Trying out different 6V6 Tubes- Can you hear a difference?

Discussion in 'Tube Audio' started by Arthur Smith, Apr 17, 2018.

  1. Arthur Smith

    Arthur Smith Well-Known Member

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    I have a fully restored Hallicrafters SX-42 receiver, known in its day as a high fidelity unit. It uses a pair of 6V6's for push pull audio. I am using a matched pair of Groove Tubes. If I pick up some NOS, or old stock tubes, and "roll my own", will I notice subtle, or dramatic differences? Yes, it can tune FM, and yes, it does also have an external input.
     

     

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  2. Lavane

    Lavane AK Subscriber Subscriber

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    I have a 6v6 console amp. I have three sets of 6v6's, all different brands. I really couldn't hear a difference.
     
  3. Arthur Smith

    Arthur Smith Well-Known Member

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    I thought it might be fun. The adjectives the distributors use in describing the sounds of the different tubes are a joke, which lead me to believe there might not be that significant of a difference. But, you know this hobby, and its members....
     
  4. kward

    kward AK Subscriber Subscriber

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    Those adjectives mostly describe guitar usage. For Hifi usage I have found less difference between the new production varieties. But I can tell a fairly distinct difference between old stock and new stock. Old stock usually sounding better but not always.

    If you're going with new stock the tung sols I think are the best sounding overall (for Hifi). My opinion of course.
     
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  5. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    I agree, with KW, that OS usually sounds better as long as they are of similar output. The 6v6 has a long pedigree and was produced in huge numbers. It was ubiquitous in automotive use as the output tube for car radios up until the 50s. So, any tube designed to be used in "mobile" equipment has to be a well made one. If you are interested try to get some black glass tubes with automotive brands like Ford, Delco, etc. They usually go for really cheap too and i find that the majority of them test very strong to like new after all these years..
     
    Last edited: Apr 17, 2018
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  6. GChief

    GChief AK Subscriber Subscriber

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    I have 2 sets, NOS Soviet somethings and the original Magnavox tubes. They sound a little bit different and if you are making me pick one it would probably be the Maggies. I haven't tried any new production yet. But that is mostly because I am happy with the sound of the 2 sets I have.
     

     

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  7. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    If you are looking for the ultimate 6v6 seek out the Bendix 5992 the ballistic missle 6v6. Here is a SEP stereo that i dubbed the "Blue Bomber" which uses 5992 outputs with a 5691 driver tube . Very good sounding amp no matter what 6v6 tubes are used. DSC05288.JPG
     
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  8. GChief

    GChief AK Subscriber Subscriber

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    Primo, do you have the JAN number for those? One of our vendors can get tubes and I am not paying the 'audiophile" NOS tube pricing.

    Edit: Ha never mind!! :confused:
     
  9. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    If you notice in the picture the tubes are marked 6v6gt. I believe that after awhile, Bendix got rid of their excess stock 5992 by relabeling them 6v6gt and selling them to a retailer. You could have bought them for pennies on the dollar. Unfortunately, price for NOS 5992 is in the WTF category.
     
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  10. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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  11. GChief

    GChief AK Subscriber Subscriber

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    Yeah the surplus vendor we use for obsolete Navy stuff sells tubes to the online stores. He will hook me up if he has any or can find some.
     

     

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  12. Lavane

    Lavane AK Subscriber Subscriber

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    I have a couple marked FOMOCO, so probably out of a car radio? One set are smoked glass Magnavox branded.
     
  13. Bill Ashton

    Bill Ashton AK Subscriber Subscriber

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    My favorite in a lower powered guitar amp is the GE 6V6GTA...
     
  14. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    Right, also the actual manufacturer is variable, RCA , Sylvania, could be almost anyone who won the bid that year.
     
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  15. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    I know one JAN number is VT-107. There might be others , too.
     
  16. GChief

    GChief AK Subscriber Subscriber

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    Asked our logistics guys to do a stock system check. 5992 worked
     

     

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  17. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    VT107 is a WW2 military number
     
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  18. trainbuftony

    trainbuftony Electron Herder Subscriber

    6v6s are a power tube. In most applications they have some ammount of feedback around the output stage. That electrical feedback works to negate any differences you might hear. For this reason I tend to run whatever power tubes get the job done (cheap ones). I'm going to go out on a limb and say your output stage most likely has global feedback, so probably a good idea to roll a different tube. Also don't let me tell you what you enjoy. If you're having a good time you're doing it right!
     
  19. GChief

    GChief AK Subscriber Subscriber

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    One of the reasons I have 2 sets of power tubes and a plenty of different 12AX7's and 6EU7s. I don't know enough ( and I really need to jump in at this point) to make that call myself but I know enough about electronics that it makes sense to me. Of course as always I am probably wrong :confused:

    The Maggie 6V6's do seem to sound better to my ears than the NOS Soviet era ones:dunno:
     
  20. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    I have found that the quality of the fb resistor can have an effect on the sound. Afterall, it takes a part of the output signal and returns it directly to the input tube. So i like to change the fb resistor/cap to 1w (rn65 or rn70) Dale metal film. Hi Q carbon film like Takman is also good too. This seems to clean things up and also firms up the soundstage. For the cap i usually use a silver mica type. That being said i don't use global negative fb on my own amps and only on stock rebuilds, where it is important for the overall amp stability.
     
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