EL84 vs 6v6

Discussion in 'Amp Central Station' started by johnnykf, Feb 21, 2006.

  1. celeste

    celeste Friend of Leo's

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    If you look at the data sheets and particularly the average characteristics graph for both tubes, you will see that at a given anode and screen voltage, for the same idle plate current, you will need 2/3-1/2 the bias voltage for the EL84. That means it needs less drive voltage for a given power output when compared to a 6V6. That shifts distortion farther back in the gain structure, and changes the tone.
     
  2. Billm

    Billm RIP

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    Bias an EL84 and a 6V6 to the same idle dissipation, same cathode current. Take their glass temp or use an IR thermometer to read the plate temp. The EL84 will always be about 20-30 percent hotter.
     
  3. Big_Bend

    Big_Bend Poster Extraordinaire

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    All I know is I sent my Blues Jr. to BillM and he notified me yesterday that it was ready.. I got almost all the mods, including the one that converts the amp from EL84s to 6V6 tubes.

    I've never really liked EL84 tube amps.. I can't wait to hear how the Blues Jr sounds now with the 6V6 tubes. I am definitely wanting more clean headroom, more Deluxe Reverb tones instead of the classic EL84 tones I had before.

    I'm pretty stoked about my 6V6 amp coming back in the mail soon. Thanks Bill!
     
  4. DOGMA Dunn

    DOGMA Dunn Friend of Leo's

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    Depends on the amp and the guitar's pickups. Each type of power tube has amps that do a specific sound well. Add in the variable of the pickup and there is a whole lot of sounds each can make.
     
  5. jefrs

    jefrs Doctor of Teleocity

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    Not a fair test ;) because they have different parameters. But the EL84 does run hot (temperature) due to its "poor" design cramming too much into a miniature bottle. However the "hifi" ECL82 triode/pentode proves it can be done. To my ears the 6V6 also has a more "hifi" sound than the EL84, less crunch when pushed and so on. Depends what you want, both are good.
     
  6. Justinvs

    Justinvs Poster Extraordinaire

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    I know this is going to sound like a stupid question, but can you fit an EL84 into a socket designed for a 6v6?

    Justin
     
  7. mgwhit

    mgwhit Tele-Holic

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    Not without an adapter (like YellowJackets). EL84's are 9-pin tubes and 6v6's are 8-pins.
     
  8. jefrs

    jefrs Doctor of Teleocity

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    And the adaptors run the EL84 in triode mode, which is a shame because they're pukka pentodes (the 6V6 is a beam tetrode).

    What you can do to some amps is fit B9A sockets alongside the octals, pull the 6V6 and run the EL84. Requires extra components to bias and run the valves right. See "octal mod" for Epi Valve Junior (EVJ).
     
  9. TaylorPlayer

    TaylorPlayer Tele-Afflicted

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    I have both in the form of a Peavey Classic 20 and a Magnatone Custom 413. Each certainly has it's own voice but the magic in my book is running the two together. Best of both worlds! :D
     
  10. Maggot

    Maggot Tele-Afflicted

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    The difference between EL84s and 6v6s is that EL 84s sound awesome, but 6v6s sound awesome. I always preferred 6v6s because they look cooler.
     
  11. hotraman

    hotraman Tele-Afflicted

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    This is good information to know. I'm not really a amp expert, so this has been very informative.
    I own a Mesa Express 5:25 with EL 84's. I love the tone I get with this amp, even at the 5 watt setting.
     
  12. Jupiter

    Jupiter Telefied Silver Supporter

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    Regarding all things being equal:

    The Egnater rebel 20 has 2 6V6s and 2 EL84s and a blend knob that can go from one set to the other and all points in between.

    Anyway, since it's the same tone stack, and volume, gain, speaker and everything like that would also be exactly the same, listening to one of those Rebels might answer your question.

    FWIW, I haven't listened myself, but I read a review (in Premier Guitar, maybe) that said the difference was pretty subtle, considering what a sales point Egnater makes of it.
     
  13. Jethro

    Jethro Tele-Afflicted

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    This is quite interesting...
    I have an old Fender Super 60 (not so common) that runs 2 6L6's. I quite like the warmth and clean tone of this amp, but I must say it really doesn't like to give any natural breakup. I can play at 10 and its still quite clear. I typically have to use a light OD pedal to achieve any. I had thoughts of possibly trying the yellow jackets with EL 84's to see if I might be able to....any thoughts there???
     
  14. Billm

    Billm RIP

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    The output tubes don't do the majority of the breakup in Fender amps. It's distributed across the preamp, phase inverter, and output stages. The Super 60 designer chose values in the preamp that limit distortion -- small coupling caps, large grid resistors.

    The output stage runs at a relatively high voltage, which extracts maximum clean from the 6L6s. Other aspects of the output stage are designed for clean, as well. I wonder if the Yellow Jackets can handle 475V.

    But the Super 60 has a switchable high-gain distortion stage. You're saying that it doesn't work?
     
  15. eggman

    eggman Friend of Leo's

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    Howdy,

    Jethro: I think you meant EL34s for your Super 60. The EL34 is the rough equivilent of the 6L6 in terms of power. BTW, I have a Super 112, which is very similar; great clean tones.
     
  16. Billm

    Billm RIP

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    No, he really meant EL84s. Yellow Jackets are cathode-biased EL84s that you can run in octal sockets to reduce output power and hopefully increase distortion tone.
     
  17. Jethro

    Jethro Tele-Afflicted

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    Thanks Bill,

    The switchable high gain stage does in fact work but I never use it. Dialing in a nice tone takes a bit of finagling the dials and it tends to be quite shrill and trebly. Of course once I dial in a tone I like I can't switch back to the clean without more finagling. Makes it difficult at gigs, so I use the pedals to simplify this issue. I do quite like the amp and get a lot of compliments for its tone....I was just toying with the idea of an earlier breakup which would allow me to just use the vol pot to dial it in or out of that.
     
  18. Jethro

    Jethro Tele-Afflicted

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    Hi Eggman,
    I think we've chatted on the Super 60 thread. Bill is right, it is the 84's I was referring to. I was thinking it may help me to achieve that earlier breakup, and without too much fussing. Although, I haven't heard much feedback/reviews on these yellow jackets
     
  19. jefrs

    jefrs Doctor of Teleocity

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    And EL84 "should not" be run in triode mode because they don't sound right then. Another thing they don't like is ultra-linear mode. Another is that there is little to no advantage running it grid biased. Something to do with the internal gain of the valve and its grid current, essentially down to its "poor" design. i.e. it's designed to do one thing well - run cheap domestic appliances in pentode mode cathode biased.

    Making the EL84 or the 6V6 or indeed any other output valve overdrive and break up needs the amp pushed to maximum - most of the distortion is in the pre-amp stages. Because the EL84 does provide a significant gain, it can perhaps break-up more than other valves doing this. The trick is to use playing dynamics to control it. High-gain amps normally have extra gain stages e.g. one stage biased hot, the next cold - to clip top and bottom.
     
  20. Billm

    Billm RIP

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    I agree in part. I have never liked the sound of an EL84 run in triode mode and have always discouraged people who ask for the so-called half power switch on their Blues Juniors.

    I do, however, like grid bias for the extra little bit of clean headroom and less compression in the tone. The old Traynor Guitar Mate is an example of a really good-sounding grid-biased EL84 amp.

    One of my Blues Juniors has switchable ultralinear and conventional pentode operation. There isn't a whole lot of difference in tone, but when you're cranking the amp into hard overdrive, there's less current in the screens and the tone holds together better.

    O'Connor has a very interesting design, the Soma 84, that uses both cathode bias and ultralinear operation to get really sweet tone from a pair of EL84s. You should build one--it's a trip! I wish I'd recorded the one that I built in a Pro Junior chassis for a customer.

    That aside, the 6V6 BJr conversion is becoming one of my most popular mods. And soon I'll have a replacement power transformer that can run 6L6s comfortably, or run 6V6s at higher voltage for more headroom.
     
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