Tube ID

I purchased these a couple of years ago,and like a goof,I never documented what they were. I’m almost certain they’re 12ax7’s. The markings are worn off,so I need the help of any tube gurus out there.

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z1a6ijv1vziu.jpeg
5wg6mknupxju.jpeg
mq5hl3wjz9js.jpeg
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Comments

  • TEAforONE
    TEAforONE Posts: 999
    After googling the interwebs, I think I solved the mystery. It looks like they are possibly RCA 5751 short black plates,halo getters. Any other guesses would be much appreciated.
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  • pitdogg2
    pitdogg2 Posts: 24,481
    Any makings between the pins?
    Yes at this point it's all guesses
    Don't ask me how I know but Windex takes a stenciling right off tubes lickety-split
  • TEAforONE
    TEAforONE Posts: 999
    pitdogg2 wrote: »
    Any makings between the pins?
    Yes at this point it's all guesses
    Don't ask me how I know but Windex takes a stenciling right off tubes lickety-split

    Let me check between the pins..........
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  • TEAforONE
    TEAforONE Posts: 999
    Not a thing between the pins. :/
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  • pitdogg2
    pitdogg2 Posts: 24,481
    Rats.... Oh well worth a shot.
  • TEAforONE
    TEAforONE Posts: 999
    I rolled these in my preamp today,and really like em. So of course I'd like to get something similar. Not as simple as one might think.
    But seriously,looking at images on the web,I'm pretty sure of what the are .
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  • F1nut
    F1nut Posts: 49,710
    edited January 2020
    They do not look like RCA 5751's. They look like 12AX7's.

    5751's are normally marked near the top in what looks like etched glass and that marking does not normally come off.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • verb
    verb Posts: 10,176
    Hey brother, can you take some close up pic's of the plates? Need a straight on view, and a side view. Hard to tell from the pics.
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    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
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  • TEAforONE
    TEAforONE Posts: 999
    F1nut wrote: »
    They do not look like RCA 5751's. They look like 12AX7's.

    5751's are normally marked near the top in what looks like etched glass and that marking does not normally come off.

    F1nut, thanks for the id. I originally had thought 12ax7,but I had no idea about the etching. Again,thanks!
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  • TEAforONE
    TEAforONE Posts: 999
    verb wrote: »
    Hey brother, can you take some close up pic's of the plates? Need a straight on view, and a side view. Hard to tell from the pics.

    Hi verb, I won’t be able to take any pics until I get home from work. That should be about 4pm. Thanks!
    See my profile for list of gear.
  • heiney9
    heiney9 Posts: 25,053
    Pretty sure it's an American made tube. Short black plates aren't normal for a 12AX7. Any American black plate I've seen is a long plate and they are usually early tubes and as a rule don't have a halo on a post for a getter.

    It could be a Canadian made version of an American tube possibly. They did that for some 12AX7's. I'll have to do some research this weekend, because a black short plate isn't common among the 12AX7. IIRC, the RCA 5751 has bump out plate not a flat plate.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2020
    I am so bad at this tube ephemera stuff! :/
    It looks like every US (North American?!?) miniature/B9A base twin triode ever made to me -- well, except a "cleartop" 12AU7, I guess.

    :p

    I.e., I got nothin'.

    I am tempted to go upstairs and see what the 5751s in that little LRE amp up there look like.
  • TEAforONE
    TEAforONE Posts: 999
    Here’s a couple more pics. Sorry,I don’t own a real camera.

    tz1wmlpdf0ld.jpeg
    g5vtl4mrxg1i.jpeg
    nlbaop7sn1sw.jpeg
    pr3g5aykdlba.jpeg
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  • pitdogg2
    pitdogg2 Posts: 24,481
    c8gaid1z4z20.png

    best picture of the bunch
  • TEAforONE
    TEAforONE Posts: 999
    I've had these for at least a couple years. I spent yesterday rolling signal tubes in my pre,and these seem to have the secret sauce. If only I took the time to write down what they are. I'm kicking myself! Hopefully someone will recognize these.
    See my profile for list of gear.
  • verb
    verb Posts: 10,176
    pitdogg2 wrote: »
    c8gaid1z4z20.png

    best picture of the bunch

    Yep. Those plates I've never seen!
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
  • TEAforONE
    TEAforONE Posts: 999
    verb wrote: »
    pitdogg2 wrote: »
    c8gaid1z4z20.png

    best picture of the bunch

    Yep. Those plates I've never seen!

    Well,that's not encouraging!
    See my profile for list of gear.
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2020
    A suggestion that might (might?!?) be helpful. Try fogging the envelope glass with your breath. Sometimes, the residual runic inscriptions that once graced the tube can be read.

    I do see some partially (mostly) eroded print on there -- don't I?

    It might not help, but it's easy to try and only takes a moment.
    I have occasionally managed to read otherwise invisible tube types printed on plinkers.
    Plus, imagine the fun you'll have explaning it if a spouse or child comes into the room while you're blowing on a vacuum tube. :#

    As an aside -- and y'all probably know this -- some tube manufacturers quite deliberately used very ephemeral print (as opposed to the etched markings) on their tubes -- to discourage unscrupulous repair persons from tube washing (literally) and selling an old tube 'pull' as a new tube.

    Inconceivable. :|

  • TEAforONE
    TEAforONE Posts: 999
    edited January 2020
    mhardy6647 wrote: »
    A suggestion that might (might?!?) be helpful. Try fogging the envelope glass with your breath. Sometimes, the residual runic inscriptions that once graced the tube can be read.

    I do see some partially (mostly) eroded print on there -- don't I?

    It might not help, but it's easy to try and only takes a moment.
    I have occasionally managed to read otherwise invisible tube types printed on plinkers.
    Plus, imagine the fun you'll have explaning it if a spouse or child comes into the room while you're blowing on a vacuum tube. :#

    As an aside -- and y'all probably know this -- some tube manufacturers quite deliberately used very ephemeral print (as opposed to the etched markings) on their tubes -- to discourage unscrupulous repair persons from tube washing (literally) and selling an old tube 'pull' as a new tube.

    Inconceivable. :|
    That seems like a GREAT idea. How on earth did you come up with that??? Will try that this evening!! And yes,that tube has some of the labeling still on it. It looks orangish red?
    Is it possibly a GE tube? The thing that sucks,is eBay purchased search doesn't go back far enough.
    See my profile for list of gear.
  • verb
    verb Posts: 10,176
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
  • verb
    verb Posts: 10,176
    Green labeled Sylvania 12AT7's
    19oq556rqrv4.png
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
  • mhardy6647
    mhardy6647 Posts: 32,926
    TEAforONE wrote: »
    mhardy6647 wrote: »
    A suggestion that might (might?!?) be helpful. Try fogging the envelope glass with your breath. Sometimes, the residual runic inscriptions that once graced the tube can be read.

    I do see some partially (mostly) eroded print on there -- don't I?

    It might not help, but it's easy to try and only takes a moment.
    I have occasionally managed to read otherwise invisible tube types printed on plinkers.
    Plus, imagine the fun you'll have explaning it if a spouse or child comes into the room while you're blowing on a vacuum tube. :#

    As an aside -- and y'all probably know this -- some tube manufacturers quite deliberately used very ephemeral print (as opposed to the etched markings) on their tubes -- to discourage unscrupulous repair persons from tube washing (literally) and selling an old tube 'pull' as a new tube.

    Inconceivable. :|
    That seems like a GREAT idea. How on earth did you come up with that??? Will try that this evening!! And yes,that tube has some of the labeling still on it. It looks orangish red?
    Is it possibly a GE tube? The thing that sucks,is eBay purchased search doesn't go back far enough.

    I... I... read it on the internet.

    Marky stuffs his hands into his pockets, looks down and shuffles his feet.

    :#
  • TEAforONE
    TEAforONE Posts: 999
    And I’ll raise you... these have almost identical plates!
    i34di23n911x.jpeg
    59av4wc85ir0.jpeg
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  • TEAforONE
    TEAforONE Posts: 999
    verb wrote: »

    I think you're on to something,however the mystery tubes sound so different from the green label sylvania's. I'm very perplexed!!!
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  • mhardy6647
    mhardy6647 Posts: 32,926
    edited January 2020
    w9zi87syt7sk.png

    a2o6x44huugr.png

    Just musing I am, you know?

    :#

    (that one on the right has a pretty funny looking seal on the exhaust tip, though, doesn't it?)
  • pitdogg2
    pitdogg2 Posts: 24,481
    edited January 2020
    most GE tubes had the glass laser etched with the brand it would NEVER go away.

    Different era tubes from Sylvania had different color stenciling for and different plants could also have different sound signatures. I know for a fact that my 6sn7 Sylvania tubes had green, red, orange and blue labels all different years Blue was the last in the mid 70's and all you can see all a little bit differently made.
  • TEAforONE
    TEAforONE Posts: 999
    edited January 2020
    I'm a relative nube with tubes,what is the seal on the exhaust tip?
    See my profile for list of gear.
  • verb
    verb Posts: 10,176
    Hard to say really. From what I've learned, a lot of history out there where manufacturers made tubes for one another, others removed the original labeling and post applied their own, you name it.

    Here's an example of the same tubes, Sylvania manufactured (except for double layer mica on top), labeled as Motorola.
    g0d851oxg5wo.png
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
  • TEAforONE
    TEAforONE Posts: 999
    Thanks pitdogg2. That rules out GE. Process of elimination!
    See my profile for list of gear.
  • pitdogg2
    pitdogg2 Posts: 24,481
    verb wrote: »
    Hard to say really. From what I've learned, a lot of history out there where manufacturers made tubes for one another, others removed the original labeling and post applied their own, you name it.

    Here's an example of the same tubes, Sylvania manufactured (except for double layer mica on top), labeled as Motorola.
    g0d851oxg5wo.png

    and yet that laser etching on the far right one screams to me GE. Except it is missing dots that GE also used.