Svetlana/Sovtek tubes
Genip
exists regarding the Sovtek/Svetlanta 6550 tube. All of the
postings/responses which I have read portray at least part of the
story correctly, but I feel it necessary to "pull things together". I
will endeavor to differentiate facts from my personal opinion.
Sovtek is a brand name owned and used by the importer (New Sensor) of
this Russian made tube. There is no Sovtek factory. It is my belief
(due to responses from several sources in the industry and one
magazine article), that the Sovtek 6550 tube may have been made by
several different manufacturers. Besides the four major manufacturers
in Russia there are several minor ones. I believe that "Glass Audio"
did an article on this, but I don't know which issue. The tubes which
I have received under the Sovtek brand in the last year or so appear
to be from the Svetlana factory, in my opinion.
Svetlana is the largest (by their claim) tube manufacturer in Russia.
These tubes are imported by R&G International (a joint venture exists
between R&B and Svetlana) and sold under the "Audio Glassic" and
"Svetlana" name.
The confusion is caused by the recently available Svetlana 6550B-2
tube. This is the tube that I feel sounds the best. So far my
customers agree and this is the default tube that I use for
repairs. The 6550B-2 can be identified by a getter attached to the
outside of the plate and two more mounted on a bar at the very top of
the tube. I believe EvaAnna Manley previously posted this
information. The older 6550B tube is the one that I think Sovtek was
importing. In my opinion, the Sovtek 6550B and the recent Svetlana
6550B tubes are one in the same. The 6550B-2 it appears, has never
been made available as a Sovtek. As stated in this forum, Sovtek is
no longer able to obtain any 6550 tubes from Russia. It appears that
the two brand names indeed intend to be rivals for the US tube
market. On the positive side, there will soon be a KT-88 proudly
bearing the Sovtek brand. They intend for this to be the replacement
for the 6550. I hope customers are made aware of which amplifiers can
interchange tubes safely!
Possibly more important than which tube is which, is the question of
where the tube was purchased. Russian tubes are sold in bulk to anyone
willing to purchase 2,000 or more. Burn in, testing, matching and even
boxing is done by the dealer/distributor who sells the tubes. This is
a primary factor in the reliability and quality of the tube! A friend
at one of the larger musical instrument manufacturers (who buy in bulk
and still have Sovtek 6550B tubes left) informs me that "raw" tubes
fail at 15%-20%. Tubes that I purchase from Audio Research (we are an
ARC dealer), Sovtek, or Svetlana typically fail at about 1%-3%. ARC
currently provides Svetlanas that they test and match. I always order
matched quads from Svetlana and check/rematch to obtain the tightest
match. Burn in of at least 24 hours is needed to stabalize a power
tube for a good match. Better amp. manufactuers, Svetlana, Sovtek,
and the "premium" suppliers (Gold Aero, RAM, etc.) can provide
this. Most manufacturers (or bulk dealers) have an agreement with the
importer where they can return any tube not "within their
specification". These tubes may or may not be perfectly good. Some
discount dealers may purchase these picked over tubes and sell them
with the importer's or their own name. This explains why some end
users may find a higher failure rate on a Sovtek or Svetlana tube.
The best advice is to ask questions and know your dealer!
Happy listening!
.
Don Manigold
GNP Audio Video, Inc.
HNDME
quality checks on tubes in current production.
Experience with Svetlana tubes has been positive (under Audio Glassic
brand name).
Regetfully, people see the price list published by a few importers,
and expect selected and tested tubes to go for the same price. If one
also takes into account tubes that not only function, but are in
reasonable tolerance of published spec, the rejection rate
increases. The cost of these rejects must be included in the selling
price of higher quality selected.
To add a little balance to the picture, I had spoken with an engineeer
from TungSol during the heyday of it's tube making time, and he was
saying the rejection was close to 25% of any batch of tubes, right off
the assembly line.
A. Cirella, Handmade Electronics.