oldest tube(s) in your system

Oldest tube in use... I guess the RCA 5693 from 1948. I use them in a Lambda 25 power supply to supply regulated 325volts to a slightly modified Croft Micro 25R preamp.

RCA Grey Glass Hamburger Font 6SN7 - 1940's Production

Measured at my end by a friend and both close matched near Factory Spec's.

I have other pairs of Valve Types all  matched near Factory Spec's. from the 50's and 60's Production Era's  

@noromance Beautiful piece of gear!  Thanks for sharing the photo.  Love the eye tube too!  Does it ’close’ (or is it open?) at 325v?

A pair of November 1943 Sylvania 6SN7 GT's in Supratek Cabernet. 

Zoiks; 82 years old!  It’s not a competition, but wow, that’s old...and no doubt great.

Brimar 6V6G st from the 40's in my Decware Mini Torii

Ken Rad JAN 6SN7 VT-231 black glass, military stock from 1944. One pair in an LTA Aero, and one pair in an LTA microZOTL L3. I like them better than the Ray Reserves — slightly wider/deeper soundstage, better imaging and decay. 

Cunningham 71A tube, in Tektron preamp (Italian company), this tube in production  from 1927 to early 40's, don't know exact date of mine. Also have any number of various 50's era tubes running in a number of  components.

 1950s RCA,and 1958 Amperex  all are Black plates D getters.

@audioman58 what kind of tubes are the RCA and Amperex and what are they in?

Other oldies in our system are: 2 x 1952 Sylvania T-plate 6BL7 GTA and 2 x 1958 Western Electric D-getter JW 2C51.

I have a set of Wurlitzer amps that were modified to run a pair of 45s. The ones I've been using are pre-war but I don't know how old. They run fine. Those amps are no longer in my system, having been replaced by a single amp of similar power that is much more compact. It uses EL95s from the 1960s.

Yea, I figure 45 or 2A3 or similar would be about the oldest tube type still heating listening spaces.  Funny that as those are power tubes; would've thought signal tubes would be more likely to be oldest still in use.  All of our power tubes are new production babies.  And all of our signal tubes are older than me!

A pair of 45's in the Will Vincent Audio West SET45 amp. Along with a pair of 6C6 pentodes as input/driver tubes. Rectifier is a 5V4. The amp is built on a white powder-coated Dynaco ST70 chassis.

National Union 45's from the 1940's in my Supratek SET / 6SN7 preamp. 

I have no idea how old are the tubes in my system.  The amp and line stage run Western Electric 348, 349 and 310a, 310b tubes which were around from the 1940's through the early 1960's.  The 348's and 349's are extremely rare.  

Most of my 6sn7's and VT231's are from the 40's and 50's. National Union, Ken Rad, Sylvania, RCA, Raytheon, Tung Sol and no doubt others. Lots of nice vintage tubes, a few newer ones from Amperex and Electro Harmonix but mostly favor the ones from the 40's and 50's. 

I also have a group of 7n7's which I haven't even tried yet. I think they are 40's and 50's, all are metal base tubes. 

For 12AX and !2AU7, I mostly prefer tubes from the 50's, Sylvania GB Gold Pin 5751's and also Amperex Bugle Boys. 50's and 60's I guess?

I used to run RCA mono-plate 2a3s made before 1936.  Those are good sounding tubes.  A friend runs extremely rare and old 252 meshplate anode tubes made in the 1920’s that pre-date the 300A.  He rarely plays the amp because those tubes cost well north of $30,000 a pair.

I run some globe 866 mercury rectifier tubes, probably made in the 1930's.