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is their a big difference between 6sj7 and rca's 5693?

Discussion in 'Tube Audio' started by osd1, Oct 20, 2012.

  1. osd1

    osd1 Member

    Messages:
    95
    im trying to decide between rca's red 5693 pre amp tubes or nos 6sj7.

    it will be paired with kt66 or el34 tubes.

    the amp is a musical paradise mp301 mk2.

    also is there a big difference between the red wrapped tubes and black wrapped tubes that are 5693?
     
    Last edited: Oct 20, 2012

     

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  2. battradio

    battradio Electron trainer

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    The big differance was original price and , the red RCA tubes where made to long life standards like Western Electric tube .
     
  3. Tom Bavis

    Tom Bavis Audiophool Subscriber

    Messages:
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    Part of the reason for their long life was derating - notice that all the "special red" tubes have lower voltage and power ratings than the base tubes. They probably were selected for close tolerance, possibly had some different materials for longer life.
     
  4. osd1

    osd1 Member

    Messages:
    95
    lol forgive my stupid question but is the above statement good or bad?
     
  5. Smitty43

    Smitty43 AK Subscriber Subscriber

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    Was going to start a thread on this same subject, I just ordered a set of NOS RCA 5693's on Ebay for my MP301. Might as well revive this old thread.
     
  6. primosounds

    primosounds SE KT120 w/ 6J5G drivers. Subscriber

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    It is not really derating, but that the operating point is tightly specified. So, if you follow the recommended operating conditions then the 10K hour lifespan can be expected.
    The Red Base RCA tubes were designed for military and industrial conditions for reliability and high vibration, etc.
     
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  7. Smitty43

    Smitty43 AK Subscriber Subscriber

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    I've had my MP301 since 2014 and still using stock preamp 6j8p tubes so i'm wondering if i'll be able to tell a difference in sound. I always order extra tubes so I guess i'll be good for 20,000 hrs. I will be using KT88's and EL34's so this will be new for me.
     
    Last edited: Oct 14, 2018
  8. primosounds

    primosounds SE KT120 w/ 6J5G drivers. Subscriber

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    I know that the Bendix tubes even show a chart with expected lifespan at certain operating conditions. With the expected longest use at the conservative conditions and lesser hours as the voltage and current increased. The filament voltage is also specified to be within 3 or 5 % of nominal.
     
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  9. juno

    juno Super Member

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    I use the red 5693 in my 301.
    I also have the Black 6SJ7, which I recently swapped back in.
    The 5693 sounds much better. Probably due to less gain. I found the 6SJ7 to be rather grating in the highs in comparison.
     
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  10. Palustris

    Palustris AK Subscriber Subscriber

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    The 6SJ7 and the 5693 are essentially the same tube which means the operating points and gain are identical. As TB says above, the 5693 is "derated" to reduce the maximum allowed plate dissipation from 2.5W for the 6SJ7 to 2W for the 5693; the screen dissipation from .7W in the 6SJ7 to .3W for the 5693. This does not qualify either of these tubes as "good" or "bad" it is just a statement of fact and a reminder that running tubes at a reduced operating point can improve the life of the tube.
     
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  11. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

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    Anyone ever compare the glass 6SJ7s to the metal ones?
     

     

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  12. Smitty43

    Smitty43 AK Subscriber Subscriber

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    The Rca's 5693s and Tungsol EL34S rocking the Mancave :beatnik: with 6.5 watts. 15418902740641332675356229312639.jpg 15418903183292610256005502804916.jpg
     
  13. trainbuftony

    trainbuftony Electron Herder Subscriber

    5693 tubes were ultra ruggedized build to withstand outrageous conditions and still work. If you can find this type, hang on to it. Nobody will ever make anything like it ever again.
    The tolerances are tighter and the physical structures are more rigid and better supported than its non military counterpart. This may result in closer matching and lower microphonics. Ymmv. And did I mention that these will never ever be produced again at any price...
     
  14. Smitty43

    Smitty43 AK Subscriber Subscriber

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    I know I have been on the look out for awhile and bought 4 as I only need 2.
     

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