Newsgroup: it.hobby.hi-fi
Titolo: 6SN7 tube performance

First of all I want to thank everyone that tried the vintage 6SN7 tubes, I am
glad you are so happy with their performance. I just got in some more in so,
as requested, I will be happy to email a list of types and prices.
Some of you have asked me to rate the 6SN7 types, so you will find the list
below. Please remember that my opinion on these tubes is just a suggestion.
The optimum tube for your system will depend on your equipment and how your
ears judge the tube's ability to reproduce live music.
Most of you were surprised that the vintage 6SN7 types sounded so much better
than the highly rated 5692 types. For years I have had Far East customers
tell me that the earliest tubes always sounded superior to the later
production types. With my background in World Class Manufacturing, I assumed
that tubes produced in the 1950s and 1960s would have had better quality
control, materials and tooling.
Happily I never let my opinions cloud the issue but always try something that
someone recommends. I am not sure why, but the early 1940 VT series tubes do
sound the best. It's not even a contest.
I will go out on a limb and suggest that maybe time or the aging of a tube has
something to do with it. The crystalline structure of metal is disrupted when
it's worked. If you draw, extrude, fold, cut, hammer or weld metal you mess it
up. If I remember correctly, metal has a memory and over time it slowly heals
itself, sort of a long term annealing process.
I know Bill Perkins of Pearl cryogenically treats tubes to reduce the tube's
noise and distortion. I know it works because he has sent me samples of
treated tubes that outperformed nontreated samples by a large margin.
Certainly the difference in materials, vacuum and internal construction must
have something to do with it. A Tung-Sol VT-231 has a round smooth plate
structure and the graphite coated(black plate) material, Its construction 
must have something to do with its wonderful sound.
I wonder why modern tube manufacturers don't just copy some of these
features, I will be happy to supply samples. The current 6SN7 tubes sound
like the best thing you can do with them is cremation not cryogenic
treatment.
Anyhow, here my list of favorite tubes ranked in the order I like them. For
those of you who don't agree, try them. If you haven't you may be missing
something.
VT-231 Tungsol, black round plates - Clean, fast, the best in everything
VT-231 Ken-Rad, flat black plates - Great Bass, drive, sweet midrange
VT-231 Sylvania, black plates, wide bandwidth, delicate & laid back
VT-231 RCA, black plates, rich harmonic structure like a super 5692
6SN7WGT, Sylvania Metal rim, big tube, big sound, super soundstage
6SN7WGT, Sylvania, Long Plate, quiet, great voicing, timbre, accurate
6SN7WGT, Syl Standard Black Plate, transparant, images very well
6SN7WGT, Syl Green Label, like the Standard but front row center
6SN7GTA, General Electric Black Plate, quiet, good bandwidth,
6SN7GT, Sylvania or RCA Black Plate, very good easy to find
5692, CBS-Hytron, fast, good dynamics, lot of air and great timbre
5692, RCA Red Base, very warm sweet sound, great on voices and jazz
6SN7GTB, RCA, sounds like a 5692 with slight veiling
6SN7GTB, Syl,  like the Syl militaries but not as focused or quiet
6SN7GTB, G.E, Gray plates, work horse, lacks refinement, a good tube
Best Regards, Dennis
Dennis Boyle, email 
chim...@mail.idt.net
Chimera Laboratories - 
www.ChimeraLabs.com/~CL/
1414 South Akard Street
Dallas, TX 75215
TEL: 
214-428-3901
FAX: 
214-426-6605
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/
       Search, Read, Discuss, or Start Your Own    

treated tubes that outperformed nontreated samples by a large margin.
...
Questa poi...

 Questa poi...
La vedo veramente tirata per i capelli !

: > 
chim...@my-dejanews.com
 ha scritto nel messaggio
: > 
: > >I know Bill Perkins of Pearl cryogenically treats tubes to reduce the tube's
: > >noise and distortion. I know it works because he has sent me samples of
: > >treated tubes that outperformed nontreated samples by a large margin.
: xxx wrote:
: > 
: > Questa poi...
Federico Paoletti (
fede...@galileo.pi.infn.it
) wrote:
: La vedo veramente tirata per i capelli !
No, e' chiarissimo: il trattamento criogenico fornisce un offset negativo
di temperatura che abbassa la temperatura di lavoro dei tubi, diminuendone
la fatica e migliorandone la linearita' oltre ad abbassare il rumore termico.
Il rovescio della medaglia e' che si perde un po' del calore delle valvole.
Va bene, la mettiamo insieme al banano.
--Stefano Rovetta
s...@dibe.unige.it


Non so bene dove la vuoi mettere, ma forse e' meglio la banana a temperatura
ambiente della valvola gelida. O serve per una migliore riproduzione
dell'acuto?
Ciao. P.F.