Do military/industrial tubes sound better than regular ones ?

If they tolerate vibrations better , they should  theoretically sound better, all other things being equal.  

@inna "Do military/industrial tubes sound better than regular ones ?” 

they don’t! typ. MIL and Industry standards have higher shock-vibe, temperatures spec to comply! 

trivema, no I have no intention to buy too many, just two or three sets of each type that I need. Did you compare those Raytheon 12AX7 black plates to RCA blackplates ?

Ralph, I see. This makes it complicated, doesn’t it ? You just have to try, no general answer really.

@inna Some do and some don't. Something to keep in mind- all tubes, regardless of the source, should be vetted prior to use in high performance tube equipment! This means they should test good and also auditioned for noise, crackling and microphonics. Even then you'll find military tubes that don't seem to sound as good as consumer counterparts.

My experience is primarily with 12AX7 and 6SN7 tube types.

First, there are truly profound differences in the way different brands of tubes constructed at different times sound. These differences are repeatable. 
 

For the 12AX7 tube in my Marantz 7C, I liked Amperex from Holland or England, as they were a better fit than Telefunken as the latter made my preamp sound a little syrupy. Telefunken was a better match tonally to my Audio Research SP6B, though I still preferred the sound of the Amperex. I was anal enough in those days that I would bias the tubes in the SP6B every time I changed them.

My experience regarding the 6SN7 runs across several Schiit and Cary preamps. For the rich world of the 6SN7, the additional rigidity from extra supports, etc in the JAN and VT231 types results in lower microphonics and a greater sense of inner detail, sense of depth, and solidity and strength in the bass. It’s remarkable how there are distinct sound characteristics of each type- my Ken-Red VT231 black glass tubes really do have more solid and defined bass, and my 5692’s from both CBS Hytron and RCA have a smooth, liquid sound. My Sylvania tubes, ranging from Bad Boys of the early 1950’s to early 60’s GTB’s all share a bit of sparkle at the top, though the early versions sound better.

 I have not played much with new stock high-end offerings from China (scared off by reliability issues), but new standard production from Russia and China do not have the sense of inner detail, depth, power, or drive of the older tubes.

so yes, tube types do sound different!

@willywonka they are still used in the Russian space program

I have a ton of 12AX7, 12AT7, and 6SN7 vintage tubes, both military, “commercial,” e.g., FAA contract tubes, and regular consumer grade.  Military tubes are more rugged with more micas, support rods, etc. I don’t think military grade sound better per-se, rather I think they were simply manufactured at the hight of US tube production expertise from early 1940’s into the 1950’s and 60’s.  Once the transistor came into the picture, emphasis on tube production declined rapidly and quality suffered. 

That being said, my absolute favorite 6SN7s are a pair of 1945 JAN Sylvania 6SN7W and 1950’s Tung Sol 6SN7 GTWA. My favorite 12AX7 is a black plate Raytheon from 1950’s with Baldwin label. I have an identical back up Raytheon with the JAN anchor on it. They sound the same, no difference.

if you can find a high testing RCA black plates from same era, factory, etc, a consumer branded will be the same tube, same construction, same sound characteristics.  RCA Command were just pulled and labeled as such because they tested higher with closer matching tolerances, so I’ve read.

Buy two or three, don’t do like I did and go crazy buying and collecting hundreds of tubes that will outlive you and your children! Can’t listen to them all enough to wear them out.
 

No matter what it really all depends on synergy. I love my GE & RCA 5751 & 5814 Black Plates, I have them in Gray versions from GE & RCA as well. I’ve also accumulated At7’s, AU7’s & AX7’s from Amprex, Mullard,Slovak, Psvane, & Northern Electric that are now just sitting in a box. I sold the bugle Boys being I could. 

I’ve tried em’ all and found it’s all dependent on what you AND your system like. My GE 5814 Black Plates sound the best  in my System’s Preamp. 
GE 5751 Black Plates sound the best in my PhonoPre 

RCA 5751 Black Plates sound the best in my DAC. (For Output)

Thank god the preamp tubes should last a long time being these tubes are getting harder to locate, at a reasonable price that is.

A tube reseller once told me Black Plate Tubes handle the internal heat better, All I can tell you from my experience, I  find Black Plates to sound better and have a better synergy with my equipment. 

But at the moment I am burning in a new set of regular 12AU7 RCA blackplates from early 50s to compare them to the same RCAs from late 50s. 25 hours of burn-in time so far, but I think I hear something indicating that they might be slightly better. Now, this is interesting, sounds crazy to non-audiophiles, I guess.

By the way, I completely disregarded Kevin of VAC’s advice regarding small tubes. He suggested some selected Chinese for 12AX7 and Brimar or Sylvania for 12AU7. I figured we had different taste, and I certainly don’t want any Chinese tubes in my amp. So after talking to knowledgeable people here and beyond, I went with vintage 12AX7 Mullards for preamp and vintage 12AU7 RCA blackplates for driver tubes. I don’t really want current production EL34 output tubes either, something he suggested as well. At best, I hear that they don’t last, and at worst that they sound like crap. Perhaps it varies wildly, I simply don’t want to throw money away for virtually nothing.

Since I make no claims to be a tube guru I started trying to go through a plethora of emails I filed away from the 6SN7 guru who bestowed that cache of vintage 6SN7s (and some 6922s) upon me. I thought I remembered him telling me that the tubes that the military had contracted out for were made to better withstand vibration as many of them were going to be used in different avionic applications.

Anyway, I have a crapload of emails on those tubes and I wasn’t finding the one I was looking for, but I’ll paste a blurb from one of the first ones I found:

The W in WGTA is the designation for "ruggedized" construction. Thicker mica supports, extra support rods, smaller bottle ... all supposed to reduce the effect of physical shock/vibrations.

That was referring to a pair of 1974 Sylvania 6SN7 WGTAs that I don’t think were made for military applications as I think that (at least our) military must have been done with vacuum tubes by then.But another pair of 6sn7s he bestowed upon me when he was cleaning out his cache of tubes he no longer used, and these really are jewels, were two ’52 Sylvania "Bad Boys" and I have to think that these were military as he sent them to me in their original packing box (not tube boxes, but a heavy duty box) with a faded placard labeled "SPARE PARTS" , and also states that the contracter was "PHILCO CORP." and "MFG BY [a faded "Sylvania is typed in] "DATE INSPECTED" [9-19-52" is typed in, faded but still legible] under that "PACKED FOR OVERSEAS SHIPMENT" and in the bottom right hand of the placrad is a little picture of an anchor with "ORD" in the middle of the anchor and "U.S.. NAVY" at the bottom.

So I assume that these were made by Sylvania for the Navy, and these are tied for first place as my absolute favorite 6SN7 sonic presentation so far.

My two runner ups were a pair of black glass RCA VT 231s and a pair of Tung Soll VT231s ("probably NLT 1947"). I think maybe the reason that military tubes have the favorable reputation that they do is because a large percentage of the tubes that were made way back then were made for the military and therefore a lot of the vintage tubes that are being sold today may have been made with a military contract in mind so when we find one we really like, it’s not unusual for it to be "military surplus" of sorts.

I've had good luck with JAN/Phillips 6922 tubes but I don't think being military is a guarantee of better sound or longer life.

Russia also has their military grade tubes. The Russian Rockets Reflektor 6N23P are a popular tube still used by many especially in heaphone amps. These tubes were used by the Russian Space program back in the 70's. I still have a set in an old tube amp. I'm sure there are many others.

Well, Brent from Audio Tubes has both regular 12AU7 RCA black plates and military/industrial ones, all from 50s, not sure early or late 50s. He also calls industrial Command Series. I have regular ones installed, so I could order a set of military/industrial, burn them in for 100 hours and then compare. Return them if I hear no difference and lose 20% which would not be much, those tubes are $99 each and I would need three of them. I just don’t want to start with this and don’t want to buy more tubes right away, last week spent $450 for a matched pair of 12AX7 NOS Mullards longplates from 50s. They are excellent tubes, hard to find, so I bought a spare pair from Brent.

Military vacuum tubes are built to specifications that ensure resistance to failure in high vibration environments and tighter tolerances³. They are not necessarily for the military, but are manufactured to meet these requirements³⁵

^{Perhaps tighter tolerances may impact the sound, but I believe the ones labeled for the military are no different than the ones labeled for any other use, probably coming off the same line, only labeled differently.}

Be careful buying " medical" and " instrument" grade tubes.  Especially 6922 as they were used in a lot of test equipment.   Many are not NOS , they were pulled from gear as it was phased out and replaced  by solid state.   "Pulls" as they are known.  Many of those tubes were robust and still tested as new when pulled.  Plain white boxes and weak lettering is a red flag. 

There is discussion of what a military tube really is so I'll add my understanding.  Military tubes generally have a military designation like vt-231 and often have JAN (joint army navy) on the box or even on the base.    They were made for a military contract and are generally the same design.  For my amp, the VT-62 is the 801A.

So I don't give military tubes more respect unless they come with a reputation.  The 6SN7 tubes have been studied to death and many of the military tubes are considered great but not because they have a military designator, because people think they sound better.  

Jerry

Yeah, no doubt, NASA grade, medical grade, scientific grade. But also for guitar amplifiers, organs, TVs etc.

Well again, not being a tube guru, I may be mistaken by all of this, but in the time period most vintage tubes are coming from, wasn't their primary intended use to be industrial?  As in, for example, oscilloscopes and other types of equipment?

And to go a little  further, military grade and industrial grade - any difference ?

I don't know about the small 12 pin tubes, but I believe that the VT231 is a military application of the 6sn7 and I was fortunate, three or so years ago, to get several pairs of vintage 6sn7s and VT231s.  After several days of tube rolling I was really wowed by a couple of the VT231s--more so than by the 6SN7s.  I make no claims whatsover to be a tube guru, but I think what may be a factor in that is that the military may have had higher specification demands for the tubes that they were using in tubed equipment at the time. 

Many are dubbed military or industrial for a variety of different reasons, so it'll depend a lot on each individual tube, and what makes them different.  Plus a lot of tubes sound different on different circuits, and it's all very subjective.  

No they don’t sound better!