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  • New production 12AX7

    Lately I've been using reissued winged C or SED power tubes (6L6) with great success. Are there any 12AX7 shipping from the same factory? Or any other 12AX7 I should know about?

    Cheers!
    In this forum everyone is entitled to my opinion.

  • #2
    "reissued"? The factory is not in production of 6L6's. They have no made 12AX7s for a long time. The plant is on the other side of the city were I live now.

    When they were more available the SED tubes were really good, rugged and tight in tolerance. The last time I was able to get any from the factory was over a year ago so switched to EH for power tubes. They are not built as well but I have had very good luck with the power tubes but terrible luck with the 12AX7's. Luckily, I have a large stock of new Chinese 12AX7's which are very good, quiet, low microphonics and good, but not great, balance. I have been getting them in large lots from the manufacturer in China who brands them for me when ordering 2k or more in a single order. JJ power tubes are a non-starter, at least the ones available here, are terrible. For working musicians who need road-worthy reliability from amps using 6L6's I recommend the cheapest tubes around as the most reliable, the 6П3с-е which are closer to a ruggedized 5881. They handle a lot of abuse, tend not to vibrate apart in combos and are consistent.

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    • #3
      Can you tell me who you get your Chinese 12AX7s from? I've had terrible luck with the batches I've bought - very poor construction, high microphonics and very noisy in general, but the ones that came out good were superb. Also, which factory for the 6П3с-е? Just done a search and find lots of Russian pages that don't translate too well into English.

      I have a story about Cyrillic; many years ago I bough a Russian 'Sub Commander' wristwatch in the days before the copies and fakes. Absolute pride and joy, and a ritual to wind it every morning. On the back is embossed a picture as viewed from a submarine; a fish-eye view of the earth's curvature, with sea gulls, setting sun, and waves. Below it is some Cyrillic lettering that I never got round to translating. I imagined it to be something romantic or meaningful. Anyhow, years later I employed a lady from St. Petersburg and we were chatting away and it struck me to ask her what it said on the back of my watch. "Vorterpruf" came the reply in a thick accent. Crashed and burned.

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      • #4
        Mick, you could have impressed her by sounding it out phonetically and discovered the meaning yourself. Many words are cyrillic versions of Latin root words or English. You could read many signs by simply memorizing the sound of the letters, those that are different than Latin characters. In this case "Ватерпруф" Which sounded out sounds close to the meaning "waterproof"

        I get my bulk tubes from Shuguang. I have had very good luck with 12AX7s but less with the power tubes. The power tubes are fine but customers want higher gain Russian or JJ. I get a drop out rate of 3-6% on the preamp tubes. My contact in the company is through a friend, a very cute girl I met traveling, who lives a km from the factory. She deals with the sales director and makes sure I get preferred tubes . She is very familiar with the tubes and electronics but her university education is English Literature. When buying 2000+, they will brand them and box but I wanted my own boxes which I printed here. They can supply printing services cheaper than anywhere in the west but I am not crazy about the gauge of cardboard used, which loses its strength and rigidity quickly if in a humid storage area.

        Speaking of tubes, EH has stopped producing 6V6 according to the admin office here. They are pushing people to the Tung Sol which are more expensive. They look better built than the very light weight EH 6V6GT which did not tolerate higher plate voltages. I had a customer with a 4x 6V6 Orange amp with shorted tubes. I found the Tung Sol's had less gain on the curve tracer but I am willing to guess that it is a more rugged tube based on build alone. The 4 tubes maxed out at 36 watts into a matched z load(checked for maximum power transfer and it came out very close to 16 ohms at 1khz). Just for reference, I tried some used NOS RCA 6V6's and bias was quite different and it produced 41 watts. Based on the plate z of the tubes and transformer, I tried a single pair of 6П3с new from the box but a date code that suggested 1978. The two tubes matched well with 16 ohm load on the 8 ohm OPT tap and generated 29 watts. The 6п3с is supposed to be very similar to a beefy 6V6 while the 6П3с-е should replace a 5881. Putting both versions on the curve tracer told me that were almost identical in curves. So maybe some smaller 6L6 based amps can get by with the cheaper 6П3с.
        I have not collected those because they are not supposed as strong as the c-e version. The "c" version are 1/2 to 1/3 the price of c-e version. I will try a torture test of a pair to see how they explode. I swept their anode voltage out to 550 volts and did not dare try higher. I can sweep or pulse to 1000 volts.
        The Russian tubes from the Soviet period came from dozens of plants, all with the same plan and specs to meet for the tubes. Some came from Svetlana, others from long gone companies or even Reflector which now makes the New Sensor tubes.
        Reading the published data sheet that comes with every tube is interesting, they rated these tubes as max plate voltage of 250V! I guess they wanted to make sure designers of equipment were overly conservative so the tubes would last many decades.

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        • #5
          The world only has so many cute girls - why do you have more than your fair share?

          Anyhow,

          A Champ II I had the other week still had its RCA 6V6 pair installed, both well cooked and one was showing a bit of white. I considered the JJs, but thought the new issue Tung-Sols would be a closer match to the originals. The bias was too far off when these were fitted - way more current draw. Fender must have had a fairly consistent supply of RCA tubes to go for non-adjustable bias. A resistor change bought it in line.

          I've noticed the Tung-Sol 6L6 pulls a lot of current as well. When fitted to a Deville I was out of adjustment on the bias and still far too hot. Needed R83 snipping and R77 changing to 120K to get the pot happily centred.

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          • #6
            I have not played with Tung Sol 6L6's but the one case of a quad of 6V6's lead me to believe that it is not anywhere as close to the spec of the original design. It will be interesting to hear of any large volume users reporting how consistent they are. I tend to not put much stock into reports for a few isolated problems or even a series of problems that total a small count.

            Tubes are "cool" but I spend more time working with Class D and SMPS's, which will surely take over gigging duties for working musicians in the near future. If there is any part that seems to be failing more often than normal it has to be FireWire port chips, 48-68 pin SMD, 3 in one week, two FW800 and 1 FW400. That is strange considering how small and part time my shop is. My main business is two incoming tour operator companies. After the recent pro audio trade show in Moscow I attended, it appears that a new direction is about to be taken and it could shake up the horrible distribution network for pro audio.

            Yeah, cute girls are fun, particularly when missing attitude and greed. I've been pretty lucky to meet a lot every time I leave the house. That is one of the main benefits of moving here.

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            • #7
              Originally posted by km6xz View Post
              The 6п3с is supposed to be very similar to a beefy 6V6 while the 6П3с-е should replace a 5881.
              Isn't 6P6S supposed to be the equivalent of 6V6GT?

              And 6P3S is more like 6L6G/GA/GB (19 watts)?

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              • #8
                The 6П6с is lower powered, closer to a big 6AQ5 but with octal base. So there are 3 tubes that were produced for low power consumer AF output, 6П6с, 6П3с and 6П3с-е. The range of power is:
                6П6с<6v6<6П3c<6L6<6П3с-e
                The power out of a c-e might not be more than a 6L6 but is sure more rugged and less prone to microphonics in combos. They are closer to the original 5881 in measurements, which was a ruggedized tube before the re-banders started using the label interchangeably with 6L6, and can take higher anode potentials. Metal players tend not to like the lower gain of the 5881 or 6П3с-е but that only make more profit for shops and tubes sellers since they end up with tubes that do not last as long.
                I have used the 6П6 in a coupe small projects, a bench monitor speaker, and a DC servo amp and found despite the size of the components inside, it is not a power house tube. I have no qualms about running the 6П3с-е in any power amp but customers usually prefer more gain over more reliability and keep insisting marginal tubes.
                The original Sovtek 6V6 as actually re-labeled surplus 6П6с and proved not to be very reliable used in circuits designed for 6V6's. They have stopped making them recently. Don't try those in something that pushes 6V6's such as the J. Kelly amps that had around 500 volts on the plates of 6V6's for 60 watts out of a quad. They sounded great but naturally were very critical of what tubes were installed. In my old shop we had a lot of well known musicians who used those amps for their studio work and some concert work, of the 600 made, our database of repairs lists 123 different serial numbers. NOS RCA's could handle it however.
                Last edited by km6xz; 11-01-2013, 08:51 AM.

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                • #9
                  Great info, thanks!

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                  • #10
                    Originally posted by km6xz View Post
                    The original Sovtek 6V6 as actually re-labeled surplus 6П6с and proved not to be very reliable used in circuits designed for 6V6's. They have stopped making them recently. Don't try those in something that pushes 6V6's such as the J. Kelly amps that had around 500 volts on the plates of 6V6's for 60 watts out of a quad. They sounded great but naturally were very critical of what tubes were installed. In my old shop we had a lot of well known musicians who used those amps for their studio work and some concert work, of the 600 made, our database of repairs lists 123 different serial numbers. NOS RCA's could handle it however.
                    Yes I've found those black-lined-glass Russian "6V6" to be unreliable in circuits with over 300V or so on the plate. Would make a nice fireworks display in a Jim Kelley amp.

                    Kelley's back in production, working with John Suhr. I asked Jim and he said RCA and Sylvania were the top choices for his amps in that initial run. Turns out JJ 6V6 are tuff-enuff for those amps currently, if you can't get your hands on old RCA or Sylvanias. I've used the JJ at up to 500V without a problem. Yes I know some other JJ tubes have a poor reputation. Somehow the 6V6 seem to be better than average, but some have remarked they're closer to a 6L6. Well, whatever, they work just fine for me.
                    Enjoy. Every. Sandwich.

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                    • #11
                      a friend got me a set of macintosh tubes instead and they sound really good...

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                      • #12
                        Originally posted by popoahi View Post
                        a friend got me a set of macintosh tubes instead and they sound really good...
                        MacIntosh did not manufacture vacuum tubes. They did, however, relabel tubes manufactured by others with their name.
                        ...and the Devil said: "...yes, but it's a DRY heat!"

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                        • #13
                          Back to the original topic

                          I like the better Chinese ones too, but if one is not in a position to buy 12AX7s by the hundreds and sort out the good ones, which reseller is doing a good job of screening them? I've had some luck with the TAD ones, anyone else have 12AX7 recommendations?

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                          • #14
                            I popped in some Chinese tubes in a Fender Twin Reverb. I got the cheapest tube I could find on ebay. Works like a charm.
                            In this forum everyone is entitled to my opinion.

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                            • #15
                              thats what I meant, lol........the printed macintosh sure looks nice,lol................TR-BF

                              no more any of them left now.....where wud I look to get another set of 6L6gc macIntosh tubes???
                              AND, sets of- 7025's, 12AT7'sZ, & 12AX7a's????

                              is this true???--EL34 can interchange with a 12AT7,,, KT88 interchange with a 12AX7a,,, and 6550 can interchange with a 7025,,,????????
                              I havent been able to check to see if the pins or size are the same for all these tube interchangeability.....

                              got it this info from where I forget, but I had this info written out and just found it so why not just ask???
                              maybe I just shud forget about this tube swapping thing for a better or different sound?? since I found this info I had written down why not just throw it up here???
                              I suppose this info cud come in handy if I was desperate for a tube???

                              popoahi

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