Shuguang have been making 845 tubes for many years, and they also made the 845 tubes sold under the Sino, Valve Art and Golden Dragon brand. Then around August last year Shuguang announced that they would stop making this tube due to supplier issues. These issues where later said to be resolved, and production would start again in January this year. So far they have only done a few small production runs, and it is likely to be a while until they can go into full scale production.
Richardson Electronics have been manufacturing 845 tubes under the Cetron brand probably as long as Shuguang, and according to their website they still are. However they are expensive and hard to get.
KR Audio made 845 tubes a few years back, but rumor has it they only produced a very limited number of tubes, and they have since stopped production due to quality issues. KR Audio 845 tubes had carbon plates, whereas the original 845 had thoriated tungsten plates.
Fullmusic have been manufacturing 845 tubes for a few years, but they where notoriously unreliable. In December last year they released a new MKII version which is said to be much better. Fullmusic tubes also use carbon plates.
Hope that helps.
Richardson Electronics have been manufacturing 845 tubes under the Cetron brand probably as long as Shuguang, and according to their website they still are. However they are expensive and hard to get.
KR Audio made 845 tubes a few years back, but rumor has it they only produced a very limited number of tubes, and they have since stopped production due to quality issues. KR Audio 845 tubes had carbon plates, whereas the original 845 had thoriated tungsten plates.
Fullmusic have been manufacturing 845 tubes for a few years, but they where notoriously unreliable. In December last year they released a new MKII version which is said to be much better. Fullmusic tubes also use carbon plates.
Hope that helps.
To clear this up, what I meant to say was that 845 tubes from KR Audio and Fullmusic both have oxide coated filaments whereas the original 845 tubes had thoriated tungsten filaments. Oxide coated filaments requires much less power and glows with a dull red glow, thoriated tungsten filaments glows with a bright yellow glow.
Hi Calvin,
I have been following this closely as I am currently building an 845 amp.
It is a hard subject to get information on - largely because it it is difficult to get information from the manufacturers directly.
Cauhtemoc has summed up my understanding of the situation perfectly. There was a small run of Shuguang 845B's released this January and they are out there at a reasonable price. I have obtained a couple of pairs and they appear to be well made.
The TJ Fullmusic MKII tube is also available (some produced in December I think) but these tubes worry me a bit as the filament current draw is very low compared with the original RCA tubes (and copies like the Shuguang) so unless you have a voltage regulated filament supply, then the filament voltage is likely to be significantly higher than the required 10v with these (Fullmusic) tubes. I have read several reviews suggesting small 'tweaks' to the amplifier are required when using these tubes - but I am not sure what these 'tweaks' might be for the average punter!
What I am really waiting for is for Shuguang to recommence the metal plate tube which they have not produced for a year or so.
Cheers,
Rob
I have been following this closely as I am currently building an 845 amp.
It is a hard subject to get information on - largely because it it is difficult to get information from the manufacturers directly.
Cauhtemoc has summed up my understanding of the situation perfectly. There was a small run of Shuguang 845B's released this January and they are out there at a reasonable price. I have obtained a couple of pairs and they appear to be well made.
The TJ Fullmusic MKII tube is also available (some produced in December I think) but these tubes worry me a bit as the filament current draw is very low compared with the original RCA tubes (and copies like the Shuguang) so unless you have a voltage regulated filament supply, then the filament voltage is likely to be significantly higher than the required 10v with these (Fullmusic) tubes. I have read several reviews suggesting small 'tweaks' to the amplifier are required when using these tubes - but I am not sure what these 'tweaks' might be for the average punter!
What I am really waiting for is for Shuguang to recommence the metal plate tube which they have not produced for a year or so.
Cheers,
Rob
I only have a printed reference, but carburized (or carbonized) filaments have carbon added by heating the thoriated tungsten filament in a hydrocarbon atmosphere such as acetylene. A layer of tungsten carbide is formed on the surface of the filament and reduces the evaporation of thorium from the tungsten thus increasing the life of the filament. The GM-70 is a good example of a tube with a carburized tungsten filament.
I wonder what KR has done differently to make an oxide-coated filament suited to plate voltages in excess of 1000 volts.
John
Hi,
thank You for the replies. At the CES last week, I heard rumours about Shuguang shutting down their plant, or at least the 845 line.
At KR (btw. the plate and filament materials are different to my knowledge as the ones suggested before in this thread) nobody seems to like the 845, not Mrs. Eunice nor her staff. So they prefer to build other and better tubes, like the 300, the T100 and the T1610.
jau
Calvin
thank You for the replies. At the CES last week, I heard rumours about Shuguang shutting down their plant, or at least the 845 line.
At KR (btw. the plate and filament materials are different to my knowledge as the ones suggested before in this thread) nobody seems to like the 845, not Mrs. Eunice nor her staff. So they prefer to build other and better tubes, like the 300, the T100 and the T1610.
jau
Calvin
I visited an authorized dealer of Shugang in ShangHai, ChinaCalvin said:
in the last November. The owner of the dealer said Shugang
would make new 845 at the end of November. I ordered 4pcs of
845 and revisited there again at the beginning of December.
The owner said that Shugang did not make 845 (all Thorium
Tungsten DHT either ?). Instead, I purchased a pair of 805
which were old stock made by BeiJin and Chinese Name as
FU-5 as shown in the attached photo.
I heard from a Chinese friend that Shugang is focus on
Mercury Discharge Lamp to be used for lighting of Chinese
Highway. It is bigger quantity and good business rather
than tubes.
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