Ah...just remembered a question I had. I picked up a nice pair of G style Sylvania that had a marking in the base after the Sylvania name. It looks like a leaf or something close and inscribed in the same green. Anyone have a clue? These appear to be older G style maybe as there's the small U shaped clip above the top mica spacer that I've seen on 6SN7's.
Holy cannoli....I knew I came to the right place for info. Big thanks to everyone that contributed to that encyclopedia. And thanks for the loctal tip. I remember that those were mentioned in the Vacuum Tube Valley review of the 6SN7 family. Great stuff here.
Ah...just remembered a question I had. I picked up a nice pair of G style Sylvania that had a marking in the base after the Sylvania name. It looks like a leaf or something close and inscribed in the same green. Anyone have a clue? These appear to be older G style maybe as there's the small U shaped clip above the top mica spacer that I've seen on 6SN7's.
"Over the course of their operation Sylvania used green on their tube boxes, technical literature, merchandise, such as clock radios, enamel advertising signs and thermometers and even the doors and windows on their factory in Emporium, PA were painted green too. The green livery and their oak leaf logo were almost certainly inspired by the verdant Pennsylvanian countryside."
1933 Sylvania logo - it changed somewhat over the years'
I haven't looked into 7A4's very much, but from what I've gathered on their twin-triode 7N7 brothers, they were only made by Sylvania and National Union. Could be the same for the 7A4's, but I have nothing definitive on that. Bunch of different labels below, but all have the same round plate style and configuration. Plate colors vary, but that could be due to date of manufacture more than anything.
I bought some sealed "GE" 7A4 a few months back and opened them up and they all had completely different internals than any other 7A4 i have ever seen.. if I had to guess, the internals look a lot like Raytheon 6J5/12J5WGT.
I bought some sealed "GE" 7A4 a few months back and opened them up and they all had completely different internals than any other 7A4 i have ever seen.. if I had to guess, the internals look a lot like Raytheon 6J5/12J5WGT.
Sometimes I wonder about our current perspective on these consumer consumables of their era. Wonder if manufacturers were more focused on fulfilling order delivery targets for the lowest cost than far distant future audiophile sensibilities.
If they had some spare parts from Raytheon, RCA or whoever and meet electrical specs - build it and ship it! "70 years from now, no one will care or pay $$$ for a $1 tube."
Sometimes I wonder about our current perspective on these consumer consumables of their era. Wonder if manufacturers were more focused on fulfilling order delivery targets for the lowest cost than far distant future audiophile sensibilities.***
*** " .... Hmm, I spy with my little eye, in this vacuum globe the image of a 'bcowen' - whatever that is . Well, well ... he plans to hoard our wares ... let's misstate the filament currents by 40% ... ... "
I bought some sealed "GE" 7A4 a few months back and opened them up and they all had completely different internals than any other 7A4 i have ever seen.. if I had to guess, the internals look a lot like Raytheon 6J5/12J5WGT.
Wonder if the period of manufacturing for those might have been toward the end of the road for single triodes in an envelope. Technology started pushing the size of active devices toward smaller ones and the 7 and 9 pin envelopes. Two wars and a space race had their influence. Maybe those were built from what was left over.
I bought some sealed "GE" 7A4 a few months back and opened them up and they all had completely different internals than any other 7A4 i have ever seen.. if I had to guess, the internals look a lot like Raytheon 6J5/12J5WGT.
Sometimes I wonder about our current perspective on these consumer consumables of their era. Wonder if manufacturers were more focused on fulfilling order delivery targets for the lowest cost than far distant future audiophile sensibilities.
If they had some spare parts from Raytheon, RCA or whoever and meet electrical specs - build it and ship it! "70 years from now, no one will care or pay $$$ for a $1 tube."
I wonder if people back in the '40's and '50's "rolled" tubes?
1950's Dude 1: "I just scored a pair of unused early '40's Sylvania 6SN7's for 38 cents!!!"
1950's Dude 2: "You overpaid. I got a pair at the corner drugstore last week for 29 cents. Dumbass."
I wonder if people back in the '40's and '50's "rolled" tubes?
1950's Dude 1: "I just scored a pair of unused early '40's Sylvania 6SN7's for 38 cents!!!"
1950's Dude 2: "You overpaid. I got a pair at the corner drugstore last week for 29 cents. Dumbass."
I wonder if people back in the '40's and '50's "rolled" tubes?
1950's Dude 1: "I just scored a pair of unused early '40's Sylvania 6SN7's for 38 cents!!!"
1950's Dude 2: "You overpaid. I got a pair at the corner drugstore last week for 29 cents. Dumbass daddi-0. And I used one S&H green stamp !!"
I haven't looked into 7A4's very much, but from what I've gathered on their twin-triode 7N7 brothers, they were only made by Sylvania and National Union. Could be the same for the 7A4's, but I have nothing definitive on that. Bunch of different labels below, but all have the same round plate style and configuration. Plate colors vary, but that could be due to date of manufacture more than anything.
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. Well, well ... he plans to hoard our wares ... let's misstate the filament currents by 40% ... 
... "
.... weren't the Hirsch-Houck lab 
