Why no Power Tube distortion pedals?

Discussion in 'Effects, Pedals, Strings & Things' started by Resonance7, Mar 8, 2015.

  1. Resonance7

    Resonance7 Member

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    So everyone is always going on about power-tube distortion..why aren't there 6v6 or el84 pedals? Just curious...
     
  2. darkinners

    darkinners Member

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    You mean like 50w output and plug it into an amp input?
     
  3. gibs5000

    gibs5000 Member

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    because power tubes supply power, and if you get a "power tube distortion" pedal, then your just getting a power amp, no need to make a pedal, unless it already has a preamp section, then it could be your amp-on-a-board pedal.

    Power tube distortion is achieved when your power tubes are pushed to the limit (turn the volume to 10). The whole 15watt, 50watt, 100watt ratings, are really giving you how much clean headroom is available before the power amp begins to distort. Generally, you look for power amp distortion in the fairly mild/clean amps (usually 2 to 3 preamp tubes, low gain stages). Typically its not that advantageous in the high gain recto amps (5 to 7 preamp tubes, with 3 or more gain stages).
     
  4. boyce89976

    boyce89976 Supporting Member

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    I think it's because power tubes don't really have their own sound... it's the sound of the circuit your hearing, and that most distortion happens in the preamp section.
     
  5. gibs5000

    gibs5000 Member

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    To add to my earlier comment, power tubes draw a whole lot more current than those mini preamp tubes in tube pedals, even more than your average 12ax7, so if you want such a pedal, you better get used to plugging it into the wall, and not a PP2+ for obvious reasons.

    Overall, power tubes do have there own sound, but that sound is really more of a "feel" thing than a hearing thing. My 6L6 amp behaves in a different way than my EL84 amp does. 6L6 is much more punchier in the lows, while EL84 is much looser, and chime-like in response. 6L6 is a little more balanced out in the EQ.
     
  6. Stratburst70

    Stratburst70 Member

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    I think the closest you'll get to power tube distortion boxes (and others have explained why better than I could) is those "amp in a box" pedals from Tech 21, Catalinbread, Wampler and others.
     
  7. Hack Prophet

    Hack Prophet vile mighty wretched Silver Supporting Member

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    David Main calls the D*A*M Sonic Titan Power Amp Distortion
     
  8. GT100

    GT100 Member

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    You can't send a guitar level signal to a power tube. It's not a large enough voltage swing. You need preamp tubes to get the signal there.
    At that point you've built an amp. To use this amp for what you wan't you would design the output transformer to have two secondary taps. One for a resistive load to dump all that unwanted power and a guitar/mic tap to send signal to your effects and amp. I'd make that tap switchable to line level to give you more options.

    Lloyd


    Sent from my iPad using Tapatalk
     
  9. jwny72

    jwny72 Member

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    I think the 2nd (hard clipping) gain stage of the Fulltone PlimSoul is supposed to emulate power amp tube distortion.
     
  10. ChampReverb

    ChampReverb Silver Supporting Member

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    Exactly.

    ...and Lumpy's and JHS and Bearfoot and others...

    -bEn r.
     
  11. Flatscan

    Flatscan Supporting Member

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    "Amp like" frequently implies a tone mimicking power tube distortion.
     
  12. Whalestone

    Whalestone Member

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  13. cj_wattage

    cj_wattage Vendor

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    And that would be correct. Inside the Sonic Titan is a tiny little 250mW* solid state amplifier (the LM386 chip). This is the same chip used in many small portable amps, like the Smokey.

    It can be made to sound really really good, as evidenced by the Sonic Titan. But it's not *tube* power amp distortion, which makes total sense given it's 9V power supply ;)


    *It could be as high as 750mW, depending on which version of the LM386 being used.
     
  14. lux_interior

    lux_interior Member

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    It's true that some power sections are made to stay clean even under difficult circumstances and more than others (example: high gain amps relying almost completely on preamp distortion while keeping the high wattage power section clean), but when tube amps are pushed to the limit like you describe, the whole amp is distorting, not just its power amp. It's the preamp section as well as the phase inverter, the tube rectifier (if there is one), the transformers are also struggling (even a bit), and of course the speaker if the signal is beyond its headroom. So it's difficult to isolate the effect of power amp distortion because you are hearing the interaction of many factors.

    There are however a few examples where the preamp section, if not hit hard in the input, stays relatively clean or just a bit gritty while the power amp section has a bit of priority in losing control. As far as I know, a rare example is the Jim Kelley amp, now reissued by Suhr.
     
    Last edited: Mar 9, 2015
  15. lux_interior

    lux_interior Member

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    True: the tonality of power tubes plays a tiny role before other far more important factors weigh in, like the speaker, the tonestack and its position in the circuit, the preamp section, the presence or absence of negative feedback, the biasing etc. You can see the small differences in amps that accept different power tubes like some from THD, Kustom etc (but even these differences concern that specific circuit and cannot be extrapolated). That's why threads like "best overdrive for EL84s" are rather naive. What people are really asking is advice on ODs matching their own specific amp.

    No, not really. It refers to the dynamic response, compression and clipping according to the pick attack and position of the guitar's volume knob. It's a bit vague, but it refers to an amp as a whole and not just its power section (which of course doesn't work on its own but linked to everything else).
     
    Last edited: Mar 9, 2015
  16. ballhawk

    ballhawk Supporting Member

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    The op should make it clearer. Are we talking actual power tubes in a pedal or a pedal that attempts to emulate that through some other means?
     
  17. Ben S.

    Ben S. Member

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    Because of the power supplies needed to run power tubes.

    Just do what Keith Richards did and run an amp into an amp, or use the possible EVH setup of slaving into another amp.
     
  18. lux_interior

    lux_interior Member

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    That's only taking a distorted amp as a whole and making it louder while adding a bit of power amp distortion. It's not anywhere near to a "power amp distortion" sound.

    Actually there are a few pedals (I think Menatone and some others that I can't remember) that include a "sag" knob, and that's one of the typical behaviours of a tube rectifier or power section overload. But again that's an effect reflecting an interaction, not an isolated one.
     
  19. DaveKS

    DaveKS Member

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    HK attempted this in their half rack stuff many years ago. As you can see on cream machine even using a 12au7 as a 1w power tube soak took a lot of components to make it work. They also had a couple other models which ran a real el84 as the power tube soak. I've got one of these, have couple of Philips Miniwatt 12au7 that when run in that 12au7 slot will actually glow that nice sky blue just like a real power tube.

    [​IMG]

    Here's one of their el84 models.
    [​IMG]
     

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