Tubes, Tubes, Tubes -- Resources for Rollers!

Discussion in 'General Audio Discussion' started by The Alchemist, Oct 7, 2015.

  1. The Alchemist

    The Alchemist MOT: Schiit - Here to help!

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    I get some hum with certain tubes as well. Sometimes the hum will be there, and sometimes the hum will be absent or intermediate. It is just the nature of tubes, even expensive ones can have these issues. It may eventually go away, after a certain amount of time used, but in my experience, some tube's hum never goes away, just sometimes comes and goes.
     
  2. fraggler

    fraggler A Happy & Busy Life

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    Thanks. I was hesitant to start rolling due to the possible finicky nature of tubes. Luckily, the Vali 2 only takes one tube so I am not blowing hundreds at a time. We'll see what happens after a couple more days.
     
  3. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    You can always try to reach out to the seller. Otherwise try cleaning pins and letting it burn in for 50-100 hours. Sometimes hum goes away.
     
  4. m17xr2b

    m17xr2b Friend

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    Do more gain stages change tube characteristics?

    Let me explain, I'm looking at 300B designs and I see two common choices, medium mu triodes e.g. 6SN7 with two gain stages or a single gain stage pentode in triode mode.

    In the case of two gain stages for 6SN7 does it change the coloration, linearity, fundamental characteristics etc. for the specific tube? Say if I like a certain 6SN7 I've heard only in a single gain stage on multiple amps, would it sound different implemented in two gain stage leaving aside all other factors(if that's even possible)?
     
    Last edited: Mar 15, 2019
  5. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    It seems our tube rolling thread got erased by the mafia. So we can use this thread instead now.

    Has anyone heard the Brimar 6SN7GT tubes that cost like $600 for a pair? I’m not going to let myself do that but I’m so curious what they sound like.
     
  6. gurubhai

    gurubhai Friend

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    Haven't rolled them in for a while now but I thought the Brimars were quite decent sounding. Overall it sounds a bit polite with a forward midrange and rolled off extremes. They aren't quite neutral but have their own distinct flavor.
    My own preference is 40's grey glass RCA though.
     
  7. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Hey Guru! So good to see you. What amp do you like those in? I tried them in my liquid glass and I seem to prefer Sylvanias. These are my favorite right now. Sylvania 6SN7WGTA with the brown base and green lettering. I think I like as close to solid state as possible in the glass with just subtle liquid leading edges from the tubes.

    [​IMG]
     
  8. gurubhai

    gurubhai Friend

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    Mine is a custom diy tube rectified 6as7 OTL with 6sn7 input that I made specifically for my Yamaha orthos. The amp doesn't use a cathode bypass capacitor at input stage and the resultant local negative feedback probably makes it different from other tube amps.
    These sylvanias are one of my favorites too, however, the RCAs have fuller lower mids and are a touch more resolving.
    I know that the general opinion on rca is that they tend to sound warm and soft but in my setup they sound quite neutral with only a hint of warmth.

    P.S. I have bunch of 6sn7 lying around and can send a pair of Brimars your way if you want to try them.
     
  9. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Huh, I tried the gray plate RCAs and they were super muddy in the Liquid Glass. But that was before I got the LCD-5's and finished my mod for them. They'r the only Audeze that works with tubes and they sound great with the Glass. I'll have to get another pair of the gray plates to try.

    I'd love some 67N7 tubes especially a pair of the Brimar's to try! thanks!

    I wish you could hear my modded LCD-5 and Liquid Glass. It's so good.
     
  10. gurubhai

    gurubhai Friend

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    Send me your current address. I'll send a pair of grey glass and brimars your way.

    I'll only end up modding them!:D
     
  11. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Does anyone have any advice or a rich, full bodied and bassy 6SN7 or 12SN7 tube that still has forward vocals and good resolution?
     
  12. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    I had a 6SN7 to 6922 (general octal to noval) tube adapter made by a friend, and I'm sure his work on it is excellent, but unfortunately the parts we bought are cheap and melting and I'd like to get one of the ebay adapters to as a backup or to use instead to avoid a melting disaster.

    I bought this one, but the tubes don't fire up at all and I don't understand why because the 12au7 is a noval tube. There must be something I'm missing becaue the adapter my friend made works with a whole shitload of noval tubes.

    https://www.ebay.com/itm/201320842633

    I just bought this one, it specifically says 6SN7 to 6922

    https://www.ebay.com/itm/203316593257

    Is there a better adapter to buy? Someone on ebay must make an octal to noval adapter that works with 12au7, 6922, EC88, etc.
     
  13. fastfwd

    fastfwd Friend

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    Do you have switchable heater voltage (6V/12V) in addition to the adapter? A 12AU7 in a 6922-to-octal adapter will want 12.6V across its heaters, but an amp designed for 6SN7 will only supply 6.3V.
     
  14. rhythmdevils

    rhythmdevils MOT: rhythmdevils audio

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    Yes, sorry it's a Liquid Glass so it has both 6V and 12 V and 200v and 300v adjustment options so I can run a ton of tubes in it. Interestingly, the amp turned on with none of the protection lights turning on, but the tubes did not turn on.

    I had the right settings with the amp, but the adapter does say 12au7, not 6922. But the adapter made by my friend works for all of them so I figured it would too.
     
  15. archer88

    archer88 Friend

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  16. fastfwd

    fastfwd Friend

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    Wait, is it specifically a 6SN7-to-12AU7 adapter, or an octal-to-6922/octal-to-generic-noval? It matters, because a 12AU7 adapter can wire the heaters in parallel, so they'll only need 6.3V. 12V would be too much for a 12AU7 in an adapter wired that way, and an adapter wired that way wouldn't work for a 6922 at all, because that tube's 9th pin isn't the center tap of the heaters.

    I'm a little lost. Can you be very specific about the problem?
    1. The adapter that didn't work -- what tube/socket combination was it built for?
    2. What's one tube/socket combination that DID work with that adapter?
    3. And what tube/socket combination did not work with that adapter?
     
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  17. Lickumms

    Lickumms Rando

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    I just got a set of RCA Victor Grey Glass 6SN7-GT tubes with round metal plates on the top and bottom, I believe they are a reprinted RCA VT-231. I am really loving the way they sound. They are very clean and accurate tubes with great bass impact and a decent amount of airiness.

    [​IMG]
     
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  18. Cspirou

    Cspirou They call me Sparky

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    Where do EU/UK people like to source tubes?
     
  19. Slade01

    Slade01 Acquaintance

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    Although I am not in the EU/UK, two good sources for tubes in the UK that I always go to is:

    Billington Export - bel-tubes.co.uk
    Langrex - www.langrex.co.uk

    Very reliable and nice selection of tubes.
     
  20. WoodyLuvr

    WoodyLuvr Friend

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    Sorry, long time no speak good sir. Life busy. Just ran across this thread and saw your unanswered question.

    These are indeed splendid sounding tubes that perform well in many different audio amplifier designs. A real shame they are so expensive these days. I remember buying pairs of these for less than ¥1,100 back in 1985 which was like five bucks.

    Knowing full well that I may be preaching to the choir here it still must be reiterated from time to time that due to the 6SN7's inherent original design as a driver tube they are naturally weak in the lower frequencies especially when compared to other tubes that were specifically designed to perform as output (power) tubes. Yes, 6SN7's can and are used quite successfully as output (power) tubes... or as single stage tubes usually in hybrid designs like your Liquid Glass. The issue however with the 6SN7 performing as a power output tube instead of at the driver stage is their high plate resistance (aka Rp). High Rp usually means very high output impedance which in turn translates to poor low frequency performance. To somewhat solve this issue they are ran in parallel to cut plate impedance in half for each tube or even in series in hybrid designs to further reduce this high plate impedance. This doesn't always solve the anemic bass though. Where high Rp value really shines is in the upper mids to lower highs which is perfect for vocals and imparting a nice detailed and airy sound.

    With that all said, have you ever tried RCA Radiotron Electron 6SN7GTB Black Plates from the mid-1940s to mid-1950s? I have had a lot success with these tubes both as drivers and as well as outputs in certain amps. They most often than not are extraordinarily quiet, crystal clear, and tend to be much more bass friendly than other 6SN7s. They are not expensive... a nice pair will cost you less than a quarter of what you may have paid for a single Sylvania 6SN7WGTA! These inexpensive tubes are a kind of secret with many of us old timers over here in Thailand/Japan and now that we are dying off it probably is best to pass on the knowledge.

    ~~~ EDITED ~~~ Corrected my statement as per @gurubhai wise post
     
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    Last edited: Jul 30, 2022

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