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#41
Posted to rec.audio.tubes
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NFB windings, was there a US style and UK style?
In article ,
Patrick Turner wrote: On May 29, 11:23*am, John Byrns wrote: In article , *John L Stewart wrote: Before this thread went off the rails did anyone mention that McIntosh uses a seperate winding on the OPT for overall NFB? A separate winding, a tertiary winding, provides better high frequency stability than taking the NFB from the secondary winding. *The down side of using a tertiary winding for NFB is that the NFB doesn't include the secondary so that the damping factor suffers, this probably has no practical consequence, but doesn't make for good ad copy. Yes but the NFB winding position relative to anode turns or secondary turns will have an effect on what is fed back. Yes, the design/positioning of the tertiary winding affects the leakage inductances between the various windings I'd say that if a fine wire NFB winding is wound right over the top of a thick wire speaker secondary then its signal is near equal to the speaker's signal and the "error" made by the secondary Rw and LL and phase shift et all is fed back for correction. No tertiary can correct for the "Rw" of the secondary! But if the FB tertiary is next to the anode primary then you have a good hum free FB source with anode signal without LL and Sec Rw effects and the amp is MUCH easier to stabilise unconditionally. Such a low voltage and grounded winding gives a conveniently small FB signal with low source resistance which can be applied to an earlier stage very effectively. Such a signal picks up a sample of the whole Va-a, and is a better NFB than using a cap plus R divider from one of the PP anodes back to an input tube cathode. But bean counters mostly hated paying for a dedicated NFB tertiary. Why have one when the speaker secondary exists? Indeed why have one? if you make the OPT with sufficient interleaving then the Williamson way of NFB is fine, but bean counters hated Williamson too, and laughed at what he said makers should do, so we all mainly ended up with OPT with very high LL and appalling stability problems. Marantz used an interesting NFB scheme that took the NFB from the secondary at low frequencies to provide a good damping factor and then used a crossover filter to take the high frequency NFB from tertiary windings. I'm not sure about that one. Some makers just used the speaker sec for normal global NFB with R divider to feed V1 cathode but then the cap that is normally strapped across the FB R to advance the phase of the fed back signal at HF is not used, but a cap from V1 cathode is taken to one of the OP tube anodes. I've always found no real joy in such measures and I prefer the normal conventional Williamson idea where one makes the OPT have wide BW which then pushes the regions where instabilty occurs further below and above the AF band and thus to where its easy to instal gain reducing and phase tailoring networks while maintaining 10Hz to 65kHz full power bandwidth with complete stability and 20dB global NFB is desired. I'll follow the Williamson principles before I'll follow any others. I happen to like using tertiary windings for NFB myself, but in the form of CFB windings which are a part of the OPT primary and which carry Ia. Its the Acoustical. Thus the OP stage is substantially linearised and given the character of triode Ra and low THD while retaining the tertrode AB1 or A1 power. Then only 10dB of global NFB is needed, if any at all. CFB is nice, but it does increase the demands on the driver stage substantially. -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
#42
Posted to rec.audio.tubes
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NFB windings, was there a US style and UK style?
So where were you when ya could have lent them your machine gun to make Britain a better place? Oh, I guess you really hate all those Mexicans crossing the border too, yet they do all the dirty work so nice and cheap now don't they? Probably you hate a browned skin man being President Of the USA, and giving speaches in Ireland last week which would have been totally beyond the capability of Dubbya, or of Sarah Palin. I preferred Obama to McCain in fact as did most WNs. He has been a disappointment to be sure but any other candidate would have been as well who would have been likely to have been nominated. I don't hate the Mexicans, although I acknowledge that the Mexicans coming here are mostly the browner and stupider ones who can't make it back home. I detest the fact that our politicians won't do what any nation has to do which is secure its borders and throw out violators. The Republicans want cheap labor to undercut the American worker, both black and white, and the Dems want the illegals to vote, and vote Democratic, which they will. Machine gunning people is not the answer. Enforcing the law firmly and acknowledging that we are White countries who should and must stay that way is. No one race is "superior", but we are who we are and should stay that way. Britain should be for the British and America for the Americans. |
#43
Posted to rec.audio.tubes
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NFB windings, was there a US style and UK style?
On Mon, 30 May 2011 02:23:45 -0700 (PDT), Patrick Turner
- Hide quoted text - - Show quoted text - wrote: On May 28, 7:59 pm, flipper wrote: On Thu, 26 May 2011 16:32:44 -0700 (PDT), Patrick Turner wrote: On May 26, 7:35 pm, flipper wrote: On Thu, 26 May 2011 00:37:17 -0700 (PDT), Patrick Turner wrote: I mentioned...... I have never seen any commercial design with PFB and NFB - Of course you have and I gave you examples the last time you said the same thing. I've been saying the same thing because I've never seen PFB used in commercial amps like the way its done in RDH4 at that amp. Now you've changed it again by adding "like the way." Sometimes bootstrapping is PFB, but usually the gain increase is mild, from gain with a load to gain which approaches µ. However, come to think about it, Dynaco bootstrapped the pentode input tube anode RL ahead of the triode concertina to boost the gain of the pentode. Told ya so. The Harmon Kardon 'Trio' also uses PFB and is the basic topology I've used in at least three of mine. The gain with bootstrapping a pentode often rises much more than with a triode tube because the pentode has its anode feedback screened off from the electron stream. Pentode µ is gm x Ra, and as pentode Ra is so high then µ is high. BTW, I have to repair the design results of acountants and bean counters all too often. You've never had to do it even once because bean counters don't do design. Never have, don't now, and never will. IMHO, Your 'opinion', and following gibberish, is twaddle. It may fool fellow ignorants who, like you, haven't a clue but it's drivel to those of us who've worked with your so called 'bean counters' and done professional product design. I don't speak from 'opinion' and cartoons. I speak from fact, having been there and done that. Its OK, every man's facts are another man's fictions, and one man's trash is another man's treasure. More gibberish. Go bang your head on a wall and see how far you get wishing it were 'fiction' rather than solid fact. I just see lots of what I don't want to buy or approve of or want to be involved in and if everyone was like me the world would collapse. But fear not and be grateful for the human diversity around you now. It should be blindingly obvious by now that you are not representative of the market. Of course, it's also blindingly obvious that accountants are trained in accounting, which is pretty much why they're called accountants, and not design but, then, it being obvious to everyone else has never stopped your delusions yet. It's true that more robust construction would have made these things last longer, but to be fair, no one realistically figured anyone would be running these things fifty or sixty years hence. Saul Marantz (yes, I know) was determined to make the finest quality hi-fi equipment and spared little in the quest to do so. His build cost was double and then some of what his nearest competitor, McIntosh, spent per unit. Avery Fisher (yes, he was too) was more mainstream but still put a lot of build cost in his product as compared to his competitors. Both businesses are out of business in terms of being an American manufacturer. McIntosh is also owned by Japanese, BUT are allowed to operate autonomously and they are still manufacturing in Binghamton. We can look at the classic Mac products and say there were several aspects where they could have done better but the salient fact is,, they are still here. Quad never set out to be the technical ulimate but to be a usable integrated system and they succeeded marvelously. Even the Dynaco ST70, which I have slammed long and hard, has to be admitted as having been insanely successful in its day. By the standards of its day it was a great product because a college kid could afford a Dyna pre and ST70, and AR table and an AR acoustic suspension speaker set in 1963. Some portable record player outfits cost nearly as much. Again, no one realistically thought thay would be running in 2011. Had the dyna been "built right" it would have had to cost more, maybe considerably more. One area where they shaved was weight to meat a Railway Express shipping target. That's why the power transformer is undersize. The profit margins in this stuff were minimal. It's like a car. Yeah, if ALL the Ford Mustangs had had 9 inch rears, five bolt disc brake setups and so forth they'd have been better cars, but 90% of them were going to the crusher in five or six years anyway. If they had overbuilt them it would have made little difference in this rate. A great many cars get driven to the crusher under their own power. |
#44
Posted to rec.audio.tubes
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NFB windings, was there a US style and UK style?
On May 31, 3:10*pm, Bret Ludwig wrote:
On Mon, 30 May 2011 02:23:45 -0700 (PDT), Patrick Turner - Hide quoted text - - Show quoted text - wrote: On May 28, 7:59 pm, flipper wrote: On Thu, 26 May 2011 16:32:44 -0700 (PDT), Patrick Turner wrote: On May 26, 7:35 pm, flipper wrote: On Thu, 26 May 2011 00:37:17 -0700 (PDT), Patrick Turner wrote: I mentioned...... I have never seen any commercial design with PFB and NFB - Of course you have and I gave you examples the last time you said the same thing. I've been saying the same thing because I've never seen PFB used in commercial amps like the way its done in RDH4 at that amp. Now you've changed it again by adding "like the way." Sometimes bootstrapping is PFB, but usually the gain increase is mild, from gain with a load to gain which approaches µ. However, come to think about it, Dynaco bootstrapped the pentode input tube anode RL ahead of the triode concertina to boost the gain of the pentode. Told ya so. The Harmon Kardon 'Trio' also uses PFB and is the basic topology I've used in at least three of mine. The gain with bootstrapping a pentode often rises much more than with a triode tube because the pentode has its anode feedback screened off from the electron stream. Pentode µ is gm x Ra, and as pentode Ra is so high then µ is high. BTW, I have to repair the design results of acountants and bean counters all too often. You've never had to do it even once because bean counters don't do design. Never have, don't now, and never will. IMHO, Your 'opinion', and following gibberish, is twaddle. It may fool fellow ignorants who, like you, haven't a clue but it's drivel to those of us who've worked with your so called 'bean counters' and done professional product design. I don't speak from 'opinion' and cartoons. I speak from fact, having been there and done that. Its OK, every man's facts are another man's fictions, and one man's trash is another man's treasure. More gibberish. Go bang your head on a wall and see how far you get wishing it were 'fiction' rather than solid fact. I just see lots of what I don't want to buy or approve of or want to be involved in and if everyone was like me the world would collapse. But fear not and be grateful for the human diversity around you now. It should be blindingly obvious by now that you are not representative of the market. Irelevant. Of course, it's also blindingly obvious that accountants are trained in accounting, which is pretty much why they're called accountants, and not design but, then, it being obvious to everyone else has never stopped your delusions yet. *It's true that more robust construction would have made these things last longer, but to be fair, no one realistically figured anyone would be running these things fifty or sixty years hence. And all the old junk needs serious care and revisions to rectify bean counter inspired shortcomings. *Saul Marantz (yes, I know) was determined to make the finest quality hi-fi equipment and spared little in the quest to do so. His build cost was double and then some of what his nearest competitor, McIntosh, spent per unit. I've never wanted anything made by Marantz, could always have been a lot better. *Avery Fisher (yes, he was too) was more mainstream but still put a lot of build cost in his product as compared to his competitors. Ha, most of the Fisher stuff is generic junk. I've had to repair, modifiy, re-do, undo bad ways all these brands used to save a dime. *Both businesses are out of business in terms of being an American manufacturer. McIntosh is also owned by Japanese, BUT are allowed to operate autonomously and they are still manufacturing in Binghamton. And of course the OWNERS exert hard financial controls over design. I've worked on the McIntosh re-issue models they sell here for $4,300. REAL CRAP. pcb boards all miniturised, hard to work on short cuts from the old circuits, tube biasing up to ****, bean counter inspired. But really, I raise my hat and salute all bean counters for destroying product quality while jacking up the price because I can compete with their dumbed down over priced garbage. Henry Ford raised his hat whenever he saw a Fiat drive past, or a Morris, or an Alfa Romeo not to mention a Rolls or a Merc. Not that I'm like Henry, but the urge to smile and raise a hat is the same. Maybe Henry would not have raised a hat if he'd seen a Toyota drive past :-) Dammit, we beat Japan and now they come back at us! The damn Gummint musta betrayed us! Tough titty, buster, the people really want the best cheap car. *We can look at the classic Mac products and say there were several aspects where they could have done better but the salient fact is,, they are still here. Just being here counts for nothing. *Quad never set out to be the technical ulimate but to be a usable integrated system and they succeeded marvelously. Indeed they tried something. Quad tubed AM tuners, and ESL57 were good, but everything else MEDIOCRE, ain't nothin special, just chic junk, like Bose Lifestyle systems and B&O is now. You should see the BO-6002 slimline speakers I have here for repair, and how badly they have failed, utter CRAP. I was never conned by ticky tacky accountant inspired crap where construction costs were pushed down and down thus smothering technical integrity. *Even the Dynaco ST70, which I have slammed long and hard, has to be admitted as having been insanely successful in its day. Desperate ppl by the cheapest muck they can, so they bought Dyanco ST70. Not many bought Mk VI monoblocks. Now these did have more merit, but SO MUCH can be done to vastly improve them if the whole circuit is junked then you just use the chassis, PT and OPT. But I find bulldozing all the old crap out and starting all over applies to each and every US made amp I have ever seen enter my shed because the owners hated the smoke and were none too keen about the sound. ARC, Manley Labs, Dynaco, VAC, Fisher, Pilot, and many more. All designed with cost minimisation in mind. standards of its day it was a great product because a college kid could afford a Dyna pre and ST70, and AR table and an AR acoustic suspension speaker set in 1963. Some portable record player outfits cost nearly as much. Again, no one realistically thought thay would be running in 2011. Yes, sure, but right out of the factory, a lotta the old junk your so proud of was crap because it was already dumbed down by cost cutting. Its going on today with a whole pile of consumer gear, you buy it, it breaks, and you chuck it out, because the cost of a repair is larger than the replacement price, and not to mention that stuff becomes obsolete, like PC boxes which we all thought were cool in 1995. Its rubbish now. AR speakers have very limited appeal for me. Their Flagship model in 1975 was the AR9, and I've had the true displeasure of spending weeks to make them right. They were $4,500 in Oz in 1975, or in today's dollars, $90,000. But what was inside? Utter generic crap and attrociously worst lowest common denominator R, C and L and speaker drivers. I've measured mint pairs of AR9 and found the response nothing like what the brochure says. The paralleled 11" bass speakers have 1.5 ohms impedance at critical bass F and ppl who buy such speakers want loud bass but they'd blow up amps real well. The AR bass drivers are probably the most insensitive bass speakers I have ever measured. The crossover design is hopeless ly inadequate. Basically AR9 should have sold for $45 in 1975, not $4,500, ie, $900 in todays dollars. So my conclusion about AR was that they had very poor management, very poor quality control, accountants who were ac****ants, a workforce of rushed and cheap dumbos with minimum skills, and engineers who knew jack ****. But they had the best promotions staffers in the world, the best liars, and maybe they employed the best advertizing company. They speaker building efforts were just an entrenerial exercize, like so many other crappy things made around the world in 1975. It was so easy to study a book or two and make your own speakers that would then cost $200 which would easily beat the AR9 for $4,500. I did just that. I baulked at building tube amps in 1975, too many other things in life to do but I bought a Linear Design receiver in 1977 for $200, less than half the price and better sounding that the equivalent Marantz rip off. I still have that receiver. *Had the dyna been "built right" it would have had to cost more, maybe considerably more. The CEO then could not have afforded a Cadillac. Ah, the wonders of capitalisic greed! One area where they shaved was weight to meat a Railway Express shipping target. That's why the power transformer is undersize. The profit *margins in this stuff were minimal. Total ****in bull**** type stuff. *It's like a car. Yeah, if ALL the Ford Mustangs had had 9 inch rears, five bolt disc brake setups and so forth they'd have been better cars, but 90% of them were going to the crusher in five or six years anyway. If they had overbuilt them it would have made little difference in this rate. A great many cars get driven to the crusher under their own power.- Hide quoted text - Well thank christ most old US made cars have been recycled so that 2 cars come from the metal used for one. We have a big car festival here each summer, see http://www.summernats.com.au/ The grounds are just 1/2 a km away from where I live. But I just don't see what the thousands or rev-heads see in their cars which are expensive, noisy, and a waste of money, like the rich men's yachts at Pit****er. All this stuff, more stuff, no end to stuff, more and more horse power and much of it crap. So Vain! So Futile, So Meaningless. So Wasteful. So Unsuccessful. I've seen the work guys put into cars, beautiful sure, but heck, its only a car, and how come it don't give 50MPG? How come most of the hotted up highly modified cars are NOT allowed on city streets but are confined to the show ground parade loop? Because so many dreadful incidents occurred when the rev-heads were allowed to drive on city streets. Strict Government control is needed. But 5,000 people manage to have a ball for 4 days and maybe spend a grand or two each. But far more income comes from big art shows at the National Gallery. Just harmless paintings on the wall, no smoke, burnt rubber, stoopid young jerks showing off and wasting so much precious fuel. Its most unfortunate that American cars have wasted so much fuel because bean counters stopped expense on developing efficiency; better to lobby the Govt about 101 favours and do all sorts of weird deals so that Joe Public funds the inefficiency, not Ford, Not GM, Not Chrysler or anyone else except Jack Buyer. Yippee, 7 litre engines and 10MPG, WOW, what progress to be proud of, I DON'T THINK! Ralph Nader should not have had anything to write about, but he did, and you ought to know that. A country and its people should never rest on its laurels, never self congratulate itself, and when the accountants and the bankers go to lunch for 3 hours every day you know things are close to ****ed. The GFC was a sure indicator of that. Maybe the US will muddle along out of its woes, but there's a long way to go, and youse will have to learn fast to reduce greenhouse CO2 just when ya don't wanna pay, while mostly denying any problem even exists. America seems like the fat guy who is told the doc won't operate because he's so fat, and the guy says he really wants that operation but he can't stop eating so much. America shows what the rest of the world should not want to copy or emulate. And in countries like mine which has addopted much of the excessiveness and greed and bull****, the carbon tax is a raging argument and people don't want to pay for the change necessary to keep the planet cool. Some will pay more than others, and as usual a whole big argument is on over that one, so muddle here is as big as muddle where you are and elsewhere. Muddle is normal. We never get over it, and I doubt you can admit you are a member of a seriously flawed species. Never mind, you will die with your beliefs like those who clung to the idea that the Earth was flat even on their death bed. The grave will take stubborn beliefs with the man, and the enligtened will inherit the Earth, and the job of energy management revolution will be done by young clever hands and minds who criticise themselves and methods each and every day, not to save a dime while charging outrageous prices. And the product of the revolution for the next 50 years might give us time to avoid the silly wars we've had, and the absurd way we treat forests, and environment. I'd like to think the coming revolution might allow some frivolity like the occasional tube amp but never again will mainstream stuff be allowed to be as bad as it was in 1950. PWM amps are very efficient, a bean counter's delight in fact, don't even need a heatsink. Tiny robot made circuitry allows highspeed switching signals. Chinese labour ruins any chance of the US charging too much like they used to. Not a perfect scene because the average Chinese worker gets shafted, but his 64c an hour is better than 20c per hour on the farm up the country where his parents eek out a living that is infinitely unacceptable to the average Oz or US person. The failure of the Chinese for 3,000 years has been to not improve life much for themselves, and the failure of the West has been to improve its material wealth far too much while swanning around and crowing about how wonderful it is. I don't care if I represent the minority view of things in general. Patrick Turner. |
#45
Posted to rec.audio.tubes
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NFB windings, was there a US style and UK style?
On May 31, 2:51*pm, Bret Ludwig wrote:
So where were you when ya could have lent them your machine gun to make Britain a better place? Oh, I guess you really hate all those Mexicans crossing the border too, yet they do all the dirty work so nice and cheap now don't they? Probably you hate a browned skin man being President Of the USA, and giving speaches in Ireland last week which would have been totally beyond the capability of Dubbya, or of Sarah Palin. *I preferred Obama to McCain in fact as did most WNs. He has been a disappointment to be sure but any other candidate would have been as well who would have been likely to have been nominated. Well, Obama means well, IMHO. If Sarah joins the race, I doubt she'd got a chance. Maybe the best Republicans are still mending fences after the GFC. *I don't hate the Mexicans, although I acknowledge that the Mexicans coming here are mostly the browner and stupider ones who can't make it back home. But that's what so many say about "boat people" from Ghan and Iraq coming here "illegally" But they are clever enough to make enough money to pay ppl smugglers and get here. I detest the fact that our politicians won't do what any nation has to do which is secure its borders and throw out violators. That's what a lot of Indians said about the white man invading their lands. Our aboriginies resented the White man coming here in boats, unwanted, and uninvited, and after they settled they practised genocide. The Republicans want cheap labor to undercut the American worker, both black and white, and the Dems want the illegals to vote, and vote Democratic, which they will. Ya can't have it both ways. Money wins, no, so illegals will stay to do work the White Fella won't. Count your blessings you don't have to work in a food processing factory at 50C all day with quotas to meet and low pay so your vegetables are cheap for you. *Machine gunning people is not the answer. Well of course not. Far too messy. I didn't mean what I said, just jesting. Fooling people to take up residence in places with signs which say Work Makes You Free would be easier, and you pop a little gas in while they have a shower before work, and then you cremate them. But you'll get spotted, some upstart will upload a mobile phone pic of the Zyclon B gas tablets to Facebook and the Feds will come straight over. Nah, extermination just won't work. Far better to fudge. Appear to be taking action, but somehow brownskins increase anyway. The Whites have remarkably low birthrates, and half end up on welfare too soon. Enforcing the law firmly and acknowledging that we are White countries who should and must stay that way is. Yeah, but youse being out ****ed and thus out bred by Brownies, happy smiling millions of 'em, God Love 'em. People here wanted Oz to stay all White, and they brought in a White Australia Policy before WW1. After WW2 It hit the dust as one of the most obnoxious, unworkable stupid political ideas we ever came up with. After WW2 we let in all these garlic eating wogs from Italy, Germany, Holland, Greece, and WHOOPPEE!!! the party began, wealth went everywhere except down, these wogs were fabulous new blood. After 1978, 200,000 Vietnamese came in. WOW. Now we have some of the worlds best medicos. No one race is "superior", but we are who we are and should stay that way. *Britain should be for the British and America for the Americans. Total unmitigated uneducated bull****! Also ********. Definate Balderdash. Even if you tried, the US cannot remain as you'd wish it, which is the product of much immigration and the overcoming of huge intolerances of differences. One most hated group of Whites were Jews. But once in America they have flourished to enrich our lives far more than they impoverished lives. Plenty of brown skins here. No troubles, taxis come on time and driven by Pakistanis. Indians grow the best tea to drink. Hospitals run finely with asians everywhere. I love them all. I go to a cafe across town, one of 3 in a row in a main street of a town center. Its the Istanbul, run by arabs, but on a sunday they only get 1/3 of the patronage of the joint next door which charges more but is run by Whites, with mainly white customers who mistakenly might think Arabs suck, and especially Islamic culture. So prejudice remains, but is still breaking down and the arabs will blend in a generation and Islam fades to relative unimportance and the whole becomes homogenous and Whites slowly appreciate what the arabs bring. It was the arabs who brought coffee to the west in the first place. And before that we sent the crusades to butcher them. Its amazing so few Islamic extremists like Arsole Bin Laden have come to spoil the party we've been having at the expense of brown skin exploitation by Whites. We have a White Woman as our dear leader and she's having dreadful trouble dealing with horrible untidy unwashed brown illegals, and she plans to do all sorts of inhumane things to them. She's also having frightful trouble getting ppl to believe in her Carbon Tax. Now just where is a good strong fit brown man who can be a good leader when you want one? Look, if Sarah makes it to the White House, send Obie down to us, we need a man like that. And we might have learnt to let him in by then. Patrick Turner. |
#46
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NFB windings, was there a US style and UK style?
On May 31, 1:09*pm, John Byrns wrote:
In article , *Patrick Turner wrote: On May 29, 11:23*am, John Byrns wrote: In article , *John L Stewart wrote: Before this thread went off the rails did anyone mention that McIntosh uses a seperate winding on the OPT for overall NFB? A separate winding, a tertiary winding, provides better high frequency stability than taking the NFB from the secondary winding. *The down side of using a tertiary winding for NFB is that the NFB doesn't include the secondary so that the damping factor suffers, this probably has no practical consequence, but doesn't make for good ad copy. Yes but the NFB winding position relative to anode turns or secondary turns will have an effect on what is fed back. Yes, the design/positioning of the tertiary winding affects the leakage inductances between the various windings I'd say that if a fine wire NFB winding is wound right over the top of a thick wire speaker secondary then its signal is near equal to the speaker's signal and the "error" made by the secondary Rw and LL and phase shift et all is fed back for correction. No tertiary can correct for the "Rw" of the secondary! I'm not so sure. if the tertiary is wound close to anode coils, sure, Sec Rw is not reduced by NFB. But if tertiary is wound close to Sec, a drop in sec voltage gives a drop in tertiary voltage, and a FB signal corrects the drop, no? , But if the FB tertiary is next to the anode primary then you have a good hum free FB source with anode signal without LL and Sec Rw effects and the amp is MUCH easier to stabilise unconditionally. Such a low voltage and grounded winding gives a conveniently small FB signal with low source resistance which can be applied to an earlier stage very effectively. Such a signal picks up a sample of the whole Va-a, and is a better NFB than using a cap plus R divider from one of the PP anodes back to an input tube cathode. But bean counters mostly hated paying for a dedicated NFB tertiary. Why have one when the speaker secondary exists? Indeed why have one? if you make the OPT with sufficient interleaving then the Williamson way of NFB is fine, but bean counters hated Williamson too, and laughed at what he said makers should do, so we all mainly ended up with OPT with very high LL and appalling stability problems. Marantz used an interesting NFB scheme that took the NFB from the secondary at low frequencies to provide a good damping factor and then used a crossover filter to take the high frequency NFB from tertiary windings. I'm not sure about that one. Some makers just used the speaker sec for normal global NFB with R divider to feed V1 cathode but then the cap that is normally strapped across the FB R to advance the phase of the fed back signal at HF is not used, but a cap from V1 cathode is taken to one of the OP tube anodes. I've always found no real joy in such measures and I prefer the normal conventional Williamson idea where one makes the OPT have wide BW which then pushes the regions where instabilty occurs further below and above the AF band and thus to where its easy to instal gain reducing and phase tailoring networks while maintaining 10Hz to 65kHz full power bandwidth with complete stability and 20dB global NFB is desired. I'll follow the Williamson principles before I'll follow any others. I happen to like using tertiary windings for NFB myself, but in the form of CFB windings which are a part of the OPT primary and which carry Ia. Its the Acoustical. Thus the OP stage is substantially linearised and given the character of triode Ra and low THD while retaining the tertrode AB1 or A1 power. Then only 10dB of global NFB is needed, if any at all. CFB is nice, but it does increase the demands on the driver stage substantially. Depends how much CFB. Mcintosh amps need a max 150Vrms to 6550 output tube grids for clipping. So the THD of the driver stage tugs at the gains of so much CFB ( 50% ) in the OP stage. Quad-II only have 10% CFB, and the KT66 are about as sensitive as a 50% UL stage. But the 10% CFB is more effective in getting Ra-a to the same level as triodes. A 50% UL stage gives Ra-a about = to RLa-a, several times the Ra-a of triode, broadly speaking. I like 20% CFB, drive voltage goes to about 75Vrms to each 6550 grid and I then build the drive amp to make far less THD than anything by McIntosh or Quad, and voila, very low THD with very little global NFB. Patrick Turner. d a -- Regards, John Byrns Surf my web pages at, *http://fmamradios.com/- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
#47
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NFB windings, was there a US style and UK style?
On May 31, 1:06*pm, John Byrns wrote:
In article , *Patrick Turner wrote: On May 29, 3:47*am, John Byrns wrote: In article , *Patrick Turner wrote: Well, I can't explain it any better than I have. If circuit gain is increased by feeding back a fraction of an output signal of one stage to an earlier stage and the gain is increased, THD increased, bandwidth reduced, then I'd say PFB exists. We see feathers, a ducks bill, wings and webbed feet, a ducks tail that wags and we say there's a duck. Unfortunately this is a completely incorrect description of how a generic paraphase inverter operates, so the duck analogy doesn't apply. Oh well, I can agree to dissagree The concertina "throws away" most of its gain so that +19Vin to a 6SN7 produces -17Va and +17Vk, with the +2Vgk needed to make the total 34Vak output, so open loop gain = 17, but closed loop gain is 34 / 19 = 1.79, and this has beautiful low THD because the 19dB current NFB present. So the concertina requires 1.12 Volts in for the specified 34V grid to grid output drive vs. 1.0 Volts in for the paraphase and 2.0 Volts in for the LTP. * 1.12 Volts is close enough to 1.0 Volts for Government work, at least it is a lot closer to 1.0 Volts than it is to 2.0 Volts. The paraphase tends to add gain "artificially" for a given number of tubes, moreso than merely cascading them. "artificial" gain is the best kind, it can be made so pure that its sound is simply sublime. If only it was true. Paraphase and PFB usually have higher than possible THD without the paraphase PFB. The sound of such stages cannot be assumed to be sublime, and wherever higher THD is allowed to breed unecessarily the sound drifts to mud. And in the case of Quad-II, the KT66 grids are biased via 680k Rgs, and one has a 2k7 at its bottom from which the signal to V2 pentode grid is wrought. Now that 2k7 is just what Walker chose, but it could be a range of values; if larger, there's more PFB and more gain and weird things happen when you increase that 2k7 too much because there is a definite limit to the amount of PFB which can be applied without terrible instability. I don't know if 2k7 is the correct value for this resistor, I assume that Quad choose correctly here, there is only one correct value for this resistor where the circuit will function properly, other values are not an option! * Don't be so sure about this. Try building an input stage identical to Quad-II in some amp you have laying around. You don't need pentodes; a single 12AX7 will do, and where the Quad has 680k plus 2k7 try putting a 5k pot to replace the 2k7, then add some NFB and make some adjustments with the pot. After awhile the penny drops about the PFB, too much is hell, just enough is all that's needed - about 6dB. You'll soon find that probably optimal R value is where there is minimum signal voltage across the 680 ohm common Rk to the two EF86, or 1/2 12AX7, so the trick of the circuit is that the EF86 tend to have a fake CCS connected to common cathodes. One may analyse the effects of a distortion signal fed back along the signal path and what happens to it in terms of gain. But the PFB increases the amount of NFB applied beyond what it appears to be. There is more to Quad-II input drive amp than 90% of people may realise. Changing the value of this resistor will change the amount of PFB as you say, thereby changing the gain of V1. *The problem with changing the value of this resistor away from the correct value, to some other value, is that in addition to changing the amount of PFB, it also unbalances the phase inverter so that the two output tubes don't receive the same amount of drive voltage. Very few Quad-II amps have well balanced drive. But I recall the 2k7 was not critical for balance. I suggest you try examining a Quad-II circuit. What I can say is that a pair of EF86 set up as a TRUE LTP with existing load values, but with large R value for common Rk taken to a rail at -400Vdc, and NFB applied to V2 EF86 grid, then the drive amp produces 1/2 the THD as the original Quad-II circuit. But sensitivity halves and twice the grid 1 input signal is needed. Quad couldn't push pentode gain higher so they needed the trick thay have used. Quad didn't think of a way to bootstrap the RL of each pentode anode to increase gain. That would have needed a twin triode for a pair of µ followers in a balanced pair but the balance of such pairs is poor because so little signal Ia exists and balance in LTPs depends of R load equality. The better way is to use an SET input triode followed by low µ twin triode for LTP, 12AU7, 6CG7 is ideal. or have LTP input with 12AU7 and CCS tail followed by balanced amp with long common R tail to -120Vdc; methinks this is the king of input/driver stages for PP. Next time you play around with a paraphase stage, try tinkering with R diver values and drive from V1 to V2. Interesting stuff happens, with not much of it of real value. What exactly are "R diver values"? *There is only one correct value for the "drive from V1 to V2", you may find other amounts of drive interesting, I'm not sure why though? Divider values. Nobody dives anywhere. 680k and 2k7 give Quad's wanted signal for V2 grid, and you can't guess the voltages. Patrick Turner. -- Regards, John Byrns Surf my web pages at, *http://fmamradios.com/ |
#48
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NFB windings, was there a US style and UK style?
In article ,
Patrick Turner wrote: On May 31, 1:06*pm, John Byrns wrote: In article , *Patrick Turner wrote: Well, I can't explain it any better than I have. If circuit gain is increased by feeding back a fraction of an output signal of one stage to an earlier stage and the gain is increased, THD increased, bandwidth reduced, then I'd say PFB exists. We see feathers, a ducks bill, wings and webbed feet, a ducks tail that wags and we say there's a duck. Unfortunately this is a completely incorrect description of how a generic paraphase inverter operates, so the duck analogy doesn't apply. Oh well, I can agree to dissagree The point is that only one variant of the paraphase inverter circuit, the one where V1 & V2 share an unbypassed common cathode resistor, as used in the QUAD II, has the PFB you describe, the generic paraphase inverter and other variants don't have the PFB you are talking about. For example, take a look at this paraphase inverter circuit. http://hhscott.com/pdf/250.pdf Where is the PFB in this circuit? The 6 dB gain increase exists even though there is no PFB in this circuit. The 6 dB gain increase is simply the result adding the voltage mirror stage which doubles the total output signal, this is typical of all paraphase inverter circuits. The PFB in the QUAD II circuit can be eliminated by tying a large electrolytic capacitor from ground to the common cathode of V1 & V2, the gain of the inverter circuit will not change when the PFB is eliminated this way, although there will be a problem applying global NFB with the capacitor in place. If you try this experiment with a capacitor from ground to the common cathode of V1 & V2, be sure and disconnect the global NFB first by disconnecting the 470 Ohm NFB resistor from the secondary of the OPT and connecting it to ground before making any measurements. The paraphase tends to add gain "artificially" for a given number of tubes, moreso than merely cascading them. "artificial" gain is the best kind, it can be made so pure that its sound is simply sublime. If only it was true. Paraphase and PFB usually have higher than possible THD without the paraphase PFB. The sound of such stages cannot be assumed to be sublime, and wherever higher THD is allowed to breed unecessarily the sound drifts to mud. It is as true as calling the 6 dB gain of the paraphase inverter "artificial", when it is actually a direct result of adding the voltage mirror circuit. And in the case of Quad-II, the KT66 grids are biased via 680k Rgs, and one has a 2k7 at its bottom from which the signal to V2 pentode grid is wrought. Now that 2k7 is just what Walker chose, but it could be a range of values; if larger, there's more PFB and more gain and weird things happen when you increase that 2k7 too much because there is a definite limit to the amount of PFB which can be applied without terrible instability. I don't know if 2k7 is the correct value for this resistor, I assume that Quad choose correctly here, there is only one correct value for this resistor where the circuit will function properly, other values are not an option! * Don't be so sure about this. Try building an input stage identical to Quad-II in some amp you have laying around. You don't need pentodes; a single 12AX7 will do, and where the Quad has 680k plus 2k7 try putting a 5k pot to replace the 2k7, then add some NFB and make some adjustments with the pot. After awhile the penny drops about the PFB, too much is hell, just enough is all that's needed - about 6dB. You'll soon find that probably optimal R value is where there is minimum signal voltage across the 680 ohm common Rk to the two EF86, or 1/2 12AX7, so the trick of the circuit is that the EF86 tend to have a fake CCS connected to common cathodes. One may analyse the effects of a distortion signal fed back along the signal path and what happens to it in terms of gain. But the PFB increases the amount of NFB applied beyond what it appears to be. There is more to Quad-II input drive amp than 90% of people may realise. You need to be a little more definite about what this faux QUAD II phase inverter circuit using 12AX7s is supposed to look like? Is it just to be an input stage without any global NFB? Assuming that we aren't worrying about the complex provisions for global NFB in the QUAD circuit, having omitted them, it is obvious by inspection that when the "R value" is adjusted for equal outputs from the two plates of the inverter circuit, then the signal voltage on the common cathodes will be minimized. Adding the QUAD style global negative feed back circuit greatly complicates things, as global NFB is applied to V1 and both global NFB and global PFB are applied to V2. I don't think I would say "that the EF86 tend to have a fake CCS connected to common cathodes", if anything I would call it a "fake piece of wire". The QUAD II input stage has much more going on in it, at multiple levels, than you seem realize, or seem have thought about. I'm not saying that your Turner circuit isn't better, however you should have made an effort to more fully understand the operation of the QUAD input circuit before ripping it out and replacing it with your design. Changing the value of this resistor will change the amount of PFB as you say, thereby changing the gain of V1. *The problem with changing the value of this resistor away from the correct value, to some other value, is that in addition to changing the amount of PFB, it also unbalances the phase inverter so that the two output tubes don't receive the same amount of drive voltage. Very few Quad-II amps have well balanced drive. But I recall the 2k7 was not critical for balance. I suggest you try examining a Quad-II circuit. I have examined the QUAD II circuit, and did so long before you were even aware of its existence, if some of your narrative here is to be believed. The 2k7 is absolutely critical for proper balance in the QUAD II, however balance is also dependent on the gain of V2 in addition to the value of the 2k7. I suspect that the reason QUAD didn't use a self balancing type of paraphase circuit in the QUAD II is because it would have required more components, including at least one electrolytic capacitor for the cathode of V1 to maintain gain, and there would have been a slight loss in open loop gain, less than 1.0 dB, due to increased loading on the driver plates, and there is little doubt that QUAD was pinching pennies in the QUAD II, so the increased cost, and very slight loss of gain would have been intolerable. -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
#49
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NFB windings, was there a US style and UK style?
In article ,
Patrick Turner wrote: On May 31, 1:09*pm, John Byrns wrote: In article , *Patrick Turner wrote: On May 29, 11:23*am, John Byrns wrote: In article , *John L Stewart wrote: Before this thread went off the rails did anyone mention that McIntosh uses a seperate winding on the OPT for overall NFB? A separate winding, a tertiary winding, provides better high frequency stability than taking the NFB from the secondary winding. *The down side of using a tertiary winding for NFB is that the NFB doesn't include the secondary so that the damping factor suffers, this probably has no practical consequence, but doesn't make for good ad copy. Yes but the NFB winding position relative to anode turns or secondary turns will have an effect on what is fed back. Yes, the design/positioning of the tertiary winding affects the leakage inductances between the various windings I'd say that if a fine wire NFB winding is wound right over the top of a thick wire speaker secondary then its signal is near equal to the speaker's signal and the "error" made by the secondary Rw and LL and phase shift et all is fed back for correction. No tertiary can correct for the "Rw" of the secondary! I'm not so sure. if the tertiary is wound close to anode coils, sure, Sec Rw is not reduced by NFB. But if tertiary is wound close to Sec, a drop in sec voltage gives a drop in tertiary voltage, and a FB signal corrects the drop, no? NO, even if the tertiary were perfectly coupled to the secondary, it still couldn't compensate for the secondary winding resistance. -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
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NFB windings, was there a US style and UK style?
*Saul Marantz (yes, I know) was determined to make the finest quality hi-fi equipment and spared little in the quest to do so. His build cost was double and then some of what his nearest competitor, McIntosh, spent per unit. I've never wanted anything made by Marantz, could always have been a lot better. Have you ever seen a marantz 2, 5 or 8B amplifier or a 9 or 9C preamp??????????? I don't think they ever sold them in Australia. Maybe you are unaware that before the Japanese bought them they were US made and quite expensive. The reissue Mc 275s are not very good as compared to the originals except for the chassis. |
#51
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NFB windings, was there a US style and UK style?
So prejudice remains, but is
still breaking down and the arabs will blend in a generation and Islam fades to relative unimportance and the whole becomes homogenous and Whites slowly appreciate what the arabs bring. It was the arabs who brought coffee to the west in the first place. And before that we sent the crusades to butcher them. Its amazing so few Islamic extremists like Arsole Bin Laden have come to spoil the party we've been having at the expense of brown skin exploitation by Whites. We have a White Woman as our dear leader and she's having dreadful trouble dealing with horrible untidy unwashed brown illegals, and she plans to do all sorts of inhumane things to them. She's also having frightful trouble getting ppl to believe in her Carbon Tax. Now just where is a good strong fit brown man who can be a good leader when you want one? 5000 years of history calls bull**** on this. You'd be smart to boot all nonwhites except for the abbos and put them in a nice, safe fenced off area where they can live as they always have with NO CONTACT with the whites. Leave them alone as if whites never came so people can see what 50,000 years of progress is for a 55 IQ race. And shoot any white who ****s one. Race mixing equals death for any people. |
#52
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NFB windings, was there a US style and UK style?
In article ,
Bret Ludwig wrote: *Saul Marantz (yes, I know) was determined to make the finest quality hi-fi equipment and spared little in the quest to do so. His build cost was double and then some of what his nearest competitor, McIntosh, spent per unit. I've never wanted anything made by Marantz, could always have been a lot better. Have you ever seen a marantz 2, 5 or 8B amplifier or a 9 or 9C preamp??????????? I owned a Marantz 8B in the day, I would have thought it would have received high marks from Patrick, at least as high he would give any commercial product. It even uses the sort of circuit he espouses, I'm not sure if the OPT would be up to his standards though. I never heard of the Marantz 9 or 9C? -- Regards, John Byrns Surf my web pages at, http://fmamradios.com/ |
#53
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NFB windings, was there a US style and UK style?
On Jun 2, 12:00*am, John Byrns wrote:
In article , *Bret Ludwig wrote: *Saul Marantz (yes, I know) was determined to make the finest quality hi-fi equipment and spared little in the quest to do so. His build cost was double and then some of what his nearest competitor, McIntosh, spent per unit. I've never wanted anything made by Marantz, could always have been a lot better. *Have you ever seen a marantz 2, 5 or 8B amplifier or a 9 or 9C preamp??????????? I owned a Marantz 8B in the day, I would have thought it would have received high marks from Patrick, at least as high he would give any commercial product. * It even uses the sort of circuit he espouses, I'm not sure if the OPT would be up to his standards though. I never heard of the Marantz 9 or 9C? -- Regards, John Byrns Surf my web pages at, *http://fmamradios.com/ I had a look at all Marantz models 5 to 9. They do look well on paper with a 6BH6 ( like a 6AU6 ) in triode for V1, then a 6CG7 direct coupled LTP like Mullard does, with EL34 outputs in UL. Not too many problems with all that but the anode loads for 6CG7 are way too low, and consist of 5k pot for AC balancing.with 15k to each anode when it really should be 47k The obvious mod to make it all work better is to have CR coupling from V1 SET 6BH6 to one 6CG7 grid biased for 0V, then have the other grid grounded, then have a negative rail of say -200Vdc to -400Vdc for the common Rk, and then get the B+ to be higher and then you have 6CG7 Ea and Ia higher with RL higher and maybe the THD of the stage is much reduced. A CCS LTP tail taken to say -50V would be best though because the pot for AC balance can be omitted if the RL for each anode is equal which is easy to do these days. The Marantz OPT takes most of its LF NFB from the 4 ohm tap on the sec. But there is an additional NFB winding with its live end connectd to the 16 ohm tap via 10 ohms, and the NFB winding feeds HF NFB to the V1 cathode via 1.2nF. I'd guess the NFB winding does not experience the same phase shift caused by LL and the load at HF, so Marantz manages to apply NFB over a wide BW without trying to fix the phase lag at HF. But without having a Marantz here to examine, I cannot say exactly how well the arrangement works, or understand exactly how Marantz wound its OPTs. How can I endorse something I have never examined properly? Impossible. But if Marantz had used a 5P x 4S interleaving pattern with 6 secondary sections each for 16, 8 &4 ohms and all paralleled, there would have been no need for a NFB winding because such interleaving with paralleled secs give wide BW for this sort of amplifier as Williamson and McIntosh have so so clearly established over the last 60 years. Tapped secondaries usually have higher winding resistance than where 4 sec sections are strapped in different patterns for the load match variations. Most manufactuers have used appallingly thin wire in OPT secs and rarely ever have 4 Sec sections; two if you are lucky, and often the two will each be a match for 4 ohms, so that the two series S sections give 16 ohms, a tap along one section gives 8 ohms, and only one section is then used for the 4 ohm match and it is with 4 ohms that there is the highest LL and worst BW and highest instability and highest winding losses. As i said, for good performance for a 50W OPT, you'll need 5P x 4S, and each Sec section should be a match for 16 and so with 4 ohms you still have 5P x 4S interleaving, even though 1/2 the sec turns are unused. The strapped method of changing Z match on OPTs is often done poorly. For example, in Quad-II there are only two link changes needed for 8 or 16 ohms, but no official match for 4 ohms. Walker must have pondered how to set up the OPT and its strapping method long and hard to satisfy a Nation Full of Dumbos who are confused if forced to count beyond 3. Quad-II would be a MUCH better amp if it were possible to strap all OPT secs to get a wasteless arrangement of secs so that every length of secondary wire had the same current density. Then the Quad-II would have allowed a P-S load match of 4k0 : 4 ohms which would better suit most modern LS, and of course using 8 ohms on the 4 ohm outlet gives 8k0 : 8 ohms and nearly all class A which suits the old junk circuit best. See why I say old junk is OLD JUNK? Its because I can see that the old gizas who designed all that old junk *could* have made masterpeices with an extra 2 hour's thought and 4 hour's more labour. But alas, the designers were addicted to mediocrity. One more thought about LTPs. I find LTP with CCS cathode tail and high RL values and lotsa Ia with a 6CG7 or a pair of EL84, EL86 etc, are good. Consider the operation of any LTP with a 6SN7/6CG7 low µ triode pair and equal + and - 30Vrms outputs, and gain of each triode = 15. With one grounded grid, you need -2Vrms input to the live grid you get -1V at the common cathodes. So the Va across the input tube is 31Vrms and Va across the grounded grid tube it is 29Vrms, and so there is slight imbalance of Ea and therefore of the 2H and the stage will produce 2H even if both triodes are really identical. But balance is fair, and the 2H is usually negligible. Maybe it cancels with 2H from the SET input stage, or with some slight 2H in the OP stage, and maybe it don't, but PP amps all seem to produce *some* 2H. But the main THD from an LTP is the 3H, which adds to that produced in the OP stage unless the OP stage 3H has oppositely phased 3H which rarely ever occurs, so one should be keen to reduce 3H anywhere it is produced, while also minimizing 2H anywhere. To get the best Va balance across each triode in an LTP the pair should have balanced drive to each grid, as it was done with Williamson's balance drive amp. Now Williamson used SET input + SET concertina, but he could have used the same 2 triodes as an LTP input stage which would have largle eliminated any 2H from teh SET input stage. Alas he didn't have a decent transistor to bung in as the tail for the input stage CCS. But where the input LTP only has to produce about a volt from each anode to drive the following balanced amp it doesn't matter about the Va imbalance and 2H because this 2H will bea microscopic amount. If the balanced amp as Willy made it has its common cathode R increased to about 4k7, then the stage self balances far better and gives less THD. In recent years I have used the LTP with CCS forthe first stage with input to one grid and GNFB to the other grid and then had a pair of EL84 in triode in a balanced amp with a common Rk of at least 4k7 to -100V, and the dynamics and clarity of music became astounding. Each EL84 in triode with Ia = 10mA does about the same job with same gain as 4 triode sections of 6SN7/6CG7, or is like 4 x 6J5 in parallel. But the Ra of the EL84 is only 2k2 at ia = 10mA so any Miller C in the OP stage is handled better. In Ming-Da I have here with PP 845, there are a pair of 300B in LTP for the driver amp. It sounds fantabulous. Old dead bean counters are spinning in their graves at what Chinese sometimes do to make their amps spectacular looking. Unfortunately, the Chinese often turn music time into a spectacular event with thunder and flames, and the repairman has to find where the Cracker was hidden, ready to go off when conditions would soon allow. But once you remove Crackers from Ming Da, wow, PP 845 are really something. How can I just consider British and American trends of the past without thought of the present, and the the Chinese? Not easily. Patrick Turner. |
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NFB windings, was there a US style and UK style?
And so often one will say to a CEO, "Jesus Fred, doncha reckon if the OPT was smaller and lighter you'd make more profit?" *CEO replies, "Yeah, your'e right again Bill, let's talk to the winder guy...", and its a little more quality demolished by a bean counter. Nothing but your wholly fabricated B.S. fantasies. OK, cross to being a fly on the wall in BP boardroom, about 4 years ago. CEO, "Fred, you got those costings of gulf drilling?" Accountant, "Yes Bill, costs are extremely high and to get a return at current gas price we need to lower costs." CEO, "Oh, how do we do that? any suggestions?" Acc, "Well if we leave out the popenfusler pipe frame and use a vargated cement system instead of the usual fiodikic kantel method, we save 6 billion dollars over 4 years thus increasing profits by 2 billion..." CEO, "Ah, of course. Well let's do that vargate method then.." And that's how acountants get to design the drilling process in the gulf near you, with seriously high risks taken. Patrick Turner. |
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NFB windings, was there a US style and UK style?
On Jun 1, 3:06*pm, Bret Ludwig wrote:
*So prejudice remains, but is still breaking down and the arabs will blend in a generation and Islam fades to relative unimportance and the whole becomes homogenous and Whites slowly appreciate what the arabs bring. It was the arabs who brought coffee to the west in the first place. And before that we sent the crusades to butcher them. Its amazing so few Islamic extremists like Arsole Bin Laden have come to spoil the party we've been having at the expense of brown skin exploitation by Whites. We have a White Woman as our dear leader and she's having dreadful trouble dealing with horrible untidy unwashed brown illegals, and she plans to do all sorts of inhumane things to them. She's also having frightful trouble getting ppl to believe in her Carbon Tax. Now just where is a good strong fit brown man who can be a good leader when you want one? *5000 years of history calls bull**** on this. You'd be smart to boot all nonwhites except for the abbos and put them in a nice, safe fenced off area where they can live as they always have with NO CONTACT with the whites. Leave them alone as if whites never came so people can see what 50,000 years of progress is for a 55 IQ race. *And shoot any white who ****s one. Race mixing equals death for any people. The world won't mind when you die. Most would think some time soon would be fine. And you'll never be missed by very many. Patrick Turner. |
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NFB windings, was there a US style and UK style?
I owned a Marantz 8B in the day, I would have thought it would have received high marks from Patrick, at least as high he would give any commercial product. * It even uses the sort of circuit he espouses, I'm not sure if the OPT would be up to his standards though. I never heard of the Marantz 9 or 9C? God catch. The 7 and 7C were the preamps, they are suspiciously identical to the Mc C22, but better built and several years earlier. The 7T is the solid state version and not a bad pre itself. The 9 (no 9B or 9C) was a power amp and does not sound all that great, but looks impressive. The 10 and 10B were the tuners, with a scope, which impresses the unwashed. The later Day Sequerra has a spec an, shich is more useful, but not as well desgned as what's in most communications service monitors. |
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NFB windings, was there a US style and UK style?
The Marantz OPT takes most of its LF NFB from the 4 ohm tap on the sec. But there is an additional NFB winding with its live end connectd to the 16 ohm tap via 10 ohms, and the NFB winding feeds HF NFB to the V1 cathode via 1.2nF. I'd guess the NFB winding does not experience the same phase shift caused by LL and the load at HF, so Marantz manages to apply NFB over a wide BW without trying to fix the phase lag at HF. But without having a Marantz here to examine, I cannot say exactly how well the arrangement works, or understand exactly how Marantz wound its OPTs. How can I endorse something I have never examined properly? Impossible. But if Marantz had used a 5P x 4S interleaving pattern with 6 secondary sections each for 16, 8 &4 ohms and all paralleled, there would have been no need for a NFB winding because such interleaving with paralleled secs give wide BW for this sort of amplifier as Williamson and McIntosh have so so clearly established over the last 60 years. Tapped secondaries usually have higher winding resistance than *where 4 sec sections are strapped in different patterns for the load match variations. That's called "British Secondaries". Americans went with the 16/8/4 arrangement because that was more convenient for the USER. The Mercury Magnetics VTO100 in the old VTLs uses this as well. I think a lot of Partridges and the Radford used this as well. My guess is the VTO100 is a Radford copy. Most manufactuers have used appallingly thin wire in OPT secs and rarely ever have 4 Sec sections; two if you are lucky, and often the two will each be a match for 4 ohms, so that the two series S sections give 16 ohms, a tap along one section gives 8 ohms, and only one section is then used for the 4 ohm match and it is with 4 ohms that there is the highest LL and worst BW and highest instability and highest winding losses. As i said, for good performance for a 50W OPT, you'll need 5P x 4S, and each Sec section should be a match for 16 and so with 4 ohms you still have 5P x 4S interleaving, even though 1/2 the sec turns are unused. The strapped method of changing Z match on OPTs is often done poorly. For example, in Quad-II there are only two link changes needed for 8 or 16 ohms, but no official match for 4 ohms. Walker must have pondered how to set up the OPT and its strapping method long and hard to satisfy a Nation Full of Dumbos who are confused if forced to count beyond 3. Quad-II would be a MUCH better amp if it were possible to strap *all OPT secs to get a wasteless arrangement of secs so that every length of secondary wire had the same current density. Then the Quad-II would have allowed a P-S load match of 4k0 : 4 ohms which would better suit most modern LS, and of course using 8 ohms on the 4 ohm outlet gives 8k0 : 8 ohms and nearly all class A which suits the old junk circuit best. See why I say old junk is OLD JUNK? Its because I can see that the old gizas who designed all that old junk *could* have made masterpeices with an extra 2 hour's thought and 4 hour's more labour. *But alas, the designers were addicted to mediocrity. Well Patrick, you are just so much smarter than those old guys.......No one did that then because it was not necessary. You are a crank, is the bottom line. |
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NFB windings, was there a US style and UK style?
On Jun 4, 3:07*pm, Bret Ludwig wrote:
The Marantz OPT takes most of its LF NFB from the 4 ohm tap on the sec. But there is an additional NFB winding with its live end connectd to the 16 ohm tap via 10 ohms, and the NFB winding feeds HF NFB to the V1 cathode via 1.2nF. I'd guess the NFB winding does not experience the same phase shift caused by LL and the load at HF, so Marantz manages to apply NFB over a wide BW without trying to fix the phase lag at HF. But without having a Marantz here to examine, I cannot say exactly how well the arrangement works, or understand exactly how Marantz wound its OPTs. How can I endorse something I have never examined properly? Impossible. But if Marantz had used a 5P x 4S interleaving pattern with 6 secondary sections each for 16, 8 &4 ohms and all paralleled, there would have been no need for a NFB winding because such interleaving with paralleled secs give wide BW for this sort of amplifier as Williamson and McIntosh have so so clearly established over the last 60 years. Tapped secondaries usually have higher winding resistance than *where 4 sec sections are strapped in different patterns for the load match variations. *That's called "British Secondaries". Americans went with the 16/8/4 arrangement because that was more convenient for the USER. *The Mercury Magnetics VTO100 in the old VTLs uses this as well. I think a lot of Partridges and the Radford used this as well. My guess is the VTO100 is a Radford copy. *Most manufactuers have used appallingly thin wire in OPT secs and rarely ever have 4 Sec sections; two if you are lucky, and often the two will each be a match for 4 ohms, so that the two series S sections give 16 ohms, a tap along one section gives 8 ohms, and only one section is then used for the 4 ohm match and it is with 4 ohms that there is the highest LL and worst BW and highest instability and highest winding losses. As i said, for good performance for a 50W OPT, you'll need 5P x 4S, and each Sec section should be a match for 16 and so with 4 ohms you still have 5P x 4S interleaving, even though 1/2 the sec turns are unused. The strapped method of changing Z match on OPTs is often done poorly. For example, in Quad-II there are only two link changes needed for 8 or 16 ohms, but no official match for 4 ohms. Walker must have pondered how to set up the OPT and its strapping method long and hard to satisfy a Nation Full of Dumbos who are confused if forced to count beyond 3. Quad-II would be a MUCH better amp if it were possible to strap *all OPT secs to get a wasteless arrangement of secs so that every length of secondary wire had the same current density. Then the Quad-II would have allowed a P-S load match of 4k0 : 4 ohms which would better suit most modern LS, and of course using 8 ohms on the 4 ohm outlet gives 8k0 : 8 ohms and nearly all class A which suits the old junk circuit best. See why I say old junk is OLD JUNK? Its because I can see that the old gizas who designed all that old junk *could* have made masterpeices with an extra 2 hour's thought and 4 hour's more labour. *But alas, the designers were addicted to mediocrity. *Well Patrick, you are just so much smarter than those old guys.......No one did that then because it was not necessary. There were very few 4 ohm speakers in 1950. *You are a crank, is the bottom line. Indeed, and I can say why. Patrick Turner. |
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