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    What's your favourite 6SN7 tube?

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    Tube Nube

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    Re: What's your favourite 6SN7 tube?

    Post by Tube Nube on Wed Mar 16, 2016 8:26 pm

    Dogstar,

    In the off chance you're in Alberta . . . Drop by, brimg your amp. I now have the Octal board in my VTA ST 70.

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Sat Mar 26, 2016 8:14 pm

    "GTB" make any difference? Seems to me that just designates the base type?

    deepee99

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    Re: What's your favourite 6SN7 tube?

    Post by deepee99 on Sat Mar 26, 2016 9:29 pm

    sKiZo wrote:"GTB" make any difference? Seems to me that just designates the base type?
    GTA and B rate the same:

    450 volt maximum and 5.0 watts per section (6SN7GTA/GTB).

    For future reference....

    6SN7GT/WGT/WGTA - 300 volt maximum and 3.5 watts per section

    5692/6SN7 - 275 volt maximum and 1.75 watts per section.

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Sat Mar 26, 2016 9:46 pm

    Thanx!

    I'm thinking the ST120 has plenty of reserve to run one of any of them then. Plan would be to use an adapter and just try one in the center position ... my only concern would be the diameter of the adapter, as my driver tubes are recessed ... the chassis holes are 25mm diameter, or just under an inch for us colonials ...

    Anyone got one of the adapters they can measure?

    Plan B would be to use a "socket saver" extension if I have to stretch the socket, but that's one more set of mechanical connections I'd rather avoid.

    EDIT >> Got an email back from the adapter guys ... 29mm, so I would have to stretch it.

    Kentley

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    Re: What's your favourite 6SN7 tube?

    Post by Kentley on Sun Mar 27, 2016 7:55 am

    Having sampled a wide range of 6SN7 types in the volt amp pair o' holes of the SP-14, I had come to the conclusion, as have many of you, that the differences and preferences are highly system-specific and subjective. Every pair seemed to have its pluses and minuses. Choose your poison....
    That is, until whispers of a certain  new-production tube from, of all places, China (!!!) that purportedly had everything. Not cheap, I hesitated for a few seconds before seeking the most inexpensive source - about $120/pair. I was also warned that the break-in period was inordinatley protracted.
    Well, I bit the bullet and a few days later had a pair of HUGE, coke-bottle, black glass Shuguang Treasure series "CV-181 Z".
    Three days later, and now I am sold 1000% on these monsters. They do indeed have everything. Best of Show in every category.
    There's a lot of interesting tech talk about these which I encourage anyone interested to Google.
    Here's a BIG caveat: THEY ARE SO TALL that they literally graze the top cover of the SP-14. Undaunted, I realizes that the cage could easily be wedged higher from the rear by one inch, thereby giving these monsters a bit of breathing room. Temps over them measure a mere 85 F.
    Apparently, the production values of these tubes are quite high, and some distributors are jacking the prices way up for "premium matched sets" and such. No point.
    I know this all sounds like the "too good to be true" category. Doesn't seem likely to me at this point. Will keep y'all posted. Cheers. Kentley.

    May the Eater platypus lay a monotremic egg on your power transformer.


    Last edited by Kentley on Sun Mar 27, 2016 8:35 am; edited 1 time in total (Reason for editing : Addition of Easter quip.)

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Sun Mar 27, 2016 1:05 pm

    Kentley wrote:That is, until whispers of a certain  new-production tube from, of all places, China (!!!) that purportedly had everything. Not cheap, I hesitated for a few seconds before seeking the most inexpensive source - about $120/pair. I was also warned that the break-in period was inordinatley protracted.  Well, I bit the bullet and a few days later had a pair of HUGE, coke-bottle, black glass Shuguang Treasure series "CV-181 Z".

    I have been running new production CV-181s for several years in the ST-120 numero uno position.  Lately the Psvane CV-181 which is excellent with KT-120 power tubes.  The Black Treasure CV-181 is a little darker sounding in my setup but I ran the Black Treasure for a year and loved it.  They take a few months to really open up so be patient.  No other 6SN7s I have tried can compare to these two.  

    Every year or so Parts Connexion has sales and last year picked up a pair of Psvanes for 30% off.

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Mon Mar 28, 2016 3:45 pm

    Come to find out, I WOULD have to stretch the adapter somehow due to the recessed sockets in my rig ...



    ... but I'm thinking I might get away with modding the adapter to reduce the diameter instead ... only talking 2mm here. The adapter is 29mm, and the chassis holes are 25mm ...



    The guts look to be encapsulated in epoxy, so it'd be (hopefully) easy to either peel the outer layer or just grind it down to size.

    (PS ... that IS the correct adapter?)

    6V 6.3V 6SN7 6SL7 to 12AU7 12AX7 tube adapter



    ~~~

    Waddaya think of the RCA coin base? Looks like it gets good reviews, and more important, it's purtier than the rest.  clown



    Should be a nice choice to get my feet wet, and then think about moving up to a higher end tube.

    And ... just to confirm ... the GTB tubes are NOT a problem in the ST120? I only plan to run the one in the center.

    deepee99

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    Re: What's your favourite 6SN7 tube?

    Post by deepee99 on Mon Mar 28, 2016 4:55 pm

    sKiZo wrote:Come to find out, I WOULD have to stretch the adapter somehow due to the recessed sockets in my rig ...



    ... but I'm thinking I might get away with modding the adapter to reduce the diameter instead ... only talking 2mm here. The adapter is 29mm, and the chassis holes are 25mm ...



    The guts look to be encapsulated in epoxy, so it'd be (hopefully) easy to either peel the outer layer or just grind it down to size.

    (PS ... that IS the correct adapter?)

    6V 6.3V 6SN7 6SL7 to 12AU7 12AX7 tube adapter



    ~~~

    Waddaya think of the RCA coin base? Looks like it gets good reviews, and more important, it's purtier than the rest.  clown



    Should be a nice choice to get my feet wet, and then think about moving up to a higher end tube.

    And ... just to confirm ... the GTB tubes are NOT a problem in the ST120? I only plan to run the one in the center.

    Those coin-based RCAs are very sweet-sounding tubes, they're cheap, reliable and they're certainly at the top of the 6SN7-GTX curve. If I had to throw away all my Cold War expensive tubes I would keep the RCAs. All 6SN7 iterations pull the same heater current. Diff between the GTAs and GTBs is that the GTB's filament is indirectly heated so it could be used in TV sets in series-connected strings. Plate volts and dissipation ratings are the same.
    The earliest 6SN7s had much lower plate capacity per stage, on the order of 50 percent than the later GLASS TUBE (GT) As and Bs. The GTAs and Bs are one heck of a tube. You won't hurt your iron and you might just like the sound.
    Here's some more trivia: http://vinylsavor.blogspot.com/2014/02/tube-of-month-6sn7.html

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Mon Mar 28, 2016 6:41 pm

    Huh ... I thought there was a 12v heater version, or is that just the adapter?

    PS ... I did find one trick to locate "GT" versions ... search for VT-231 instead.

    Kentley

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    Re: What's your favourite 6SN7 tube?

    Post by Kentley on Mon Mar 28, 2016 7:04 pm

    sKiZo wrote:Huh ... I thought there was a 12v heater version, or is that just the adapter?
    Baffling description. But I believe it means that you must change the filament voltage supply in your amp to 6v before using this adaptor. Why is beyond me - I don't see why it couldn't handle 12v if you wished to use 12SN7. Or simply a translation confusion: they are warning us not to expect the adaptor to convert for us. Unless, of course, the pin-out is different....???


    Last edited by Kentley on Mon Mar 28, 2016 7:13 pm; edited 1 time in total (Reason for editing : addition)

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Mon Mar 28, 2016 7:39 pm

    Fiddlybit I guess ... the Latino's are all 6.3vac heater voltage, unless that's one of my better hallucinations.


    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Mon Mar 28, 2016 7:45 pm

    (PS ... that IS the correct adapter?)

    6V 6.3V 6SN7 6SL7 to 12AU7 12AX7 tube adapter
    --------------
    I've ordered two adapters off of Ebay that look much different from each other but both work fine.  Usually the seller will confirm how you want it wired when the order is placed. The more expensive ones sometimes include a nice label so you won't blow up any of you vintage tubes!!

    12SN7 to 12AU7 Adapter

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Mon Mar 28, 2016 7:48 pm

    sKiZo wrote:Fiddlybit I guess ... the Latino's are all 6.3vac heater voltage, unless that's one of my better hallucinations.


    Yep, you are correct so a 12SN7 would not work very well in the ST-120.


    Last edited by arledgsc on Mon Mar 28, 2016 8:54 pm; edited 1 time in total

    deepee99

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    Re: What's your favourite 6SN7 tube?

    Post by deepee99 on Mon Mar 28, 2016 8:34 pm

    sKiZo wrote:Huh ... I thought there was a 12v heater version, or is that just the adapter?

    PS ... I did find one trick to locate "GT" versions ... search for VT-231 instead.
    VT just means "Vacuum Tube" and was mostly a military designation. The JAN (Joint Army Navy) designation tubes of the VT-231s are supposed to have been built to higher tolerances, but RCA stamped all of them out of the same dies, as I would bet most of the the other tube-makers did. They weren't building these babies for yuppie hi-fi junkies.

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Mon Mar 28, 2016 9:41 pm

    My point on the VT-231 is that it seems to return a LOT more matches when searching. Same tube, different number.

    As far as the adapters are concerned, where it gets interesting is the 12AU7 is actually a 12.6vac heater circuit with half fed to each of two pins. That's where it gets confusing.

    So, at risk of being obtuse, which one again?

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Mon Apr 11, 2016 9:19 am

    I am trying out a new DAC with a LOT of detail and really low noise.  This means I go through a bunch of #1 tubes in the ST-120 to find the right balance.  This weeks winner is an early 50s Ken-Rad VT-231.  It was a bargain basement Ebay purchase as a tube pull that tests "good".  Great bass, smooth highs with virtually no unwanted sibilance, and well painted mid-range/ vocals with nice harmonic content.  Amazing these old tubes can keep up with modern recordings.

    Kentley

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    Re: What's your favourite 6SN7 tube?

    Post by Kentley on Mon Apr 11, 2016 9:27 am

    arledgsc wrote:I am trying out a new DAC with a LOT of detail and really low noise.  This means I go through a bunch of #1 tubes in the ST-120 to find the right balance.  This weeks winner is an early 50s Ken-Rad VT-231.  It was a bargain basement Ebay purchase as a tube pull that tests "good".  Great bass, smooth highs with virtually no unwanted sibilance, and well painted mid-range/ vocals with nice harmonic content.  Amazing these old tubes can keep up with modern recordings.
    It cannot be overstated that this kind of fine-tuned tube matching is highly system-specific as well as subjective. Ain't it nice when you find a real bargain-basement driver tube that just "works"? I've gotten some great matches that cost all of $5 - and lots of bummers that ran $50 or more. One never knows, does one?

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Mon Apr 11, 2016 9:41 am

    Kentley wrote:It cannot be overstated that this kind of fine-tuned tube matching is highly system-specific as well as subjective. Ain't it nice when you find a real bargain-basement driver tube that just "works"? I've gotten some great matches that cost all of $5 - and lots of bummers that ran $50 or more. One never knows, does one?

    You are correct. What works for me or someone else may not be ideal for another. Experimentation though is highly recommended and I am always surprised at the results. I've had my share of bummers as well and chalk it up to experience gained.


    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Sat Apr 16, 2016 12:17 am

    Got all the bits and pieces together ...

    Here's the adapter I used ...



    And here it is mounted to the RCA coin base tube, along with the short "socket tester" extension I needed to clear the hole in the chassis plate ...



    I added the rubber washer and shaved down a grommet to dress it up and steady the base ...



    Dressed up and fits nice - certainly stands tall with the rest of the tall trees! Gotta say, I'm impressed with what I'm hearing so far ... bit more punch and the stage is noticeably wider, with better definition. However ... I'm getting some noise in the left channel on idle so I may have a problem tube. The noise DOES go away if I switch back to the trusty old 12BH7a - an easy swap with this setup. Doesn't detract from the music, so I'm gonna play with this one a bit while looking for another one to try.

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Sat Apr 16, 2016 9:34 am

    sKiZo wrote:Got all the bits and pieces together ...

    Looking good!  I had a noise with one of my new 6SN7s as well.  Had to send it back.

    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Sat Apr 16, 2016 2:47 pm

    Found me another one last nite ... wish me luck!

    One thing I noticed, the iron seems to be running a bit hotter - might have been something about the decibel levels cranking Porcupine Tree last night. Surprised Russia On Ice didn't shred the woofs - they do some serious pure sine that will rattle your eyeteeth loose ... clown

    Anyway, still good to touch at the end of a session, so nothing I expect to have to worry about. What I MAY do is crank the bias down from my usual 60mV on the KT120's to a more "normal" 55mV ... that should put the load back down to where it was. The 6SN7GTB series doubles the load the ST120 would see from a 12AU7, but I'm only running the one ...

    * Your noise ... was it sort of a low pitched steady drone? I get just a very small touch of hiss out of the right channel if I put my ear up close, but no more than what I'm used to hearing. The drone from the left is also relatively easy to ignore and is only really noticeable on idle ... maybe just some industrial crap that's got to burn off and it'll cure itself by the time the other tube gets here. Good to have a spare anyway, right?


    Last edited by sKiZo on Sat Apr 16, 2016 2:49 pm; edited 1 time in total

    deepee99

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    Re: What's your favourite 6SN7 tube?

    Post by deepee99 on Sat Apr 16, 2016 2:49 pm

    I've never encountered a noisy RCA in the 6SN7 category, but suppose it can happen. Microphonic, yes, noisy, no.
    RCA built a tube factory in Brazil, making mostly 6CG7s but might've made some 6SN7s there as well. Beyond my curiosity. The 6CG7s turned out there were not of the same calibre as the U.S.-made ones, and were intended only as replacement parts to keep obsolete television sets running as the switch to solid solid state was fairly well complete and they shuttered their U.S. facilities.




    sKiZo

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    Re: What's your favourite 6SN7 tube?

    Post by sKiZo on Sat Apr 16, 2016 2:55 pm

    It's my understanding the coin base tubes were only built in the '70's, but I could be wrong ...

    Tap dancing around the web, I find that this is a tube that people love to hate ... except of course for the ones who really really love em ... From what I can find, qc IS an issue, but if you find a good one, you've hit the motherlode ...

    deepee99

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    Re: What's your favourite 6SN7 tube?

    Post by deepee99 on Sat Apr 16, 2016 3:57 pm

    sKiZo wrote:It's my understanding the coin base tubes were only built in the '70's, but I could be wrong ...

    Tap dancing around the web, I find that this is a tube that people love to hate ... except of course for the ones who really really love em ... From what I can find, qc IS an issue, but if you find a good one, you've hit the motherlode ...
    The button-based were at the later part of the series. IIRC their production began in 1968.
    RCA used the same dies and tooling throughout the entire production run of its 6SN7s, so the newer the tube, the greater the slop factor I would think. I have quite a collection of them dating back to the VT-231s of war-era up through the coin- or button-based tubes. The only things they changed were the bottle, base and getter locations; the basic two triode stages are all identical regardless of year. They also made a red-based tube, ultra HQ, but I believe the heater current draw is pushing the edges for VTA iron.
    You can get a dozen button-bases for the price of just a couple of mil-spec 1940s VTs. Of the two dozen RCAs I've got, I've only had to chuck one out. Mebbe I got lucky, but of the NOS tubes I own, the RCA failure rate has been the lowest. Again, beware of anything they made in Brazil.

    arledgsc

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    Re: What's your favourite 6SN7 tube?

    Post by arledgsc on Sat Apr 16, 2016 9:08 pm

    sKiZo wrote:* Your noise ... was it sort of a low pitched steady drone? I get just a very small touch of hiss out of the right channel if I put my ear up close, but no more than what I'm used to hearing. The drone from the left is also relatively easy to ignore and is only really noticeable on idle ... maybe just some industrial crap that's got to burn off and it'll cure itself by the time the other tube gets here. Good to have a spare anyway, right?

    The new 6SN7 I sent back had 60 Hz hum in one channel.  Low level but constant.  Replacement dead quiet.  

    One other tube after 500 or so hours had random mild popping with a rushing sound.  Similar to a coupling capacitor on its way out.

    I hope there is nothing wrong with the adapter you recently purchased but try other tube.

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