[mab1376]

I think its BS, is was more for the tube image.

 

[mordy]

Hi All,
 
Just found an answer to a question I had for a long time: Why do some tubes have little colored splashes on top of the nib? In the past I had Western Electric tubes with red on the nib, and these Sylvanias below have a blue color on the nibs. Why? (Answer below)
 
 

" Tiny drips of paint on tube tops meant the tubes passed extra quality control tests. For preamp tubes this meant best for microphonics".
 
Now, all that's left to know is how to decipher the date codes on the Tung Sol tubes...lol

 

[Oskari]

  " Tiny drips of paint on tube tops meant the tubes passed extra quality control tests. For preamp tubes this meant best for microphonics".

 
Or perhaps some other test criteria depending on application. Unless the painter was just some less than scrupulous profiteer. I'm a little bit skeptical because paint is very easy to apply.
 

Now, all that's left to know is how to decipher the date codes on the Tung Sol tubes...lol

 
And Sylvania. 

 

[Oskari]

  a totally different breed, even as an object.

 

  They look pretty much the same and were made in the same factory.

 

[zedmeco]

http://lampizator.eu/UPGRADE/upgrade%20noval%20tubes%20to%206H6P.html
Hi can someone with more knowledge then me have a look at this article, he seems to imply the 6n1p can be a direct replacement for the 6n6p, and that it sounds better! can this be right. 
 
a massive sorry to the regulars that messaged me about the seimens tubes, i haven't logged on for ages! i still have them but they hum in my mk3 and you all seem to rate them. i have two pairs, i will take some pictures and post them for your perusal. thanks Z

 

[mordy]

Hi Oskari,
 
Here is a little information on Sylvania (if it is repetitious I apologize). At the end of this post I have put in my 2 cents worth of personal opinion on Sylvania date codes:
 
"What does J.H.S. and J.A.N. mean?

Sylvania was a major manufacturer of Military tubes and selected a 3 digit lettering system to designate Sylvania products. One system prefixes a three-digit number with the letters "VT", presumably meaning "Vacuum Tube". Other systems prefix the number with the letters JHS or JAN. J.A.N. is believed to stand for Joint Army Navy, where as, J.H.S. sometimes remains a mystery, and is commonly thought to just signify Sylvania product.

The numbers following these prefixes can be special four-digit numbers, or domestic two- or three- digit numbers or simply the domestic North American RETMA numbering system. Like the British military system, these have many direct equivalents in the civilian types. Confusingly, the British also had two entirely different VT nomenclatures, one used by the Royal Air Force and the other used by the General Post Office, responsible for post and telecommunications at the time, where it may have stood for Valve, Telephone; none of these schemes corresponded in any way with each other. It was introduced during the Second World War to rationalize the previous nomenclatures maintained separately by the War Office/Ministry of Supply, Admiralty and Air Ministry/Ministry of Aircraft Production on behalf of the three armed services for CRTs, receiving and transmitting valves used in army equipments.

I personally have researched this in the past, and have come up with the theory that JHS was chosen by Sylvania meaning Joint Havells Sylvania or J.H.S.

Havells Sylvania is an international designer and manufacturer of lighting products. It has plants throughout Europe, Asia, North Africa and Central and South America, and is one of the few lighting companies that produces both lamps and lighting fixtures. It is owned by Havells.Founded in the early 1900s as a business that renewed burned-out light bulbs, Sylvania and its predecessor companies ultimately began producing new lamps and then vacuum tubes for the radio industry.

Mark Kawecki
tubemuseum
 

MEANINGLESS CODES by TUBE REMARKETERS:

Both Tung-Sol and RCA utilized the "Stop-Sign" logo [5751] in brackets. The "hole" in the top mica identifies these USA made tubes from the TUNG-SOL factory in Newark, New Jersey, USA in the 1950's.

THE UNITED-ELECTRIC RELABEL CODE 88-37 IS MEANINGLESS AS THEY SIMPLY RELABELED NEW OLD STOCK TUBES FROM TUNG-SOL. RCA, SYLVANIA, AND OTHERS. NO ONE MADE D-GETTER OR SQUARE-GETTER TUBES IN 1988! AND UNITED-ELECTRONICS WAS OUT OF BUSINESS IN 1988! SO 88-37 WAS UNITED-ELECTRONICS INTERNAL NUMBERING SYSTEM AND DID NOT SIGNIFY ANY MANUFACTURING DATE.

Especially, during the 1950's war effort, it was a common practice for USA factories to source tubes from each other and re-label them. When a government requirement for CV4017 tube specification came in a Request For Proposal (RFP) to the 4 major USA tube factories they all worked together to source from one another to fill the orders. This is why we see so many tubes made by Tung-Sol labeled as RCA, RCA made tubes labeled Sylvania, Sylvania made tubes labeled GE ... and so on, Sylvania, RCA, Tung-Sol and everyone else at some time relabeled tubes! This is why we have to LOOK AT THE ORIGINAL FACTORY CODES IF PRESENT (NOT THE UNITED ELECTRONICS RELABEL CODE),, and identify the real tube manufacturer by codes, inner construction, shape of the tip, and shape of the getter ring to determine the real origin of the tubes.

UNITED (United Electrics Company, Newark, N.J., USA) was a company that simply re-labeled Tung-Sol, RCA, Sylvania, and GE USA made tubes for resale.

All tubes have Tung-Sol acid codes shown as in above picture on top and Made in USA in 1960. In the actual pair above you can see "60 - 40" code = "1960 - 40th week" and "60 - 33" code = "1960 - 33rd week" TUNG-SOL USA

Made in USA in 1964. In the actual pair you can see "64 - 02" code = "1964 - 2nd week" and "65 - 20" code = "1965 - 20th week" TUNG-SOL USA"

 
In my personal notes I have a notation that a Sylvania tube coded L7V was manufactured in December 1957/67 in plant V, but I don't remember my source for this. Anyhow, the months would go in order of the alphabet; A=January, B= February and so on until L =December.
The digit 7 would indicate the year, 1957 or 1967. The last letter would be a code for a plant, in this case plant V.
 
Stuck my fingers into my 6AK5 box and fished out a couple of Sylvania tubes. Two tubes are coded GB and GH. ???
The next one says H1. Maybe August 1951/61.
The next tube has a yellow nib and says F2E. Maybe June 1952/62 plant E.
Next is H0E. What do u say? August 1950/60 plant E.
Next is E1E: May 1951/61 plant E.
Next B2E: February 1952/62 plant E.
All of them have square getters and look pretty old, so maybe the 1950's.
 
I am getting a headache, but maybe we have some kind of pattern here?
 
PS: About the colored nibs, the pair of  Western Electric tubes with the red paint came from boxes that indicated that they were made for the Sperry Rand Corporation on Long Island, NY, which produced gyroscopes for military use.

 

[Audiofanboy]

   

  They look pretty much the same and were made in the same factory.

 
They may look similar, but they are different tubes made with different alloys, tooling and parts. Mojorisin had made a very nice post about how to recognize a DR from an new production tube:
 
http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/1425#post_9480971
 
Having had both in my hands, I can say that they do not give off the same feel; the DRs feel like you could throw them against a wall and they would fine lol. They sound surprisingly different though, moreso than I would have thought for tubes made in the same factory.

 

[Oskari]

  http://lampizator.eu/UPGRADE/upgrade%20noval%20tubes%20to%206H6P.html
Hi can someone with more knowledge then me have a look at this article, he seems to imply the 6n1p can be a direct replacement for the 6n6p, and that it sounds better! can this be right. 

 
I see no such implication there.

 

[Iron58p]

I'm burning GE JG-5750 6BE6W, setting EF92, year 1958
 
Are fantastic tubes on my opinion, medium hights transparent, clear and very detailed, bass fast and not invasive on medium, female voices very nice, soundstage the best unltil now,  on corus is possible closing the eyes to collocate the position of each singer on the scene.
 
Uaww, make me dream !!

 

[Audiofanboy]

  A pair of GE 6DT6A tubes have arrived from Canada... though on the tubes they are marked as having been manufactured in Japan.  It's hard to see the glow with the way the grids are set up...

 
 

  After a short warm up and just a couple of tunes I can hear exactly what you mean by the bass in the 6DT6As... awesome. 

  And I'm running them unstrapped in EF95 at the moment... 

 
Those tubes you mention are CGE 6DT6A Japan "made to CGE specifications" right? I just got the same tubes in the mail, and threw them on the amp for a thorough burn-in; so I'm interested in your experience with them!
 
First impressions are favorable; indeed the bass roars with these! Too many of the recent tubes I tried either smeared mid-bass and bass or just left it out of the picture entirely.
 
EF92'd, these 6DT6A are very nice out of the box: surprisingly musical and toe-tapping from the start, delicious and pretty tactile bass, very nice mids that beautify voices. Hopefully they'll stay that way after 20 hours, and just tighten up. Still, finally having a bit of low-mids and bass is a nice change!
 
Why EF92 setting you say? (Please don't hit me lol) Because it's what sounded the best on the GE Canada-made 6DT6A I tried, for one. And also because it is one the two solutions that intuitively make sense with this tube type. I see no reason to float grid 3 with these tubes, so plain EF95 is bleh. Strapping the two control grids together (1-7) is OK but the tube doesn't require it to work well, so meh, but it's worth a try. Now, Strapping the suppressor/2nd control grid (grid 3) to the cathode (2-7) is pretty logical, but grid 3 on these tubes is pretty weird and like a tightly woven suppressor, so I don't know how it behaves 2-7'd with grid 2 strapped to the anode; but it makes sense. Finally, Strapping grid 3 to the anode and grid 2 (EF92) makes sense since you get a textbook triode-strapped pentode -dual control or not, whatever. That setting sounds the best to me so far.
 
Yeah, call me too scholar or Manichean if you want, and there's no harm in testing things, but some settings just don't make much sense... Floating grid 3 on a pentode is just kind of purposeless imho...

 

[Oskari]

  "What does J.H.S. and J.A.N. mean?

Sylvania was a major manufacturer of Military tubes and selected a 3 digit lettering system to designate Sylvania products. One system prefixes a three-digit number with the letters "VT", presumably meaning "Vacuum Tube". Other systems prefix the number with the letters JHS or JAN. J.A.N. is believed to stand for Joint Army Navy, where as, J.H.S. sometimes remains a mystery, and is commonly thought to just signify Sylvania product.

I personally have researched this in the past, and have come up with the theory that JHS was chosen by Sylvania meaning Joint Havells Sylvania or J.H.S.

Havells Sylvania is an international designer and manufacturer of lighting products. It has plants throughout Europe, Asia, North Africa and Central and South America, and is one of the few lighting companies that produces both lamps and lighting fixtures. It is owned by Havells.Founded in the early 1900s as a business that renewed burned-out light bulbs, Sylvania and its predecessor companies ultimately began producing new lamps and then vacuum tubes for the radio industry.

Mark Kawecki
tubemuseum

 
Mark's research is weak. The "systems" were military and hardly "selected" by Sylvania. Havells Sylvania is a recent creation, so that theory is bollocks. I believe JHS is just a contraction of JAN-CHS where CHS indicates Sylvania (or Hygrade Sylvania as it was previously known as).

 

[Oskari]

  PS: About the colored nibs, the pair of  Western Electric tubes with the red paint came from boxes that indicated that they were made for the Sperry Rand Corporation on Long Island, NY, which produced gyroscopes for military use.

 
In which case it is entirely plausible that there was a rigorous selection process.

 

[Oskari]

  Stuck my fingers into my 6AK5 box and fished out a couple of Sylvania tubes. Two tubes are coded GB and GH. ???

 
It's these two-letter and three-letter (no digits) Sylvania codes that I've seen no explanations of. Sometimes you see both of them together.
 

The next one says H1. Maybe August 1951/61.
The next tube has a yellow nib and says F2E. Maybe June 1952/62 plant E.
Next is H0E. What do u say? August 1950/60 plant E.
Next is E1E: May 1951/61 plant E.
Next B2E: February 1952/62 plant E.
All of them have square getters and look pretty old, so maybe the 1950's.
 
I am getting a headache, but maybe we have some kind of pattern here?

 
I agree that the digit is probably the last digit of the year. Have you got any to double-check like with a date on the box?

 

[zedmeco]

I see no such implication there.

6N1P

The beauty of this tube is that is pin-compatible with not only 6N6P, but also with ECC 88, E88cc, 6DJ8, and 6922 popular tubes. The sound of 6N1 is more crisp and energetic than the sound of 6N6P and it is more easy and natural than that of the ECC 88, E88cc, 6DJ8, and 6922.

 

[Oskari]

"Usually - in amplifiers - I would use 6N1P as input amplifier and the 6N6P as driver (high current !!!)"