A nice review that I found.

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by BLUECASTER, May 1, 2012.

  1. Blue Strat

    Blue Strat Member

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    Interesting. As always, one mans nirvana is another man's garbage. Subjectivity is what it is.
     
  2. BLUECASTER

    BLUECASTER Member

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    I understand that the tests and review are not with a guitar amplifier.
    But it is interesting how different people find the sounds of different 12AX7s.
    This is about U.S.A made, blackplate 12AX7s.

    I am curious about that RCA "U-Getter with Foil Crossbar, White Lettering, early '50's, ULTRA-RARE".
    I am not sure I know which tube he is talking about...:)
     
  3. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    RCA's first 12AX7, made between 1947-1950, had a very wide-U or D-shaped getter wire, and the plates were a little more shiny than the flat black '50s RCA 12AX7 that is much more common. Those early RCA 12AX7 have a somewhat thinner tonal character and a little later breakup than their later '50s siblings. I like them a lot!

    But this question gets to the heart of a problem: which tube is being discussed? With accurate identification of the tube in question, I'm confident that the presumed inconsistencies in reports on their characteristics would fall away. When one doesn't know exactly which tube is being discussed, it seems that the tonal descriptions become random and subjective. One always has to look (and listen) more closely, and pay attention to detail.

    - Thom
     
  4. BLUECASTER

    BLUECASTER Member

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    Hello T.:)
    Did you read the interview?
    It refers to 6 different RCA blackplate 12AX7 types.

    I am talking about the No 6 tube, I don't think I have seen it.

    I have a RCA 12AX7 with shiny blackplates and large D getter like the one you speak about(if I understand correctly) from 1947-50, but I don't think it is the same tube:


    1. Long 'D' Getter, early 50s, White Lettering: The tone was excellent and even with very good articulation. The timpani attacks in a large symphony recording came through sharp and musical. The ambience was engaging. One listener commented "There is so much room in sound". Highly Recommended
    2. Large Horseshoe Getter with double crossbar mount, '50's, ULTRA-RARE!: If you took the tubes from #1 and sprinkled magic fairy dust on them, you might come close to the sound of this tube. Far superior IMHO to a smooth plate Telefunken--I did NOT want to stop listening. Utterly Sublime, and very rare.
    3. 7025 Bent 'D" getter, Orange Lettering and reinforced top mica: The 7025 label is often a military version, or ruggedized version of the standard 12AX7 or ECC83. This tube was very similar to #1, but we felt that solo instruments came forward in the sound stage just a little more. A classical guitar solo entranced us, as did the french horn. Highly recommended.
    4. JRC (Military) Long 'D' Getter, White Lettering, early '50s: Again this military version of #1 was very similar to it, but with even greater resolution of the sound stage and articulate subtlety. The bass was tight and wonderful. Descriptive words: Subtle, Gentle, Strong, Fast. Very Highly Recommended.
    5. Early '60's Long D Getter, Orange Lettering: Not as articulate as #4 or #2, but still very musical and smooth. Reminded me more of a Sylvania style sound than traditional RCA. Recommended.
    6. U-Getter with Foil Crossbar, White Lettering, early '50's, ULTRA-RARE: Absolutely wonderful sound! Enormous sound stage. Super articulation without any harshness. Tight Bass. Possibly my favorite Black Plate.
     
  5. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Yes - I read it. Photos would have helped i.d. the tubes under consideration. I don't believe they're all RCA...

    #2 "horseshoe getter" may actually be CBS

    #3 "bent D getter" sounds more like a Tung-Sol, though they didn't make a black-plate 7025. I wonder if this might be Canadian?

    #5 "early '60s" - RCA blackplate? RCA stopped making black-plate 12AX7 in 1959

    #6 "U-getter with foil crossbar" sounds as if it could be Ken-Rad (GE)

    RCA is the most common default false-i.d. due to the incorrect mythology about the octagon around the tube number (many hold the untrue notion that octagon = RCA). Without knowing what exact tube is being discussed, the review is only of minimal interest to me - especially since the review does not involve guitar amp use. It goes right in to the gee whiz pile in my brain, where it is rapidly composted. I'd love to see photos of those tubes, linked to the review.

    - T
     
  6. BLUECASTER

    BLUECASTER Member

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    Cool info T., as always.
    Thanks!
     
  7. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Here's a photo, to illustrate the pre-'50s RCA 12AX7:

    [​IMG]

    I broke it open so you could get a good, clear look at it. ;)

    Note the very wide-U getter wire, the semi-gloss black plates, two staples per plate, and flat-cut plate tabs (part of plate emerging from the mica). I like these - when they're intact.

    - Thom
     
  8. cap47

    cap47 Member

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    What is an RCA red label Gray Plate made in Yugoslavia? EI? It certainly is not made by RCA! So there are many with RCA stamped on them and made for them. Makes it hard to compare in a large sample of RCA tubes. The yugo stamp is gray. As TW says a picture would have been nice in his review!
     
  9. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Yes - that would be Ei. RCA really has nothing to do with it.

    - T
     
  10. BLUECASTER

    BLUECASTER Member

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  11. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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