How much will a GTA se-40 improve with mods? What power tubes?

Discussion in 'High End Audio' started by maxdm, Jun 2, 2004.

  1. maxdm

    maxdm Guest


    I just bought an se-40 used.
    The sound of the amp is slow and fuzzy. I believe this is due to in
    part the (old) sovtek 5881 tubes.

    I am wondering if changing them to 6l6eh, sylvania 6l6gc, modern kt66
    or el34 is the way to go.

    I do not want a warm and fuzzy sound, I want a natural-sounding amp
    with excellent imaging.

    Is it worth trying to mod this amp, or should I just sell it and go
    for triodes instead.

    It would be nice to have a higher power amp like this ANYWAY, but only
    if I can make the amp more involving as far as soundstage and
    transients go.

    Can any owner who has modded the amp help?

    maxdm, Jun 2, 2004
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  2. Get any good 60-watt solid-state amp - there are plenty out there to
    choose from.
    Most triode amps will only make the warm fuzziness, warmer and more
    fuzzy - sell it and go for solid-state. Remember, the very best tube
    amps such as the ARC VT-150 and C-J Premier Eight, sound just like a
    good SS amp anyway!
    Stewart Pinkerton, Jun 2, 2004
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  3. maxdm

    Uptown Audio Guest

    There are nicer currently produced tube amplifiers that will be a a
    good match for your speakers. Or you could choose to go with a nice
    solid state amp as Stewart suggests. I'd sell the amp if you don't
    like it and move on. Putting more money into anything with limited
    capabilities like that is not the best move when you can get a more
    satisfactory product with a warranty.
    Roanoke VA
    (540) 343-1250
    Uptown Audio, Jun 3, 2004
  4. maxdm

    maxdm Guest


    I am aware of the sonic differences between tube and solid state
    because of my experience with recording equipment.
    A good tube amp should not sound like solid state, because that would
    imply a large dose of negative feedback, high current circuits and
    peakyness in the top end and a large component count.
    These things are all needed to get the spectral balance and dynamics
    which people expect from a modern hi-fi amp.

    Just listen to a condenser microphone with a fet internal amp and then
    the same mic with a tube amp (not miniature ecc83 6072 and the like)
    and you will understand how much depth is lost with just one stage of
    solid state components.

    fuzzyness is due mostly to using shitty commercial tubes (ecc83's 5881
    sovteks etc.) which were designed for P.A., radio set -- commercial
    amps, and instrument amps.

    Having said this, a badly designed amp is a badly designed amp.

    I have heard a small single-ended amplifier that I modded with just
    two stages of amplification and the end result is the effect of going
    back in time to the moment the recording was made.

    To me this is much more important and fun to listen to that super-fast
    high-current solid state amps that sound their best when played loud!

    this is why I was curious about the se-40 and bought one.

    My conclusion is that all the hype about this amp has it's foundation
    in the fact that the circuit is single ended, and this is a very
    musically accurate type of design used in the absolute best musical
    reproduction amplifiers.

    Esentially a Class A output.

    The fact is that the se-40 is actually a lower Watt amp than
    described, with inferior internal components and it is not a zero
    feedback amp.
    Had the amp really been zero feedback, there would have been NO WAY to
    use the 5881's because with no feedback you'll hear all the crud
    that these P.A. tubes put out (10% distortion?). They were built for
    high power push-pull (in itself a distortion cancelling topology)
    circuits w/ neg. feedback

    there is a feedback winding for the cathode of the 5881s and the 2k7
    resistor in the driver tube acts as local feedback for the driver

    My question remains: are the 6l6EH tubes noticeably better that the
    sovteks, or should I spend more and get 6l6gc sylvania tubes or??

    Anyone out there that actually OWNS and has changed the output tubes
    of this amp?
    maxdm, Jun 4, 2004
  5. maxdm

    Uptown Audio Guest

    You are free to spend whatever you like on your new toy. Everyone has
    their own tastes, but my original recommendation also remains -
    replace the amp. You don't have to get a solid state amp or even an
    amp that sounds like one, just a good amp. My advice was only to save
    you the time and money spent going down a long road to find the dead
    end which you knew was there before you started. Why trouble yourself
    with walking back? Anyway, it sounds like you are enjoying the project
    which is the most important aspect. You might find that you have
    completely rebuilt the amp by the time you are satisfied. I know I
    Roanoke VA
    (540) 343-1250
    Uptown Audio, Jun 5, 2004
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