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Well, my current set of power tubes finally began to flake out after 3
years. They were the original factory tubes that came with the amp, a
Carr Rambler. They started getting flaky about a month ago. They would
go into these funky hum generating states and if I tapped the tube
with a pick they would quit and go back to normal, but then after a
while they would start humming and distorting again. They were
Svetlana tubes, recommended by Steve Carr in this amp. I had so many
other choices, but had never tried any other tubes in this amp, I
wasn't sure which way to go--NOS RCA, the new GT 6l6gc, Mike Mathews
version of Svetlana, Tesla JJs or the SED flying C branded tubes
coming out of the old Svetlana plant.
After reading a lot of reviews, I stumbled on these 'cryo' versions of
the SED tubes. At first, I thought, maybe this is another audiot type
of phenomena where they jack up the price after gold plating the pins.
But then, I considered the fact that I like the cryo strings from Dean
Markley, which last longer, and it is true that machine tools treated
with extreme cold acquire super properties. Also, they run extensive
quality tests on the tubes that they dip, so that only the cream of
the cream gets the treatment. On that basis alone, I figured they were
worth a premium. Well, after plugging them in, I have to say that
there is an observable improvement over the previous Svetlanas. They
are slightly noiser in their nominal modes, maybe a tad more
microphonic, but much more resonant and sweet--more open. I don't know
how else to describe it, but the tone seems to 'blossom'. I feel goofy
trying to find words that fit. The tone is not as tight as it was--it
has more flexibility, more 'air'. If you bear down it kind of bulges
out, it expands, so to speak, like it has more headroom. I like it. It
was worth the extra few bucks if that is what will sit in the amp for
the next 3 years.
The amp is cathode biased class 'a', so I don't know how they would
fare in other designs. This amp is like a Tweed--Blackface hybrid. The
cryos are more expensive than the normal SED tubes, but less than the
GT 6l6gc's, and way less than NOS RCA. Although, many swear by Tesla
JJ's, and these SED cryo tubes are quite a bit more than the Teslas.
I've seen the cryo treatment for some NOS RCA 6l6gs's where they
wanted hundreds of dollars. The SED cryo tubes are a bargain, by
comparison.
Jorge
