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6SN7

70.55.108.141
Posted on March 18, 2010 at 20:54:38
fred.hammersmith
Audiophile

Posts: 23
Joined: December 19, 2007
 Hi... Time for me to change the input tubes on my beloved S30 MkII.
i'd love to buy from Ralph, but the price is a bit too much for me at the moment.
Looking through E-Bay listings, I see loads of choices...
Sylviana, RCA, GE, Russian tubes, Chinese tubes...
Any advice? Are there some to avoid?

(I was told that the input tubes have more influence on sound than the output tubes. Is it accurate?)
All commentaries welcome...

 

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RE: 6SN7, posted on March 19, 2010 at 07:47:06
shermanr@prw.net
 I currently own and enjoy a pair of MK2.3 Atmasphere M60 amps already for over 2 years.

My experience with NOS tubes in the front end of my M60's has not always been succesfull.

But I also have to be honest; NOS tubes have generaly fared better than current production 6SN7 tubes.

I have used old 5692's and Sylvania Green leaf 6SN7's and they work with no buzzes or noises.

But the current production tubes I am specifically referring to that have been sourced from Ebay have not worked for me.

Recently I got rid of (8) 6SN7-GTB Current Production tubes that resulted worked in a Cary SLP-08, while in my M60's were intolerable, the buzz was very loud.

So my conclusion is that it's not the tubes but the demands of the circuit surrounding them.

I have not experienced any of the massive hum and noise that current production Ebay tubes have given me from old 6SN7's.

The extra money spent on a tested 6SN7 tube that has been actually used and guaranteed to work in Atmasphere circuits is probably worth the extra money.

Currently, I am using (8) Platinum Tested SINO 6SN7 tubes with spectacular results for 22 month's.

I have already posted my experiences with both EH and Tung-Sol current production tubes in my M60's.

As soon as I flip the operate switch, a very strong audible buzz is heard 9 feet away from both types.

The common denominator for these current production tubes is that they were not sourced from a seller who runs real guaranteed testing.

 

RE: 6SN7, posted on March 19, 2010 at 07:58:12
Audio Pharaoh
Audiophile

Posts: 4502
Joined: January 24, 2001
 Could you please advise the source of the Sino tubes you purchased..

TIA!

AP

 

RE: 6SN7, posted on March 19, 2010 at 08:20:40
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 Some years ago there was an article in the now defunct magazine, Vacuum Tube Valley. The manuscript may be available on-line if you Google the correct key words. In that article, a whole gaggle of NOS 6SN7s were auditioned in a simple linestage circuit using the same downstream components throughout. KenRad, Raytheon, Sylvania, Brimar, and Mullard tubes fared well in this survey, but there was some discordance among different types within the same brand family. For example, one of the Raytheon versions was top rated while another was said to sound bad. Ditto for Sylvanias. I can only recall that KenRad 6SN7GT, Sylvania 6SN7WGT (the one with the metal base), Brimar CV1988 were among the best sounding. This article became a bible for 6SN7 users, perhaps moreso than it should have been. Nowadays, I would bet that it is a pain in the arse to find any of the top rated tubes, because of it. I've got a little stash of some of these myself.

In selecting tubes, make sure that the tubes used in the driver stage are GTA or GTB types, as Ralph has often reminded us. Those are rated for 450V at the plate, which is needed for the drivers in the Atma circuit. GT's are only rated for something less than 300V. OK for input stage.

 

VTV issue on 6SN7s, posted on March 19, 2010 at 08:24:07
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 I found the URL for VTV quite easily. Here is the issue of the magazine that was devoted to the 6SN7. You can buy it for the equivalent of 9 Pounds. Knock yourself out.

http://www.hificollective.co.uk/magazines/vacuum_tube_valley_issue11.html

 

RE: leakage problems., posted on March 19, 2010 at 09:33:12
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 The 6SN7 will buzz if it has leakage. This is easy to test for on a good tube tester.

 

RE: my impresssions, posted on March 19, 2010 at 09:44:46
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 The main problem you will run into with current production Russian tubes is leakage. That will manifest as a buzz. If they don't have it, they will sound great, but we have found that that might be a very temporary situation, ultimately a frustrating one, so we recommend that you avoid Sovtek 6SN7s made after 1987, EH 6SN7s and Tung Sol-branded Russian 6SN7s.

Any 6SN7 can buzz if it has excessive leakage which is an easy test on a good tester like a Hickok. Most of the Chinese tubes have no problem, though sometimes it crops up with them; the tall metal-based tubes have been particularly prone. OTOH, the short metal base ones with the dimple on top that we have seen recently have been quite good. The red base ones have been too.

Leakage is rare in older American and Euro types, but you can still run into it. More commonly you can have bad connections due to the fact that the Chinese tubes that we use have slightly longer and larger diameter pins than the American tubes. Its easy enough to tighten up the contacts on the socket if that's the case. Generally though you don't get a buzzing problem if you encounter this, as a bad connection on one of the 6SN7s will cause the amp to stop playing.

 

RE: 6SN7, posted on March 19, 2010 at 09:57:43
Zero Cool
Industry Professional

Posts: 75
Location: Midwest
Joined: March 12, 2006
 Ok Ralph So now I'm curious. as you know i have a Hickok 539B. (I cant remember if you have a B or a C but same tester in any case). What are we talking about in terms of leakage? Are there some Approximate figures to be aware of? What should we look for?

 

Hickok tester, posted on March 19, 2010 at 12:36:25
Lew
Audiophile

Posts: 10912
Location: Bethesda, Maryland
Joined: December 11, 2000
 FWIW, my old decrepit Hickok 533 does a good job detecting leaky tubes, IF you check for it.

 

RE: 6SN7, posted on March 20, 2010 at 11:45:29
shermanr@prw.net
 Upscale Audio
[No relation to this company]

 

Thanks ! ...n/t, posted on March 20, 2010 at 14:47:20
Audio Pharaoh
Audiophile

Posts: 4502
Joined: January 24, 2001
 ..

 

RE: 6SN7, posted on March 21, 2010 at 10:23:58
marc g.
Audiophile

Posts: 3330
Location: New Orleans
Joined: October 14, 1999
 I take it this is the $15 Chinese tube that Kevin has tested and ranked based on test results? Not a bad premium to pay to have the less desirable ones weeded out for you.

voolston - audiophile by day, music lover by night!

 

RE: 6SN7, posted on March 21, 2010 at 10:43:53
baileyler
Audiophile

Posts: 359
Location: Chadds Ford, PA
Joined: January 17, 2007
 I have an S-30 Mk II.3.

The information I have is that the first two tubes (position 1 and 2 from the front) can be any 6SN7 type, but the third tube has to be a GTA or GTB.

While I can't say I have rolled a lot of tubes, my favorite tube to date in position 1 (which I believe has the most effect on sound) is a 1950s Sylvania 6SN7WGTA (brown base, 3-rivet t-plate, shorter bottle). Of course, that is for my particular setup where I need something a little livelier. I have put about 5 different types of GTs (and WGTs) in position 1, and they always seem to sound a little too soft for me.

I have not noticed that much difference for tubes in positions 2 and 3 (but again not a lot of experimentation). Right now I have a pair of Sylvania 6SN7GTAs (green print) in position 2, and a pair of Sylvania 6SN7GTBs in slot 3.

When they come up for auction on Ebay, these Sylvania WGTAs don't seem to fetch outrageous prices (although the corresponding WGTs seem to go for a notch higher).

 

RE: 6SN7, posted on March 21, 2010 at 12:16:36
fred.hammersmith
Audiophile

Posts: 23
Joined: December 19, 2007
 Very interesting info in this thread.
I'd like to understand a bit more the test results we can read on tubes descriptions.
For instance, this pair:
TUBE 1: 8,70 mA / 9,20 mA * 2,60 mA/V / 2,70 mA/V * 80,5 / 80,5
TUBE 2: 10,8 mA / 10,6 mA * 2,70 mA/V / 2,70 mA/V * 80,0 / 80,0
A brief explanation for the un-initiated would be welcome.

 

RE: 6SN7, posted on March 22, 2010 at 15:46:54
fred.hammersmith
Audiophile

Posts: 23
Joined: December 19, 2007
 So, is this would have been a good buy?

http://cgi.cafr.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=290408158860&ssPageName=ADME:B:WNA:CA:1123#ht_1155wt_926

 

RE: 6SN7, posted on March 26, 2010 at 04:23:41
Glen3


 
I really like the RCA VT-231's. For less money the Sylvania GTB's are the budget go to NOS tubes very good for the money, but don't have the bass of the RCA's. The Sylvania Gts are more expensive but have a little more refinement than the GTB's.

I have a pair of National Union Gts on order for comparison.

I'll sell you a pair of Bladwin (Sylvania GTB) 6SN7's that sound great just not as good as the expensive RCA's for $20 if you are interested they only have a few hours on them LMK.

 

RE: leakage problems., posted on March 26, 2010 at 13:20:52
shermanr@prw.net
 My tube tester is not able to provide meaningful leakage readings so I learned something new. Back to the drawing board, or Ebay for a Hickok!

 

RE: 6SN7, posted on March 29, 2010 at 04:28:50
Mike C


 
After much agonizing and swapping, I have arrived at the following lineup for my Silver Edition MA-1 3.1s:
CCS RCA smoked glass
voltage amplifier cascode (bottom?)Sylvania WGTA (x2)
Voltage Amplifier cascode (top?) Shuguang Treasure
Driver Tung Sol GTB
The Shuguang Treasure are excellent, worthy of inclusion among the best NOS tubes, although pricey. They still sounded best mixed with other tubes; too many Treasures sounded too bright. I do have the original blue glass tubes, not the current black coated glass, though.

 

RE: 6SN7, posted on March 30, 2010 at 08:42:03
acres verde
Audiophile

Posts: 723
Location: Big Easy
Joined: November 13, 2004
 I just ordered some of the new Chinese 6SN7s from Synergy/Create to try in a few strategic positions in my MP-1 and M60s. I'll post results aftera prudent amount of time.

 

RE: 6SN7, posted on April 10, 2010 at 08:32:54
fred.hammersmith
Audiophile

Posts: 23
Joined: December 19, 2007
 "In selecting tubes, make sure that the tubes used in the driver stage are GTA or GTB types, as Ralph has often reminded us. Those are rated for 450V at the plate, which is needed for the drivers in the Atma circuit. GT's are only rated for something less than 300V. OK for input stage. "

The driver stage being which position (I have a S30 Mk II)?
Do you have more references on that, I'd like to relay the info...

 

RE: Russian 6AS7G and 6SN7, posted on September 4, 2010 at 09:34:11
fred.hammersmith
Audiophile

Posts: 23
Joined: December 19, 2007

So I finally bought Russian tubes that go for very low prices on e-bay right now. Since I needed to change all of my tubes, it seems a sensible (or economical) thing to do. Tube rolling will come later!

As I am a complete novice in tubes, I'd like to share with u some pictures of the tubes. Maybe just upon visual inspection you would have some comments you would like to share? I was surprised to see two completely different sizes for the output tubes. Do u think I can mix them? Anyway, any comment will be appreciated.

Next step: playing with different kind of input tubes.

[Since i do not know how to post more than 1 image here, i included a link to the complete gallery... ]

 

Any more-current experiences with 'N7s in A-S amps?, posted on April 3, 2016 at 15:42:43
jeffreybehr
Audiophile

Posts: 5719
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since: December 13, 2004
 My experience with 6SN7s has been with pairs of ASL Hurricanes, ASL 845-based SETs, and M-60 Mk.3.1s maybe a half-dozen years ago. (I sold those after a few months of trying to drive the upper-eight octaves of Vandersteen 5As, NOT a good match.)

As I now recall, early in my 'N7 life, I eventually determined that RCAs were the nicest-sounding 'N7s of random batches of inexpensive tubes purchased thru eBay, sounding a little richer in the lower frequencies and not lacking anywhere else. Then I found that Ken-Rad VT-231/6SN7GTs had just a little more of that really nice-sounding richness*. Then I heard the Tung-Sol roundplate 'N7 (hereafter TSRP) and stopped looking for other 'N7s. The TSRPs have a tonal balance that is even more beautiful and rich and natural, just the way I want my reproduced music to be and which is so difficult to find. Starting pursuing those, ended up with a few more than 20, but then slowly sold all the equipment that used them. Sold a few to friends and stopped with 15 in the drawer.

I now have a new pair of M-60s coming this week from my buddies at USA Tube Audio, and over the last couple weeks have bought four more TSRPs, carefully selected from the stuff on eBay. Paid c. $290 delivered for the four, and all test good-enough** to excellent, and they turned out to be a mechanically-matched quad with NO brown spots on their tops and with two having the same date code.
photo 2016 TSRPs 4_1500w_zpsfojuneca.jpg

I expect to use 2 of these TSRPs in each amp, since (probably) I'll be using the gain-reduction plugs in the V2 positions* and ought not to use them in the V4 cathode-follower position due to Voltage requirements. After I get at least 48 hours of warm-up time on the new pair of amps plus some hours of listening thru them, I'll start moving some 'N7s around.

One other thing I discovered was that Herbie's tube dampers...
http://herbiesaudiolab.net/rx.htm
...do really well at reducing or eliminating any residual 'nervousness' resulting from microfonics in tubes...and ALL tubes are microfonic, and the more gain being squeezed out of a tube, the more likely you can hear the microfonics.
photo Amppad with amp_1280w_zpskiy5odz3.jpg

Oh ya...I bought a carton of Winged-C 6H13Cs (6AS7Gs) from an eBay seller radiohouse...
http://www.ebay.com/itm/111933819746?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
They arrived promptly in perfect condition.

More later.


* I looked for them on eBay recently and OH MY--are they ever expensive now, almost to the Tung-Sol roundplate level!
** I learned with my three 'N7-using amps that they do NOT require high-testing tubes to sound excellent.

 

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