Hi! I'm a new guy...
Most of military purpose Sylvania tubes (i.e. the Green Logo) were manufactured after 1980s.
The Green Logo tells you that it was made for military purpose (especially American).
If you see the tube carefully, you might be able to find a word "JAN". This word means 'American Military Purpose'
Most of military purpose Sylvania tubes (i.e. the Green Logo) were manufactured after 1980s.
The Green Logo tells you that it was made for military purpose (especially American).
If you see the tube carefully, you might be able to find a word "JAN". This word means 'American Military Purpose'
Hi,
This is what I've found so far:
"The gtb version of the 6sn7 increased the plate voltage from the gt's 300 volts to an impressive 450 volts (most audio circuits have a net 200 volt or less plate voltage) and added a "controlled-warmup" for series-string circuits. The date codes "c-k" and "d-k" are part of sylvania's mysterious coding system but it is estimated that the date of mfg was in the late fifties or early sixties. The plates are black and "t" shaped. The getter (located in the top) produces the ornate flashing and hence the name, "chrome dome". The base is the short intermediate (.6 inches) type."
Cheers,
This is what I've found so far:
"The gtb version of the 6sn7 increased the plate voltage from the gt's 300 volts to an impressive 450 volts (most audio circuits have a net 200 volt or less plate voltage) and added a "controlled-warmup" for series-string circuits. The date codes "c-k" and "d-k" are part of sylvania's mysterious coding system but it is estimated that the date of mfg was in the late fifties or early sixties. The plates are black and "t" shaped. The getter (located in the top) produces the ornate flashing and hence the name, "chrome dome". The base is the short intermediate (.6 inches) type."
Cheers,
I have some Philips ECG JAN 6188 tubes which I think is a 6SL7 and 5691 JAN tubes which have green writing on the base.
Both made in the 80's. The date code seems to be to the right of the logo. One says "8626" underneath it says "ABA" .
Says "4/86" on the box.
The other says "8539" the box says "9/85"
I would assume this is the date code, and that they all use a similar coding system.
By the way, the Philips JAN 6188 is one of the fastest sounding octal base 6SL7 types I've ever used in my amps.
Both made in the 80's. The date code seems to be to the right of the logo. One says "8626" underneath it says "ABA" .
Says "4/86" on the box.
The other says "8539" the box says "9/85"
I would assume this is the date code, and that they all use a similar coding system.
By the way, the Philips JAN 6188 is one of the fastest sounding octal base 6SL7 types I've ever used in my amps.
I have managed to find this
6SN7GT, 6SN7WGT, 6SN7GTA, 6SN7WGTA 6SN7GTB 1950s Sylvania Commercial and Military Green Label “Chrome Dome” or “Silver Top”, first top getter on the list, non-fatiguing, smooth, with good detail resolution, bandwidth and speed. Bass can be a bit warm and exaggerated, a good think if your speakers are bass shy. Does not have the midrange ambience and resolution of the VT-231 types. But very good overall.
I managed to find an old Sylvania Red Label that I can remember as being retired from an old "Bendix TV" we had when I was young. Dad always changed tubes usually when they didn't need it. It was replaced in 1959.
J
6SN7GT, 6SN7WGT, 6SN7GTA, 6SN7WGTA 6SN7GTB 1950s Sylvania Commercial and Military Green Label “Chrome Dome” or “Silver Top”, first top getter on the list, non-fatiguing, smooth, with good detail resolution, bandwidth and speed. Bass can be a bit warm and exaggerated, a good think if your speakers are bass shy. Does not have the midrange ambience and resolution of the VT-231 types. But very good overall.
I managed to find an old Sylvania Red Label that I can remember as being retired from an old "Bendix TV" we had when I was young. Dad always changed tubes usually when they didn't need it. It was replaced in 1959.
J
You have got to love the beauty of these tubes. Whoops! Sorry Frank. You have got to love ALL TUBES!
The Red Label on the left is from the 1953-1959 era as it was pulled from the first TV I grew up with. The Green label on the right(not JAN) is most probably a commercial model.
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The VT range is in no way different from their domestic equivalent; the 6SN7GT, it's just a number used by the military. May I assume sonically there is little difference?
J
The Red Label on the left is from the 1953-1959 era as it was pulled from the first TV I grew up with. The Green label on the right(not JAN) is most probably a commercial model.
Quote
The VT range is in no way different from their domestic equivalent; the 6SN7GT, it's just a number used by the military. May I assume sonically there is little difference?
J
Attachments
Hi,
If you can find a VT-231 from say, Tung-Sol, and a 6SN7GT with the same date code then there shouldn't be any difference sonically.
Some vendors will try to push the VT-231s as there are still so much more around that had been sitting idle for decades on the military stock shelves.
Cheers,
If you can find a VT-231 from say, Tung-Sol, and a 6SN7GT with the same date code then there shouldn't be any difference sonically.
Some vendors will try to push the VT-231s as there are still so much more around that had been sitting idle for decades on the military stock shelves.
Cheers,
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