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Building a Tube Amp

Discussion in 'Electronic Design' started by Jon Slaughter, Oct 14, 2008.

  1. I've been wanting to build my own tube amp for a while now and I think I'm
    going to go ahead and order the parts.

    Anyone know a good source of parts(transformers, tubes, tube sockets,
    etc...) and maybe have any tips? I have a few old tube books and of course
    mostly they are similar to transistor amps. But I, of course want a decent
    sound also.

    I know one can buy "kits" but these tend to be either over priced and/or low
    quality.
     
  2. 2 x 807 zero bias drive?
     
  3. It's going to be class A but I'm not sure exactly what tubes I'm going to
    use. Probably try to make it switchable for different power settings.
    Basically the "stock" guitar amp tubes are the 6L6, 12AX7, EL34, EL84 and a
    few variants.

    http://www.vacuumtube.com/guitartubes.htm

    Although I'd like potentially to "branch" out into other non-standard types
    I also don't want to pay an arm and a leg for crappy tubes.

    The main thing right now is to find a good transformer... looks like I'll
    end up spending more to build an amp than just buy a good one ;/ (which is a
    real shame since labor isn't even factored in ;/)
     
  4. Eeyore

    Eeyore Guest

    Not even remotely.

    The best output transformers are in Europe IMHO. Lundahl and Sowter for example
    but hardly cheap. SS amps don't need output transformers.

    But why do you want to add tube distortion to the sound ?

    May I suggest you Google 'gainclone' for something half decent ?

    Graham
     
  5. Eeyore

    Eeyore Guest

    Mischief !

    Graham
     

  6. 807very popular here, 2 make for 100W.
    'Zero bias' drive, here an example:
    http://www.triodeel.com/mi12246.gif


    Near class A:
    http://www.montagar.com/~PATJ/mi12188a.htm


    You may want to read this:
    http://www.webace.com.au/~electron/tubes/screens.htm

    EL84 is rather low power, I used those in a guitar amp once, 4 IIRC.

    That is why I spend say about 100$ on a Chinese 2 x 100W RMS transistor amp.
    Cheaper, better, and faster too, as it came working.

    Just forget about tubes :)
    And the voltages can byte you too.
     
  7. FYI, Tube's break up differently than SS. Tubes have even order harmonic
    distortion which is much more pleasent than odd order. This has to do with
    how they clip... hence tubes are prefered over SS any time distortion is
    involved. (and with the need for an overdriven sound for guitar it is
    necessary)
     
  8. You are aware, I hope, that you can make any waveform at low level,
    and then amplify it by a normal transistor amp (without it clipping)?
    Seems like you have been bitten by a tubophile !
     
  9. Huh?

    You do realize that overdriven guitar amps purposely distort the signal?

    I guess you guys don't know much about guitar amps?
     
  10. I guess I wasn't clear(actually I don't see that I mentioned it). The amp is
    specifically for guitar and not hi-fi.
     
  11. GregS

    GregS Guest

    Seems like you can make a lot of money marketing your device.

    Seems like overdriving the power output stage might not
    have the same irregularities as a low level stage.

    Guitars can be played with any kind of amp and don't necessarily
    need to be driven into distortion. Thats determined by the artist.
    The type of speaker distortion is also part of the power output
    stage.


    greg
     
  12. Guest

    That doesn't follow. What we do know is that it is lot cheaper to
    distort a signal with semiconductors and subsequently amplify it with
    semiconductors than it is to amplify and distort it with valves.
    Semiconductors have the additional advantage that you can have a lot
    more control over the nature of the distortion you introduce and the
    signal level where it becomes perceptible, if you happen to know what
    you are doing.

    Since you seem to be planning on building a valve amplifier for your
    guitar, you presumably don't have a clear idea of what you are doing.
     
  13. Nah, all been done likely.

    Possible, but that is not what I suggested.

    Sure, google 'guitar distortion box' without the quotes.
    Only 212000 hits.

    :)

    Just typed:
    # killall -KILL tubophiles
    # tubophiles: no process killed
    mm
    Oh well.
     
  14. On a sunny day (Tue, 14 Oct 2008 10:06:12 -0500) it happened "Jon Slaughter"
    <9y2Jk.2515$>:

    START:
    GOTO START
     
  15. For 'amplification' one would like as little distortion as possible.
    For wave shaping, it is better done at lower power levels.

    If you can specify the waveform (distortion type) you want,
    then you can can make that either digitally or analog at a low
    level, and then use a HiFi power amp.
    At least you would have a decent amp :)
     
  16. You can't... the components in a tube amp react completely different than
    digital algorithms. Analog solid state tends to end up sounding very
    harsh(because of the way they clip as I mentioned).

    If you don't believe me go to your local music store and ask one of the guys
    to show you how a real tube amp sounds. Compare it to a solid state amp and
    then to a modeling amp. The tube amp wins in sound quality.

    Supposedly there are many factors in tube amps that make them sound better
    such as the power transformer "sagging", the tubes themselfs, etc... I do
    not know how much is true but what I do know is that tube amps sound much
    better than solid state... although some of the newer modeling amps do sound
    decent but still are not "reactive" to the playing. (they are not dynamic or
    "organic" as it's still just a simple algorithm that reacts the same way
    every time)


    (Remember, I'm specifically talking about distortion here... but even then
    many people claim hi-fi tube amps are the best. (and I've seen research that
    claims they are))
     
  17. They have these but generally the power amp distortion(along with speaker
    distortion) is also needed. A simple preamp tube driver with solid state
    doesn't sound all that great.

    You would be supprised what they do with tube guitar amps though.

    check out

    http://www.mesaboogie.com/Product_Info/Rectifier_Series/roadking/roadking.htm

    and look at the back for all the switching possibilities.
     

  18. Maybe you have not noticed, but whole orchestras come out of the paper cone of your loudspeaker,
    and the plastic membranes of your headphone.
    Probably amplified by ....
    Ah come on!!!!
    And that would be difficult?
    Hell the only limiting factor doing it all digitally was the introduced delay.
    Today, with GHz FPGAs and very fast DSPs, I think there is hardly any problem
    doing simple things like that.

    I like that article that Guy Macon pointed to:
    http://www.trueaudio.com/at_eetjlm.htm

    That whole tube stuff is marketing, just like oxygen free cables.
    Some will prefer to ride horses as those feel so 'soft' versus driving
    in a car I guess.
     
  19. Well, dear Jon, I have build several tube amps, how many did you build?
    But really I would not recommend tube amps, unless you like to look
    at red hot glowing anodes, those look nice, and show you that it is time to
    turn the volume down.
    And, if you have limited experience with electronics, the voltages in tube amps
    can kill, so better make something that works on 2 x 40 V with transistors.
     
  20. You are confusing 2 things, first there is the input from the *player*,
    then there is the sound of the *instrument*.
    Naturally both are tightly coupled, but I am pretty sure (well assumption),
    that if Stradivarius played some run of the mill made in Mechico violin,
    he could still keep an audience in awe.



    That is a straw man.
    The issue is 'can we make a tube sound at low level'.
    Well any diode clipper does that.
    Now you can add other stuff, like 'sagging supply', quite easily, by doing a peak detection
    and lowering the diode biases, etc etc.
    Asymmetric? Can be done too, the 'Joerg way', couple of discretes,
    some JFETS, what not.
    There is no problem there.
    The problem is in their idiotic specs, 'soft', colourful', 'sexy', 'fuzzier',
    'warmth', 'alive', 'organic' hey, what does it mean?
    Does it mean the same thing to person A as to person B?
    So you first have to come up with some real tests, scope it,
    see what is different, and recreate that with some hardware, software,
    lookup tables if you must (AD EPROM DA for curve, now there is hardly latency),
    etc.
    Formulate the exact problem, and you have the solution.

    Sure, right.

    No way, I do not like to sell snake oil, and I do not want to stimulate anybody
    to believe in snake oil.
    And I would have to advertise in their snake oil language to sell it.
    Simple as that.

    Personally I think very few real guitarist give a dime.
    They can play, and use the instrument to express themselves.
    A lot of others will just go for some sort of special sound, well it is not that
    what makes music, Hendrix burned his guitar on stage IIRC, good thing too.

    (am I gone hear about this LOL).

    Oh, did not know that.
    To each his own ;-)
     
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