I've been rolling some different tubes in my 25th Anniversary modified CSP3 preamplifier for the last month. Settled on ta Raytheon JAN 5R4 WGB "potatoes masher" rectifier. A nice matched pair of Reflektor 6N5P tubes in the output positions, been there for a long time, such clarity. Next up the all important input tube in the front.

After several folks recommended the 6SN7 tubes, particularly the long lived VT-231 varieties, I got an adapter and began listening. The grey glass RCA's 1940-50's are very dimensional and sounded excellent, but lack a bit of treble extension. A lot of the clear glass versions - RCA, Raytheon, GE, and other sounded ok but lacked dimensionality in my system.

While I haven't tried the ultra pricey Tung-Sol black glass with copper rods 1940's, I did get a chance to try a NOS Russian Melz Metal Base variant 6N8S = 1578 = 6SN7 = ECC32 hole plate this past week. Holy Crap does this tube sound exceptional! Outstanding note attack and decay, tonality, and midrange just to die for. I'm in listener heaven.

I'll be comparing it with a Sylvania VT-231 JAN-CHS-6SN7GT 2-Hole "BAD BOY" tube later this week, but so far the Melz tube is champ and I sourced a couple more NOS tubes for back ups.

Needless to say the 6SN7 tubes with the 6922-6SN7 adapters have added another dimension to the versatile CSP3 and some more dents in my wallet.

Cheers,

HK

I've been following the discussion about the 6SN7 and the Soviet 6H8C tubes.  I really did not want to get into any more tube rolling but my curiosity was once again peaked.  I had settled on the ADZAM E188CC SQ for the input tube but trying to get a back up at what IMO is a reasonable price has been difficult and frustrating.

It seems that there are still possibilities with the 6NS7 so I thought I would look into that and ended up researching the 6H8C which, if you were trying to get the 1587 stamped version, is also in the ridiculous price category IMO.

I ended up talking to anRussian ebayer that gave me his opinion at the risk of loosing a sale.  In his opinion:

- 6H8C with the 1587 stamp are not the "holy Grail" tubes for audio.  These were made for the Nuclear Industry in the late 50's - 60's and were selected for the matching sections.

- whether the plates had holes or not doesn't matter.  What does matter is whether the plates are grey or shiny black.  This was corroborated by another review

- all should be metal base

I also noted that there are 3 possible plate structures not just two.  I did end up ordering the earliest tube to see what it would sound like at a very reasonable price.  I may also order a USA made 6NS7 to compare.

I decided to post my findings as an buyer beware FYI not as a summation of which to my ears is the better option.  I won't be hearing any for a while.  Supposed to be getting my headphones next week.  The speakers probably not till the end of Feb and the tube, some time in Feb.

Brad,
He said that the "Shiny Black Plates" were preferred for audio, holes or no holes in the plates.  The one that I picked up is a 1951 vintage, black plates no holes, metal base.  It was not a NOS tube but has very closely matched sections and strong test readings.

Of the three that he offered, the other two were NOS circa mid to late fifty's.  The one I got was $50.00 the other two I think were $75.00 ea. I did not buy on price but on the readings.  After I bought he told me the year it was released and that it is very rare and the best choice of the three.

Hope this helps, once I get it I'll post my thoughts on the 6CH8's.