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6SN7 Tube Addicts

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  1. TheSnafu
    Here is 6SN7 (top) to 6922 (bottom) adapters with TungSol 6SN7GTB's. Sounds pretty good, better than TAD 6922's. Tube s are awfully close and can't fit any fatter tubes there.

    6NS7 to 6922 2.jpg
  2. Scutey
    Picked up a pair of Psvane CV 181 TMK2 for my Feliks Elise a couple weeks ago and I have to say I'm quite impressed with them.

    Sound wise I would say they are neutral with a hint of mid range warmth, transparent, well extended highs, detailed wide soundstage with very good depth and separation, bass is tight and hard hitting, but could use just a tad more depth, otherwise an excellent sounding, new generation tube, biggest downside is the price and possibly life expectancy.

    Last edited: Mar 30, 2018
  3. larcenasb
    Hi, I'm searching intensely for some info about date code interpretation of Ken-Rad tubes, hopefully one of you can help me.

    I just acquired a couple beautiful Ken-Rad 6F8G round plate tubes.

    The tube to the left marked "Ken-Rad" and "VT-99" has a date code of "P2R," and the tube to the right marked "WARDS SUPER AIRLINE" has a date code of "E9R."

    Their constructions are identical except that the WARDS has copper tabs holding the plates (see color difference between the tubes). Possibly, I'd guess, that the copper version is of earlier manufacture--but I'm not sure and would really like to know for a fact. So, if anyone has a data sheet for Ken-Rad date codes, or can please tell me how to interpret them, I'd be deeeeeply appreciative. Thanks so much and happy listening!
    Last edited: Mar 31, 2018
  4. gibosi
    Early Ken-Rad date codes indicated the end of the warranty period rather than the date of production. So P2R indicates that the warranty period ended February, 1943. And E9R indicates a warranty period ending April, 1940. Warranties of one year were typical at this time, but I don't know about Ken-Rad. And further, it is certainly possible that a Ken-Rad labeled tube purchased from your local electronics shop might have a different warranty period than a replacement purchased from your local Wards dealer. So it can be difficult to know precisely when these older tubes were manufactured, but this gets you somewhat close....
    larcenasb and Monsterzero like this.
  5. larcenasb
    Thank you, gibosi! But how are the letters and numbers interpreted? What's the code to see what letter/number represents what? Thanks again for your help and time.
  6. gibosi
    I don't really have the "code". In Ludwell Sibley's book, "Tube Lore", page 177, a short table is presented regarding Ken-Rad date codes. And in order to answer your question, I attempted to infer a pattern and extend the table to include the codes indicated on your tubes.

    Since "Tube Lore" is a copyrighted publication, and I haven't seen this information anywhere on the web, I am reluctant to be more specific...

    However, I would encourage you to pick up a copy of this book. Lots of good information there that can't be found anywhere else.
  7. larcenasb
    Thanks for the info, but at $200 all the way up to $3000 for the book, maybe I'll get it once my life amounts to something. :)
  8. gibosi
    That much? Wow! I picked up my copy on eBay last summer for $90...
    larcenasb likes this.
  9. larcenasb
    Haha, yeah, I'll keep an eye out to hopefully find a lower price!

    In case anyone was wondering, the Ken-Rad round-plate 6F8Gs sound glorious! There is definitely a house sound with Ken-Rad, it's very similar to their 6SN7GT/VT-231 (black and clear glass both sounding the same, as most of you know). Compared to the RCA <1946 6F8G, the Ken-Rads sound cleaner, less bloat (which I love about the RCA for certain music types and classic films), and puts forth supremely resolving mids--if a singer's voice is raspy, you hear all the starts-and-stops in the voice with sharp clarity, whereas the RCA will smudge things and smooth it out a bit. As usual, bass performance is sublime: fast, punchy, deep, and a control to it that is atypical of the "tube" sound. Cheers and happy listening! :)

    EDIT: I should add more...

    Transparency is really what I was hinting at when talking about Ken-Rad's mids--the feeling of being in front of the singers is more obvious with Ken-Rads (6F8G and 6SN7GT staggered-plates) than with any of my other tubes, including RCA, Raytheon, Sylvania, National Union, and even the coveted Tung-Sol round-plates (all <1946). The Tung-Sol has a very balanced and natural (many say beguiling or magical) sound that I think wins most people over, but Ken-Rad's upsides (bass and transparency) are definitely more striking, more in your face.

    Highs are a bit subdued. For example, when there's a peak in the highs, especially with female vocals, the RCA and Raytheon (flat-plates) reach me and evokes a physiological reaction where I almost get goosebumps...the Ken-Rad sounds clear, clean and nice but don't force that physiological response. Obviously, that physical reaction makes the music more emotional, makes me literally connect with it, feel it...and not merely listen to it.

    Those are just some quick impressions, thanks for reading and take care!
    Last edited: Mar 31, 2018
    Wes S likes this.
  10. Wes S
    Larcenasb - those are very good descriptions, of the differences I hear between my 40's ken rad and rca grey glass 6sn7gt's. They both have a there own magic.
  11. attmci
    In the earlier days, many tube manufacturer used these secret codes and made the date decoding very difficult.

    I may have this tube somewhere, but the round plate version are rare. I believe the only reason we use 6f8g is due to the price (cheaper than their 6sn7gt cousins).

    However, the adapters will usually increase the noise floor in many amps.
    Last edited: Apr 1, 2018
  12. larcenasb
    Thanks Wes S, I'm actually going to try and give impressions of my treasure box collection of some of the more sought-after tubes, hopefully you'll like that as well! I'll post it here by tonight.

    Yeah, attmci, that's too bad about those sphinx-like tube manufacturers. At least RCA has clear date codes for their wartime tubes--I'm grateful for that. For me, the beautiful coke-bottle shape is another small reason I enjoy having a 6F8G in my amp. :)
    Wes S likes this.
  13. larcenasb
    Last edited: Apr 3, 2018
    Monsterzero and JohnBal like this.
  14. quimbo
    Hi. New to the thread. Picked up a Lyr 3 this weekend with a Tung-Sol 6NS7. Listened for a few hours last night, much nicer than the LISST tube. Amp is playing unattended while I am at work, looking froward if there is more difference tonight. Just ordered a 6SN7gt Ken-Rad Tube *Flat Black Plates*1950* and looking forward to hearing that
    Last edited: Apr 2, 2018
  15. attmci


    Pretty sure you had visited the threads because you are one of the first lyr-3 owners. Should have some great discussion soon.

    Damn, why they changed to 6SN7... This will make 6SN7 more expensive. :)
    Last edited: Apr 3, 2018
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