I have been trying to decide the best supplier of the
845M ( metal plate ) tube.

So far super tnt seems may be a best chinese supplier,
they test what comes from the Shuguang factory, and not all of the
factory
claims are supported by supertnt test results. See the description of
testing methods ....

http://www.supertnt.com/default/Howwetest.asp

The worrying thing is that they say the tubes will drift away from being
matched
after only 12hrs, and they cannot predict if a tube is likely to be an
"invalid"
tube, ie, a dud.

Pentalaboratries.com were rather vague about
replying to my emails, and have not so far explained to me exactly
what type of chinese 845 they have, and when thy did finally quote
something, the price was
$140 for a pair but the website says $100 each.
And the freight from the US was a lot more than the china to Oz freight.

Anyone have any dealings with any of these dudes or anyone any better??

But from what I do see of the test curves for the chinese 845M, it looks
like a very linear triode,
and quite suitable for what I have in mind.

Patrick Turner.

"François Yves Le Gal" wrote:

On Wed, 11 Jan 2006 14:22:30 GMT, Patrick Turner
wrote:

But from what I do see of the test curves for the chinese 845M, it looks
like a very linear triode,
and quite suitable for what I have in mind.

I've been using the basic Shuguang 845's, as supplied in tested/matched
pairs by Nagra CH, for the last 5 years or so in my VPA amplifiers. They're
really excellent tubes at rock-bottom prices (around 90.00 EUR per pair in
Shuguang guise).

BTW, I've tested NOS 845's, including the famous RCA version, or fancy new
tubes, such as the KR (offered by Nagra as an option) and found that they
weren't worth their inflated prices: yes, the basic 845's are really good.

Could you be so kind as to describe exactly which type of 845 you have,
graphite or metal plated?

Where exactly did you obtain the tubes at 90 euro per pair?

If you wish to email me privately, I am at
at the moment.

Patrick Turner.

"François Yves Le Gal" wrote:

On Wed, 11 Jan 2006 15:03:54 GMT, Patrick Turner
wrote:

Could you be so kind as to describe exactly which type of 845 you have,
graphite or metal plated?

I use the Shuguang "improved", standard aluminum base, graphite plate 845's.

Where exactly did you obtain the tubes at 90 euro per pair?

A number of European retailers sell them for less than 40 EUR ea. Check for
instance DIYparadisio in Belgium, their current ex. VAT price is 33.40 EUR
ea.

http://www.diyparadiso.com/price/stock-buizen.htm

Yes, these guys have them at

Shuguang
845 chinese best
excellent 845 improved design
selected version

33.4

39.75
shuguang
845 new version
best 845 IMHO copper base
great value

76.18

90.66

Since there are usd $2.0 per euro,
the cheapest option is the 33.4 euro which is about usd $67 each, but probably
not matched.

But the 76 euro price is usd $152 each, and much more than the price
from supertnt for the supposed to be better 845M.
I am also enquiring about the 845B, maybe better than the 845M.
The 845B has 100W Pda rating, 845M only 70W.

freight from europe would be more....

Just think what selling one of these tubes means to the chinese.
Their wages are pitifully low compared to ours, and
maybe only $2 per day, a one tube is worth many many weeks of pay.....

There are pictures at supertnt of the shuguang factory
and lotsa women working with microscopes to assemble 12AX7s.

They said the factory had good lighting, but some pictures looked like it was a
bit dark....

But supertnt does seem to be making an effort to control quality; they don't
want poor reports.

Patrick Turner.

Patrick Turner wrote:
I have been trying to decide the best supplier of the
845M ( metal plate ) tube.

So far super tnt seems may be a best chinese supplier,
they test what comes from the Shuguang factory, and not all of the
factory
claims are supported by supertnt test results. See the description of
testing methods ....

http://www.supertnt.com/default/Howwetest.asp

The worrying thing is that they say the tubes will drift away from being
matched
after only 12hrs, and they cannot predict if a tube is likely to be an
"invalid"
tube, ie, a dud.

Pentalaboratries.com were rather vague about
replying to my emails, and have not so far explained to me exactly
what type of chinese 845 they have, and when thy did finally quote
something, the price was
$140 for a pair but the website says $100 each.
And the freight from the US was a lot more than the china to Oz freight.

Anyone have any dealings with any of these dudes or anyone any better??

But from what I do see of the test curves for the chinese 845M, it looks
like a very linear triode,
and quite suitable for what I have in mind.

Patrick Turner.

I don't know what you're going on about, Patrick. I paid 33 euro each
in matched pairs for the last set of 845 I bought. I also got
guaranteed, matched pairs from Billington for something life 50 stg,
which is about 80 euro, and I was given a killer-matched pair in a
trade by Koji in Japan (a trader who doesn't give anyone a bargain...)
for an agreed value of 100 USD which is near enough 80 euro. I have
three left, a pair and an odd one, presumably from giving someone a
spare or using one for a shunt regulator (there was a time when I
shunted every tube with an 845). All that I ever had appear, judging by
the three left, to have been ali-base metal plate tubes. I don't know
why you want special tubes, especially if what you say is true, that
the special tubes aren't as capable as the standard tubes; I checked
the 845M spec, and they appear to be rather different from the 100W RCA
and Sylvania tubes that were the model for the standard 845 tube. I
used to run the standard Chinese tubes at 76W and the only one I
remember popping was one that fell on its head anyway before being
inserted. I occasionally ran them higher than that too, but not for
extended periods; Chinese 845 and 211 were said on the Joenet to be
sturdy tubes. It seems to me that the Chinese are doing to naive
punters what RCA and others used to do to the military: derate the
tube's paper spec and charging more for it because of course it will
last longer if more conservatively used! It is true that 845 is a
handmade tube, and that you get the occasional one on which the glass
is skew on the base (I have one in my hand that is like that) but that
doesn't affect its workings. I don't see how the 845M is going to be
any better: it will be handmade by the same people, just (maybe) better
selected. I were you, I'd buy three matched pairs of the standard tubes
from a known-good supplier (Billington, Benny at Paradiso, whoever you
use in Australia), so that I could test one pair to destruction if
necessary, and have a spare pair instantly available. In any event, I
wouldn't start work on a new amp with the most expensive versions of a
particular tube that I could find; that's tempting fate!

HTH.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

Andre Jute wrote:

Patrick Turner wrote:
I have been trying to decide the best supplier of the
845M ( metal plate ) tube.

So far super tnt seems may be a best chinese supplier,
they test what comes from the Shuguang factory, and not all of the
factory
claims are supported by supertnt test results. See the description of
testing methods ....

http://www.supertnt.com/default/Howwetest.asp

The worrying thing is that they say the tubes will drift away from being
matched
after only 12hrs, and they cannot predict if a tube is likely to be an
"invalid"
tube, ie, a dud.

Pentalaboratries.com were rather vague about
replying to my emails, and have not so far explained to me exactly
what type of chinese 845 they have, and when thy did finally quote
something, the price was
$140 for a pair but the website says $100 each.
And the freight from the US was a lot more than the china to Oz freight.

Anyone have any dealings with any of these dudes or anyone any better??

But from what I do see of the test curves for the chinese 845M, it looks
like a very linear triode,
and quite suitable for what I have in mind.

Patrick Turner.

I don't know what you're going on about, Patrick.

I'll try to explain, to make things clearer to you, myself, and the group.

The emails back from pentalaboratories.com said that the new price for their
845 is now $140 per pair, and they advised me that the new price was
established today
and placed at their website today to replace the price shown as usd $100 per
pair.

But they won't say what sort of 845 it is, maybe its an 845B, maybe an 845M,
they like to keep me guessing eevn though I said i would NOT
purchase anything unless they give me the full details of
what they are offering.

And they don't seem able to supply a matched six pack,
so two tubes can be used for replacements.
They have ignored my request for tube sockets.
Freight from the US to Oz was quoted at usd $237,
so the total would be USD $657, but They cannot read my emails
and don't understand me, even though I have tried to be very clear with them,
and I have no idea what type of 845 it is that they have.





I paid 33 euro each
in matched pairs for the last set of 845 I bought. I also got
guaranteed, matched pairs from Billington for something life 50 stg,
which is about 80 euro, and I was given a killer-matched pair in a
trade by Koji in Japan (a trader who doesn't give anyone a bargain...)
for an agreed value of 100 USD which is near enough 80 euro.

I was wrong about the exchange rate.

Today, 1.00 AUD = 75c US = 0.625 Euro = 0.43 BP.
So 1USD = $1.33 AUD = 0.83 Euro = 0.57 BP,

so 100USD = 133AUD = 83 Eu = 57 BP.

meanwhile, the guys at supertnt in China have offered
a matched sixpack of 845M for USD $774, or $129 USD each,
but freight is only USD $72, and with 6 tube sockets the total with frieght is

USD $882, maybe enough to to buy a house in china.




I have
three left, a pair and an odd one, presumably from giving someone a
spare or using one for a shunt regulator (there was a time when I
shunted every tube with an 845). All that I ever had appear, judging by
the three left, to have been ali-base metal plate tubes.



I don't know
why you want special tubes, especially if what you say is true, that
the special tubes aren't as capable as the standard tubes; I checked
the 845M spec, and they appear to be rather different from the 100W RCA
and Sylvania tubes that were the model for the standard 845 tube.

Nothing is really "special"; but it appears 845M, or mrtal plate versions
and 845B graphite plate versions are available.

supertnt is yet to reply to my second request for a price for
the 845B.

It appears to me that both these companies are unprofessional about how they
present their product and go about careful reading and answering of emails.



I
used to run the standard Chinese tubes at 76W and the only one I
remember popping was one that fell on its head anyway before being
inserted. I occasionally ran them higher than that too, but not for
extended periods; Chinese 845 and 211 were said on the Joenet to be
sturdy tubes. It seems to me that the Chinese are doing to naive
punters what RCA and others used to do to the military: derate the
tube's paper spec and charging more for it because of course it will
last longer if more conservatively used!

Yes, well supertnt, the claimed direct distributors of Shuguang 845
do their own testing and evaluations of Shuguang tubes.
Indeed they say at their site in the chinglish if you read carefully
that the metal plate 845M version tended to reflect heat from the plate back
to the
cathode and raised the cathode temp at 100W so the tube can only have about 70
watts.

The 845B was a graphite plate tube which could be run at 100W but
then supertnt said it had other problems with cement used for joining the
graphite
anode to plate support rods....

It is true that 845 is a
handmade tube, and that you get the occasional one on which the glass
is skew on the base (I have one in my hand that is like that) but that
doesn't affect its workings. I don't see how the 845M is going to be
any better: it will be handmade by the same people, just (maybe) better
selected. I were you, I'd buy three matched pairs of the standard tubes
from a known-good supplier (Billington, Benny at Paradiso, whoever you
use in Australia),

I am not sure of any reliable supplier in Oz, and was hoping to avoid their
rather high margins when they sell imported tubes.
evatco has listed Golden Dragon 845 at USD $94 each.

But at
http://www.vacuumtube.com/tubes.htm
They have have matched **pairs** of 845 for USD $90, but I bet that may not
be the price if I emailed them.


so that I could test one pair to destruction if
necessary, and have a spare pair instantly available. In any event, I
wouldn't start work on a new amp with the most expensive versions of a
particular tube that I could find; that's tempting fate!

Yes, but I still have not got all the prices in yet, and i have not decided
yet
exactly what to buy, and the two suppliers
would of course like to make me purchase their most expensive offering.

I would be using a pair in each mono, with Ea = 1,250V, Ia = 55 mA, Pda = 69W,

Eg2 about -210V, fixed bias, one adjust pot per tube.

Supertnt say this is a standard set up, and so a max of about 48 watts of
power
is available into a 10k load. This is 692Vrms at the anodes,
and plotting the load lines reveals I would get about this OK.

Patrick Turner.





HTH.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

"François Yves Le Gal" wrote:

On Wed, 11 Jan 2006 15:59:14 GMT, Patrick Turner
wrote:

Since there are usd $2.0 per euro,
the cheapest option is the 33.4 euro which is about usd $67 each

Actually the exchange rate is 1.00 EUR = 1.21 USD = 1.61 AUD.

I checked the rates today, and that is about right.

Patrick Turner



but probably not matched.

Matched pairs are usually available for 10 EUR more.

freight from europe would be more....

Yup.

Patrick Turner in
. au:

Indeed they say at their site in the chinglish if you read carefully
that the metal plate 845M version tended to reflect heat from the plate back
to the
cathode and raised the cathode temp at 100W so the tube can only have about 70
watts.

Actually I read that

"Firstly we have discussed this problem with the technician in Shuguang. When
we found some relative material, we thought that the anxiety was
self-contradiction. Some technical material indicates that the inside of anode
should not be black, because black anode will eradiate energetic infrared ray
to filament and grid and the bright inside does not. The temperature of
filament in bright environment is perhaps not higher than the one in black
environment. "

so it's perhaps not yet a fully researched issue.

The 845B was a graphite plate tube which could be run at 100W but
then supertnt said it had other problems with cement used for joining the
graphite
anode to plate support rods....

Really? Did you really read that anywhere? Carefully?

What I read is "Because Shuguang hasn’t the skill of cementite to deal with
thick anode and formed anode," and "Because the main part of anode hasn’t been
blacken, the dissipation power of anode is only one of the fourth of the anode
dealing with the skill of cecentite." (sic)

"cementite" is iron carbide. Look it up.

I think you assumed the bit about joining.
I think it's to do with blackening and improving dissipation.

The other interesting thing is the comment about the quality (and density) of
their "black lead" (which is a synonym for graphite) which they state as "The
density of the black lead which Shuguang used in 845 is between 1.56 cm3 and
1.6 2 cm3". Apparently (pure?) graphite is considered to have a density of
2.09–2.23 g/cm³, so that is indeed low. Yet further down on their page
http://www.supertnt.com/default/news20.asp they say "When Shuguang has
excellent grid, filament and filament supporting structure, they want to
improve their anode material. It is difficulty to process black lead anode and
it is more difficulty to improve its purity and density. If you want to
improve the density from 1.62g/ cm3 to 1.82g/ cm3, the material cost is 5
twice more than the former one."

I'm clueless about various qualities of graphite though, so merely wonder.

No offence intended - the article had just happened to catch my eye earlier.
--
Regards,
Ross Matheson

RdM wrote:

Patrick Turner in
. au:

Indeed they say at their site in the chinglish if you read carefully
that the metal plate 845M version tended to reflect heat from the plate back
to the
cathode and raised the cathode temp at 100W so the tube can only have about 70
watts.

Actually I read that

"Firstly we have discussed this problem with the technician in Shuguang. When
we found some relative material, we thought that the anxiety was
self-contradiction. Some technical material indicates that the inside of anode
should not be black, because black anode will eradiate energetic infrared ray
to filament and grid and the bright inside does not. The temperature of
filament in bright environment is perhaps not higher than the one in black
environment. "

The blackness of the anode would be because its graphite I thought, and
it may well run cooler than a metal plate.

In my 13E1 amps, there are a pair of directly heated cathodes and a metal plate.
The rated Pda = 90 watts, but if you run the anodes at 90 watts, ie, 24omA x 375V,
the anodes start to glow red after 30mins when the tube finally gets
up to its maximum steady op temp.

I backed off to 375V x 190mA, ie, Pda = 72 wattsand no more glow or hot spots.

But in a class B pp amp you could design for Pda = 90 watts
because the average duty cycle for AM RF or audio is much less than 90
watts, unlike class A SE audio where the tube works hardest
with no signal present.



so it's perhaps not yet a fully researched issue.

Indeed, and so I was doubtful about chinese 845....



The 845B was a graphite plate tube which could be run at 100W but
then supertnt said it had other problems with cement used for joining the
graphite
anode to plate support rods....

Really? Did you really read that anywhere? Carefully?

What I read is "Because Shuguang hasn’t the skill of cementite to deal with
thick anode and formed anode," and "Because the main part of anode hasn’t been
blacken, the dissipation power of anode is only one of the fourth of the anode
dealing with the skill of cecentite." (sic)

I didn't know what cementite was. I figured there must be a connection between
the graphite anode, ie, carbon anode, and the metals supporting the anode.



"cementite" is iron carbide. Look it up.

I think you assumed the bit about joining.
I think it's to do with blackening and improving dissipation.

I have seen metal plate tubes with black plates.



The other interesting thing is the comment about the quality (and density) of
their "black lead" (which is a synonym for graphite) which they state as "The
density of the black lead which Shuguang used in 845 is between 1.56 cm3 and
1.6 2 cm3". Apparently (pure?) graphite is considered to have a density of
2.09–2.23 g/cm³, so that is indeed low. Yet further down on their page
http://www.supertnt.com/default/news20.asp they say "When Shuguang has
excellent grid, filament and filament supporting structure, they want to
improve their anode material. It is difficulty to process black lead anode and
it is more difficulty to improve its purity and density. If you want to
improve the density from 1.62g/ cm3 to 1.82g/ cm3, the material cost is 5
twice more than the former one."

I'm clueless about various qualities of graphite though, so merely wonder.

I read all this and began to worry.

So I concluded that the metal plate 845 may be a more reliable tube,
even though it cannot run at 100W, and only 65W.
That's where I want to run then anyway, so I will have
130W of dissipation from two tubes, with Ea = 1,250, Ia = 52mA, and I calculate
efficiency is over 37%, very decent for triodes,
so 48 watts max is possible.

No offence intended - the article had just happened to catch my eye earlier.

No offense taken.

I am trying to eak out the real story behind the 845 that the Chinese
would very much like us to buy; the price of a tube will keep a worker in rice for
about a year......

Patrick Turner.



--
Regards,
Ross Matheson