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(RCA) 6SN7 GTC spec?

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can't say i've heard of GTC. Looks like a relatively recent run though, judging by the box.

Looks like a jan box.. so there should be an acceptance date (sometimes just says "A" and then a date.. )

could be a 1980's revision or something, that has little more difference than the name or something.. i dont know.
 
Are you sure that it is a metal tube? why would a metal tube have the GTC (Glass Tubular, revision C) designation. Also, the base looks different (shorter, with a ring around the bottom where the metal envelope clamps on) on the metal tubes I have seen. The base lookslike that a glass tube would have. Are you sure it is a metal tube and not just a glass tube with internal frosting?
 
metal 6sn7

Hi all,

Tomchaoda is right. These RCA 6SN7M do really exist and as there name already indicates....the M stands for "metal".

Last year i bought a quad at Ebay. Nobody new what they were....the name did not ring any bells. So i bought them quite cheap. The postage from the USA to the Netherlands were higher !

The metal container is quite lightweight, but not uncommon with tubes. The complete metal body made it possible to discard the glass inard container. So the total tube is actually light. And there is NO glass inside.

Soundwise they're nice tubes. Not as good as Tung-Sol VT-231 roundplates (love the bass), or the Sylvania 6SN7W as pictured beside the RCA 6SN7M but on the same level as early RCA's or Ken-Rad's.
They are really better then young Sylvanias (aarrghhh..coinbase) or glass RCA's from the same date.

So yes: i like this Brazilian variety.

I do have to agree with Colt45 on the date: all my 4 tubes have a "D75" imprint. 1975 ?

regards,
Reinout
 

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