An experiment with 1940's Marconi 6V6G Coke Bottle tubes

Discussion in 'Ampage Area' started by JHowdy, Jul 31, 2020.

  1. JHowdy

    JHowdy Country Gent

    Nov 16, 2013
    This is going to be a long story of scattered thoughts, so I suggest you take a seat in your favorite chair and take a cup of coffee or something. Or do something else.

    A friend here on the forum had mentioned the 1940-50’s Marconi-Westinghouse 6V6G “Coke Bottle” tubes several times and had made me think about them and occasionally search for them for a year or two. After the latest talk about them here a few weeks ago I then finally found a good-looking pair, allegedly NOS, in original packages, and decided to give them a try.

    I know you can’t be 100% sure of what you get when you buy old tubes like these, but my very own philosophy says that you can’t ever achieve anything if you haven’t got the guts to try. All I can lose is some money, right? This may well be one of the last opportunities for me to try something like this, so I said to myself: Go for it!

    I found this very pair from ebay, within Europe, tested with a tube tester, with matching currents, NOS, never used, in original packages – or that’s what it said, anyway. I got them yesterday and tried them very briefly after work and before our weekly sauna turn (a very Finnish phenomenon) and here are my very first thoughts about them.

    The print in the carton boxes says Oct. 1, 44. Nineteen fourty four, that is. Some dirt on the cartons, some oldish odour. I’ve never seen one of these before, but I’ve seen other 1940s stuff, old books and such in the past and these boxes may well be original, not fake. I am a sceptic by nature and don’t take things for granted – but have trust in people in the same time. I don’t go fooling people, only petty people do that. If somebody should fool me, then it’s going to be their shame, not mine…

    So much for philosophy, let’s get down to business. In the following pictures you’ll see the tubes and their boxes, with a unique cradle for the tube. The tubes had some dust on them and it shows in these pictures. I wiped them with a clean cloth before use and they look super clean with no evident signs of use.

    When I got the tubes out of their boxes I thought that they are not so big after all – that’s what I had heard before – until I put them side by side with a pair of 6V6GTs. Then I saw the difference, these really are BIG BOTTLES.

    The tube bases were a bit loose, they don’t sway yet, but they move a little if you twist them, and there is some rattle if you shake them. Otherwise they looked like new. All this says to me that these are the real things and may well be NOS NIB, too.

    I put them in my Tweed Deluxe amp to find out that even the tube bases were much larger in diameter and thus a bit hard to put in place into the clamps that I have there. I then hooked the amp, put it on and the first chord from the guitar – wow – what a sound! A bit over-warmish perhaps, but incredibly powerful, thick, a HUGE soundstage. So much oomph from the amp that I had never heard before. And you can hear every note so clearly, they really stand out now - which is not so good with my poor playing skills. So much more bass frequencies that it might even be overkill with Dynasonic pickups (I've got TVJ's in my G6118T). The amp got much louder, but not tiring (on hifi terms: "not fatiguing to your ears"). Someone said here on the forum not so long ago that a good tube amp “fills the room”. This one really does that and especially with these tubes. The soundstage is H U G E, as I said already. The minus side on all that is that me living in a block of flats can’t play too loud without making the neighbours crazy, so it’s not very easy to use the amp right now and I’ll have to find all new settings for the volume controls on both the amp and guitar to be able to drive the amp nicely, at lowish volume levels. But that should be a pleasant chore, shouldn’t it?

    I had thought that I should measure the operating voltages and calculate the currents of these tubes before real use, but I don’t know. They sound right, they warm up right, so maybe I won’t after all. We’ll see…

    Summary: It really doesn’t matter if these tubes should last a week or ten years, this is going to be an experience worth all the bucks.

    If someone should get interested in these tubes, at your own risk, particularly if you live in Europe, then PM me and I’ll give you the ebay seller's information. He seems to have two of these still in stock. Happy hunting!


    Pictures 1-3. The 1940’s carton boxes. The stickers on the top say "tested to give even 36mA operating currents".



    Picture 4. The tube cradle.

    Pictures 5-6. Coke Bottles on the table.


    Picture 7. The difference between 6V6G “Coke bottles” and the more common 6V6GT type.

    Pictures 8-9. Tubes in their sockets, note the slight tube clamp issue with the bigger tube base. I had to bend the clamps really wide to get the tubes in place.
    Henry, EarleG, Waxhead and 13 others like this.
  2. thunder58

    thunder58 Super Moderator Staff Member

    Dec 23, 2010
    tappan ny
    Admin Post
    Very cool story @JHowdy . The 1940's ..... a time that i actually wished I had grown up in . Glad you're loving them . And the pictures are awesome too . Thanks for sharing
    JHowdy likes this.
  3. BrianW

    BrianW Synchromatic

    Oct 21, 2014
    Vancouver Island
    Seems like you made the right choice trying these tubes out; and I agree it's better to try and know than not try and wish you had. Money is only money but regret can last a long time!

    Great that you like the sound you are getting with these tubes, have fun finding the "balance" for your neighbour's sake.

    Ironic to me that if I wanted them I would be sending to Europe for Canadian tubes... something I have been going through with an old motorcycle lately.
    JHowdy likes this.
  4. JHowdy

    JHowdy Country Gent

    Nov 16, 2013
    Thanks Rich! I may have lived in the 1940s (it get a feeling like that sometimes), just to be born too late once again to miss the 1950s :).
    thunder58 likes this.
  5. JHowdy

    JHowdy Country Gent

    Nov 16, 2013
    I think I've seen these for sale in Canada and USA, too. Quite a lot of Marconi tubes seem to be offered from Italy, that's where I got mine.
  6. G5422T

    G5422T Country Gent

    May 24, 2012
    Best cup of coffee that I've had in a while.

    Glad that you're enjoying them. My favorites, but you already know that! Lol
    capnhiho, JHowdy and Jeff67 like this.
  7. Gretschtim1

    Gretschtim1 Country Gent

    Dec 4, 2012
    Dundalk, Md
    If there is movement of the base and glass I would suggest leaving the tube in the amp until they die.
    The tubes are 80 years old and the base have become somewhat brittle. Swapping tubes that old in and out of different amps is only going to cause problems and possibly failure. So leave them in the amp and enjoy their great sound.
    lathoto, Bertotti, new6659 and 2 others like this.
  8. wabash slim

    wabash slim Gretschified

    Feb 10, 2010
    lafayette in
    So, the adage, "They don't make 'em like they used to." is actually true!

    MilSpec means that they had to perform to a specific rating. People did their best as part of the war effort. Consider that they used tubes in proximity fuses for antiaircraft artillery (of course, they only had to work once)---literally shot from a cannon. At the time, tubes were state of the art devices. Ten years later, the transistor appeared, and tubes fell by the wayside. Now, sadly, only audiophiles and guitarists use them.
    Last edited: Jul 31, 2020
    JHowdy likes this.
  9. swivel

    swivel Country Gent

    May 13, 2018
    Cool, I have one or two old 6V6 coke bottles laying around here. That looks like a nice set.

    Some Mil Specs are so broad manufacturer's would relabel one number tube as a different number... and they still fit the requirement. Many other Mil stuff is like that also.
    wabash slim and JHowdy like this.
  10. Jeff67

    Jeff67 Country Gent

    Nov 3, 2019
    Crockett, Texas
    Those coke bottle 6V6s really are magical in some amps.:)
    JHowdy likes this.
  11. Shadowy_Man

    Shadowy_Man Gretschie

    May 18, 2020
    Fascinating! Thank you for sharing
    JHowdy likes this.
  12. montereyjack66

    montereyjack66 Country Gent

    Feb 29, 2012
    Those are a danger to the environment! They are forbidden by law! Send them to me and I may yet be able to keep you out of prison!
  13. JHowdy

    JHowdy Country Gent

    Nov 16, 2013
    Yes, where would I be now without your suggestion? Wandering out in the rain, wondering what a sad and dark world this has become, ha :D. Many thanks!!
    G5422T likes this.
  14. JHowdy

    JHowdy Country Gent

    Nov 16, 2013
    Good advice, thanks! Not that I would go swapping tubes to make A to B comparisons, no. I rather let them stay there until problem arises or I happen to get a new idea from someone.
  15. G5422T

    G5422T Country Gent

    May 24, 2012
    Well, you might be wandering around with a few more bucks in your pocket, but still wondering? Lol

    Your welcome, and glad you like what they do for a tweed Deluxe.

    JHowdy likes this.
  16. Uncle Daddy

    Uncle Daddy Friend of Fred

    Jan 19, 2012
    Maldon UK
    My wife's grandfather did his apprenticeship at Marconi's in the early 1930s, when valves were cutting edge technology. There wasn't much he didn't know about the things. He said he remembered the excitement when transistors were developed, but they were never quite as good.
    JHowdy and YouFellowRebels like this.
  17. capnhiho

    capnhiho Synchromatic

    Feb 16, 2013
    I think I could fit those in my Tweaker 15 but I’d need to pull the grille and they would still poke out the top! I can only fantasize about how good they would sound.

    Thanks for your efforts, your write up, and your photos!
    JHowdy likes this.
  18. Bertotti

    Bertotti Friend of Fred

    Jul 20, 2017
    South Dakota
    A good tube amp fills the room! Yes it is true and I have yet to run into any hybrid (tube SS) amp or SS amp that can do that. The presence is incredible! I am glad these are doing that for you everyone should get to experience that. Wait until you add a smidge or trem verb vibrato or delay.
    JHowdy and YouFellowRebels like this.
  19. new6659

    new6659 Country Gent

    This thread is wonderful. My father worked for Marconi in Montreal from about 1955-1962.
    JHowdy, YouFellowRebels and G5422T like this.
  20. G5422T

    G5422T Country Gent

    May 24, 2012
    That's cool.

    20200626_114516.jpg 20200626_112457.jpg
    JHowdy, new6659 and YouFellowRebels like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.