845B Tube Review
by Ed Sawyer
June 23rd 2004
The new
845B
Serial numbers for the pair in this
review are 0005 and 0006
The
845B is a recent development by Shuguang, and structurally it is a very close
copy of the 1940's vintage Amperex brass base 845. It has a graphite plate
(like all 845s since the 1930s), and a beautiful copper base. Pins appear to be
nickel-plated brass. Like the Amperex, it has no top mica connecting the plate
structure to the glass envelope. (current production 845s from China, Kron and
Cetron all have top micas which couple the plate structure to the glass). These
845B have full 845 dissipation ratings and 1250v plate rating and as far as I
can tell are compatible with any 845 amplifier application. Like all 845s
except Kron, these have Thoriated Tungsten filaments, which glow brightly. It
has two ring getter halos at the base of the tube.
Build Quality
Internal construction is done to a high
standard, definitely a cut above the normal Chinese 845 tube. Welds and metal
forming seem to be quite well done and accurate, no sloppiness from what I can
see upon close inspection. Comparing directly to an old stock Amperex 845, the
caliber of construction of the 845B is good but not quite as well done. This is
not surprising, given that in the old days thousands of these tubes were made
by highly skilled workers who had been doing it for years, and the tube
industry and its' body of knowledge was enormous compared to today. That
Shuguang is able to do as well as they have, with construction as good as it
is, is an impressive feat, especially considering this pair is one of their
first production pairs released to the public.
Packaging
The packaging supplied with these is
the best 845 packaging I have seen - quite robust, with a nested clamshell box
made from high-density mat board, and an inner 2-piece foam cushion and foam
wrapper. Despite the outer box being a good bit beat up from it's trip from
China (via DHL), these tubes survived fine with no damage - an impressive feat
in itself.
Electrical Tests
Running these tubes on my curve
tracer setup shows traces which are well matched and clearly well within specs,
as compared to other (vintage Amperex) 845s. The curve tracer, A Systron-Donner
6200B, runs up to 1000v on the plate and negative grid steps from 0v to -100v
on the grid. In both cases, the tubes had curves which were textbook accurate,
even at the top and bottom. Electrically, they are perfect, as one would expect
from new production tubes. Quality control on this aspect has no problems at
all. They biased up fine in my amplifiers. Running on AC filaments, they
required some adjustment of the filament hum pot. With adjustment, residual hum
was the same as other 845s I have been running, and a non-issue. Running on DC
filaments of course there were no problems, with zero AC hum.
Left: Tube # 0005
Center: Tube # 0005
Right : Vintage Amperex 845 brass base
Sound
I
ran these in my Electronluv 45-845 amps, for several days. I compared to other
845s concurrently (one 845B in one amp, and another 845 in the other amp), and
also comparing the tubes in pairs. Other amps included Antique Sound Lab AQ
1006-845, which were used but not as extensively. The Electronluv amps run
these tubes in the 80-90% dissipation range, a nice high voltage sweet spot
without over stressing the tubes by running them at max dissipation. Output
power is about 18-20w, using a SET Parafeed topology.
The 845B is a great sounding tube. Very close
to the sound of NOS 845s, and definitely better than the well known regular
Chinese 845. The highs are slightly less sibilant than a Cetron 845 (a tube
which tends towards a touch of brightness - good for systems that are a little
dark). The upper mids, in the female vocal range, are nicely rich without being
overly warm. In comparison to Cetron and the other chinese 845, the 845B is
more harmonically pleasing in this range. Bass is the equal of any other 845 I
tried. They are as non microphonic as any other 845 I have. (due to low gain,
845s in general are not microphonic to any noticeable degree, even with abuse
like tapping the tube while in operation).
Conclusion
Do NOS vintage tubes sound better? Well, yes -
as expected. The difference however, is slight - the 845B comes closer than the
regular Chinese 845 by a fair margin. Even in back to back comparisons, one has
to listen closely to discern differences between vintage 845s and the 845B. In
casual listening, it's so close as to be of little concern. The vintage NOS
tubes are a bit better (cleaner, a bit more extended, slightly better
harmonically and somewhat more musical), but considering the difficulty and
cost to acquire them, the 845B is a more logical choice for all but the most
discerning and well-heeled 845 user and collector. I'd have no problem
recommending the 845B to anyone who uses 845s. No matter how high resolution
the system, these 845B tubes will not disappoint sonically, based on my
experience with them. These are far and away the best tube made in China that I
have seen and heard, and the only Chinese tube I'd use in my own equipment.
The future: A metal plate 845?
SuperTNT has said they will be
developing a metal-plate variety (845M), hopefully to debut in August of 2004. I
eagerly await these, hopefully they will work out as planned. Metal-plate
vintage 845s are quite rare, and finding good ones which test and work as they
should is rarer still. Many people consider a metal plate 845 as the holy grail
of 845s - it will be interesting to see how things develop from Shuguang and
SuperTNT on this front. A reasonably priced, metal plate 845 that worked well and
sounds great, would be a nearly untoppable coup in the world of 845s.
Product Weakness: Not quite as good as NOS/vintage 845s, but
differences are minor. Would be nice if base was polished/clearcoated. No USA
distributor (yet?)
Product Strengths: Nice build quality and sound, reasonably priced, the best value current production 845 made today.
Associated Equipment for this
Review: |
|
Amplifier: |
Electronluv 45-845 monoblocks |
Preamplifier (or None if
Integrated): |
Electronluv AV20/801 |
Sources (CDP/Turntable): |
SCD-1 |
Speakers: |
Martin Logan CLS |
Cables/Interconnects: |
Cardas Neutral Reference |
Music Used
(Genre/Selections): |
various |
Time Period/Length of
Audition: |
2 weeks so far |
Other (Power Conditioner etc.): |
Equitech 2Q with OFC toroid |
Type of Audition/Review: |
Product Owner |