Tube myths Joint Army Navy vs Non Joint Army Navy

My understanding is that sometimes (not always)there is a difference in military tubes. If the original use is to use them in Mig fighters or something that is understandable. Sometime it is just quality control too. Generalizations are probably hard to make in this area. I'd be interested in hearing opinions on this point.

There are some good crossreferences such as the bottom of this page. I have a more complete site but can't find it at the monment. I'll post it if I find it.
http://www.hndme.com/storetroubleshootingtips.html

Here is list that might help newbies too. The first few explain tube numbering which is a bit of a mystery when you start out. The second set are online sources for tube data. The first three (Duncan, Frank's and Triode Electronics) will usually have the info needed.

P.S. Hey Fletch. Nice posts for newbies but you sure use a lot of commas when you write.

Tube Numbering explained:
*) Åke’s Tube Numbering: http://w1.871.telia.com/~u87127076/tabeller/index.htm
*) Tube Numbering Systems (Frank’s site) http://home.wxs.nl/~frank.philipse/frank/tubnum.html
*) Philip, Valvo & Mullard Valve Coding: http://www.cs.helsinki.fi/u/oheinone/valves/pvm-coding.html
*) Tube Numbering (MachMat’s Site): http://www.machmat.com/info/index.htm
*) Russian encoding system: http://www.arrakis.es/~igapop/russianotes.htm
*) Coding systems: http://www.arrakis.es/~igapop/referenc.htm
*) Phillips factory and tube codes: http://www.triodeel.com/images/philipstubecodes.pdf [Note that all Philips subsidiary companies (Mullard, Valvo, etc) and all factories that made tubes under Philips license used these codes (Ei, Toshiba, Siemens, etc) so it's not limited to European Philips tubes.]

Tube data:
1) Duncan Amps: http://www.duncanamps.co.uk/cgi-bin/tdsl3.exe/searchform
2) Frank’s Tube Data Page http://frank.nostalgiaair.org/index.html
3) Triode Electronics Tube Data Sheets: www.triodeel.com/tubedata.htm
4) Radau5”s tube data sheets: http://www.radau5.ch/valves.html
5) Tubebuilder Tube Data: http://www.tubebuilder.com/tubedata.html
6) Vacuum Tube Valley: http://www.vacuumtube.com/FAQ.htm.
7) Svetlana, Tube Dictionary: http://www.svetlana.com/docs/dictionary.html
8) Audiomatica, Tube Directory: http://www.mclink.it/com/audiomatica/tubes/home.htm
9) National Valve Museum’s list of Equivalents: http://www.valve-museum.org/
10) 4Tubes. http://www.4tubes.com
11) Tube Collector’s Association: http://www.tubecollectors.org/
12) Mach-Mat: http://www.machmat.com/sheet/index.htm
13) Kytelabs Tube infobase: http://www.qsl.net/dl7avf/roehren/roehren.html#TOC
14) An Intro to NOS tubes: http://www.soundstage.com/tubeor/tube.htm
15) Western Electric Archives: http://www.westernelectric.com/spec_sheets/we_spec_sheets.htm
16) Tom Jennings: http://www.wps.com/archives/tube-datasheets/index.html
17) Åke’s TubeData: http://www.tubedata.com/
18) Magic Sound of Tubes (NOS): great pictures of NOS tubes. http://spazioinwind.libero.it/themagicsound/index.htm
19) Bill’s (NJ7P) Database: http://hereford.ampr.org/cgi-bin/tube?index=1

I remain,

Newbie In some contracts, the specs for the tube, accounted for this. The tube, then, had a special construction(such as stabilizing rods, extra mica etc) This is when the tube, was different, and it had a different designation usually. But it only takes to look at a tube, and see the same internal construction, to know that there are no differences.

said above by Fletch >>>"But it only takes to look at a tube, and see the same internal construction, to know that there are no differences>"

Can you really do this????

If you can just look at a tube and do a visual inspection and see there is no difference then why go to the trouble of an electronic tube tester and matching?

There can be small differences in tubes of the same type and even the same run. This is just part of what they are and the tolerances involved and the production process. My understanding is that some tubes used in some critical military applications (Mig fighters etc...) were subject to much higher testing and Q control. I was also told that one reason that some old tubes are so good is that they threw so many away in the QC testing. Making tubes was apparently a process where a good portion of the runs went straight into the bins. This makes a certain amount of sense.

To the extent it is true I cannot say.

It may also be true that for some/many audio applications it may not make a big difference.

Sincerely
I remain,

One of the dirty little secrets of tube use in audio gear is that one of the primary, make that the primary, consideration is audible noise.NOS manufacturer grading of tubes generally has nothing to do with noise. Likewise, the conventional testers that we use - I have both a Hickock 752 and a TV-7DU - check for filament, transconductance and/or emission. I don't really think that any of these parameters is going to say anything about noise. All we can really do is tell if a tube is outside of its operating specs or match tubes. Without listening, we can say that a tube is bad, but probably not how quiet it is in an audio circuit.

Bought a pair of tube amps from circa 1955. The owner had JAN tubes recently installed. The amps sounded OK, but when i replaced the tubes with Amperex tubes, the amps sound incredible, they just SING !!!

So much for the "sound quality" of JAN tubes.