production.

    With NOS EL34's being one of the few NOS power tubes that are actually sound beautiful and are affordable, I can't see any point in buying modern production EL34's anyway.
     
    Rolltide likes this.
  4. I know they are supposed to be non reliable, but JJ makes 5 different tubes in the EL34 family:
    EL34
    EL34II
    EL34L
    KT77
    6CA7

    Maybe the first one on the list could be a true pentode? I wouldn't know how to recognize them anyway...
     
  5. SandAndGlass

    SandAndGlass Twilight Forum Resident

    You could not tell from looking at the tube from the outside.

    You would need to see a diagram.

    [​IMG]

    In the diagram above, instead of a third set of grids, there are a pair of beam forming plates, which are connected to the cathode.

    Like in the diagram below.

    [​IMG]
     
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  6. gov

    gov Forum Resident

    Location:
    NYC
    And to me the first sentence of your reply holds the most truth. I’ve tried 5 different 6l6gc’s—both current production and NOS—in my amp and in a few cases I did not find the “conventional” wisdom to be the reality in my amp and room.

    As an example I found the fabled RCA blackplates to be a bit edgier and brasher than alternatives despite their reputation as having “creamy” mids.
     
    Salectric likes this.
  7. Salectric

    Salectric Forum Resident

    Location:
    Maryland
    That is interesting and a good example of the importance of the platform, i.e. the amp, when evaluating tubes. In my amps the RCA blackplates do sound creamy—smooth and relaxed in the midrange especially—but they are rather soft in the bass and treble.
     
  8. Larry I

    Larry I Forum Resident

    Location:
    Washington, D.C.
    Salectric and gov,

    Have you tried 35o's in your amp? I know they draw a bit more current than 6L6-type tubes, but, most 6L6 amps can run them.
     
  9. Salectric

    Salectric Forum Resident

    Location:
    Maryland
    I would love to try some WE 350B tubes but that's not likely to happen given today's prices.
     
  10. gov

    gov Forum Resident

    Location:
    NYC
    Same as @Salectric ...interestingly enough I was just looking at them last week but since I need 4 and a quick survey of prices range from $800-$1400 per tube I'm self ejecting from that rabbit hole. I'd love to hear them in my amp one day to compare and get a sense of what they do differently...maybe a SHF tube meetup--tubejam?
     
  11. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    Yet another reason to only buy NOS tubes. Modern equivalents sometimes aren't accurate such as EL34 or KT66.

    Meanwhile, I suggest for the OP to read through this thread for some ideas on what to buy.

    Best EL34 tubes
     
  12. Salectric

    Salectric Forum Resident

    Location:
    Maryland
    For output tubes I don't buy into the only-NOS mindset. My Tung-Sol 6L6GC STR sound great and you can buy a carefully matched quad for a bit more than 10% of a matched quad of NOS RCA grayplates.

    Input and driver tubes are a different story. For those spots I use only NOS because the modern reissues were far inferior the last time I checked. However, maybe they have improved as well. I really don't know since I have a nice stash of NOS vintage tubes that should be sufficient to cover my needs for as far as I can see into the future.
     
  13. vinylkid58

    vinylkid58 Forum Resident

    Location:
    Victoria, B.C.
    If the windows in the plates are big enough, you can see all three grid wires. I have an old pair of Shuguang EL34A's, and you can see all 3 grids.

    jeff
     
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  14. Larry I

    Larry I Forum Resident

    Location:
    Washington, D.C.
    A friend just got a WE 124 amp for a mono system (found by his brother). It looks almost brand new. The amp came with WE 348 and 350B tubes and, I believe, a WE 274B rectifier. I think he had someone modify the input circuit to match the gain needed for his system (reversible modification, of course). Now, if you think the 350B is an unobtainable tube, check out what 348's go for (if you can even find them being offered) and the 274B (fortunately, only one per channel is needed).
     
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  15. IanL

    IanL Forum Resident

    Location:
    Oneonta, NY USA
    In my amp they have excellent bass and treble. Midrange is good too, but kind of flat in presentation.
     
  16. musicera1969

    musicera1969 Member

    Location:
    LA
    -------------------------------------------------------------------------------------------------------------------
    Power tubes: The tube to choose - not just for quality sound but AVAILABILITY.
    EL34 with 6CA7 and KT77 drop ins - are in plentiful supply among several brands. Many like the Gold Lion KT77 but they have an price tag of $50.00 each .
    The Tung Sol EL34B are outstanding tubes with excellent sound at less than half the price per tube of GLs. NOS are cost prohibitive.
    Many like and still talk about the Svetlana winged C but that tube ceased production in 2012 with those loyal to that tube snapping up the supply.

    Power tubes last 1000 hours. Playing at high volume figure less than that. With prices going up - an back up set or two is a good idea.

    You said " my room is small and I no longer play loud music" Well then your power tubes will NOT be stressed and will have an longer lifespan
     
  17. Ralph Karsten

    Ralph Karsten Forum Resident

    Location:
    St. Paul MN
    One tube you might consider is the 6B4. This is similar to a 2A3 but in an octal package and is available fairly cheap. If you go more than about 7 watts bandwidth is often an issue with SETs. If you are intent on using pentodes or tetrodes you might look into horizontal sweep tubes as they are often inexpensive and powerful, although they have the downside of having to use a plate cap which would be an exposed voltage.

    Its the distortion of an SET that convinces you that you don't need much power. Take away the distortion and its natural to use more power since the ear uses higher ordered harmonics to sense sound pressure. Essentially SETs or SEPs can fool you into thinking they are louder than they really are.
     
  18. SandAndGlass

    SandAndGlass Twilight Forum Resident

    With high sensitivity speaker's, SET's and SEP's can play quite loud.

    What I found it that with my 3.9-Watt SEP, I find that the music sounds so real and so full that I can listen at substantially lower SPL's than I usually listen to with a class A/B tube amp.
     
  19. Ralph Karsten

    Ralph Karsten Forum Resident

    Location:
    St. Paul MN
    My speakers are 98 dB 1 watt/1 meter and 16 ohms. I find that I actually use the power when I put 60 watt amps on them. But my amps, while being all triode and class A, make about 1/10th or less of the distortion made by SETs. So they lack the artificial loudness cues common with single-ended power output sections (IOW, triode, tetrode or pentode). When it doesn't sound loud, there is a natural tendency to turn up the volume. But if it does sound loud (even when it isn't) you'll have less incentive to crank it up. I get the part about involving qualities of SETs, but if a push-pull amp is properly designed it can be just as involving if not more so at any volume.
     
  20. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Before I bought my SET & SEP amps, I tried ten other A/B class amps.

    I like the sound of all of them.

    One of them in particular, a 30-Watt L4 ANK amp with NOS EL34 tubes comes very close.
     
  21. Burt

    Burt Forum Resident

    Location:
    Kirkwood, MO


    7C5 is a Loktal, not an octal tube. Loktal tubes have an eight pin base but it has fine pins and a center post with a locking arrangement. If you're of a certain age like I am it will remind you of a movie projector bulb.

    Loktal types that have a 7 or 14 in the number actually have 6.3 or 12.6 heaters but they use the higher number to let you know of the different base.
     
  22. misterdecibel

    misterdecibel Bulbous Also Tapered

    I'd make sure it has enough heater current for EL34s before going that route.

    Also, push-pull 6V6 or EL84 may be an option as well, since they can be biased AB1.
     
  23. Burt

    Burt Forum Resident

    Location:
    Kirkwood, MO
    Other than the fact that NOS is becoming unobtanium for any desirable tube types....that would be a good idea.
     
  24. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    It isn't for most tubes, though. Just overpriced for lots of models... IMHO.
     
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  25. iDigital

    iDigital Well-Known Member Thread Starter

    Location:
    Australia
    Hi All, Okay, I will definitely make this build a single ended one, mainly because I have never experienced one and I need to, I am also contemplating jumping on two other complete amps, based on the Mullard 5-10 design and make mono blocks, as the seller intended to do as well, so some fun times coming up
     
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