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RCA 7025 preamp tube

Discussion in 'Amp Tech Center' started by figaro, Jan 20, 2014.

  1. figaro

    figaro Tele-Meister

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    The original RCA 7025 seems to be the favorite preamp tube of many players.

    How many different versions of the RCA 7025 are there?

    Which current production 12AX7 sounds the closest to the RCA 7025?
     
  2. telex76

    telex76 Doctor of Teleocity Ad Free Member

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    Great tube, I have 6 black plates that came in various vintage amps I bought. Been awhile since I read up on them, but black plate, and gray plate. Sure there are other designations. Can't believe what the NOS ones go for, but you can hardly ever find anyone who has them anyway.
    When I first got my BFDR and looked up what the tubes were worth, I boxed mine up to save. I finally asked myself what I was saving them for, knew I'd never sell them, so I put them in my favorite amp and play them.

    No new production tube really comes close, but I like the Tung-sol 12AX7.
     
  3. figaro

    figaro Tele-Meister

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    Here are some 7025s from my stash. I picked these because they are all marked differently. The first one from the left is not an RCA. It is marked 12AX7, 7025, Fender and made in the USA. The other three are RCA. The 3rd one has long plates and is marked Made in Yugolavia. They all have grey plates. Any info on these appreciated!

    [​IMG]
     
  4. LKB3rd

    LKB3rd Friend of Leo's

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    The tube makers back then would contract out batches of tubes to other makers. So, you'll get RCA labeled tubes made by someone else, and vice versa. RCA will have a "stop sign" etching if I recall correctly with the tube type inside. Sometimes you can scoop up an RCA (or whatever you are looking for) tube cheap if it is labelled with a less desirable brand and the seller doesn't know on ebay if you look close at the pictures for things like the stop sign.
     
  5. uriah1

    uriah1 Telefied Gold Supporter

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    Also, long plate, short plate, triple mica, Military stuff (JAN), spacer, getters, etc, etc,......
     
  6. muchxs

    muchxs Doctor of Teleocity

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    12AX7, 7025 Fender made in the U.S.A. is a Sylvania.

    The one with the etched lettering (lettering looks sandblasted) is probably GE relabeled RCA. For example RCA bought a lot of 12AY7s from GE.

    Made in Yugoslavia is Ei relabeled RCA. Does it have smooth plates? It might be a relatively recent bootleg or it might be graymarket from back in the day. U.S. tube production started to peter out in the late '70s during the Cold War. Greymarket production came from behind The Iron Curtain. Take a big batch of unmarked tubes to an undisclosed location. Mark 'em "RCA Made in Gt. Britain" or "Raytheon Made in England". Just check off the U.K. as the country of origin on the Customs paperwork.

    I have a smooth plate "RCA" 12AX7 / ECC83 Made in Gt. Britain, my favorite bootleg tube. It's probably kin to your Yugo 7025. The 12AX7 / ECC83 markings are ink just like any other European tube not etched or printed permanently like U.S. made tubes. It's a real weirdo. It looks like a Telefunken. It's certainly not British. It's debatable whether RCA had anything to do with it.

    Radio Shack imported a lot of greymarket tubes under their "Lifetime" brand. That was the tube market in the late '70s through '80s. U.S. supply was dwindling so they got 'em where they could get 'em, sometimes from a guy in a trenchcoat in the back alley. :lol:
     
  7. BiggerJohn

    BiggerJohn Friend of Leo's

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    the one on the left is either a Philips or a GE.
     
  8. marshman

    marshman Poster Extraordinaire Silver Supporter

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    I was under the impression that the dots were pretty much exclusive to GE...
     
  9. DaveKS

    DaveKS Friend of Leo's

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    GE didn't have a monopoly on dot codes.

    CBS, yes it's labeled Sylvania but etching and internals 100% CBS. Note smaller dots under etching, much like a GE but font and dot size smaller. Absolutely a must try 7025, excellent tube.
    [​IMG]

    Westinghouse. One in center is true Westinghouse, small dots around etching.
    One on right a RCA relabeled by Westinghouse. Those true Westinghouse carbon plate 12au7 in center are pure magic in audio preamps. Better than telefunken or bugle boy 12au7, what a soundstage, drops right front of what ever your listening to.
    [​IMG]
     
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