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#1
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
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. |
#2
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
"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. |
#3
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
"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. |
#4
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
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 |
#5
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
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 |
#6
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
"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. |
#7
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
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 |
#8
Posted to rec.audio.tubes
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Shuguang 845M use in SET amps.
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 |
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