new 845? Who produces it?

[Calvin]

Hi,

which manufacturers are actually producing the 845? Is there any left, or is just NOS and used stuff available?

jauu
Calvin

[pjp]

Shuguang. See the wikipedia page.

[lowtherdream]

KR audio

http://www.kraudioproducts.com/Kr/Pr...3&ProductID=6#

[pjp]

More informative website here: http://www.kraudio.cz/

[Cauhtemoc]

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.

[SpreadSpectrum]

You must mean oxide coated filaments vs thoriated tungsten filaments instead of carbon plates vs thoriated tungsten plates.

[jlsem]

He probably means the KR 845 has carbonized (or carburized) thoriated tungsten filaments instead of plain thoriated tungsten.

John

[SpreadSpectrum]

I always thought KR 845 had oxide coated filament. In pictures it glows red and it consumes less than on third the power of the thoriated tungsten filaments.

Do you have a reference that talks about carbonized thoriated tungsten filaments? I have never heard of them and am curious.

[Cauhtemoc]

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.

[Rob11966]

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