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The 6SN7 Identification Guide - Page 4

post #46 of 88
Glod, I know yours is an old message but I must ask something...

I have this Mullard-branded 6SN7GT the manufacturer of which has been a mystery to me. See photo. It can't be Mullard-made because they apparently never made any 6SN7GTs.

Then I found this photo on the natubes site. This Tungsram-branded 6SN7GT is exactly like my Mullard-branded one. Next I read this:

Originally Posted by Glod View Post
Interestingly, the Tungsram CV1988’s I have, have grey coating to the top mica, brown (micanol?) bases and black, staggered, ladder-ridged-flat-plates. The micas are racetrack formed, and the top one, with spikes at the round parts, touching the glass. Barely visible bottom getter. They are also stamped 6SN7GT (note not GTY).

The base is without print, but the envelope is marked with the KB/T stamp with arrow, which means government ordered, approved, made to specification K1001 or K1006 and manufactured by Tungsram, Tottenham.
Your description of the tube fits very well (except the base color). This makes me think that also my Mullard-branded tube was in fact made by British Tungsram, or the Tottenham factory when it wasn't owned by Tungsram anymore.

What do you think? I'd be delighted to see a photo of one of your CV1988s with the KB/T stamp if you could provide one.
post #47 of 88
Mullard did label tubes 6SN7GT and GTB for the export market. However, most of these were late in the tube game are clearly Russian-made (in spite of saying "Made in Britain" on them). Yours do not look Russian, however.
post #48 of 88


All of the sudden I am noticing information about NOS 1950's Russian 6H8C tubes, a 6SN7 sub, with very positive reviews and high prices. The well rated tube has specific plates and a nickle base. They are showing up on EBAY and someone is selling what looks like the same tube here on Head-Fi. Coincidentally the ad here and also one of the ads on EBAY quote the tube seller Jesse Brent as giving this tube high marks.


Rare 6H8C Russian Military 6SN7GT Nickel Base Tubes NOS - eBay (item 170304968308 end time Mar-03-09 09:51:23 PST)

Anyone tried this tube?


post #49 of 88
There have been quite a few head-fiers who tried them and loved them I liked it fine but still prefer quite a few of the US and UK variants.

In any case ONLY the ones labeled 1578 are the good ones - they have a very unique plate structure. NEITHER the ones in the head-fi ad OR the Ebay ad you linked to are the right tube - those are just your typical Russian 6H8C with a nickel base are aren't worth $10. You can tell because they have the exact same plate structure as a normal 6H8C that you can buy on EBay for $5.

This is the tube people rave about:

RARE! 1 USSR TUBE 1578=6SN7 Unique military development - eBay (item 250376900280 end time Feb-28-09 21:00:00 PST)
post #50 of 88
Originally Posted by Skylab View Post
Mullard did label tubes 6SN7GT and GTB for the export market. However, most of these were late in the tube game are clearly Russian-made (in spite of saying "Made in Britain" on them). Yours do not look Russian, however.
They don't look Russian to me either.

By the way, here is something that I haven't seen mentioned in this thread:

6SN7GT made by MBLE in Brussels (branded Miniwatt)

This one has got a typical Philips group code between pins with L (=MBLE) factory code. Internally, this tube is quite like my Mullard-branded ones, but not an exact match.
post #51 of 88
looks like GTA plates to me, probably a re-brand of a US made tube
post #52 of 88
Originally Posted by glitch39 View Post
looks like GTA plates to me, probably a re-brand of a US made tube
Are you referring to my presumed MBLEs? I guess that is possible but I am not convinced. They have a proper code (r93 L1E) on them.
post #53 of 88
Skylab is correct,
I bought what were supposed to be 1578 tubes from Siberian tubes they are con artists don't buy from them.
Greentulip/Ukraine is the man to buy from he is 100%. I have bought lots of 1578 from him. A dutch friend bought from him and one was dud, Greentulip replaced it ASAP.

You either love them or only find them OK - I love them. IMHO they are excellant top to bottom, very dynamic, crystal clear, great edge definition without being hard in any way. I do have one criticism of this tube - they can be described as slighty dry, I intend to experiment with PIO coupling caps to counter this small (and I do mean small negative). In comparison I find other 6SN7s are very coloured I hav'nt tried SylWs or TS/RP so take that into account when reading my opinion.

One huge point in their favour they are totally non-microphonic and you can't say that about a lot of 6SN7 tubes. In fact it is the least microphonic of any tube I have tried.
post #54 of 88

Real 1578s

Contact Paul Lindeman AKA Chowbeardog on AA and he will set you up with the real deal. I have several pairs and am very satisfied with this tube. Mine were 100% NOS. The 1578 is a very well balanced tube with a lot of detail and a nice mid-range that is not entirely neutral. The bass is tight and low and the top end has a lot of extension and "sparkle" (not brightness). It combines some of the best elements of the TSRP and Sylvania 6SN7W.
post #55 of 88
Thanks for the replies on the 1578's. I have some Tungsol vt231's now and am always wondering what might be better :-)
post #56 of 88
I'd be interested in hearing in more detail about the mid-range 'not being entirely neutral'. Totally agree about the bass, it's the best I've ever heard in any signal valve/tube. I recently fitted some Z foils in my Bada and at first it's difficult to accept just how much detail is masked by inferior components. especially in the bass.

Today I tried a pair of 6F8G Tung Sol R/P s as o/put . If these are truly the same as Tung Sol RP 6SN7 then I have to say that the 1578s are much better in the bass than these but that is just first impressions and the bass may improve.

If a really deep, expressive bass is important to you then these 1578s' are 'the business'.
post #57 of 88

Baldwin 6SN7GTB

I have four Baldwin branded 6SN7GTB's which came off a Baldwin organ allegedly manufactured in 1960. They are new looking identical tubes with clear glass, straight sided walls, black bases, green lettering on the bases, chrome/silver tops, and rings shaped like halos at the top. No printing on the tubes themselves. They are each marked with a number (P28060-13C, P28060-25C et. al.) One of them has an additional number in very small letters: 6W6 or 9M9, depending on how you hold the bottle. Does anyone have an idea as to the manufacturer? I don't have a digital camera that's why I haven't posted a picture but all of the pertinent information is listed.
post #58 of 88
IIRC, the vast majority of Baldwin branded tubes were Sylvanias.
post #59 of 88
Originally Posted by mourip View Post
I have some Tungsol vt231's now and am always wondering what might be better :-)
Find some loctal-octal adapters and use the 7N7. you can find some round plate 7N7's for cheap. exact 6SN7 equivalent on a different package
post #60 of 88
The NU 7N7 round plates are very, very fragile. Almost everyone i have talked with have had some problems. The T plates are very good and very rugged.
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