Hey all, I work in a very old oil refinery and was wandering through an old warehouse at work where they had old electronics equipment from long long ago stacked all over the place...
Anyway, I found a box full of vacuum tubes that seemed very odd - I know that these old Controls and Monitoring equipment years ago had tubes just like TVs and radios back then, but some of the the tubes I found were audio types - like 2A3, 6L6, 6V6, 12AX7, 12AU7, 6SN7, 6SL7, 6J7, 6SJ7, etc... does this seem odd? Were these tubes used ubiquitously back in 40 / 50 / 60's?
Maybe the guy back then ordering all the tubes was ordering a few for himself for a home hobby?
Anyway, I found a box full of vacuum tubes that seemed very odd - I know that these old Controls and Monitoring equipment years ago had tubes just like TVs and radios back then, but some of the the tubes I found were audio types - like 2A3, 6L6, 6V6, 12AX7, 12AU7, 6SN7, 6SL7, 6J7, 6SJ7, etc... does this seem odd? Were these tubes used ubiquitously back in 40 / 50 / 60's?
Maybe the guy back then ordering all the tubes was ordering a few for himself for a home hobby?
i dont know allot about tubes. but i dont think allot of tubes where made for just audio.
they where the transistors of the day. just like some jfets where used in radar just so happens they are great for audio. allot of the tubes i ask and talk to my dad about he knows from his analog microwave days on the railroad.
they where the transistors of the day. just like some jfets where used in radar just so happens they are great for audio. allot of the tubes i ask and talk to my dad about he knows from his analog microwave days on the railroad.
These tubes and many others were widely applied where their particular characteristics suited an application industrial or otherwise. No tube was specialized in its range of use.
All of these types were commonly found in industrial applications.
Industrial equivalents existed for many of these types and were generally used in less cost sensitive applications.
All of these types were commonly found in industrial applications.
Industrial equivalents existed for many of these types and were generally used in less cost sensitive applications.
This really belongs in tubes / valves so I will move it there.
A few years ago I was working at an old scrap yard and there was a long forgotten x-ray machine in the corner. (Don't worry, the source had been removed long ago) I got curious and looked into the side of it and lo and behold I saw a pair of Sylvania black plate 6L6 tubes. I removed these and blew the dust off them and began looking further into the machine. I then found 4 Mullard 6SN7 tubes and of course I pulled those. I figured those had long ago been burned out but what the heck right? Well, they sat in my tube drawer for awhile and then I got bored and started building a little SE amp. I plugged in the 6L6 tubes for power and used the 6SN7s for drivers and powered up. All tubes came to life again! WOW what a sweet sound! I don't know how much life these tubes have left in them as I do not have a tester but at least in their sunset years they will be making some sweet music.
We had a shaker amp that was all tubes in our environmental qualification lab. It was a dedicated rack about 7ft. tall with lots of ventilation. Must have had 20-30 or so large power tubes in it. Never saw it in use.
It wasn't a Mac though
What I did see a McIntosh power amp do once was amplify a 60Hz tone and drive an industrial vacuum cleaner at it's speaker terminals but it wasn't a tube amp.
The vacuum cleaner sounded amazing however.
A look at early tube manuals gives a good indication of what tubes were desinged for.
I expect that in the early years tubes were used almost exclusively in radios both entertainment and communications as well as for telephone amplification. Not much else of an application up to the mid 30s. Power tubes were Audio Output Tubes. Small signal tubes were either RF, IF, or audio amplifiers, or a combination of the three.
The period leading up to WWII saw a great change as military applications overshadowed commercial use.
Reading the tube manuals after WWII there are fewer application statements in the tube specs compared to pre-WWII. That is, until you get to compactrons which were specifically designed for TV sets.
So, yes. A lot of tubes were specifically designed for audio purposes. On the other hand, "if it works, use it". Look at all the power supplies using 2A3s, 6L6s etc.
Once an industrial application developed, the tube manufacturers designed specific tubes for those applications (if there was enough demand). Look at the big Triode Pass Regulator tubes that are now being adapted to audio use. The data sheets are pretty specific as to what the intended application was for the tubes.
The 4164 was designed as an RF amplifier, but found application in commercial audio amplifiers.
I expect that in the early years tubes were used almost exclusively in radios both entertainment and communications as well as for telephone amplification. Not much else of an application up to the mid 30s. Power tubes were Audio Output Tubes. Small signal tubes were either RF, IF, or audio amplifiers, or a combination of the three.
The period leading up to WWII saw a great change as military applications overshadowed commercial use.
Reading the tube manuals after WWII there are fewer application statements in the tube specs compared to pre-WWII. That is, until you get to compactrons which were specifically designed for TV sets.
So, yes. A lot of tubes were specifically designed for audio purposes. On the other hand, "if it works, use it". Look at all the power supplies using 2A3s, 6L6s etc.
Once an industrial application developed, the tube manufacturers designed specific tubes for those applications (if there was enough demand). Look at the big Triode Pass Regulator tubes that are now being adapted to audio use. The data sheets are pretty specific as to what the intended application was for the tubes.
The 4164 was designed as an RF amplifier, but found application in commercial audio amplifiers.
Same with Bogens. MO-100 and 200 are the ones used most. TheCitation II was commonly used in engraving studios because of the high frequency capabilities.
Tubes were being designed in as late as 1968 and were still in use in industry in 1973 when I became a tech. The 2n3055 was out by then but retailed for $12 and only could handle ~50v unless specially selected. Tubes like the 5881 were $3 and could handle a lot more power than a 2n3055. Although the tube had to run into a transformer to do anything useful.
The company I worked for explored for oil with a bladder that did a sine wave sweep from 0.5 hz to 20 hz. The device that produced the sine wave was a DTL logic assembly. The 4 power tubes amplfied the sine wave to a useful power, then to a transformer. Then the transformed sine wave controlled a vickers analog hydraulic valve, that converted electricity to hydraulic pressure. The device pumping sound into the ocean was a large rubber bladder. The hydraulic pump feeding the vickers valve was a 1500 hp 12 cylinder catepillar.
This thing was pulled out of service about '74. A whole bin of tired 5881 tubes came back with it.
The company I worked for explored for oil with a bladder that did a sine wave sweep from 0.5 hz to 20 hz. The device that produced the sine wave was a DTL logic assembly. The 4 power tubes amplfied the sine wave to a useful power, then to a transformer. Then the transformed sine wave controlled a vickers analog hydraulic valve, that converted electricity to hydraulic pressure. The device pumping sound into the ocean was a large rubber bladder. The hydraulic pump feeding the vickers valve was a 1500 hp 12 cylinder catepillar.
This thing was pulled out of service about '74. A whole bin of tired 5881 tubes came back with it.
Tubes were used for lots of industrial applications,
I will list a few:
Xray control and monitor.
Closed loop amplifiers for conveyor control systems.
PECel amplifiers for loop control.
Any monitors using CRT for machines.
Control systems for speed control.
Dekatron counters used for length measurement and cut cycles.
Dekatron counter - YouTube
Field control on motors.
Tubes used for audio in PA systems in factories.
It was common to see EL34 in variable power supplies and scopes using tubes like EF86 ecc88.
6SN7 ECC33 6l6 the stores had racks of hundreds of types<<<sigh they used to be lying about in engineering workshops.
It was common to even find electricians with a few in there locker that failed or went unstable on control systems
They usually also had a stash for the home TV just in case.LOL
Just a few that come to mind.
I visited a few factories recently that the stores had tipped boxes of tubes into a glass crusher.
Its a bit sad really because most were tubes from the early years still in boxes.
To the industry they had no value anymore and big companies aren't interested in Ebay, but they still wouldn't let people have them for free.
The techs in hospitals used them as well.
Regards
M. Gregg
I will list a few:
Xray control and monitor.
Closed loop amplifiers for conveyor control systems.
PECel amplifiers for loop control.
Any monitors using CRT for machines.
Control systems for speed control.
Dekatron counters used for length measurement and cut cycles.
Dekatron counter - YouTube
Field control on motors.
Tubes used for audio in PA systems in factories.
It was common to see EL34 in variable power supplies and scopes using tubes like EF86 ecc88.
6SN7 ECC33 6l6 the stores had racks of hundreds of types<<<sigh they used to be lying about in engineering workshops.
It was common to even find electricians with a few in there locker that failed or went unstable on control systems
They usually also had a stash for the home TV just in case.LOL
Just a few that come to mind.
I visited a few factories recently that the stores had tipped boxes of tubes into a glass crusher.
Its a bit sad really because most were tubes from the early years still in boxes.
To the industry they had no value anymore and big companies aren't interested in Ebay, but they still wouldn't let people have them for free.
The techs in hospitals used them as well.
Regards
M. Gregg
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I bought a surplus polygraph for 10 bucks a few years ago. It was a Grass, not that I'm familiar. Behind the racked dc amps, it had several telefunken 12ax7a's and 12au7a's. When I tested them on my simple tester (with the "good" meter) each tube pegged the meter in the exact same place. It had a couple vibrators in it and mercury batteries and a large plate of magnesium and all sorts of fun stuff.
Don't forget the Philbrick-Nexus vacuum tube analog computer modules. (12AX7, and an assortment of others)
http://www.philbrickarchive.org/
http://www.philbrickarchive.org/
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