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Need ‘5963’ gray plate tube ID... RCA??

Discussion in 'Glowing Bottle Tube Amp Forum' started by scout2112, Jan 13, 2019.

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  1. scout2112

    scout2112 Tele-Holic

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    C6A03AE3-AFAE-465A-A25A-D252D49EAFFE.jpeg I tried out a bunch of 12a...7 tubes and their ilk that I bought in a lot from eBay. Most of them turned out to be too microphonic and unuseable, but one tube that that sounded great is simply labeled ‘5963’ with no other markings, (as pictured). Can anyone give me more info on the identity of these tubes and when/where they came from? I’d like to know/buy more. I think the auction said they were RCA brand tubes.
     
    Last edited: Jan 14, 2019
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  2. archetype

    archetype Fiend of Leo's

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    The subject matter experts will need closeup pics of any codes or numbers on the tubes, also a pic of the bottom. Brent Jessee stocks these in RCA, Sylvania, and Tung-Sol.

    These seem to be pretty close in specs to a 12AU7, which is about the lowest gain of the 12A_7 tubes. 12AX7 has a gain of 100 and 12AU7 has a gain of around 17. These are mostly stereo audio tubes and I can't think of a guitar amp that's designed around them, but, as always, do what sounds good to you.
     
  3. Wally

    Wally Telefied Ad Free Member

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    Duncan Tube Data Sheet is a great resource for tube info and links to full technical data.

    http://tdsl.duncanamps.com/

    The 5963 was built for use in computers. They can be used in audio circuits but they have different specifications that are more appropriate for their design. I have a slew of them from a military tube stash.

    http://frank.yueksel.org/sheets/127/5/5963.pdf

    Fwiw, a 12AU7 and its big brother the 12AT7 were not designed as signal processing positions but rather were designed as drivers. That is why Leo Fender never placed a 12AT7 anywhere except in the Reverb driver position OT the phase inverter(driver) slot. 12AX7, 5751 and 12AY7 tubes are better suited for those preamp gain positions. The 5751 has a gain of 70 as does the 12AT7, but other specs are different. The 12AY7 has an even lower gain and is comparable to the 12AU7 regarding gain...but again, these two tubes differ in other specs.
    Yes...people use all of these tubes as interchangeable, but their design is different.
     
  4. uriah1

    uriah1 Telefied Gold Supporter

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    I have seen 12AU in some reverb returns and in old Gibsons.
     
  5. Wally

    Wally Telefied Ad Free Member

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    Most Gibson amps I have seen use a 6EU7 in that position. Some people retire the socket for the 12A-7 pinout.
     
  6. scout2112

    scout2112 Tele-Holic

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    Don't know about tube specs, but all I can say is that this 5369 tube tamed a very harsh and metal-sounding Mesa/Boogie lead channel that originally had a 12ax7 in V2. The tube may have been originally designed for computers, but it's very musical... classic-rock, chimy sounding overdrive. In the past I've had other success using EHX 12AU7 in the preamp slot in a Bugera V5.
     
    Last edited: Jan 14, 2019
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  7. uriah1

    uriah1 Telefied Gold Supporter

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  8. Wally

    Wally Telefied Ad Free Member

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    I agree that One can find oddities in Gibson amps. However, the schematic for that amp and all of the Gibson/Epiphone Amps Reverb that I have had and some of which I still own have used the 6EU7 in that position. I have two GA35RVT’s from early ‘66 right now.....both use the 6EU7. I am going to doubt that Gibson change that horse in the middle of that stream. As I noted, many people rewire the sockets for the more available 12A-7 tubes.
    That may have been what was done to that amp, Uriah.
     
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  9. scout2112

    scout2112 Tele-Holic

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    8793373B-877E-43F2-BEC0-5A8954F30859.jpeg F0A71B2B-2AC7-472E-A155-D59E1AA6B469.jpeg Here’s the only markings on the tube; ‘5963’ and ‘TA’. I tried a few others that said '48' instead of 'TA', and they did not work well.
     
    Last edited: Jan 17, 2019
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