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#1
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
Hello!
Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! |
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#2
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 18, 1:59*pm, Tube747 wrote:
Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at http://www.audio-talk.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 |
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#3
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
Dear Andre Jute,
Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? I know the 2 x 6D22S is able handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) -- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. Thanks again! On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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 |
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#4
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 18, 6:02*pm, Tube747 wrote:
Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? I know the 2 x 6D22S is able handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. Thanks again! On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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- Hide quoted text - - Show quoted text - 1500VDC at 300mA is sufficient to roast anyone that desires to become a toast. Heavy duty insulation is not pretty to look at all. GM70 is a pig of a tube - typical modulator, though fairly robust. |
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#5
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 19, 10:02*am, Tube747 wrote:
Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. If you have 1,500V between anode and cathode and Ia =185mA then anode heat generated at idle, ie Pda = 1,500 x 0.185A = 277.5Watts. This is more than 3 times what you should have for ONE tube. I might ask you to think a little more about tube audio design and setting tubes up for any class of operation. What you will get if you follow your guesses is SMOKE. The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Some tubes go better than others with class A2, ie, with grid current. But to partially overcome the distortion generated in driver stages while traversing from class A1 to A2, one needs some very rugged circuit techniques which are best left right out in favour of having more OP tubes paralleled and using class A1. But to find out about what sort of engineering is needed you first need to understand load line analysis. Go to my pages on tubes and please start reading. http://www.turneraudio.com.au/loadmatch1-se-triodes.htm Now there are NO curves for how to deal with a GM70 at my site. If you are at all intelligent enough to understand the basics at my site then maybe you can just plot your load lines with a set of Ea - Ia curves from the data on GM70. The METHOD of thought is the same for *every* triode. I know the 2 x 6D22S is able handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. I don't where data is for the tube. But it is a single anode indirectly heated cathode type. I don't know why on earth you would ever bother with tube rectifiers; they never make the sound any better!!!!! For +1,200V Its quite easy to have an 890Vac winding and use a bridge made of 16 x 1N5408 and have a string of series 4 x 470uF x 450V caps, then a choke of 4H, then another string of the same caps, and you will have a well filtered B+ rail. But take a look at the schematics of amp and PSU of my class A1 SE55 at http://www.turneraudio.com.au/monobloc845se55.html In this I have voltage doubler psus and a split rail for the SE triodes. This means the insulation on the OPT is not stressed. Not a single bloomin stoopid tube rectifier to be seen anywhere. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? First of all, do the load line analysis. One rarely if ever needs to use 1,500V for any SET using large tubes like 845, 211, or GM70. Pda should never be more than 75W for these sorts of tubes so if you have 33% efficiency maximum A1, then you'll get about 25W. Class A2 can allow efficiency of up to 45%. But you really have to work and pay hard to achieve the extra few watts. So it always works out better if you settle for A1, then just increase the output tube numbers to get more PO. Of the 3 tubes, 211, 845, only the 845 is really the best for hi-fi. But one does need to be able to make up to about 160Vrms of drive signal, but use only about 120Vrms for A1. Class A2 is a Pain In The Arse because the driver amp must be able to make **linear** voltage swings into grids drawing so much current during positive going voltage swings that the load value becomes very low, maube only 1k during the part of the swing where grid current is drawn. T get the needed linearity with A2 in the grid current region there must be a cathode follower between the driver tube producing the VOLTAGE so that you can also get the high CURRENT needed. Using a 300B as a driver is OK. I am repairing Push Pull Ming Da 100Wpch amps here now with 845 and they have 300B driver tubes but gain is just under 4.0, so there is a 6SN7 long tail pair to drive the 300B and a single 6SN7 to drive the LTP. There is just enough gain. at max PO, 300Vrms grid to grid is needed at the 845 grids. About 1/2 this may be needed for PP GM70 A1. I designed but never built an amp for GM70. It has B+ at anode at +980V, and cathode has nice simple cathode biasing where Ek = 80V, and so for A1 the grid swing is +/- 80pkV, = 56Vrms, and this is from a common cathode gain stage using 6SN7 paralleled and R loaded with CR coupling to the GM70 grid. The SE triode should be set up at voltages which favours A1. For example, With SE 211, if you want A1, then one uses Ea = 1,250V quite OK and Ia 60mA. RL is then about 13kohms. Now one might try to use A2, and get a bigger Eminmum swing so RL has to be higher, maybe 20k, lest you have cut off when Emax is increased. So some folks run 211 at a much lower Ea, maybe 800V, Ia 94mA and use a large A2 grid swing and RL = 8k, because the OPT is a lot easier to wind, or there is an available 10k primary OPT which can be used; even a PP OPT will do if you cap couple that to the anode which is fed from a B+ supply via 50H choke. ( Its called parafeed ). My design for GM70 is another paralleled 6SN7 and there is 10dB global NFB to get the output resistance low enough to control speakers properly. One could use trioded EL34, gain about 8. When using 300B as driver tubes, or probably better 2A3 tubes then consider having a CT choke and series R to each anode as suggested at http://www.turneraudio.com.au/300w-1...tput-jan06.htm This is for PP but the principle is the same for SE as you can see in my SE845 55W amps. The CT choke allows a lower grid bias R and a wider and less distorted V swing for the driver regardless of what driver tubes you have. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. These would NOT ever be my choice. I made my own plugs and sockets for the SE55 I built because there was nothing commercially available which had 9 pins, each of which could have 5A and +/- 700Vdc. The plugs and sockets on the amp I made are large clunkin' things but very rugged, and the plug only fits ONE way into ONE channel, so they are idiot proof. My design uses sophisticated active protection against bias failure etc, so the 9 wires in the umbilical cables are essential, also for safety reasons. I have used octal plugs and sockets for amps where B+ does not exceed 500V. But finding well made commercially off the shelf samples for plugs and sockets is like searching for rocking horse droppings - you seek but you don't find. Remote PSU are the best way to maintain noise in the output below 0.25 mV at any time or situation. Especially with DH triodes which MUST have *very wel* smoothed DC cathode supplies. Patrick Turner. Thanks again! On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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- Hide quoted text - - Show quoted text - |
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#6
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 18, 11:02*pm, Tube747 wrote:
Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. See http://www.audio-talk.co.uk/fiultra/...dre%20Jute.htm for working with the tube parameters graphically on the loadlines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at http://www.audio-talk.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 On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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 |
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#7
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 19, 4:50*pm, Andre Jute wrote:
On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the loadlines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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 On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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- Hide quoted text - - Show quoted text - Small triodes don't sound bad at all, provided the speakers are efficient enough. 2A3 is a great example. |
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#8
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 20, 6:35*am, wrote:
On Feb 19, 4:50*pm, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the loadlines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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 On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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- Hide quoted text - - Show quoted text - Small triodes don't sound bad at all, provided the speakers are efficient enough. 2A3 is a great example. That's why I say that it is worth getting sensitive speakers before you even start thinking of which tube you'll choose. The minute you have sensitive speakers, horizons open to you. I personally use 300B amps most of the time, There's a design -- The Impresario -- for sensitive speakers on my netsite that can be inexpensively built. It sounds superb with the cheapest amp I ever designed, a 2W EL34 SE operating striclty in Class A1. Andre Jute Visit Jute on Thisthatandtheother http://www.audio-talk.co.uk/fiultra/...20ARISING.html |
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#9
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 19, 5:40*pm, Patrick Turner wrote:
On Feb 19, 10:02*am, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. If you have 1,500V between anode and cathode and Ia =185mA then anode heat generated at idle, ie Pda = 1,500 x 0.185A = 277.5Watts. This is more than 3 times what you should have for ONE tube. I might ask you to think a little more about tube audio design and setting tubes up for any class of operation. What you will get if you follow your guesses is SMOKE. What about 1180V 115ma? I guess this is not exceeding the plate dissipation rating of the GM70. The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Some tubes go better than others with class A2, ie, with grid current. But to partially overcome the distortion generated in driver stages while traversing from class A1 to A2, one needs some very rugged circuit techniques which are best left right out in favour of having more OP tubes paralleled and using class A1. But to find out about what sort of engineering is needed you first need to understand load line analysis. Go to my pages on tubes and please start reading.http://www.turneraudio.com.au/loadmatch1-se-triodes.htm Now there are NO curves for how to deal with a GM70 at my site. If you are at all intelligent enough to understand the basics at my site then maybe you can just plot your load lines with a set of Ea - Ia curves from the data on GM70. The METHOD of thought is the same for *every* triode. Thanks for the advice! I know the 2 x 6D22S is able handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. I don't where data is for the tube. But it is a single anode indirectly heated cathode type. I don't know why on earth you would ever bother with tube rectifiers; they never make the sound any better!!!!! For +1,200V Its quite easy to have an 890Vac winding and use a bridge made of 16 x 1N5408 and have a string of series 4 x 470uF x 450V caps, then a choke of 4H, then another string of the same caps, and you will have a well filtered B+ rail. But take a look at the schematics of amp and PSU of my class A1 SE55 athttp://www.turneraudio.com.au/monobloc845se55.html In this I have voltage doubler psus and a split rail for the SE triodes. This means the insulation on the OPT is not stressed. Not a single bloomin stoopid tube rectifier to be seen anywhere. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? First of all, do the load line analysis. One rarely if ever needs to use 1,500V for any SET using large tubes like 845, 211, or GM70. Pda should never be more than 75W for these sorts of tubes so if you have 33% efficiency maximum A1, then you'll get about 25W. Class A2 can allow efficiency of up to 45%. But you really have to work and pay hard to achieve the extra few watts. So it always works out better if you settle for A1, then just increase the output tube numbers to get more PO. Of the 3 tubes, 211, 845, only the 845 is really the best for hi-fi. But one does need to be able to make up to about 160Vrms of drive signal, but use only about 120Vrms for A1. Class A2 is a Pain In The Arse because the driver amp must be able to make **linear** voltage swings into grids drawing so much current during positive going voltage swings that the load value becomes very low, maube only 1k during the part of the swing where grid current is drawn. T get the needed linearity with A2 in the grid current region there must be a cathode follower between the driver tube producing the VOLTAGE so that you can also get the high CURRENT needed. Using a 300B as a driver is OK. I am repairing Push Pull Ming Da 100Wpch amps here now with 845 and they have 300B driver tubes but gain is just under 4.0, so there is a 6SN7 long tail pair to drive the 300B and a single 6SN7 to drive the LTP. There is just enough gain. at max PO, 300Vrms grid to grid is needed at the 845 grids. About 1/2 this may be needed for PP GM70 A1. I designed but never built an amp for GM70. It has B+ at anode at +980V, and cathode has nice simple cathode biasing where Ek = 80V, and so for A1 the grid swing is +/- 80pkV, = 56Vrms, and this is from a common cathode gain stage using 6SN7 paralleled and R loaded with CR coupling to the GM70 grid. The SE triode should be set up at voltages which favours A1. For example, With SE 211, if you want A1, then one uses Ea = 1,250V quite OK and Ia 60mA. RL is then about 13kohms. Now one might try to use A2, and get a bigger Eminmum swing so RL has to be higher, maybe 20k, lest you have cut off when Emax is increased. So some folks run 211 at a much lower Ea, maybe 800V, Ia 94mA and use a large A2 grid swing and RL = 8k, because the OPT is a lot easier to wind, or there is an available 10k primary OPT which can be used; even a PP OPT will do if you cap couple that to the anode which is fed from a B+ supply via 50H choke. ( Its called parafeed ). My design for GM70 is another paralleled 6SN7 and there is 10dB global NFB to get the output resistance low enough to control speakers properly. One could use trioded EL34, gain about 8. When using 300B as driver tubes, or probably better 2A3 tubes then consider having a CT choke and series R to each anode as suggested athttp://www.turneraudio.com.au/300w-1+2-schem-input-driver-output-jan0... This is for PP but the principle is the same for SE as you can see in my SE845 55W amps. The CT choke allows a lower grid bias R and a wider and less distorted V swing for the driver regardless of what driver tubes you have. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. These would NOT ever be my choice. I made my own plugs and sockets for the SE55 I built because there was nothing commercially available which had 9 pins, each of which could have 5A and +/- 700Vdc. The plugs and sockets on the amp I made are large clunkin' things but very rugged, and the plug only fits ONE way into ONE channel, so they are idiot proof. My design uses sophisticated active protection against bias failure etc, so the 9 wires in the umbilical cables are essential, also for safety reasons. I have used octal plugs and sockets for amps where B+ does not exceed 500V. But finding well made commercially off the shelf samples for plugs and sockets is like searching for rocking horse droppings - you seek but you don't find. Remote PSU are the best way to maintain noise in the output below 0.25 mV at any time or situation. Especially with DH triodes which MUST have *very wel* smoothed DC cathode supplies. Patrick Turner. Thanks again! On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.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 ... read more »- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
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#10
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
Dear Andre Jute,
My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review- Hide quoted text - - Show quoted text - |
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#11
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 21, 1:24*am, Tube747 wrote:
Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - Any vacuum tube/valve/lamp can potentially cause microphonic defect. I am very disturbed to hear that even the 300B is not immune against this dreadful illness. Must be of PRC manufacture, like the rest of their mass products = low grade... |
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#12
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 21, 6:24*am, Tube747 wrote:
Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. Why? Perhaps your techie should stick to soldering. But the microphonic is what I concern! Eh? Microphonic 300B? Not that I ever heard of, and I started in the days of really wretched Chinese 300B. One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver I like the 5687 and its computer cousin the 7044 but have you studied the spec and discovered how much swing you can actually generate? And another six sockets! Has your friend ever actually designed and built any amp, never mind something as fundamentally heavy as a kilovolt amp? In any event, the purpose of using a power triode is to get enough current to overcome Miller capacitance. See http://www.audio-talk.co.uk/fiultra/...dre%20Jute.htm where I explain how the necessary slew rate current is calculated. since my friend hate power triode to drive another power triode. These are electrical matters. It appears your friend deals in street corner gossip. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Your friend is talking crap through the back of his neck. The nine pin miniatures are hugely compromised. Check the history of their development, the purposes of their invention. Ask yourself why they do so well in guitar amps -- it is because they distort the sound. Your friend has listened to so many cheap and rubbishy amps built with 9- pin tubes, he now thinks that's what music should sound like. Those of us who have spent a lifetime in concert halls, listening to live performers, know better. Again thanks for the valuable advice! I really suggest that you educate yourself before you waste a lot of money building an amp designed by street corner gossip, or a hodge- podge of ideas from here, there and everywhere which will do nothing but fight each other. You can start at http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm which was written for people just like you, and you should also look at http://www.audio-talk.co.uk/fiultra/...trafi-crct.jpg This the KISS Amp 300B 'Ultrafi' circuit. Two-stage, all-triode, single-ended, zero negative feedback, ultra-silent tube amplifier with Western Electric WE417A high-mu triode and WE300B DHT, Mullard GZ37 tube rectification, with twin-choke smoothing (zero electrolytic capactiors, of course!). This is also the control amp (think of a 300B pre-amp) which boosts my 75W SE SV-572-xx amp into life. Extended description in THE KISS AMP 300B. *****If you seriously want us to help you, start by telling us which speakers you want to drive and what their sensitivity is. From there we can work out how much power you truly need, and then help you specify a tube and a topology to best serve your musical needs. Choosing a monstrous tube like the GM70 first and then trying to make it work is a romantic endeavour -- and building custom amps is about building good-sounding but dangerous electronics, not about romance, and certainly not about street corner gossip. Andre Jute Visit Jute on Amps at http://www.audio-talk.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 On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review- Hide quoted text - - Show quoted text - |
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#13
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 21, 6:36*am, wrote:
On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - * * *Any vacuum tube/valve/lamp can potentially cause microphonic defect. *I am very disturbed to hear that even the 300B is not immune against this dreadful illness. Must be of PRC manufacture, like the rest of their mass products = low grade... First I hear of microphonic 300B! Sounds to me like the rumour mill is working overtime. -- AJ |
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#14
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
Dear Andre Jute,
I hear what you said, and decided to build a much simple amplifier. This is what I'm trying to do. I'll build an amplifier by using C3g as driver tube and KR 300B-XLS as output tube. The circuit is based on Jack Ellianos DRD, this means the C3g triode wired is choke loaded and feeding the grid of the KR 300B-XLS; and the output stage is para-feed in Ultra-path arrangement (return back to cathode) with 5K primary impedance. As far as power supply goes, 6D22S full wave rectification plus 50mf oil filled poly caps, low DCR choke, 8 x 150mf oil filled poly caps, current source and shunt regulator; this is because PS regulation is critical for DRD circuitry. The output tube tubes is running in A1. I guess this amplifier is much safety than the GM70. Thanks again! On Feb 22, 5:39*am, Andre Jute wrote: On Feb 21, 6:36*am, wrote: On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. |
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#15
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 21, 4:39*pm, Andre Jute wrote:
On Feb 21, 6:36*am, wrote: On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. |
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#16
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 22, 6:08*am, Tube747 wrote:
Dear Andre Jute, I hear what you said, and decided to build a much simple amplifier. This is what I'm trying to do. I'll build an amplifier by using C3g as driver tube and KR 300B-XLS as output tube. The circuit is based on Jack Ellianos DRD, this means the C3g triode wired is choke loaded and feeding the grid of the KR 300B-XLS; and the output stage is para-feed in Ultra-path arrangement (return back to cathode) with 5K primary impedance. As far as power supply goes, 6D22S full wave rectification plus 50mf oil filled poly caps, low DCR choke, 8 x 150mf oil filled poly caps, current source and shunt regulator; this is because PS regulation is critical for DRD circuitry. The output tube tubes is running in A1. I guess this amplifier is much safety than the GM70. Thanks again! When you finish this amp, you will have not only an excellent sounding amp of your own design and making, but the perfect booster amp to drive a transmitting tube amp if you decide you still need one. Good luck. -- Andre Jute On Feb 22, 5:39*am, Andre Jute wrote: On Feb 21, 6:36*am, wrote: On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube.. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially the filament to cathode 600V rating. 5. Forget solid state and the usual GZ34 rectifiers, and so on, damper diodes put you straight away in sonic heaven, and the 6D22S is the king of the damper diodes. You've lucked out, feller. 6. Kilovolt and higher transmitting tube amps can grow monstrously heavy. Give thought before you start designing about separation of units, and where you will get umbilical connectors that are both capable and affordable. Andre Jute ... read more » |
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#17
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
Dear Andre Jute,
Again thanks for your help! These are very helpful discussion!! I have some questions for you about the 300B XLS project. 1) How you comment between WE 437A and C3g when use as driver tube for KR 300B XLS? 2) Other than 6D22S, What about 5U4GB? Does it as good? Thanks! On Feb 23, 7:14*am, Andre Jute wrote: On Feb 22, 6:08*am, Tube747 wrote: Dear Andre Jute, I hear what you said, and decided to build a much simple amplifier. This is what I'm trying to do. I'll build an amplifier by using C3g as driver tube and KR 300B-XLS as output tube. The circuit is based on Jack Ellianos DRD, this means the C3g triode wired is choke loaded and feeding the grid of the KR 300B-XLS; and the output stage is para-feed in Ultra-path arrangement (return back to cathode) with 5K primary impedance. As far as power supply goes, 6D22S full wave rectification plus 50mf oil filled poly caps, low DCR choke, 8 x 150mf oil filled poly caps, current source and shunt regulator; this is because PS regulation is critical for DRD circuitry. The output tube tubes is running in A1. I guess this amplifier is much safety than the GM70. Thanks again! When you finish this amp, you will have not only an excellent sounding amp of your own design and making, but the perfect booster amp to drive a transmitting tube amp if you decide you still need one. Good luck. -- Andre Jute On Feb 22, 5:39*am, Andre Jute wrote: On Feb 21, 6:36*am, wrote: On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute.htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium.. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability.. For transferring more than a kilovolt? You're joking, of course.. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...p%20INDEX..htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps stand in direct relationship to the current you burn both in the driver and the power tube. Current 'wasted' is in fact a superior substitute for negative feedback. See my KISS articles at the URL under my sig. 3. Unless you have experience of high voltage amps, you don't want to mess with kilovolt plus power supplies. They can and will kill you. Even worse, caps and other components start to become *very* expensive. 4. Be sure you understand the 6D22S's parameters before you start designing, especially ... read more »- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
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#18
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 22, 7:38*pm, Tube747 wrote:
Dear Andre Jute, Again thanks for your help! These are very helpful discussion!! I have some questions for you about the 300B XLS project. 1) How you comment between WE 437A and C3g when use as driver tube for KR 300B XLS? 2) Other than 6D22S, What about 5U4GB? Does it as good? Thanks! On Feb 23, 7:14*am, Andre Jute wrote: On Feb 22, 6:08*am, Tube747 wrote: Dear Andre Jute, I hear what you said, and decided to build a much simple amplifier. This is what I'm trying to do. I'll build an amplifier by using C3g as driver tube and KR 300B-XLS as output tube. The circuit is based on Jack Ellianos DRD, this means the C3g triode wired is choke loaded and feeding the grid of the KR 300B-XLS; and the output stage is para-feed in Ultra-path arrangement (return back to cathode) with 5K primary impedance. As far as power supply goes, 6D22S full wave rectification plus 50mf oil filled poly caps, low DCR choke, 8 x 150mf oil filled poly caps, current source and shunt regulator; this is because PS regulation is critical for DRD circuitry. The output tube tubes is running in A1. I guess this amplifier is much safety than the GM70. Thanks again! When you finish this amp, you will have not only an excellent sounding amp of your own design and making, but the perfect booster amp to drive a transmitting tube amp if you decide you still need one. Good luck. -- Andre Jute On Feb 22, 5:39*am, Andre Jute wrote: On Feb 21, 6:36*am, wrote: On Feb 21, 1:24*am, Tube747 wrote: Dear Andre Jute, My technician who will build the amplifier for me also suggest I try the 211 as driver. But the microphonic is what I concern! One of my friend suggest I parallel few 5687 (2 or 3 tubes) and use as a driver since my friend hate power triode to drive another power triode.. He said the 300B is microphonic, other than that, it kills the beautiful things that the 9 pins miniature possess. Again thanks for the valuable advice! On Feb 20, 5:50*am, Andre Jute wrote: On Feb 18, 11:02*pm, Tube747 wrote: Dear Andre Jute, Thank you very much for the valuable advice! I'm thinking about running the GM70 (copper plate version) either 1500V @185ma in class A2 OR 1200V @100ma in pure class A. You can't do that because it exceeds the power rating of the tube. Seehttp://www.audio-talk.co.uk/fiultra/KISS%20112%20by%20Andre%20Jute..htm for working with the tube parameters graphically on the load lines, which takes all these matters and many more into consideration on a single sheet of paper that you can, with practice, take in instantly. In addition, nobody needs 1500V amps, or even 1200V ones. Something under a kilovolt generally does even the most ambitious. And even those aren't for people who don't yet understand how to read the specs, as you clearly don't. To be blunt, I think you should first build several much more modest amps before starting work on a transmitting tube amp in the kilovolt range. Even a 300B amp is more than dangerous enough to people who already know what they're doing! The reason I'm interested in A2 due to reading Lynn Olson postings on other forum about running A2 on both 300B and 845 for finest result! Jack Elliano from Electraprint has also wrote about A2 operation with favorable result. What's your suggestion? Perhaps they're right. Perhaps they're just bored and looking for something new. However that may be, A2 amps are trickier to design than you may think and I've never found one that sounded as good as Class A1. The whole point of choosing hefty transmitting tubes is to get enough power in Class A1 without even having to consider drawing grid current. I consider A2 suitable for people forced by their financial circumstances to choose some mickey mouse tube that doesn't have the oomph to drive the speakers in A1. By way of example, an SE 845 can easily be made to give 20W in A1, and you just add tubes for more power. It is difficult to conceive of a finer sound than an 845 driven in SE Class A1 by a 300B, playing through a reasonably sensitive speaker (which includes QUAD Electrostats). A Svet SV572-2 might shade it slightly, if built right, but they're unobtanium. I know the 2 x 6D22S is able to handle 300ma max current, but not sure its high voltage capability, such as 1500V and 1200V. The dissipation is always V x A = W and must never exceed the manufacturer's rating, and in well-designed amps never comes within 20 per cent of it, in Patrick Turner's version within 25 per cent of it. This is my proposal for building the amplifier. The input tube is C3g triode wired, and then DRD couple to Full Music 300B mesh feeding 1:1 interstage transformer and driving the GM70. Have you considered the good-sounding 845? It's a lot easier to work with, it's only downside a high drive requirement (both signal voltage and current), and sounds even better when driven with a 300B. Very simple 845 circuits work a treat; that saves cost and weight. Power supply will be in a separate chassis. B+ supply for both driver stage and output stage is totally independent with separate power transformer! My first approach for the driver stage's PS is using the 5U4GB -- 25mf -- constant current source -- shunt regulator (solid state); But now might think about to use the 2 x 6D22S instead of 5U4GB after your rave on this rectifier tube. Regard the output stage PS, this is the diagram: 2 x 6D22S (full wave rectification) *-- 50mf 2000V caps -- Low DCR choke -- 10 x 50mf 2000V caps What do you think? If you're spending these extravagant amounts of money, you should have the best possible power supply, and that is choke input. So you might want to look into a bridge of rectifier tubes, choke, cap, choke, cap filter, with decoupling downstream. That sound simple but it is the best-sounding power supply. All connectors between the PS unit and main chassis will be Neutrik Power Con due to its high voltage and high current capability. For transferring more than a kilovolt? You're joking, of course. Read the spec again. Thanks again! I really suggest very strongly that you build several less puissant amps first. You might start any project by calculating carefully how much power you truly need. It is always more satisfactory to spend money up front getting the best possible sensitive speakers and then reducing your amp's power requirements and building it accordingly, than to try and hog the maximum power from tubes. More information you might find of use starts he *http://www.audio-talk.co.uk/fiultra/...mp%20INDEX.htm Hope this helps. You really want to spend a good deal of time reading on my site and Patrick's, and in the RDH, and reflecting on what you read, before you start specifying tubes and operating classes based on what anyone, including Lynn and Jack, say *about the last amp they built*. Your amp must fit into your system, and your system sound is actually 80 or 90 determined by your speakers. Andre Jute Visit Jute on Amps at *http://www.audio-talk.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie Tube CAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review On Feb 19, 5:38*am, Andre Jute wrote: On Feb 18, 1:59*pm, Tube747 wrote: Hello! Can I use 2 x 6D22S in full wave rectification for GM70's B+ supply that running at 1500VDC? Thanks! That should be no problem, as several people easily made a bridge of 6D22S give 500mA at around 900V, and I ran PSE Svet SV572-3 and -10 high and hot with 6D22S rectification. However, the question arises why you would wish to run GM70 at 1500V, which is max plate voltage, and how much current you intend to use. Here are six not necessarily unrelated thoughts: 1. Power dissipation in amps that actually work and keep working is usually no higher than 80% of Pdmax and none of the limits are maxed out as you intend to do with the GM70. Those are 'don't go here' maxima, *not* suggested operating conditions. 2. It may be sonically a lot smarter to up the current a bit and lower the voltage. The sweetness of your sound in simple amps ... read more »- Hide quoted text - - Show quoted text - 5U4 is another pig in the vacuum kingdom. At 3 A for the filament alone why would anyone even think of using one in this time and day? And to have a full bridge rectifier you will need two of them! Silicon rectifier is almost perfect, now germanium is even better provided it is obtainable. A small delay circuit for B+ turn-on is all that is needed. |
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#20
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 23, 10:03*am, John Byrns wrote:
In article , wrote: * * * * * * * * * * * * * *5U4 is another pig in the *vacuum kingdom. At 3 A for the filament alone why would anyone even think of using one in this time and day? * *And *to have a full bridge rectifier you will need two of them! * * Silicon rectifier is almost perfect, now germanium is even better provided it is obtainable. A small delay circuit for B+ turn-on is all that is needed. I'd like to see a design for a "full bridge rectifier" using only two 5U4s? *I would think it would take a minimum of three 5U4s. -- Regards, John Byrns Surf my web pages at, *http://fmamradios.com/ Each 5U4 contains two anodes. 2x2=4 (a bridge). No use for another energy sucking vampire pig of a tube. Vacuum tube/valve rectifiers do have certain characteristics that don't pertain to s.s. dodes. According to some, they supply 'softer' sounding B+ that may ( I cannot agree) develope a higher dynamic range (which I do not hear). Whatever one decides to build, power supply is no less important than the audio stages and requires equal attention. Beware of lethal shocks. Even when unplugged, capacitors and inductors can store a charge for a long time! |
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#21
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
In article
, wrote: On Feb 23, 10:03*am, John Byrns wrote: In article , wrote: * * * * * * * * * * * * * *5U4 is another pig in the *vacuum kingdom. At 3 A for the filament alone why would anyone even think of using one in this time and day? * *And *to have a full bridge rectifier you will need two of them! * * Silicon rectifier is almost perfect, now germanium is even better provided it is obtainable. A small delay circuit for B+ turn-on is all that is needed. I'd like to see a design for a "full bridge rectifier" using only two 5U4s? *I would think it would take a minimum of three 5U4s. Each 5U4 contains two anodes. No argument there. 2x2=4 (a bridge). Only if there are no constraints on connecting the "anodes" that makes the bridge configuration impossible. No use for another energy sucking vampire pig of a tube. There is if you want to build a "full bridge rectifier" using 5U4s. I would like to see or hear an actual description of how you propose connecting only two 5U4s as a "full bridge rectifier"? -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
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#22
Posted to rec.audio.tubes
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1500V for 6D22S in full wave rectification
On Feb 24, 9:40*am, John Byrns wrote:
In article , wrote: On Feb 23, 10:03*am, John Byrns wrote: In article , wrote: * * * * * * * * * * * * * *5U4 is another pig in the *vacuum kingdom. At 3 A for the filament alone why would anyone even think of using one in this time and day? * *And *to have a full bridge rectifier you will need two of them! * * Silicon rectifier is almost perfect, now germanium is even better provided it is obtainable. A small delay circuit for B+ turn-on is all that is needed. I'd like to see a design for a "full bridge rectifier" using only two 5U4s? *I would think it would take a minimum of three 5U4s. * *Each 5U4 contains two anodes. No argument there. 2x2=4 (a bridge). Only if there are no constraints on connecting the "anodes" that makes the bridge configuration impossible. No use for another energy sucking vampire pig of a tube. There is if you want to build a "full bridge rectifier" using 5U4s. *I would like to see or hear an actual description of how you propose connecting only two 5U4s as a "full bridge rectifier"? -- Regards, John Byrns Surf my web pages at, *http://fmamradios.com/- Hide quoted text - - Show quoted text - 'Full' somehow crept into this sentence all by itself. Meant to say full-wave bridge rectifier. I don't like tube rectifiers as you can see! However, I have lots of respect for tube voltage regulators. |
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