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#1
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The making of a triode
Hi Joes,
For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond |
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#2
Posted to rec.audio.tubes
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The making of a triode
Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond Thanks for posting this Raymond. I know a guy who makes neon signs, and it would be fun to show him this and get a few tubes made for me. Without specs on the size of the parts, their distance from each other, their composition, etc. the results would be quite sporadic, though. Is there a resource on the web that, at the very least, has ballpark figures for those qualities (and whatever others I can't even think of)? I wouldn't want to go into production, but he's a True Artist in every sense of the word, so he's even flakier than I am! He would look upon variations from tube to tube as a good thing. It would be good to give him some definite guidelines. |
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#3
Posted to rec.audio.tubes
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The making of a triode
Raymond Koonce wrote:
Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond Excellent video! Thanks for sharing Ray. How did they sound? Transparent? lol! |
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#4
Posted to rec.audio.tubes
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The making of a triode
steppenvalve wrote: Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond Thanks for posting this Raymond. I know a guy who makes neon signs, and it would be fun to show him this and get a few tubes made for me. Without specs on the size of the parts, their distance from each other, their composition, etc. the results would be quite sporadic, though. Is there a resource on the web that, at the very least, has ballpark figures for those qualities (and whatever others I can't even think of)? I wouldn't want to go into production, but he's a True Artist in every sense of the word, so he's even flakier than I am! He would look upon variations from tube to tube as a good thing. It would be good to give him some definite guidelines. I think that Guido used the original patent documents for his design. The modern components (filament, cathode coatings, spot welder, vacuum pumping gear, etc.) obviously made it easier to do. I would think a neon guy would have most of the expertise to do what Guido did, but probably in a different manner. Having access to the Philps R&D lab was indispensible. Best regards, Raymond |
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#5
Posted to rec.audio.tubes
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The making of a triode
Güs wrote: Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond Excellent video! Thanks for sharing Ray. How did they sound? Transparent? lol! They actually sounded pretty good to me. We heard them on 300B monoblocs with Altec horns. Guido told me that the specifications were really horrible. He build about 20 tubes in all and some were non-functional, gassy, etc. (he said one even glowed like a neon tube). They have *very* high plate R and very low gm, but the mu is about 50. There's an auction at the end of the festival and two additional triodes were sold to a member of the French group, Melaudia (www.melaudia.net, all in French). I'm waiting for their preamp.... Best regards, Raymond |
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#6
Posted to rec.audio.tubes
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The making of a triode
Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Best regards, Raymond Stunning and apt celebration. I knew Guido and Manfred back in the days of the Joenet, two very helpful guys. Give them my regards. It must help to have the resources of Philips R&D at one's beck and call for private experiments! Of course, this is inexpensive publicity for Philips (not to mention that it is with people who are probably opinion-formers in other walks of life too), and I bet it gave the guys with the yes-power a thrill to be connected back to the source of some of Philips wealth. Thanks for sharing. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#7
Posted to rec.audio.tubes
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The making of a triode
Hi RATs!
Tubes ain't much, couple pieces of metal in a jar of nothing. Transistors ain't much, neither. Listening is great. Reading about various tricks and gimmicks is fun, too. Having the discussion of the joys of tube hobby listening hit by a Tsunami of techno BS from some really unhappy and desparate reptilian cortex EE types is OK. It gives them a sense of purpose, which many engineers lack in this world. Perhaps not surprisingly. I like listening. I have known firsthand the emptiness of engineering for money  I choose to enjoy the noises MY audio junk makes. Others may enjoy shouting their nasty opinions. It is a free world. All the idiots think they know important facts. Wiser men are content to fool their ears, if not their Creator. Happy Ears! Al PS newsgroups have helped teach people to find something they like in this world, but, hyperactive fools insist, ad nauseum, that there is nothing to like ... the Nazi Gestapo praised methamphetamine, it gave one the illusion that to keep talking after others had fallen asleep was the same as winning the argument. Sigh. You can set fire to your enemies, but, it won't make you smart, nor correct, just sooty. Flame On! |
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#8
Posted to rec.audio.tubes
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The making of a triode
Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Very entertaining. Thanks for the link. It got me thinking about the characteristics of DHTs too. Has anyone got any example(s) of their transfer characteristics ? Graham |
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#9
Posted to rec.audio.tubes
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The making of a triode
In article ,
Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Does anyone have any details on the design and specs. of the "preamp"? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
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#11
Posted to rec.audio.tubes
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The making of a triode
Andre Jute wrote: I knew Guido and Manfred back in the days of the Joenet, two very helpful guys. What would actually be surprising is if they knew you. Peter Wieck Wyncote, PA |
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#12
Posted to rec.audio.tubes
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The making of a triode
Peter Wieck wrote: Andre Jute wrote: I knew Guido and Manfred back in the days of the Joenet, two very helpful guys. What would actually be surprising is if they knew you. I was wondering something similar. Graham |
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#13
Posted to rec.audio.tubes
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The making of a triode
Hi John,
No real details, but you can find pictures of it at http://www.timebanditaudio.com/ETF2006/etf2006.html It was a breadboard construction and I think you can see most of the components. Best regards, Raymond John Byrns wrote: In article , Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Does anyone have any details on the design and specs. of the "preamp"? Regards, John Byrns |
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#14
Posted to rec.audio.tubes
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The making of a triode
Hi Raymond,
Hmm, looks like there may be a bit of cheating going on there, I see a factory built tube that looks like it is probably doing the heavy lifting. Thanks for the link. Regards, John Byrns In article , Raymond Koonce wrote: Hi John, No real details, but you can find pictures of it at http://www.timebanditaudio.com/ETF2006/etf2006.html It was a breadboard construction and I think you can see most of the components. Best regards, Raymond John Byrns wrote: In article , Raymond Koonce wrote: Hi Joes, For an interesting video, about 8 minutes, see http://www.youtube.com/watch?v=8_eLO0exato where you can see Guido Tent of the Netherlands build a triode in honor of the centennial of Lee DeForest's patent. This was presented at the European Triode Festival held in Biezenmortel, Netherlands the first weekend in December. We actually got to hear music using two of these hand-made tubes in a preamp built by Manfred Huber of Germany. Guido and Emile Sprenger were this year's organizers and they did a bang-up job. Thanks guys! Does anyone have any details on the design and specs. of the "preamp"? Regards, John Byrns -- Surf my web pages at, http://fmamradios.com/ |
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#15
Posted to rec.audio.tubes
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The making of a triode
"Patrick Turner" wrote in message ... : : Trying to make a useful triode with a decent cathode coating and : gettering and to equal a 6J5 takes slightly more effort : than the Guido Tent deployed. : : Home brew tubes are doable, it just takes a lot of knowledge, : determination, time, and basically many things must be done : 'just right', or else you have a useless outcome. : Triodes are easier than pentodes. : : Making triple triodes in the one envelope would be neat because : the whole input triode and LTP pair is in one envelope, but : a twelve pin base is needed.....Compactrons were made because of : space savings and manufacturing cost reductions. : : Patrick Turner. ...it's a shame no chinese corp has come up (yet) with ceramic compactron sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) R. eg 8BU11 for guitar amps, the 6HV5-A for high B+ hifi amps |
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#16
Posted to rec.audio.tubes
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The making of a triode
"Ruud Broens" wrote in message ... : : "Patrick Turner" wrote in message : ... : : Making triple triodes in the one envelope would be neat because : : the whole input triode and LTP pair is in one envelope, but : : a twelve pin base is needed.....Compactrons were made because of : : space savings and manufacturing cost reductions. : : : : Patrick Turner. : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : R. : : eg 8BU11 for guitar amps, : the 6HV5-A for high B+ hifi amps ok, hands up anyone who checked up on the 6HV5-A ? ;-) actually, with prices from 2 to 8 USD i've seen, 35W Pa, could be a good candidate from using the new Hammond 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, 199 euro's, not *that* cheap, 3 6HV5-A's, running at 1100V, 30 mA, in parallel, would make some pristine 25W SE, with ample opportunity for nfb, as the voltage gain of the powertubes is larger than the voltage reduction by the ot :-) Rudy |
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#17
Posted to rec.audio.tubes
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The making of a triode
"Ruud Broens" wrote in message ... : : : the 6HV5-A for high B+ hifi amps : : ok, hands up anyone who checked up on the 6HV5-A ? ;-) : actually, with prices from 2 to 8 USD i've seen, 35W Pa, : could be a good candidate from using the new Hammond : 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, : 199 euro's, not *that* cheap, : : 3 6HV5-A's, running at 1100V, 30 mA, in parallel, : would make some pristine 25W SE, : with ample opportunity for nfb, as the : voltage gain of the powertubes is larger : than the voltage reduction by the ot :-) : : Rudy : whatever you're listening to, using SS, hybrid or tubes, SE, PP, ppp, fff, heh merry Xmas R. |
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#18
Posted to rec.audio.tubes
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What are you listening to on Christmas Day
whatever you're listening to, using SS, hybrid or tubes, SE, PP, ppp, fff, heh merry Xmas R. Merry Christmas to you too, Rudy, and to all the tubies on RAT. I've sat up all night listening to my new electrostatic earphones. Quad 67 player into Stax SR-252 amp into SR-202 earspeakers. The Best of Peggy Lee, previously The Bonzo Dog Band, before that Schutz's Weinachtshistorie, Bach Cantata (several boxes of the Ton Koopman complete set, including No 199, My Heart Swims in Blood to set the mood), some really rude Jacques Brel, a whole boxful of the cellist Jacqueline DuPre. My family are wondering if I'll get enough sleep before our Christmas dinner tonights so I'd better put my new toy aside. Happy days to all vacuumlanders, however near heaven you might be. Andre Jute Visit Jute on Amps at http://members.lycos.co.uk/fiultra/ "wonderfully well written and reasoned information for the tube audio constructor" John Broskie TubeCAD & GlassWare "an unbelievably comprehensive web site containing vital gems of wisdom" Stuart Perry Hi-Fi News & Record Review |
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#19
Posted to rec.audio.tubes
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The making of a triode
Ruud Broens wrote: "Ruud Broens" wrote in message ... : : "Patrick Turner" wrote in message : ... : : Making triple triodes in the one envelope would be neat because : : the whole input triode and LTP pair is in one envelope, but : : a twelve pin base is needed.....Compactrons were made because of : : space savings and manufacturing cost reductions. : : : : Patrick Turner. : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : R. : : eg 8BU11 for guitar amps, : the 6HV5-A for high B+ hifi amps ok, hands up anyone who checked up on the 6HV5-A ? ;-) actually, with prices from 2 to 8 USD i've seen, 35W Pa, could be a good candidate from using the new Hammond 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, 199 euro's, not *that* cheap, 3 6HV5-A's, running at 1100V, 30 mA, in parallel, would make some pristine 25W SE, with ample opportunity for nfb, as the voltage gain of the powertubes is larger than the voltage reduction by the ot :-) Rudy OK, TDSL tube data says:- 6HV5A.. TriodePlate Voltage ................................. 5500 VPlate Dissipation ............................. 35 W Plate Current ................................. 325 mA Grid No. 1 Circuit Resistance Fixed Bias ................................... 240 O Characteristics and Typical Operation Class A AmplifierPlate Voltage ................................. 3500 V Grid No. 1 Voltage ............................ -4.4 V Amplification Factor .......................... 300 Plate Resistance (approx) ..................... 4.6K O Transconductance .............................. 65K µ Plate Current (Maximum Signal) ................ 300 mA Grid No. 1 Voltage for Ib ..................... 1000 µa @ -13.0 V So Pda is a useful 35W, but exactly what would be the ideal class A conditions for SE use is anyone's guess because I guess the the anode voltages mentioned above are maximums. I assume the µ of 300, Ra of 4.6k, and Gm of 6.5mA/V is in pentode mode, and I bet the linearity could be horrible. Best way to find out is to run a lot of tests with variable anode B+ voltage, screen voltage, idle current and grid voltage and after maybe 30 combinations of the above variables one might find the best class A SE operating point in tetrode. Triode connection could be awful of fabulous; tubes meant for strange purposes in TV sets have a habit of being fairly useless for linear audio circuits; the 6DQ6 is a classic case IMHO, and it hates being strapped as a triode. However, the 6CM5 or the identical rated non topcap 6FW5 when connected in triode are just as good as a 2A3.... and two make a very nice 25 watts AB1. They can happily dissipate 18 watts each all day, Ra is 600 ohms in triode... Ab2 is fine, even in triode.... Patrick Turner. |
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#20
Posted to rec.audio.tubes
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The making of a triode
"Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : "Ruud Broens" wrote in message : ... : : : : "Patrick Turner" wrote in message : : ... : : : : Making triple triodes in the one envelope would be neat because : : : the whole input triode and LTP pair is in one envelope, but : : : a twelve pin base is needed.....Compactrons were made because of : : : space savings and manufacturing cost reductions. : : : : : : Patrick Turner. : : : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : : R. : : : : eg 8BU11 for guitar amps, : : the 6HV5-A for high B+ hifi amps : : ok, hands up anyone who checked up on the 6HV5-A ? ;-) : actually, with prices from 2 to 8 USD i've seen, 35W Pa, : could be a good candidate from using the new Hammond : 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, : 199 euro's, not *that* cheap, : : 3 6HV5-A's, running at 1100V, 30 mA, in parallel, : would make some pristine 25W SE, : with ample opportunity for nfb, as the : voltage gain of the powertubes is larger : than the voltage reduction by the ot :-) : : Rudy : : OK, TDSL tube data says:- : : 6HV5A.. : : TriodePlate Voltage ................................. 5500 : VPlate Dissipation ............................. 35 W : Plate Current ................................. 325 mA : Grid No. 1 Circuit Resistance Fixed Bias : .................................. 240 O : Characteristics and Typical Operation : Class A AmplifierPlate Voltage ................................. 3500 V : Grid No. 1 Voltage ............................ -4.4 V : Amplification Factor .......................... 300 : Plate Resistance (approx) ..................... 4.6K O : Transconductance .............................. 65K µ : Plate Current (Maximum Signal) ................ 300 mA : Grid No. 1 Voltage for Ib ..................... 1000 µa @ -13.0 V : : : So Pda is a useful 35W, but exactly what would be the ideal class A : conditions for : SE use is anyone's guess because I guess the the anode voltages : mentioned above are maximums. : : I assume the µ of 300, Ra of 4.6k, and Gm of 6.5mA/V is in pentode mode, : and I bet the linearity could be horrible. : : Best way to find out is to run a lot of tests with variable anode B+ : voltage, : screen voltage, idle current and grid voltage and after : maybe 30 combinations of the above variables one might find the best : class A SE operating point in tetrode. The GE datasheet is available, interesting enough, they call it a Beam Triode :-) so the pin 3/10 'beam forming plate' connections are typically connected to the cathode. the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K seems optimal, so the only practical way to use it is with some in parallel, to get both voltage and current swing of usable magnitude. Allowing it to run slightly above rated max Pa (it is rather cheap, after all  1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* 180 mApp or 9App, in other words, still able to deliver 30W from that tap into a 1.5 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm secondary tap, used for cathode fb, would give some 13 dB nfb, for distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. without fb, you could drive it straight from a cd players' output, some 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single input/driver tube will be more than enough to drive it with any line level signal. : Triode connection could be awful of fabulous; tubes meant for strange : purposes : in TV sets have a habit of being fairly useless for linear audio : circuits; the 6DQ6 is a classic case IMHO, : and it hates being strapped as a triode. : However, the 6CM5 or the identical rated non topcap 6FW5 : when connected in triode are : just as good as a 2A3.... and two make a very nice 25 watts AB1. : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : triode... : Ab2 is fine, even in triode.... : : Patrick Turner. sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) Rudy |
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#21
Posted to rec.audio.tubes
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The making of a triode
In article ,
"Ruud Broens" wrote: The GE datasheet is available, interesting enough, they call it a Beam Triode :-) so the pin 3/10 'beam forming plate' connections are typically connected to the cathode. the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K seems optimal, so the only practical way to use it is with some in parallel, to get both voltage and current swing of usable magnitude. Allowing it to run slightly above rated max Pa (it is rather cheap, after all 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* 180 mApp or 9App, in other words, still able to deliver 30W from that tap into a 1.5 Ohm load. How did you come up with 30m Watts for 9App into a 1.5 Ohm load? I get only 15 Watts. 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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The making of a triode
Ruud Broens wrote: "Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : "Ruud Broens" wrote in message : ... : : : : "Patrick Turner" wrote in message : : ... : : : : Making triple triodes in the one envelope would be neat because : : : the whole input triode and LTP pair is in one envelope, but : : : a twelve pin base is needed.....Compactrons were made because of : : : space savings and manufacturing cost reductions. : : : : : : Patrick Turner. : : : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : : R. : : : : eg 8BU11 for guitar amps, : : the 6HV5-A for high B+ hifi amps : : ok, hands up anyone who checked up on the 6HV5-A ? ;-) : actually, with prices from 2 to 8 USD i've seen, 35W Pa, : could be a good candidate from using the new Hammond : 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, : 199 euro's, not *that* cheap, : : 3 6HV5-A's, running at 1100V, 30 mA, in parallel, : would make some pristine 25W SE, : with ample opportunity for nfb, as the : voltage gain of the powertubes is larger : than the voltage reduction by the ot :-) : : Rudy : : OK, TDSL tube data says:- : : 6HV5A.. : : TriodePlate Voltage ................................. 5500 : VPlate Dissipation ............................. 35 W : Plate Current ................................. 325 mA : Grid No. 1 Circuit Resistance Fixed Bias : .................................. 240 O : Characteristics and Typical Operation : Class A AmplifierPlate Voltage ................................. 3500 V : Grid No. 1 Voltage ............................ -4.4 V : Amplification Factor .......................... 300 : Plate Resistance (approx) ..................... 4.6K O : Transconductance .............................. 65K µ : Plate Current (Maximum Signal) ................ 300 mA : Grid No. 1 Voltage for Ib ..................... 1000 µa @ -13.0 V : : : So Pda is a useful 35W, but exactly what would be the ideal class A : conditions for : SE use is anyone's guess because I guess the the anode voltages : mentioned above are maximums. : : I assume the µ of 300, Ra of 4.6k, and Gm of 6.5mA/V is in pentode mode, : and I bet the linearity could be horrible. : : Best way to find out is to run a lot of tests with variable anode B+ : voltage, : screen voltage, idle current and grid voltage and after : maybe 30 combinations of the above variables one might find the best : class A SE operating point in tetrode. The GE datasheet is available, interesting enough, they call it a Beam Triode :-) so the pin 3/10 'beam forming plate' connections are typically connected to the cathode. the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K seems optimal, so the only practical way to use it is with some in parallel, to get both voltage and current swing of usable magnitude. I don't follow you here. Its either got a screen or it ain't, and if it has, plus beam former plates then its a beam tetrode, period. For most beam/pentode tubes, RL = 0.9 x Ea / Ia, whatever that may be, and ya gottra consider Ra, ie, anode dynamic resistance to be much higher than RL... Allowing it to run slightly above rated max Pa (it is rather cheap, after all 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* 180 mApp or 9App, in other words, still able to deliver 30W from that tap into a 1.5 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm secondary tap, used for cathode fb, would give some 13 dB nfb, for distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. without fb, you could drive it straight from a cd players' output, some 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single input/driver tube will be more than enough to drive it with any line level signal. Phew. Let's see now, I'll do it my way and compare results with yours, 1,250V div by 0.03A = about 41,666 ohms, so mult x 0.9 = 37,500 ohms for RL. From the data, Ra = 4.6k, but that's way below RL, so something seems wrong. But we do have RA lower than RL, so its a bonus perhaps. So with 3 tubes paralleled, you'd have RL = about 12.5k. With peak anode Vswing of say +/- 0.8 x Ea, you get 707Vrms which is 40 watts into 12.5k. So if secondary RL = 6 ohms, VRL = 15.5Vrms. Vgk = say 3.5Vrms, and with all of the secondary voltage fed back the Vg in = 19Vrms, and you'd have 14.7dB of NFB. So you'd need a 6SN7 input driver or something set up in µ follower to give a gain of about 18 so Vin = about 1.1Vrms. Would it work out?????? I have not the fientest idea, and you can always try it out on a bread board to find out, but I suspect THD without any NFB will be 15% at 40 watts and maybe Rout will be dissapointingly high, but with NFB the situation will be better but still THD at 40 watts probably will be 1 to 2 %, and at 0.4 watts its 0.1% at least, or about 4 times what i like THD to be at low levels. : Triode connection could be awful of fabulous; tubes meant for strange : purposes : in TV sets have a habit of being fairly useless for linear audio : circuits; the 6DQ6 is a classic case IMHO, : and it hates being strapped as a triode. : However, the 6CM5 or the identical rated non topcap 6FW5 : when connected in triode are : just as good as a 2A3.... and two make a very nice 25 watts AB1. : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : triode... : Ab2 is fine, even in triode.... : : Patrick Turner. sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) Rudy The 6FW5 looks much nicer than the 6CM5 and has no top cap but has the same characteristics I found. Its a little known secret, and in fact the 6FW5 seems like a really fab replacement for KT66 in Quad II amps, where probably they coulkd be coaxed to run in CFB tetrode mode as the original circuit has them or else in triode mode with slight revision of the drive amp to get the increased drive, my website has details for the use of KT88 with all twin triode driver and fixed bias for those interested. 6FW5 and 6CM5 in triode both need about -50V applied Egk for bias even with Ea&Eg2 at only +350V. But the much lower Ra of these tubes compared to KT66 in triode means the FW5/CM5 anode voltage swing is larger without hitting grid current, and hence there is more power, and 20 watts is easy with triode connection. But 6DQ6 and 6CD6 are not nearly so good in triode as we would like them to be. Patrick Turner. |
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#23
Posted to rec.audio.tubes
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The making of a triode
"John Byrns" wrote in message ... : In article , : "Ruud Broens" wrote: : : The GE datasheet is available, interesting enough, they call it a Beam Triode : :-) : so the pin 3/10 'beam forming plate' connections are typically connected to : the : cathode. : the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K : seems optimal, so the only practical way to use it is with some in parallel, : to get both voltage and current swing of usable magnitude. : Allowing it to run slightly above rated max Pa (it is rather cheap, after : all : 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about : 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* : 180 mApp or 9App, in other words, still able to deliver 30W from that tap : into a 1.5 Ohm load. : : How did you come up with 30m Watts for 9App into a 1.5 Ohm load? I get : only 15 Watts. : : : Regards, : : John Byrns : : -- : Surf my web pages at, http://fmamradios.com/ you are right, make that into 3 Ohm - lost a factor 2 ;-) thanks, R. |
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#24
Posted to rec.audio.tubes
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The making of a triode
"Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : "Patrick Turner" wrote in message : ... : : : : : : Ruud Broens wrote: : : : : "Ruud Broens" wrote in message : : ... : : : : : : "Patrick Turner" wrote in message : : : ... : : : : : : Making triple triodes in the one envelope would be neat because : : : : the whole input triode and LTP pair is in one envelope, but : : : : a twelve pin base is needed.....Compactrons were made because of : : : : space savings and manufacturing cost reductions. : : : : : : : : Patrick Turner. : : : : : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : : : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : : : R. : : : : : : eg 8BU11 for guitar amps, : : : the 6HV5-A for high B+ hifi amps : : : : ok, hands up anyone who checked up on the 6HV5-A ? ;-) : : actually, with prices from 2 to 8 USD i've seen, 35W Pa, : : could be a good candidate from using the new Hammond : : 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, : : 199 euro's, not *that* cheap, : : : : 3 6HV5-A's, running at 1100V, 30 mA, in parallel, : : would make some pristine 25W SE, : : with ample opportunity for nfb, as the : : voltage gain of the powertubes is larger : : than the voltage reduction by the ot :-) : : : : Rudy : : : : OK, TDSL tube data says:- : : : : 6HV5A.. : : : : TriodePlate Voltage ................................. 5500 : : VPlate Dissipation ............................. 35 W : : Plate Current ................................. 325 mA : : Grid No. 1 Circuit Resistance Fixed Bias : : .................................. 240 O : : Characteristics and Typical Operation : : Class A AmplifierPlate Voltage ................................. 3500 V : : Grid No. 1 Voltage ............................ -4.4 V : : Amplification Factor .......................... 300 : : Plate Resistance (approx) ..................... 4.6K O : : Transconductance .............................. 65K µ : : Plate Current (Maximum Signal) ................ 300 mA : : Grid No. 1 Voltage for Ib ..................... 1000 µa @ -13.0 V : : : : : : So Pda is a useful 35W, but exactly what would be the ideal class A : : conditions for : : SE use is anyone's guess because I guess the the anode voltages : : mentioned above are maximums. : : : : I assume the µ of 300, Ra of 4.6k, and Gm of 6.5mA/V is in pentode mode, : : and I bet the linearity could be horrible. : : : : Best way to find out is to run a lot of tests with variable anode B+ : : voltage, : : screen voltage, idle current and grid voltage and after : : maybe 30 combinations of the above variables one might find the best : : class A SE operating point in tetrode. : : The GE datasheet is available, interesting enough, they call it a Beam Triode :-) : so the pin 3/10 'beam forming plate' connections are typically connected to the : cathode. : the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K : seems optimal, so the only practical way to use it is with some in parallel, : to get both voltage and current swing of usable magnitude. : : I don't follow you here. : : Its either got a screen or it ain't, and if it has, plus beam former : plates : then its a beam tetrode, period. heh, ok, it only has G1 and the beam forming plate connection, so it's a triode resembling a trioded beam power tube alright ;-) i've e-mailed the datasheet to you. : : For most beam/pentode tubes, RL = 0.9 x Ea / Ia, whatever that may be, : and ya gottra consider : Ra, ie, anode dynamic resistance to be much higher than RL... : : Allowing it to run slightly above rated max Pa (it is rather cheap, after all : 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about : 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* : 180 mApp or 9App, in other words, still able to deliver 30W from that tap : into a 1.5 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm : secondary tap, used for cathode fb, would give some 13 dB nfb, for : distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. : without fb, you could drive it straight from a cd players' output, some : 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single : input/driver tube will be more than enough to drive it with any line level : signal. : : Phew. Let's see now, I'll do it my way and compare results with yours, : 1,250V div by 0.03A = about 41,666 ohms, so mult x 0.9 = 37,500 ohms for : RL. : From the data, Ra = 4.6k, but that's way below RL, so something seems : wrong. : But we do have RA lower than RL, so its a bonus perhaps. : So with 3 tubes paralleled, you'd have RL = about 12.5k. : : With peak anode Vswing of say +/- 0.8 x Ea, you get 707Vrms which is 40 : watts into 12.5k. : So if secondary RL = 6 ohms, VRL = 15.5Vrms. : Vgk = say 3.5Vrms, and with all of the secondary voltage fed back the Vg : in = 19Vrms, : and you'd have 14.7dB of NFB. : : So you'd need a 6SN7 input driver or something set up in : µ follower to give a gain of about 18 so Vin = about 1.1Vrms. : : Would it work out?????? : I have not the fientest idea, and you can always try it out on a bread : board to find out, : but I suspect THD without any NFB will be 15% at 40 watts and maybe Rout : will be dissapointingly high, but with NFB the situation : will be better but still THD at 40 watts probably will be 1 to 2 %, : and at 0.4 watts its 0.1% at least, or about 4 times what i like THD to : be : at low levels. well, my estimate is from the published GE curves, which require some curve guestimation at the currents used for an SE audio application, but it is much better than you'd think, thus it has a rather fine price/q. quotient ;-) : : : : : Triode connection could be awful of fabulous; tubes meant for strange : : purposes : : in TV sets have a habit of being fairly useless for linear audio : : circuits; the 6DQ6 is a classic case IMHO, : : and it hates being strapped as a triode. : : However, the 6CM5 or the identical rated non topcap 6FW5 : : when connected in triode are : : just as good as a 2A3.... and two make a very nice 25 watts AB1. : : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : : triode... : : Ab2 is fine, even in triode.... : : : : Patrick Turner. : : sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) : Rudy : : The 6FW5 looks much nicer than the 6CM5 and has no top cap but has the : same characteristics I found. : Its a little known secret, and in fact the 6FW5 seems like a really fab : replacement : for KT66 in Quad II amps, where probably they coulkd be coaxed to run in : CFB tetrode mode : as the original circuit has them or else in triode mode with : slight revision of the drive amp to get the increased drive, my website : has details for the use of KT88 with all twin triode driver and fixed : bias for those interested. : 6FW5 and 6CM5 in triode both need about -50V applied Egk for bias : even with Ea&Eg2 at only +350V. : But the much lower Ra of these tubes compared to KT66 in triode means : the : FW5/CM5 anode voltage swing is larger without hitting grid current, and : hence there : is more power, and 20 watts is easy with triode connection. : : But 6DQ6 and 6CD6 are not nearly so good in triode as we would like them : to be. : : Patrick Turner. comparing powertubes of ~same Pa, you'll note that when a high heating power is used, the 0V gridline will be pretty close to the 0 V or y-axis, whilst lower heater power tubes only have appreciable currents available at much higher voltages along the 0 V gridline: there's no free lunch in nature, better (trioded) plate efficiency comes from larger amount of heater Watts per plate dissipation W :-). two extremes: 6EM7/6EW7, triode 2 Pa=10W, heating . using the 'where does it reach 70 mA on the 0V gridline' criterium, that is at 50V , so large downward voltage swing possible 12A6, trioded, Pa+g2=9W, heating 70mA now at about 215V, not terribly efficient (unless grid drive current is used Rudy |
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#25
Posted to rec.audio.tubes
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The making of a triode
Ruud Broens wrote: "Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : "Patrick Turner" wrote in message : ... : : : : : : Ruud Broens wrote: : : : : "Ruud Broens" wrote in message : : ... : : : : : : "Patrick Turner" wrote in message : : : ... : : : : : : Making triple triodes in the one envelope would be neat because : : : : the whole input triode and LTP pair is in one envelope, but : : : : a twelve pin base is needed.....Compactrons were made because of : : : : space savings and manufacturing cost reductions. : : : : : : : : Patrick Turner. : : : : : : ..it's a shame no chinese corp has come up (yet) with ceramic compactron : : : sockets for 2 USD or so, some interesting NOS tubes bein'round ;-) : : : R. : : : : : : eg 8BU11 for guitar amps, : : : the 6HV5-A for high B+ hifi amps : : : : ok, hands up anyone who checked up on the 6HV5-A ? ;-) : : actually, with prices from 2 to 8 USD i've seen, 35W Pa, : : could be a good candidate from using the new Hammond : : 1638SEA ot. 10K::4/8/16, 30W, 90mA DC max, 2kVrms tested, : : 199 euro's, not *that* cheap, : : : : 3 6HV5-A's, running at 1100V, 30 mA, in parallel, : : would make some pristine 25W SE, : : with ample opportunity for nfb, as the : : voltage gain of the powertubes is larger : : than the voltage reduction by the ot :-) : : : : Rudy : : : : OK, TDSL tube data says:- : : : : 6HV5A.. : : : : TriodePlate Voltage ................................. 5500 : : VPlate Dissipation ............................. 35 W : : Plate Current ................................. 325 mA : : Grid No. 1 Circuit Resistance Fixed Bias : : .................................. 240 O : : Characteristics and Typical Operation : : Class A AmplifierPlate Voltage ................................. 3500 V : : Grid No. 1 Voltage ............................ -4.4 V : : Amplification Factor .......................... 300 : : Plate Resistance (approx) ..................... 4.6K O : : Transconductance .............................. 65K µ : : Plate Current (Maximum Signal) ................ 300 mA : : Grid No. 1 Voltage for Ib ..................... 1000 µa @ -13.0 V : : : : : : So Pda is a useful 35W, but exactly what would be the ideal class A : : conditions for : : SE use is anyone's guess because I guess the the anode voltages : : mentioned above are maximums. : : : : I assume the µ of 300, Ra of 4.6k, and Gm of 6.5mA/V is in pentode mode, : : and I bet the linearity could be horrible. : : : : Best way to find out is to run a lot of tests with variable anode B+ : : voltage, : : screen voltage, idle current and grid voltage and after : : maybe 30 combinations of the above variables one might find the best : : class A SE operating point in tetrode. : : The GE datasheet is available, interesting enough, they call it a Beam Triode :-) : so the pin 3/10 'beam forming plate' connections are typically connected to the : cathode. : the Rp is about 400V/50mA or 8 K at low currents, a load of about 40K : seems optimal, so the only practical way to use it is with some in parallel, : to get both voltage and current swing of usable magnitude. : : I don't follow you here. : : Its either got a screen or it ain't, and if it has, plus beam former : plates : then its a beam tetrode, period. heh, ok, it only has G1 and the beam forming plate connection, so it's a triode resembling a trioded beam power tube alright ;-) i've e-mailed the datasheet to you. : : For most beam/pentode tubes, RL = 0.9 x Ea / Ia, whatever that may be, : and ya gottra consider : Ra, ie, anode dynamic resistance to be much higher than RL... : : Allowing it to run slightly above rated max Pa (it is rather cheap, after all : 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about : 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* : 180 mApp or 9App, in other words, still able to deliver 30W from that tap : into a 1.5 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm : secondary tap, used for cathode fb, would give some 13 dB nfb, for : distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. : without fb, you could drive it straight from a cd players' output, some : 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single : input/driver tube will be more than enough to drive it with any line level : signal. : : Phew. Let's see now, I'll do it my way and compare results with yours, : 1,250V div by 0.03A = about 41,666 ohms, so mult x 0.9 = 37,500 ohms for : RL. : From the data, Ra = 4.6k, but that's way below RL, so something seems : wrong. : But we do have RA lower than RL, so its a bonus perhaps. : So with 3 tubes paralleled, you'd have RL = about 12.5k. : : With peak anode Vswing of say +/- 0.8 x Ea, you get 707Vrms which is 40 : watts into 12.5k. : So if secondary RL = 6 ohms, VRL = 15.5Vrms. : Vgk = say 3.5Vrms, and with all of the secondary voltage fed back the Vg : in = 19Vrms, : and you'd have 14.7dB of NFB. : : So you'd need a 6SN7 input driver or something set up in : µ follower to give a gain of about 18 so Vin = about 1.1Vrms. : : Would it work out?????? : I have not the fientest idea, and you can always try it out on a bread : board to find out, : but I suspect THD without any NFB will be 15% at 40 watts and maybe Rout : will be dissapointingly high, but with NFB the situation : will be better but still THD at 40 watts probably will be 1 to 2 %, : and at 0.4 watts its 0.1% at least, or about 4 times what i like THD to : be : at low levels. well, my estimate is from the published GE curves, which require some curve guestimation at the currents used for an SE audio application, but it is much better than you'd think, thus it has a rather fine price/q. quotient ;-) : : : : : Triode connection could be awful of fabulous; tubes meant for strange : : purposes : : in TV sets have a habit of being fairly useless for linear audio : : circuits; the 6DQ6 is a classic case IMHO, : : and it hates being strapped as a triode. : : However, the 6CM5 or the identical rated non topcap 6FW5 : : when connected in triode are : : just as good as a 2A3.... and two make a very nice 25 watts AB1. : : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : : triode... : : Ab2 is fine, even in triode.... : : : : Patrick Turner. : : sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) : Rudy : : The 6FW5 looks much nicer than the 6CM5 and has no top cap but has the : same characteristics I found. : Its a little known secret, and in fact the 6FW5 seems like a really fab : replacement : for KT66 in Quad II amps, where probably they coulkd be coaxed to run in : CFB tetrode mode : as the original circuit has them or else in triode mode with : slight revision of the drive amp to get the increased drive, my website : has details for the use of KT88 with all twin triode driver and fixed : bias for those interested. : 6FW5 and 6CM5 in triode both need about -50V applied Egk for bias : even with Ea&Eg2 at only +350V. : But the much lower Ra of these tubes compared to KT66 in triode means : the : FW5/CM5 anode voltage swing is larger without hitting grid current, and : hence there : is more power, and 20 watts is easy with triode connection. : : But 6DQ6 and 6CD6 are not nearly so good in triode as we would like them : to be. : : Patrick Turner. comparing powertubes of ~same Pa, you'll note that when a high heating power is used, the 0V gridline will be pretty close to the 0 V or y-axis, whilst lower heater power tubes only have appreciable currents available at much higher voltages along the 0 V gridline: there's no free lunch in nature, better (trioded) plate efficiency comes from larger amount of heater Watts per plate dissipation W :-). two extremes: 6EM7/6EW7, triode 2 Pa=10W, heating . using the 'where does it reach 70 mA on the 0V gridline' criterium, that is at 50V , so large downward voltage swing possible 12A6, trioded, Pa+g2=9W, heating 70mA now at about 215V, not terribly efficient (unless grid drive current is used Rudy Thanks for sending me the curves for that GE 6HV5A It IS a queer sort of triode with huge gain potential. My worry would be that with only -2V on the g1 needed to bias the tube at 1,250V x 30mA ( roughly ), bias drift could be a bother unless you had a large Rk taken down to a -ve supply and then bypass the k to 0V. so you have best dc regulation by the Rk. The downward Ea swing of triodes mainly depemds on a low Ra, and the more vertical the Ra data curves are the easier is is to get a good -ve going swing without grid current. Maybe your'e right about the heater power as well, but tubes like 6CM5 etc were not big heater power users, and the peak cathode current is 500mA. But never mind, using a cathode follower drive to the grid you can drive the grid positive probably with this tube and thus get the efficiency up to near tetrode performance. ( few folks realise that instead of getting only 12 watts from a pair of KT66/6L6 in triode in AB1, with AB2 up to around 30 watts is doable with the same Ea...) The need for such a high Ea is reduced by operating with grid current; its done with 211.... And BTW, I mistakenly thought the gm was 6.5mA/V but its not, its a massive 65mA/V, a function of the frame grid probably, since such grids can be closer to the cathode and with finer wire more closely spaced than normal helical wound grids. ( I wonder what the latest 2006 triode gm would have become if SS hadn't been developed ). Anyway, give the tubes a try in SE mode, and see how it goes. If you didn't wanna use CFB, there is always simple resistance shunt NFB. But I bet you will need lotsa NFB. And consider choke feeding the anode with the 1,250V and cap coupling the OPT. It means the DCV is across the coupling cap and the OPT primary can be at 0V potential, which may be a trifle safer to experiment with especially if the shunt FB option is tried. |
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#26
Posted to rec.audio.tubes
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The making of a triode
"Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : : : : Ruud Broens wrote: : : : : "Patrick Turner" wrote in message : : ... : : : : : heh, ok, it only has G1 and the beam forming plate connection, so it's : a triode resembling a trioded beam power tube alright ;-) : i've e-mailed the datasheet to you. : : : : For most beam/pentode tubes, RL = 0.9 x Ea / Ia, whatever that may be, : : and ya gottra consider : : Ra, ie, anode dynamic resistance to be much higher than RL... : : : : Allowing it to run slightly above rated max Pa (it is rather cheap, after : all : : 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about : : 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* : : 180 mApp or 9App, in other words, still able to deliver 30W from that tap : : into a 3 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm : : secondary tap, used for cathode fb, would give some 13 dB nfb, for : : distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. : : without fb, you could drive it straight from a cd players' output, some : : 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single : : input/driver tube will be more than enough to drive it with any line level : : signal. : : : : Phew. Let's see now, I'll do it my way and compare results with yours, : : 1,250V div by 0.03A = about 41,666 ohms, so mult x 0.9 = 37,500 ohms for : : RL. : : From the data, Ra = 4.6k, but that's way below RL, so something seems : : wrong. : : But we do have RA lower than RL, so its a bonus perhaps. : : So with 3 tubes paralleled, you'd have RL = about 12.5k. : : : : With peak anode Vswing of say +/- 0.8 x Ea, you get 707Vrms which is 40 : : watts into 12.5k. : : So if secondary RL = 6 ohms, VRL = 15.5Vrms. : : Vgk = say 3.5Vrms, and with all of the secondary voltage fed back the Vg : : in = 19Vrms, : : and you'd have 14.7dB of NFB. : : : : So you'd need a 6SN7 input driver or something set up in : : µ follower to give a gain of about 18 so Vin = about 1.1Vrms. : : : : Would it work out?????? : : I have not the fientest idea, and you can always try it out on a bread : : board to find out, : : but I suspect THD without any NFB will be 15% at 40 watts and maybe Rout : : will be dissapointingly high, but with NFB the situation : : will be better but still THD at 40 watts probably will be 1 to 2 %, : : and at 0.4 watts its 0.1% at least, or about 4 times what i like THD to : : be : : at low levels. : : well, my estimate is from the published GE curves, which require some : curve guestimation at the currents used for an SE audio application, : but it is much better than you'd think, thus it has a rather fine price/q. : quotient ;-) : : : : : : : : : Triode connection could be awful of fabulous; tubes meant for strange : : : purposes : : : in TV sets have a habit of being fairly useless for linear audio : : : circuits; the 6DQ6 is a classic case IMHO, : : : and it hates being strapped as a triode. : : : However, the 6CM5 or the identical rated non topcap 6FW5 : : : when connected in triode are : : : just as good as a 2A3.... and two make a very nice 25 watts AB1. : : : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : : : triode... : : : Ab2 is fine, even in triode.... : : : : : : Patrick Turner. : : : : sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) : : Rudy : : : : The 6FW5 looks much nicer than the 6CM5 and has no top cap but has the : : same characteristics I found. : : Its a little known secret, and in fact the 6FW5 seems like a really fab : : replacement : : for KT66 in Quad II amps, where probably they coulkd be coaxed to run in : : CFB tetrode mode : : as the original circuit has them or else in triode mode with : : slight revision of the drive amp to get the increased drive, my website : : has details for the use of KT88 with all twin triode driver and fixed : : bias for those interested. : : 6FW5 and 6CM5 in triode both need about -50V applied Egk for bias : : even with Ea&Eg2 at only +350V. : : But the much lower Ra of these tubes compared to KT66 in triode means : : the : : FW5/CM5 anode voltage swing is larger without hitting grid current, and : : hence there : : is more power, and 20 watts is easy with triode connection. : : : : But 6DQ6 and 6CD6 are not nearly so good in triode as we would like them : : to be. : : : : Patrick Turner. : : comparing powertubes of ~same Pa, you'll note that when a high : heating power is used, the 0V gridline will be pretty close to the 0 V : or y-axis, whilst lower heater power tubes only have appreciable : currents available at much higher voltages along the 0 V gridline: : there's no free lunch in nature, better (trioded) plate efficiency comes : from larger amount of heater Watts per plate dissipation W :-). : two extremes: : 6EM7/6EW7, triode 2 Pa=10W, heating . : using the 'where does it reach 70 mA on the 0V gridline' criterium, : that is at 50V , so large downward voltage swing possible : : 12A6, trioded, Pa+g2=9W, heating : 70mA now at about 215V, not terribly efficient (unless grid drive current : is used : : Rudy : : Thanks for sending me the curves for that GE 6HV5A : : It IS a queer sort of triode with huge gain potential. : : My worry would be that with only -2V on the g1 needed to bias the tube : at 1,250V x 30mA ( roughly ), bias drift could be a bother : unless you had a large Rk taken down to a -ve supply and then : bypass the k to 0V. : so you have best dc regulation by the Rk. : : The downward Ea swing of triodes mainly depemds on : a low Ra, and the more vertical the Ra data curves are the easier is is : to get a good -ve going swing without grid current. : Maybe your'e right about the heater power as well, but tubes like 6CM5 : etc were not big heater power users, and the peak cathode current : is 500mA. : But never mind, using a cathode follower drive to the grid you can drive : the grid : positive probably with this tube and thus get the efficiency up : to near tetrode performance. : ( few folks realise that instead of getting only 12 watts from a pair of : KT66/6L6 : in triode in AB1, with AB2 up to around 30 watts is doable with the same : Ea...) : : The need for such a high Ea is reduced by operating with grid current; : its done with 211.... : : And BTW, I mistakenly thought the gm was 6.5mA/V but its not, its : a massive 65mA/V, a function of the frame grid probably, since such : grids : can be closer to the cathode and with finer wire more : closely spaced than normal helical wound grids. : ( I wonder what the latest 2006 triode gm would have become if : SS hadn't been developed ). : : Anyway, give the tubes a try in SE mode, and see how it goes. : If you didn't wanna use CFB, there is always simple resistance shunt : NFB. : : But I bet you will need lotsa NFB. : : And consider choke feeding the anode with the 1,250V and cap coupling : the OPT. : It means the DCV is across the coupling cap and the OPT primary : can be at 0V potential, which may be a trifle safer to experiment with : especially if : the shunt FB option is tried. 1250V plate, around 1300 V B+ , just within practical range, as in you can use 450V caps, triple stacked with a ladder R netw., use 2 power transformers and stack the secondary 500V windings but it is serious juice we're talking, i'd incorporate some bootup diagnostics, heh, on switchon, pull the grids with a 100 Ohm to -12V, use an opamp to measure grid current measure cathode current when heated up, grid still at -12V and only if that is ok, release the G1 to the driver stage. and something to watch over the tubes dynamically and use common sense with layout, wire type, etc. :-) i don't have that tube stocked, as you can see from the filename, i thought of it as a candidate for driving electrostatic panels directly, choke fed B+, also, you need good sockets for such high voltages, i haven't seen them for compactron (must be a lot easier in the US but if someone is going the hi B+ route, with an 845 or so, this 6HV5A may be a good 'first try' using the OT intended for the 845 R. |
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#27
Posted to rec.audio.tubes
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The making of a triode
"Ruud Broens" wrote in message ... : : "Patrick Turner" wrote in message : ... : : : : : : Thanks for sending me the curves for that GE 6HV5A : : : : It IS a queer sort of triode with huge gain potential. : : : : My worry would be that with only -2V on the g1 needed to bias the tube : : at 1,250V x 30mA ( roughly ), bias drift could be a bother : : unless you had a large Rk taken down to a -ve supply and then : : bypass the k to 0V. : : so you have best dc regulation by the Rk. : : : : Anyway, give the tubes a try in SE mode, and see how it goes. : : If you didn't wanna use CFB, there is always simple resistance shunt : : NFB. : : : : But I bet you will need lotsa NFB. : : : : And consider choke feeding the anode with the 1,250V and cap coupling : : the OPT. : : It means the DCV is across the coupling cap and the OPT primary : : can be at 0V potential, which may be a trifle safer to experiment with : : especially if : : the shunt FB option is tried. : : 1250V plate, around 1300 V B+ , just within practical range, : as in you can use 450V caps, triple stacked with a ladder R netw., : use 2 power transformers and stack the secondary 500V windings : but it is serious juice we're talking, : i'd incorporate some bootup diagnostics, heh, : on switchon, pull the grids with a 100 Ohm to -12V, : use an opamp to measure grid current : measure cathode current when heated up, grid still at -12V : and only if that is ok, release the G1 to the driver stage. : and something to watch over the tubes dynamically : and use common sense with layout, wire type, etc. :-) : : i don't have that tube stocked, as you can see from the filename, : i thought of it as a candidate for driving electrostatic panels : directly, choke fed B+, : also, you need good sockets for such high voltages, i haven't : seen them for compactron (must be a lot easier in the US : : but if someone is going the hi B+ route, with an 845 or so, : this 6HV5A may be a good 'first try' using the OT intended for the 845 : : R. Maybe Yves Monmagnon can tell us about the B+ he uses with that 845 amp in progress? Is there a reason something like this could not be done: use a 100 Ohm series R in the 0V line, an SCR switching on when current is above 100 mA for longer than 1 sec., breaking the B+ line with a suitable relais ? Or using a spark plug as a overvoltage protection for the primary winding (/tube & sockets) in case the amp is run without a (proper) load ? let's rename the 6HV5A the 815c hehe Rudy |
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#28
Posted to rec.audio.tubes
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The making of a triode
Ruud Broens wrote: "Patrick Turner" wrote in message ... : : : Ruud Broens wrote: : : : : : Ruud Broens wrote: : : : : "Patrick Turner" wrote in message : : ... : : : : : heh, ok, it only has G1 and the beam forming plate connection, so it's : a triode resembling a trioded beam power tube alright ;-) : i've e-mailed the datasheet to you. : : : : For most beam/pentode tubes, RL = 0.9 x Ea / Ia, whatever that may be, : : and ya gottra consider : : Ra, ie, anode dynamic resistance to be much higher than RL... : : : : Allowing it to run slightly above rated max Pa (it is rather cheap, after : all : : 1250V at 30 mA, with 3 tubes in parallel loaded with 10K gives about : : 30W out, df about 3.5, max current from a 4 Ohm secondary sqr(10K/4)* : : 180 mApp or 9App, in other words, still able to deliver 30W from that tap : : into a 3 Ohm load. With the tubes' voltage gain of about 220, the 4 Ohm : : secondary tap, used for cathode fb, would give some 13 dB nfb, for : : distortion (est.) below 0.1..0.2 %, mainly 2H, for any power up to 30W. : : without fb, you could drive it straight from a cd players' output, some : : 5Vtt required for 30W out, even with fb from a 16 Ohm tap, a single : : input/driver tube will be more than enough to drive it with any line level : : signal. : : : : Phew. Let's see now, I'll do it my way and compare results with yours, : : 1,250V div by 0.03A = about 41,666 ohms, so mult x 0.9 = 37,500 ohms for : : RL. : : From the data, Ra = 4.6k, but that's way below RL, so something seems : : wrong. : : But we do have RA lower than RL, so its a bonus perhaps. : : So with 3 tubes paralleled, you'd have RL = about 12.5k. : : : : With peak anode Vswing of say +/- 0.8 x Ea, you get 707Vrms which is 40 : : watts into 12.5k. : : So if secondary RL = 6 ohms, VRL = 15.5Vrms. : : Vgk = say 3.5Vrms, and with all of the secondary voltage fed back the Vg : : in = 19Vrms, : : and you'd have 14.7dB of NFB. : : : : So you'd need a 6SN7 input driver or something set up in : : µ follower to give a gain of about 18 so Vin = about 1.1Vrms. : : : : Would it work out?????? : : I have not the fientest idea, and you can always try it out on a bread : : board to find out, : : but I suspect THD without any NFB will be 15% at 40 watts and maybe Rout : : will be dissapointingly high, but with NFB the situation : : will be better but still THD at 40 watts probably will be 1 to 2 %, : : and at 0.4 watts its 0.1% at least, or about 4 times what i like THD to : : be : : at low levels. : : well, my estimate is from the published GE curves, which require some : curve guestimation at the currents used for an SE audio application, : but it is much better than you'd think, thus it has a rather fine price/q. : quotient ;-) : : : : : : : : : Triode connection could be awful of fabulous; tubes meant for strange : : : purposes : : : in TV sets have a habit of being fairly useless for linear audio : : : circuits; the 6DQ6 is a classic case IMHO, : : : and it hates being strapped as a triode. : : : However, the 6CM5 or the identical rated non topcap 6FW5 : : : when connected in triode are : : : just as good as a 2A3.... and two make a very nice 25 watts AB1. : : : They can happily dissipate 18 watts each all day, Ra is 600 ohms in : : : triode... : : : Ab2 is fine, even in triode.... : : : : : : Patrick Turner. : : : : sure, fine tubes, topcaps in general as a bonus are quite cheap ;-) : : Rudy : : : : The 6FW5 looks much nicer than the 6CM5 and has no top cap but has the : : same characteristics I found. : : Its a little known secret, and in fact the 6FW5 seems like a really fab : : replacement : : for KT66 in Quad II amps, where probably they coulkd be coaxed to run in : : CFB tetrode mode : : as the original circuit has them or else in triode mode with : : slight revision of the drive amp to get the increased drive, my website : : has details for the use of KT88 with all twin triode driver and fixed : : bias for those interested. : : 6FW5 and 6CM5 in triode both need about -50V applied Egk for bias : : even with Ea&Eg2 at only +350V. : : But the much lower Ra of these tubes compared to KT66 in triode means : : the : : FW5/CM5 anode voltage swing is larger without hitting grid current, and : : hence there : : is more power, and 20 watts is easy with triode connection. : : : : But 6DQ6 and 6CD6 are not nearly so good in triode as we would like them : : to be. : : : : Patrick Turner. : : comparing powertubes of ~same Pa, you'll note that when a high : heating power is used, the 0V gridline will be pretty close to the 0 V : or y-axis, whilst lower heater power tubes only have appreciable : currents available at much higher voltages along the 0 V gridline: : there's no free lunch in nature, better (trioded) plate efficiency comes : from larger amount of heater Watts per plate dissipation W :-). : two extremes: : 6EM7/6EW7, triode 2 Pa=10W, heating . : using the 'where does it reach 70 mA on the 0V gridline' criterium, : that is at 50V , so large downward voltage swing possible : : 12A6, trioded, Pa+g2=9W, heating : 70mA now at about 215V, not terribly efficient (unless grid drive current : is used : : Rudy : : Thanks for sending me the curves for that GE 6HV5A : : It IS a queer sort of triode with huge gain potential. : : My worry would be that with only -2V on the g1 needed to bias the tube : at 1,250V x 30mA ( roughly ), bias drift could be a bother : unless you had a large Rk taken down to a -ve supply and then : bypass the k to 0V. : so you have best dc regulation by the Rk. : : The downward Ea swing of triodes mainly depemds on : a low Ra, and the more vertical the Ra data curves are the easier is is : to get a good -ve going swing without grid current. : Maybe your'e right about the heater power as well, but tubes like 6CM5 : etc were not big heater power users, and the peak cathode current : is 500mA. : But never mind, using a cathode follower drive to the grid you can drive : the grid : positive probably with this tube and thus get the efficiency up : to near tetrode performance. : ( few folks realise that instead of getting only 12 watts from a pair of : KT66/6L6 : in triode in AB1, with AB2 up to around 30 watts is doable with the same : Ea...) : : The need for such a high Ea is reduced by operating with grid current; : its done with 211.... : : And BTW, I mistakenly thought the gm was 6.5mA/V but its not, its : a massive 65mA/V, a function of the frame grid probably, since such : grids : can be closer to the cathode and with finer wire more : closely spaced than normal helical wound grids. : ( I wonder what the latest 2006 triode gm would have become if : SS hadn't been developed ). : : Anyway, give the tubes a try in SE mode, and see how it goes. : If you didn't wanna use CFB, there is always simple resistance shunt : NFB. : : But I bet you will need lotsa NFB. : : And consider choke feeding the anode with the 1,250V and cap coupling : the OPT. : It means the DCV is across the coupling cap and the OPT primary : can be at 0V potential, which may be a trifle safer to experiment with : especially if : the shunt FB option is tried. 1250V plate, around 1300 V B+ , just within practical range, as in you can use 450V caps, triple stacked with a ladder R netw., use 2 power transformers and stack the secondary 500V windings but it is serious juice we're talking, i'd incorporate some bootup diagnostics, heh, on switchon, pull the grids with a 100 Ohm to -12V, use an opamp to measure grid current measure cathode current when heated up, grid still at -12V and only if that is ok, release the G1 to the driver stage. and something to watch over the tubes dynamically and use common sense with layout, wire type, etc. :-) i don't have that tube stocked, as you can see from the filename, i thought of it as a candidate for driving electrostatic panels directly, choke fed B+, also, you need good sockets for such high voltages, i haven't seen them for compactron (must be a lot easier in the US but if someone is going the hi B+ route, with an 845 or so, this 6HV5A may be a good 'first try' using the OT intended for the 845 R. I am building a pair of 845 monos with two 845 each in parallel. The OPT is 6k:6, Ea =1,100V, Ia for both tubes = 120mA. I'd not like to have to use 12 pin compactron tube sockets with 1,250V. The ESL use a 100:1 ratio step up tranny, so that if the input V = 20Vrms, the panel V = 2,000Vrms, which is +/-2,800 peakV, and you'd need maybe Ea = 3,500V to accomodate such a swing using triodes if a direct connection is anticipated. I think I will leave that sort engineering for others to perfect. My 845 design so far has evolved so that the power supply has approx +600V and -600V. These voltages are derived from a pair of voltage doublers and 4 x 470uF x 450V electro caps are involved across the total 1,200V. There will be LC and RC filters, so 12 x 470uF caps are involved. I don't like oiler caps or huge choke values and I do like lots of capacitance so that the final impedance values anchoring down the output tube and its connected OPT will be nice and low and non resonant. The +ve is applied to the anode via the OPT and -ve to the cathode via a pair of CCS to each cathode, and then cap bypassing is used to ground the cathodes to 0V. The grids are at -600V, but are cap coupled to the EL34 choke loaded stage which is the driver to make up to about 140Vrms. The turn on behaviour should be docile because the CCS set ups take time to begin current conduction. Its not the voltage across a to k that causes the blue smoke, but the current that flows, so limit the current and control it, and no blue smoke. I hope to never ever have to repair or replace the OPT due to arcing or insulation breakdown due to having a peak voltage of 2,000V across insulation including the ac peak swing upwards. I am considering potting the OPT in the 2mm thick steel cans I just had made and using oil in them but that means the can would be upside down on the chassis with sealed terminals facing down, and sure as God made little apples, such sealed connections would leak damn oil, and there are a large number of connections to allow more load matches than just one lousy match to 6 ohms. And I don't want to face the cans upright, since that means cable runs from the top to bottom externally. So probably I will settle for wax potting compound in addition to the two pack polyurethane varnishing applied very liberally during the wind up process. Probably this is good enough for 2,000V++...I have yet to test it all. After a few more repair/restoration jobs I will finally be able to devote time to some real craft work for a few months and not perish financially. Patrick Turner. |
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#29
Posted to rec.audio.tubes
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The making of a triode
Ruud Broens wrote: "Ruud Broens" wrote in message ... : : "Patrick Turner" wrote in message : ... : : : : : : Thanks for sending me the curves for that GE 6HV5A : : : : It IS a queer sort of triode with huge gain potential. : : : : My worry would be that with only -2V on the g1 needed to bias the tube : : at 1,250V x 30mA ( roughly ), bias drift could be a bother : : unless you had a large Rk taken down to a -ve supply and then : : bypass the k to 0V. : : so you have best dc regulation by the Rk. : : : : Anyway, give the tubes a try in SE mode, and see how it goes. : : If you didn't wanna use CFB, there is always simple resistance shunt : : NFB. : : : : But I bet you will need lotsa NFB. : : : : And consider choke feeding the anode with the 1,250V and cap coupling : : the OPT. : : It means the DCV is across the coupling cap and the OPT primary : : can be at 0V potential, which may be a trifle safer to experiment with : : especially if : : the shunt FB option is tried. : : 1250V plate, around 1300 V B+ , just within practical range, : as in you can use 450V caps, triple stacked with a ladder R netw., : use 2 power transformers and stack the secondary 500V windings : but it is serious juice we're talking, : i'd incorporate some bootup diagnostics, heh, : on switchon, pull the grids with a 100 Ohm to -12V, : use an opamp to measure grid current : measure cathode current when heated up, grid still at -12V : and only if that is ok, release the G1 to the driver stage. : and something to watch over the tubes dynamically : and use common sense with layout, wire type, etc. :-) : : i don't have that tube stocked, as you can see from the filename, : i thought of it as a candidate for driving electrostatic panels : directly, choke fed B+, : also, you need good sockets for such high voltages, i haven't : seen them for compactron (must be a lot easier in the US : : but if someone is going the hi B+ route, with an 845 or so, : this 6HV5A may be a good 'first try' using the OT intended for the 845 : : R. Maybe Yves Monmagnon can tell us about the B+ he uses with that 845 amp in progress? Is there a reason something like this could not be done: use a 100 Ohm series R in the 0V line, an SCR switching on when current is above 100 mA for longer than 1 sec., breaking the B+ line with a suitable relais ? Or using a spark plug as a overvoltage protection for the primary winding (/tube & sockets) in case the amp is run without a (proper) load ? Just monitoring the cathode current is usually enough protection. One can use low value cathode R and having excessive Ik trigger an SCR that trips a relay that turns off the B+. This works much better than a fuse and is re-setable. But having high voltage +ve excursions with no load are a worry, except that triodes tend not to do it because of their inherent NFB; Ea rises, and the Ia increases, wheras a pentode Ea rises allarmingly without limitation by increasing Ia. And NFB also limits such excursions because its a voltage controlled regulation mechanism. If one allows 0.025mm per 75V for a spark gap, then for +2,000V one needs 0.67 mm, or 26thousanths of an inch . So a spark plug is doable. When the spark occurs, high current flows, perhaps the cathode SCR is trigered and the B+ is turned off, and the owner MUST connect a load to get anywhere. Patrick Turner. |
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#30
Posted to rec.audio.tubes
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The making of a triode amp
"Patrick Turner" wrote in message ... : : : : Ruud Broens wrote: : : : : comparing powertubes of ~same Pa, you'll note that when a high : : heating power is used, the 0V gridline will be pretty close to the 0 V : : or y-axis, whilst lower heater power tubes only have appreciable : : currents available at much higher voltages along the 0 V gridline: : : there's no free lunch in nature, better (trioded) plate efficiency comes : : from larger amount of heater Watts per plate dissipation W :-). : : two extremes: : : 6EM7/6EW7, triode 2 Pa=10W, heating . : : using the 'where does it reach 70 mA on the 0V gridline' criterium, : : that is at 50V , so large downward voltage swing possible : : : : 12A6, trioded, Pa+g2=9W, heating : : 70mA now at about 215V, not terribly efficient (unless grid drive current : : is used : : : : Rudy : : : : Thanks for sending me the curves for that GE 6HV5A : : : : It IS a queer sort of triode with huge gain potential. : : : : My worry would be that with only -2V on the g1 needed to bias the tube : : at 1,250V x 30mA ( roughly ), bias drift could be a bother : : unless you had a large Rk taken down to a -ve supply and then : : bypass the k to 0V. : : so you have best dc regulation by the Rk. : : : : The downward Ea swing of triodes mainly depemds on : : a low Ra, and the more vertical the Ra data curves are the easier is is : : to get a good -ve going swing without grid current. : : : Maybe your'e right about the heater power as well, but tubes like 6CM5 : : etc were not big heater power users, and the peak cathode current : : is 500mA. : : But never mind, using a cathode follower drive to the grid you can drive : : the grid : : positive probably with this tube and thus get the efficiency up : : to near tetrode performance. : : ( few folks realise that instead of getting only 12 watts from a pair of : : KT66/6L6 : : in triode in AB1, with AB2 up to around 30 watts is doable with the same : : Ea...) : : : : The need for such a high Ea is reduced by operating with grid current; : : its done with 211.... : : : : And BTW, I mistakenly thought the gm was 6.5mA/V but its not, its : : a massive 65mA/V, a function of the frame grid probably, since such : : grids can be closer to the cathode and with finer wire more : : closely spaced than normal helical wound grids. : : : : ( I wonder what the latest 2006 triode gm would have become if : : SS hadn't been developed ). : : : : Anyway, give the tubes a try in SE mode, and see how it goes. : : If you didn't wanna use CFB, there is always simple resistance shunt : : NFB. : : : : But I bet you will need lotsa NFB. : : : : And consider choke feeding the anode with the 1,250V and cap coupling : : the OPT. : : It means the DCV is across the coupling cap and the OPT primary : : can be at 0V potential, which may be a trifle safer to experiment with : : especially if : : the shunt FB option is tried. : : 1250V plate, around 1300 V B+ , just within practical range, : as in you can use 450V caps, triple stacked with a ladder R netw., : use 2 power transformers and stack the secondary 500V windings : but it is serious juice we're talking, : i'd incorporate some bootup diagnostics, heh, : on switchon, pull the grids with a 100 Ohm to -12V, : use an opamp to measure grid current : measure cathode current when heated up, grid still at -12V : and only if that is ok, release the G1 to the driver stage. : and something to watch over the tubes dynamically : and use common sense with layout, wire type, etc. :-) : : i don't have that tube stocked, as you can see from the filename, : i thought of it as a candidate for driving electrostatic panels : directly, choke fed B+, : also, you need good sockets for such high voltages, i haven't : seen them for compactron (must be a lot easier in the US : : but if someone is going the hi B+ route, with an 845 or so, : this 6HV5A may be a good 'first try' using the OT intended for the 845 : : R. : : I am building a pair of 845 monos with two 845 each in parallel. : The OPT is 6k:6, Ea =1,100V, Ia for both tubes = 120mA. : : I'd not like to have to use 12 pin compactron tube sockets with 1,250V. : well, the four pins closest to the plate are nc, so it should be ok with ceramic or teflon sockets : The ESL use a 100:1 ratio step up tranny, so that if the : input V = 20Vrms, the panel V = 2,000Vrms, which is +/-2,800 peakV, : and you'd need maybe Ea = 3,500V to accomodate such a swing using : triodes : if a direct connection is anticipated. : I think I will leave that sort engineering for others to perfect. : : : My 845 design so far has evolved so that the power supply has approx : +600V and -600V. : These voltages are derived from a pair of voltage doublers and 4 x 470uF : x 450V : electro caps are involved across the total 1,200V. : There will be LC and RC filters, so 12 x 470uF caps are involved. : I don't like oiler caps or huge choke values and I do like lots of : capacitance : so that the final impedance values anchoring down the output tube : and its connected OPT will be nice and low and non resonant. : The +ve is applied to the anode via the OPT and -ve to the cathode : via a pair of CCS to each cathode, : and then cap bypassing is used to ground the cathodes to 0V. : : The grids are at -600V, but are cap coupled to the EL34 : choke loaded stage : which is the driver to make up to about 140Vrms. : : The turn on behaviour should be docile because the CCS set ups : take time to begin current conduction. Its not the voltage across : a to k that causes the blue smoke, but the current that flows, : so limit the current and control it, and no blue smoke. : : I hope to never ever have to repair or replace the OPT due to : arcing or insulation breakdown due to having a peak voltage of : 2,000V across insulation including the ac peak swing upwards. : : I am considering potting the OPT in the 2mm thick steel cans I : just had made and using oil in them but that means the can would be : upside down on the chassis : with sealed terminals facing down, and sure as God made little apples, : such sealed connections would leak damn oil, and there are a large : number of connections to allow more load matches than just one : lousy match to 6 ohms. : And I don't want to face the cans upright, since that means : cable runs from the top to bottom externally. So probably I will settle : for wax potting compound in addition to the two pack polyurethane : varnishing applied very liberally during the wind up process. : Probably this is good enough for 2,000V++...I have yet to test it all. : : After a few more repair/restoration jobs I will finally be able to : devote time to : some real craft work for a few months and not perish financially. : : Patrick Turner. thanks, interesting stuff. Rudy |
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#31
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The making of a triode amp
: I'd not like to have to use 12 pin compactron tube sockets with 1,250V. : well, the four pins closest to the plate are nc, so it should be ok with ceramic or teflon sockets Yes, indeed the live pin distances to anything earthy may be OK. But hey, the large sockets for the 845 just seem like they'd resist lightning strike... Patrick Turner. |
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#32
Posted to rec.audio.tubes
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The making of a triode amp
"Patrick Turner" wrote in message ... : : : I'd not like to have to use 12 pin compactron tube sockets with 1,250V. : : : well, the four pins closest to the plate are nc, so it should be ok : with ceramic or teflon sockets : : Yes, indeed the live pin distances to anything earthy may be OK. : : But hey, the large sockets for the 845 just seem like they'd resist : lightning strike... : : Patrick Turner. :-) on the using of the 6HV5A for a directly driven es speaker driver, i was not thinking about a Quad, more along a mid/high DIY panel, quite a lively scene in NL, building those ;-), an integrated solution, with some 3400V, 10mA for each tube, -9.5V bias from using a regulated +8.5V supply and a 100 Ohm cathode R should do it (if one succeeds building such a B+ supply heaters with a ccs from that 8.5V, grid R's probably needing to be rather low, 1K or so, could be driven from a passive XO, probably Rudy |
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#33
Posted to rec.audio.tubes
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The making of a triode amp
Ruud Broens wrote: "Patrick Turner" wrote in message ... : : : I'd not like to have to use 12 pin compactron tube sockets with 1,250V. : : : well, the four pins closest to the plate are nc, so it should be ok : with ceramic or teflon sockets : : Yes, indeed the live pin distances to anything earthy may be OK. : : But hey, the large sockets for the 845 just seem like they'd resist : lightning strike... : : Patrick Turner. :-) on the using of the 6HV5A for a directly driven es speaker driver, i was not thinking about a Quad, more along a mid/high DIY panel, quite a lively scene in NL, building those ;-), These don'r need such a high voltage drive compared to a bass panel, but they can still be highly capacitive to drive.. an integrated solution, with some 3400V, 10mA for each tube, -9.5V bias from using a regulated +8.5V supply and a 100 Ohm cathode R should do it (if one succeeds building such a B+ supply heaters with a ccs from that 8.5V, grid R's probably needing to be rather low, 1K or so, could be driven from a passive XO, probably I leave you to experiment further.... Patrick Turner. Rudy |
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