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#1
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Phil Allison is dumb on OPTs.
Six more abusive following posts from PA have followed since my last one
on OPTs and using mains trannies as such, and there is no reason for me to reply. All the posts were insult laden, repititious, and without any good design ideas about OPTs. Even Phil's friend, Andre Jute, would roundly condemn any idea that decent performance with tubed PP with 2 x 6L6 is possible using mains derived toroidals, even those with "special" twin 240v windings to make the P a bit bigger. Andre rightly has said a lot in favour about Plitrons which are toroidals. They are a little more expensive, but they come with the right number of turns per volt to suit tube usage. Meanwhile, Phil Allison hasn't a clue about how to wind a really decent OPT fit for use with 2 x 6L6, or any other tubes. We should simply assume he is pig ignorant on the subject until he prooves otherwise. Good OPT design cannot be summed up in a series of simple one liners, interspersed with insults. We can assume PA has never designed, wound, and tested an OPT. For more about decent OPT design theory, turn to the RDH4, wherin there is all one needs to know about OPTs, but there is nothing about using toroidal transformers. Exactly how to wind toroidal OPTs with all the formulae to get a predictable result is a little thin on the Web, or in the old books, because toroidals were never wound in the old days en-masse; they have only come into vogue because modern winding machines can wind them more cheaply than an E&I transformer. Nearly all toroidals wound are mains transformers. The makers of E&I trannies responded to calls from their bean counter staff to reduce E&I tranny costs further by winding bobbins with a primary, and another with a secondary, and the two bobbins are slid together offering excellent isolation. GOSS E&I core material has been improved to the point where interleaving the laminations isn't needed, the bundle of Es and Is is simply butted together and welded. Even with an effective air gap, the core U is still high enough to keep the magnetising current low enough. There are no human hands involved in the process, and transformers for 1,001 purposes stream off production lines like sausages from a sausage machine. With a little refinement, and 10 minutes longer of machine time, decent OPTs could be made en-masse, but demand is infinitessimally small compared to mains trannies for SS amps, so we have to pay through the nose for OPTs. Even so, the cost of a replacement mains transformer for a Marantz SS hi-fi amp is quite high. The big companies like their profits to be high when they sell spares. Patrick Turner. |
#2
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On Sun, 18 Jan 2004 19:11:22 +1100, Patrick Turner wrote:
snip For more about decent OPT design theory, turn to the RDH4, wherin there is Unfortunately I'm not likely to be able to find that easily around here. It *may* be available via a reference library but that's about it. I suspect it is probably rather advanced for me at the moment too... ;-) snip With a little refinement, and 10 minutes longer of machine time, decent OPTs could be made en-masse, but demand is infinitessimally small That sums up the whole problem in a nutshell. Supply & demand. If I buy (what appears to be) Sowter's cheapest EL34 UL p-p 6k6 a-a transformer it is over 124ukp +carriage. To put that into perspective, it is over half my total income for a 3-day week. A 110+110:9+9 mains torroid is about 17ukp delivered. For that difference in price I can live with a 7W limit and a steep bass roll-off at anything up to 200Hz! ;-) I have a pair of "guitar amp" transformers which are about 4k a-a IIRC (I can check, but have no other info). I suspect that they would be worse than mains torroids at the top end - and there may not be much bass either with only a 32mm lamination stack. On the whole, I think it has been worth asking the question, even if Mr Allison's opinion of me has sunk somewhat... I'll not let it worry me. ;-) Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that has what appear to be "music centre" OPTs, probably intended for EL84s. Such is life... -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#3
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"Form@C" ... Patrick Turner wrote: For more about decent OPT design theory, turn to the RDH4, wherin there is Unfortunately I'm not likely to be able to find that easily around here. ** That book was written in 1952. Modern, machine wound, plastic wrap insulated, low cost toroidals came out much more recently. The transformer game has changed - the Turneroid is yet to catch up. ................. Phil |
#4
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On Sun, 18 Jan 2004 22:05:15 +1100, Phil Allison wrote:
"Form@C" ... Patrick Turner wrote: For more about decent OPT design theory, turn to the RDH4, wherin there is Unfortunately I'm not likely to be able to find that easily around here. ** That book was written in 1952. Modern, machine wound, plastic wrap insulated, low cost toroidals came out much more recently. The transformer game has changed - the Turneroid is yet to catch up. I will certainly be looking at torroids in some form. Even if I can't get "hi-fi" quality out of them it doesn't really matter. That isn't my field - I can't afford it! I like building with valves though; that's the attraction for me. I'll ask around for custom winding as you suggested. If the price isn't prohibitive I'll get one (or probably two) wound with dual primaries of as many turns as they can comfortably manage, put my own secondary on top by hand, and give them a spin to see (hear! - but "spin" sounds more apt for torroids!) how they work. I don't have much in the way of test gear, but since I'm only building for *me* the test results would mainly be just for academic interest. I might be able to do a response curve of sorts for the amp if I can persuade my old scope & kit-built oscillator to function. :-) Steve Bench's notch filter for distortion measurements may get built too. -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#5
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"Form@C" I will certainly be looking at torroids in some form. Even if I can't get "hi-fi" quality out of them it doesn't really matter. ** You easily can - hard to get otherwise. I'll ask around for custom winding as you suggested. ** Just ask that a secondary winding *equal in turns* to the primary one be fitted. Go for an 80 VA core size - the turns per volt is more manageable. put my own secondary on top by hand, ** Perfectly doable. The response will be flat to 50 kHz at least. Ignore what that lying Turnip arsehole says. He is just trying to prop up his transformer winding scam - at any cost to the truth. ........... Phil |
#6
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On Sun, 18 Jan 2004 23:51:38 +1100, Phil Allison wrote:
"Form@C" I will certainly be looking at torroids in some form. Even if I can't get "hi-fi" quality out of them it doesn't really matter. ** You easily can - hard to get otherwise. I'll ask around for custom winding as you suggested. ** Just ask that a secondary winding *equal in turns* to the primary one be fitted. Go for an 80 VA core size - the turns per volt is more manageable. put my own secondary on top by hand, ** Perfectly doable. Yep. Just added a 6.3 winding onto a little core to feed some heaters. As long as they don't pot the thing... :-) The response will be flat to 50 kHz at least. Ignore what that lying Turnip arsehole says. He is just trying to prop up his transformer winding scam - at any cost to the truth. grin Thanks for the advice. I'll investigate further & see what I can come up with. -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#7
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"Form@C" wrote: On Sun, 18 Jan 2004 19:11:22 +1100, Patrick Turner wrote: snip For more about decent OPT design theory, turn to the RDH4, wherin there is Unfortunately I'm not likely to be able to find that easily around here. It *may* be available via a reference library but that's about it. I suspect it is probably rather advanced for me at the moment too... ;-) OK. People who say what you have just said can start with the basics, and work up, so reading text books given to first year tech college students should be where you start, as well as build your own workshop where you can try circuits using basic R L and C. snip With a little refinement, and 10 minutes longer of machine time, decent OPTs could be made en-masse, but demand is infinitessimally small That sums up the whole problem in a nutshell. Supply & demand. If I buy (what appears to be) Sowter's cheapest EL34 UL p-p 6k6 a-a transformer it is over 124ukp +carriage. To put that into perspective, it is over half my total income for a 3-day week. But how long will it take you to make what Sowter supply? 3 mths? and six failed first attempts? I wound 3 terrible OPTs before I started to get predictable, and the items were usable. From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. That's a pretty decent paying job you got, ain't it? It takes me longer than 3 days to make two OPTs, and then there is the cost of materials. And the design calculations, testing, varnishing, etc..... A 110+110:9+9 mains torroid is about 17ukp delivered. For that difference in price I can live with a 7W limit and a steep bass roll-off at anything up to 200Hz! ;-) I have a pair of "guitar amp" transformers which are about 4k a-a IIRC (I can check, but have no other info). I suspect that they would be worse than mains torroids at the top end - and there may not be much bass either with only a 32mm lamination stack. I have pointed out in other posts why a 17 ukp mains tranny would be hopeless with a pair of 6L6. But to understand why I said what i said means you'd ned to undertsand the terminology, and the simple formulas governing the design parameters. That takes study. Don't worry, I am hopeless at studying Latin, or the habits of gay left flippered whales. On the whole, I think it has been worth asking the question, even if Mr Allison's opinion of me has sunk somewhat... I'll not let it worry me. ;-) Allison works on the principle that all students should be shot because they are ignorant. He bashes ppl into the dust, rather than lift them up with enlightenment. But accordingly, *you* have to make an effort to understand. Some folks have to spend years at a uni to know anything. Keep trying, but the PC may not be your saviour this time, and that's why teachers and colleges have not yet all been abandoned. I think I was lucky to make something from what I read at uni and tech college libraries, and from an array of ols books I acquired, and from several years spent locked up in my workshop well before I acquired a PC, and instead of watching TV, or socialising at the pub. Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that has what appear to be "music centre" OPTs, probably intended for EL84s. Such is life... The first watt might be total audio heaven, but what then when you want 10 watts? Patrick Turner. -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#8
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Phil Allison wrote: "Form@C" ... Patrick Turner wrote: For more about decent OPT design theory, turn to the RDH4, wherin there is Unfortunately I'm not likely to be able to find that easily around here. ** That book was written in 1952. The laws of physics have not changed since 1952, and RDH4 remains a classic tome which is very useful to anyone interested in tube circuit building. Each and every sentence says so much. Modern, machine wound, plastic wrap insulated, low cost toroidals came out much more recently. The transformer game has changed - the Turneroid is yet to catch up. ................ Phil I explained the background about toroidals and E&I trannies in enough detail in an earlier post which perhaps you failed to comprehend. Patrick Turner. |
#9
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Ignore what that lying Turnip arsehole says. If folks ignore what I have been saying for years about audio trannies, they will get very poor results from their efforts. He is just trying to prop up his transformer winding scam - at any cost to the truth. I don't supply audio trannies. I wind them, and place them in an amp, and sell the amp. I have no intention to compete with the low end of the transformer market. Now exactly what capablilities does Phil Allison have with regard to manufacturing anything? Has he ever built a tube amp? Has he ever designed and built any transformers? Or does he want to remain a dunderhead who recommends using mains trannies for tube PP hi-fi OPTs? Answer me this Phil, If what you say about toroidal mains trannies is true, then why have there not been a plethera of ready made available OPTs manufactured just like mains toroids? Its because none of the toroidal mains trannies have anywhere near enough turns per volt for audio use. For that one must go to Plitron. No use going to Phil for an OPT, he ain't even got a clue how to wind a decent one. Patrick Turner. |
#10
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On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote:
snip From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. Nope - That price was *each*. They are 6 days per pair - if I don't include for minor things like supporting the family, paying for food & other necessities... My job isn't that brilliant! It probably works out at about 12 months in real terms to get a pair of Sowter's EL34 babies. :-( snip I have pointed out in other posts why a 17 ukp mains tranny would be hopeless with a pair of 6L6. Yes, thank you very much, But to understand why I said what i said means you'd ned to undertsand the terminology, and the simple formulas governing the design parameters. That takes study. Don't worry, I am hopeless at studying Latin, or the habits of gay left flippered whales. grin I'll certainly have a bash at the theory. snip Oh - my SE 6L6 amp sounds quite pleasant now... Unfortunately, that has what appear to be "music centre" OPTs, probably intended for EL84s. Such is life... The first watt might be total audio heaven, but what then when you want 10 watts? If I get 10 out of this, then I'm probably in trouble and had better watch for the smoke... ;-) I appreciate what you say though. -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#11
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"Form@C" wrote: On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote: snip From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. Nope - That price was *each*. They are 6 days per pair - if I don't include for minor things like supporting the family, paying for food & other necessities... My job isn't that brilliant! It probably works out at about 12 months in real terms to get a pair of Sowter's EL34 babies. :-( Hey guys It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s #7 Try to get the "made in China" transformers somehow. It's not impossible I have heard about people using mains transformers and also 70V line transformers to good effect, in budget projects involving EL-84s. I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? I bet it would be possible to do a philips push pull OTL cct with a torroidial mains transforomer to match the output to normal speakers. Sure you wouldn't use either of these options in a high dollar project, but if your object is having some fun messing around with tubes, and getting a decent sounding amplifier out of the deal, then go for it. I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. Just my $0.02 Max |
#12
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"Patrick Turner" Ignore what that lying Turnip arsehole says. If folks ignore what I have been saying for years ... ** Then the whole human race would be enormously better off. Or does he want to remain a dunderhead who recommends using mains trannies for tube PP hi-fi OPTs? ** What a ****ing liar the Turneroid is. What an unmitigated pig ignorant ****. Answer me this Phil, If what you say about toroidal mains trannies is true, ** Post under my words - you stinking, lying arsehole. Its because none of the toroidal mains trannies have anywhere near enough turns per volt for audio use. ** Massive lie - quite normal for the brain ****ed Turneroid ............ Phi; |
#13
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"Patrick Turner" wrote in message ... Phil Allison wrote: ** That book was written in 1952. Modern, machine wound, plastic wrap insulated, low cost toroidals came out much more recently. The transformer game has changed - the Turneroid is yet to catch up. ................ Phil I explained the background about toroidals and E&I trannies in enough detail in an earlier post ** You explained NOTHING. Since you know NOTHING. Go drop dead. ........... Phil |
#14
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On Sun, 18 Jan 2004 21:07:43 +0000, Max Holubitsky wrote:
snip It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond hmmm... Only 1 official outlet that I know of in the UK, Farnell. They don't carry the audio range though. #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) All good fun if you are in the right place at the right time! Radio rallies are the best, but they are few & far between. #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s They do, but don't stock them in the shops - only to order. They have reduced the prices slightly now: about £30 each. I've found the firm that winds them and they can do a "better" version (but still no full spec) for £45-38 inclusive. That probably partially accounts for the reduction - and they are probably about to discontinue them anyway! #7 Try to get the "made in China" transformers somehow. It's not impossible guitar amp trannies are available if you can find places that repair them. There are one or two smaller manufacturers around, but their products (like the Maplin ones) are not really hi-fi, but a step up from most guitar amps... snip I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. Just my $0.02 ....and worth every cent! I pointed out somewhere that bass response wouldn't be too important with smallish sealed boxes. They just won't go low enough to be able to hear the distorted bass! Mechanical high-pass filtering. :-) These are supposed to be -4dB at 85Hz. From the graph (optimist!) they are almost -20dB at 40Hz, so my chances of hearing the clipping on a 20Hz signal are pretty low I should think. http://www.allansonline.com/Anatomy/...y/pages/p7.htm if you fancy a trip down memory lane... :-) insert Deity here knows what the response is now that they've been carved up over the years... ;-) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#15
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"Form@C" wrote: On Sun, 18 Jan 2004 21:07:43 +0000, Max Holubitsky wrote: snip It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond hmmm... Only 1 official outlet that I know of in the UK, Farnell. They don't carry the audio range though. Special order is possible... I have no idea about who would sell them in the UK, perhaps someone here could help? I'm from Canada, so of course I have to recommend a local product. #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) All good fun if you are in the right place at the right time! Radio rallies are the best, but they are few & far between. Never underestimate the power of eBay Or this newsgroup for that matter... Jon Yaeger sold me a McIntosh preamp for $100... it's not in mint condition, but jeez $100 for a McIntosh, how can you beat that! I use it as a phono preamp, pretty much constantly! I recently picked up a Dynaco ST-70 Series II, from the early 90s, on rec.audio.marketplace. For $200, it comes with two broken output tubes, but it's in good physical condition. Now there's 2 output transformers, a power transformer - in fact an entire amplifier for less than what you would pay for one Sowter transformer. I intend to use it in the living room, with a Rotel SS preamp, where my old RCA theatre amps would seem a little bit too rugged. I must say that this was a pure impulse buy, but it just goes to show that good deals can be had, and all you have to do is keep your eyes open, and jump on a bargain as soon as you see it. #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s They do, but don't stock them in the shops - only to order. They have reduced the prices slightly now: about £30 each. I've found the firm that winds them and they can do a "better" version (but still no full spec) for £45-38 inclusive. That probably partially accounts for the reduction - and they are probably about to discontinue them anyway! Nothing's wrong with mail order, and a little waiting. Sowter would make you wait, anyhow. The 4-20 was no overachiever, but the specs looked good enough. #7 Try to get the "made in China" transformers somehow. It's not impossible guitar amp trannies are available if you can find places that repair them. There are one or two smaller manufacturers around, but their products (like the Maplin ones) are not really hi-fi, but a step up from most guitar amps... I've never tried any of those options... except in guitar amps. One half assed sub the radio guys use, is to replace an output transformer in an AA5 with a 117:6.3 V filament transformer. snip I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. Just my $0.02 ...and worth every cent! Thanks! I pointed out somewhere that bass response wouldn't be too important with smallish sealed boxes. They just won't go low enough to be able to hear the distorted bass! Mechanical high-pass filtering. :-) These are supposed to be -4dB at 85Hz. From the graph (optimist!) they are almost -20dB at 40Hz, so my chances of hearing the clipping on a 20Hz signal are pretty low I should think. Building a high pass filter into the amplifier may also be a good idea, just to avoid letting the distortion occur in the output tranny, as its higher harmonics will be clearly audible, despite the fundamentals being filtered out. http://www.allansonline.com/Anatomy/...y/pages/p7.htm if you fancy a trip down memory lane... :-) insert Deity here knows what the response is now that they've been carved up over the years... ;-) Look neat... I haven't got much experience with KEF's, aside from some reference series from the late 80s. Those were some killer sounding speakers, driven by a Carver 200wpc power amp... not my system though, but my grandfather's hi-fi... I still use it when I visit. |
#16
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Max Holubitsky wrote: "Form@C" wrote: On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote: snip From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. Nope - That price was *each*. They are 6 days per pair - if I don't include for minor things like supporting the family, paying for food & other necessities... My job isn't that brilliant! It probably works out at about 12 months in real terms to get a pair of Sowter's EL34 babies. :-( Hey guys It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s #7 Try to get the "made in China" transformers somehow. It's not impossible Gee, I dunno what sort of audiophile I might be, but you just mentioned 7 unacceptable options for me. And No 8, using mains toroidals is a worser option than 1-7. I have heard about people using mains transformers and also 70V line transformers to good effect, in budget projects involving EL-84s. I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? Nope. I bet it would be possible to do a philips push pull OTL cct with a torroidial mains transforomer to match the output to normal speakers. Sure you wouldn't use either of these options in a high dollar project, but if your object is having some fun messing around with tubes, and getting a decent sounding amplifier out of the deal, then go for it. I suggested an SE design using paralleled tubes might just work with a toroidal with a 240 primary, using a parafeed arrangement. A second 240v winding wound over the top of the existing 240v P and Sec would just give enough P turns to allow B to be low enough for audio. If the tubes are 6AS7 triodes, Vo might be only 100v, indeed B would then be OK. Circlotron is also a good PP option. I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. I am peeved at the folks whose net worth is $500,000, say a house, car, and all their gear, and an expensive wife, but when it come to their real passion, audio, they try to wheedle out of spending anything. They think nothing of spending $300 to get a plumber to unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's smile, or 10k on a kitchen for the missus, but whinge for 6 mths about transformer costs, and end up making one compromise after another. Patrick Turner. Just my $0.02 Max |
#17
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Patrick Turner wrote: Max Holubitsky wrote: "Form@C" wrote: On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote: snip From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. Nope - That price was *each*. They are 6 days per pair - if I don't include for minor things like supporting the family, paying for food & other necessities... My job isn't that brilliant! It probably works out at about 12 months in real terms to get a pair of Sowter's EL34 babies. :-( Hey guys It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s #7 Try to get the "made in China" transformers somehow. It's not impossible Gee, I dunno what sort of audiophile I might be, but you just mentioned 7 unacceptable options for me. And No 8, using mains toroidals is a worser option than 1-7. Pat, what's wrong with Hammond? And also, what's wrong with the transformers from, say, a Sansui 1000A? We're not talking ultra-fi here, but an amplifier built around either of those options is going to measure okay, and provide enjoyment to whoever built it. The Maplin 4-20, while again not in the ultra high fidelity category still provided what many people considered acceptable performance. Also, what's wrong with option #5? I've seen lots of people selling used transformers over the years... I would have no problem using an old pair of Arcosound units, Hammond, or even Stancor. Please keep in mind these options are *presented for people on a budget, who want to make a tube amplifier*, and not for someone with an unlimited budget. Given an unlimited budget, I'd buy the most expensive potted Japanese transformers money could buy and call it a day! I have logged many thousands of hours on a pair of Hammonds I bought in 1994, and although they're currently out of service, I got much satisfaction out of the amplifiers I built around them. In 1994, as a 16 year old I had to scrape together a large bit of my savings to pay for the transformers (mind you, they've gone way up in price since then) According to you I should have not got them, and given up on audio? How arrogant! I have heard about people using mains transformers and also 70V line transformers to good effect, in budget projects involving EL-84s. I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? Nope. Why not? EL-86s have a lower working voltage, and need a lower impedance output transformer, so they'll not saturate the transformer as quickly as an EL84, etc would. I bet it would be possible to do a philips push pull OTL cct with a torroidial mains transforomer to match the output to normal speakers. Sure you wouldn't use either of these options in a high dollar project, but if your object is having some fun messing around with tubes, and getting a decent sounding amplifier out of the deal, then go for it. I suggested an SE design using paralleled tubes might just work with a toroidal with a 240 primary, using a parafeed arrangement. A second 240v winding wound over the top of the existing 240v P and Sec would just give enough P turns to allow B to be low enough for audio. Parafeed? You may as well just get a gapped OPT and be done with it. What is the advantage to this setup, in either dollars, or performance, over buying a pre made gapped OPT from any reasonable supplier? If the tubes are 6AS7 triodes, Vo might be only 100v, indeed B would then be OK. Circlotron is also a good PP option. Why would someone who is saving money on transformers to the point of using a mains transformer want to build the complicated power supply arrangements required by a circlotron? I agree with you about the 6AS7 option however, it sounds like a good one to me. I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. I am peeved at the folks whose net worth is $500,000, say a house, car, and all their gear, and an expensive wife, but when it come to their real passion, audio, they try to wheedle out of spending anything. They think nothing of spending $300 to get a plumber to unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's smile, or 10k on a kitchen for the missus, but whinge for 6 mths about transformer costs, and end up making one compromise after another. This sounds like a personal issue to me. Anyone whose real passion is audio, i.e. members of this newsgroup, is more likely to spend a disproportionate amount of their disposable income on audio. If they are really being cheap, then maybe their paission lies elsewhere? Maybe family is more important to them? Maybe it's hard to justify buying thousand dollar transformers to the wife, when there exists bills to pay? Who are you to judge? If on the other hand, the individual really does have a low income, why should he deny himself the right to having some fun with tube audio equipment just because his transformers don't meet Mr. Turner's spec? I for one would much rather see a person spending his free time lashing together a simple amplifier out of the cheapest bottom end Hammond products, and some used parts salvaged from old radios and TVs, than see him throw up his arms and buy a Sony home theatre receiver. Maybe he will learn the limitations of his modest setup, and then move on to bigger and better things once he has the funds in place. Or, maybe he'll decide tube equipment is not for him... if so, then so what? Patrick Turner. Just my $0.02 Max |
#18
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Hi Max,
I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? EL86/6CW5 is a *mucho*difficult* beast to deal with, at least in rather conventional PP circuitry. I am no tube expert at all, but I had EL86 PP on the breadboard during the last 1/4 year with lots of power stage and PI stage topologies. My notes in the scratchbook of this project are covering more than 30 pages already by now ... To put a long story quite short, I think EL86/6CW5 in PP (pure pentode or UL - I didn't try pseudo triode) is very discriminating regarding the iron, when it comes to "measure _AND_ sound right". Sonically, I failed completely when using the seemingly very suitable iron of a highly regarded small German company. Technically, I had lots of trouble to get some standard Hammond iron to work decently with EL86. Don't use EL86/6CW5 in PP mode unless you have *lots* of time to spare to fiddle with seamingly "little side problems" like really suitable iron, or PI stages which have to deliver quite some voltage swing while only having ~200 volts of B+ available ... I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers what would make it worthwhile anyways. At least regarding my situation, your assumption is wrong. I _have_ very good (and quite expensive to me) speakers to test my DIY projects with, but I am not willing to spend Sowter iron prices "for a try to see/hear/learn what happens" amp type project. Eventually I got it sounding and measuring right (compared to a commercial German 70's design, Klein & Hummel VS70, I am lucky to have at hand to run measurements and and sound test against), but at the moment I am right on the edge of dropping this EL86 PP project completely in favour of much "simpler" and better sounding tube/iron combinations. So, I suggest to avoid EL86/6CW5 PP op, unless you have much time to spent to get it right. Tom -- The first rule of magick is simple: Don't waste your time waving your hands and hoping, when a rock or club will do. |
#19
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Hi Max,
EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? Nope. Why not? EL-86s have a lower working voltage, and need a lower impedance output transformer, so they'll not saturate the transformer as quickly as an EL84, etc would. In the context of this thread, which (partly) is about saturation issues of toroid (PP) OPTs, you are probably right when thinking of chosing EL86 instead of EL84 just because of the lower B+ voltage. But that is just only one part of the story, when EL86 is mentioned. Please see my other article in this thread - I found EL86 definitely is not an "easy going" tube to deal with like, say, EL84/6BQ5. But, to stay with the intention of what you ment, there surely are lots of other "high current, low B+" type tubes which one could have a try with regarding "not intended for audio usage" toroid OPTs. Especially pass regulator tubes like 6AS7 and the EL504/EL509 family come to mind. Maybe even those 6C33C monsters :-) Tom P.S.: I am slowly working my DIY way to replace a Velleman K4000 (double EL34 PP / ch) in my living room with a DIY'd amp. The Velleman K4000 (and its successor K4040) uses toroid core OPTs of not-known-to-me origin. The circuit and the OPTs surely deliver tons of sheer power, but I suspect that just these OPTs are the (sonical) reason, why I am working to replace this amp by a DIY one, since the rest of the K4000 circuit doesn't explain why I dislike the K4000 this much sonically compared in double blind tests (not only by myself) to several of my first DIY amps. But I know too less about tube amp technology to surely point at the K4000 OPT toroids to say "that's the reason why". -- Okay, maybe i am paranoid. But that doesn't mean they are not out to get me. - unknown |
#20
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A couple of opinions to add to the soup . . .
To your point, Max, I've heard that Sansui transformers were often Tamuras and that one fellow claimed he measured the bandwidth on the 1000A iron and that it was better than the Dyna ST70 OPTs. I'm not far from completing a Sansui 1000A rebuild (for a photo see www.yaegeraudio.com) and I'll soon be able to confirm or dispute that claim. If you can't afford good OPT iron, you might try an OTL - I'm also building a variation on Bruce Rosenblitz's 25W/channel amp using EL509s. I bought custom power supply iron from Plitron to save on space and probably expense .. . . I'll have a few photos of that project eventually. I really miss Fred Nachbaur and his hobbyist ethic - to try to use almost anything and everything (especially "budget" parts) to try to make a purse out of a pig's ear . . . Best of all was his helpful attitude and inobtrusive manner. I'm sure he's had a few brilliant successes along the way. Many folks here could learn a lot from Fred. From what I've read and heard there are problems with 6AS7s such as bad matching between sections; the tendency of some brands to flash over (with the possibility of further catastrophe). I bought a mess of them but decided to abandon the project. I guess I'll use them for PS regulation . . .. - Jon Pat, what's wrong with Hammond? And also, what's wrong with the transformers from, say, a Sansui 1000A? We're not talking ultra-fi here, but an amplifier built around either of those options is going to measure okay, and provide enjoyment to whoever built it. The Maplin 4-20, while again not in the ultra high fidelity category still provided what many people considered acceptable performance. Also, what's wrong with option #5? I've seen lots of people selling used transformers over the years... I would have no problem using an old pair of Arcosound units, Hammond, or even Stancor. Please keep in mind these options are *presented for people on a budget, who want to make a tube amplifier*, and not for someone with an unlimited budget. Given an unlimited budget, I'd buy the most expensive potted Japanese transformers money could buy and call it a day! I have logged many thousands of hours on a pair of Hammonds I bought in 1994, and although they're currently out of service, I got much satisfaction out of the amplifiers I built around them. In 1994, as a 16 year old I had to scrape together a large bit of my savings to pay for the transformers (mind you, they've gone way up in price since then) According to you I should have not got them, and given up on audio? How arrogant! I have heard about people using mains transformers and also 70V line transformers to good effect, in budget projects involving EL-84s. I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? Nope. Why not? EL-86s have a lower working voltage, and need a lower impedance output transformer, so they'll not saturate the transformer as quickly as an EL84, etc would. I bet it would be possible to do a philips push pull OTL cct with a torroidial mains transforomer to match the output to normal speakers. Sure you wouldn't use either of these options in a high dollar project, but if your object is having some fun messing around with tubes, and getting a decent sounding amplifier out of the deal, then go for it. I suggested an SE design using paralleled tubes might just work with a toroidal with a 240 primary, using a parafeed arrangement. A second 240v winding wound over the top of the existing 240v P and Sec would just give enough P turns to allow B to be low enough for audio. Parafeed? You may as well just get a gapped OPT and be done with it. What is the advantage to this setup, in either dollars, or performance, over buying a pre made gapped OPT from any reasonable supplier? If the tubes are 6AS7 triodes, Vo might be only 100v, indeed B would then be OK. Circlotron is also a good PP option. Why would someone who is saving money on transformers to the point of using a mains transformer want to build the complicated power supply arrangements required by a circlotron? I agree with you about the 6AS7 option however, it sounds like a good one to me. I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. I am peeved at the folks whose net worth is $500,000, say a house, car, and all their gear, and an expensive wife, but when it come to their real passion, audio, they try to wheedle out of spending anything. They think nothing of spending $300 to get a plumber to unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's smile, or 10k on a kitchen for the missus, but whinge for 6 mths about transformer costs, and end up making one compromise after another. This sounds like a personal issue to me. Anyone whose real passion is audio, i.e. members of this newsgroup, is more likely to spend a disproportionate amount of their disposable income on audio. If they are really being cheap, then maybe their paission lies elsewhere? Maybe family is more important to them? Maybe it's hard to justify buying thousand dollar transformers to the wife, when there exists bills to pay? Who are you to judge? If on the other hand, the individual really does have a low income, why should he deny himself the right to having some fun with tube audio equipment just because his transformers don't meet Mr. Turner's spec? I for one would much rather see a person spending his free time lashing together a simple amplifier out of the cheapest bottom end Hammond products, and some used parts salvaged from old radios and TVs, than see him throw up his arms and buy a Sony home theatre receiver. Maybe he will learn the limitations of his modest setup, and then move on to bigger and better things once he has the funds in place. Or, maybe he'll decide tube equipment is not for him... if so, then so what? Patrick Turner. Just my $0.02 Max |
#21
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Hey Jon,
Jon Yaeger wrote: A couple of opinions to add to the soup . . . To your point, Max, I've heard that Sansui transformers were often Tamuras and that one fellow claimed he measured the bandwidth on the 1000A iron and that it was better than the Dyna ST70 OPTs. I've heard this from a few people too - with that sort of iron I suspect that your rebuild is going to sound as good as it looks, which is pretty nice! I'm not far from completing a Sansui 1000A rebuild (for a photo see www.yaegeraudio.com) and I'll soon be able to confirm or dispute that claim. If you can't afford good OPT iron, you might try an OTL - I'm also building a variation on Bruce Rosenblitz's 25W/channel amp using EL509s. I bought custom power supply iron from Plitron to save on space and probably expense . . . I'll have a few photos of that project eventually. OTL amplifiers may have their advantages, but is cost savings really one of them? Once you add together the price of all the tubes, the huge transformers, filter capacitors, sockets, etc. and then replacement tubes and power consuption, I'm willing to bet that one could buy a decent quality output transformer. An OTL amplifier is the proverbial combination space heater/boat anchor, as well as being the only form of tube amplifier which is flat practically down to DC. All the same it sounds like a really cool project, and I am interested in finding out how it works out for you. I really miss Fred Nachbaur and his hobbyist ethic - to try to use almost anything and everything (especially "budget" parts) to try to make a purse out of a pig's ear . . . Best of all was his helpful attitude and inobtrusive manner. I'm sure he's had a few brilliant successes along the way. Many folks here could learn a lot from Fred. I agree with you completely. Fred's approach kept the fun aspect in the hobby, which is really the reason why I'm interested in it. From what I've read and heard there are problems with 6AS7s such as bad matching between sections; the tendency of some brands to flash over (with the possibility of further catastrophe). I bought a mess of them but decided to abandon the project. I guess I'll use them for PS regulation . . I've read that the Russian 6AS7's are supposedly good. The Atma-Sphere amplifiers have used them for many years, so I think that despite all negativity about them, 6AS7's are not half bad. I have also seen them used in a World Audio Design SET amplifier from the early 90s, using a single tube for both channels. I think it was rated at something like 4wpc, and was built for quite a few years. I don't know how long the tubes lasted in them, but the amplifier was on the market for quite a while. Russ Sadd, who used to post here regularly, also built an amp based on the 6AS7. I think it worked well for him as well, so I wouldn't totally rule out using these in a practical amplifier. |
#22
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On Mon, 19 Jan 2004 16:42:09 -0500, Jon Yaeger wrote:
snip From what I've read and heard there are problems with 6AS7s such as bad matching between sections; the tendency of some brands to flash over (with the possibility of further catastrophe). I bought a mess of them but decided to abandon the project. I guess I'll use them for PS regulation . . . I read something about poor matching somewhere. I think it was a p-p amp using one or two. The designer put a balance pot to the cathodes IIRC to help correct it. I've considered trying one with a mains transformer opt.... (Oh No! Not THAT again!!! - Shut up Mick!) -- Mick http://www.nascom.info for Nascom & Gemini information Also at http://www.mixtel.co.uk where the collection started. Currently deserting M$ for linux... :-) |
#23
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Max Holubitsky wrote: Patrick Turner wrote: Max Holubitsky wrote: "Form@C" wrote: On Mon, 19 Jan 2004 03:07:44 +1100, Patrick Turner wrote: snip From what you are saying, it takes you three days to earn enough to buy 2 Sowter trannies. Nope - That price was *each*. They are 6 days per pair - if I don't include for minor things like supporting the family, paying for food & other necessities... My job isn't that brilliant! It probably works out at about 12 months in real terms to get a pair of Sowter's EL34 babies. :-( Hey guys It's fun being a low budget audiophile. There's a few ways to get low cost OPT's. #1. Hammond #2 Hammond #3 Used, from 60s receievers. #4 Used, from old PA amplifiers #5 Used, from other hobbiests who went half way, and gave up on a project (WTB: OPT's for amplifier project, etc) #6 Maplin may still sell the trannies they made for their Millenium 4-20 back in the 90s #7 Try to get the "made in China" transformers somehow. It's not impossible Gee, I dunno what sort of audiophile I might be, but you just mentioned 7 unacceptable options for me. And No 8, using mains toroidals is a worser option than 1-7. Pat, what's wrong with Hammond? And also, what's wrong with the transformers from, say, a Sansui 1000A? We're not talking ultra-fi here, but an amplifier built around either of those options is going to measure okay, and provide enjoyment to whoever built it. Nothing wrong with Hammond et all, as long as non ultra hi-fi is all you want. I have used rather poor quality OPTs meant for 6GW8 with 6CM5 in triode ( no way UL or b.terode is possible ). I get a reasonable 22 watts /channel. 12 dB global FB is the max possible, and cap loads peak the output. Sounds OK though. The Maplin 4-20, while again not in the ultra high fidelity category still provided what many people considered acceptable performance. Also, what's wrong with option #5? Usually option 5 is onobtainium, a very rare commodity. I've seen lots of people selling used transformers over the years... I would have no problem using an old pair of Arcosound units, Hammond, or even Stancor. Please keep in mind these options are *presented for people on a budget, who want to make a tube amplifier*, and not for someone with an unlimited budget. Given an unlimited budget, I'd buy the most expensive potted Japanese transformers money could buy and call it a day! Or learn to wind your own properly, and find that maybe the potted japanese transformers were no big deal..... I have logged many thousands of hours on a pair of Hammonds I bought in 1994, and although they're currently out of service, I got much satisfaction out of the amplifiers I built around them. In 1994, as a 16 year old I had to scrape together a large bit of my savings to pay for the transformers (mind you, they've gone way up in price since then) According to you I should have not got them, and given up on audio? How arrogant! Calm down. People with limited means have to compensate with intelligence and careful choice and techniques to acquire a decent system over time. The amount of recycled OPTs I find to use with larger octal tubes is miniscule. Nearly everyone bought 10 watt amps back in 1960, and ran sensitive speakers. Most of theose speakers are dead, and so are the OPTs.... Probably a few good ones buried at the tip, but I ain't gonna dig em up. I just go to my shed and wind them up. The material for a 100 watt OPT can be got for US $70, and the rest is just time and patience, instead of watching mindless TV shows, or boozing at the pub, etc. Follow what RDH says, and you can't go wrong. The slightly better core material made now ensures what you wind will have less distortion than the cores available in 1952. In the old days, amateur radio folks built their own receivers, transmitters, RF coils, and antennas. Audio amateurs do the same but its amps, transformers, speakers, etc..... When making the amps that I sell to ppl, I have not lost sight of idealism. Patrick Turner. I have heard about people using mains transformers and also 70V line transformers to good effect, in budget projects involving EL-84s. I wonder if EL-86's would be a good choice for mains XFMR's, due to their lower working voltage? Nope. Why not? EL-86s have a lower working voltage, and need a lower impedance output transformer, so they'll not saturate the transformer as quickly as an EL84, etc would. I bet it would be possible to do a philips push pull OTL cct with a torroidial mains transforomer to match the output to normal speakers. Sure you wouldn't use either of these options in a high dollar project, but if your object is having some fun messing around with tubes, and getting a decent sounding amplifier out of the deal, then go for it. I suggested an SE design using paralleled tubes might just work with a toroidal with a 240 primary, using a parafeed arrangement. A second 240v winding wound over the top of the existing 240v P and Sec would just give enough P turns to allow B to be low enough for audio. Parafeed? You may as well just get a gapped OPT and be done with it. What is the advantage to this setup, in either dollars, or performance, over buying a pre made gapped OPT from any reasonable supplier? If the tubes are 6AS7 triodes, Vo might be only 100v, indeed B would then be OK. Circlotron is also a good PP option. Why would someone who is saving money on transformers to the point of using a mains transformer want to build the complicated power supply arrangements required by a circlotron? I agree with you about the 6AS7 option however, it sounds like a good one to me. I don't think it's a huge jump of logic to say that if you can't afford to spend what Sowter is asking on OPT's, you can't afford speakers that would make it worthwhile anyways. Personally I'd put an amp together with mediocre trannies, then spend the $$$ on good speakers, and after that go for the high dollar transformers. I am peeved at the folks whose net worth is $500,000, say a house, car, and all their gear, and an expensive wife, but when it come to their real passion, audio, they try to wheedle out of spending anything. They think nothing of spending $300 to get a plumber to unblock a toilet in an hour, or paying thousands on orthodontics for the daughter's smile, or 10k on a kitchen for the missus, but whinge for 6 mths about transformer costs, and end up making one compromise after another. This sounds like a personal issue to me. Anyone whose real passion is audio, i.e. members of this newsgroup, is more likely to spend a disproportionate amount of their disposable income on audio. If they are really being cheap, then maybe their paission lies elsewhere? Maybe family is more important to them? Maybe it's hard to justify buying thousand dollar transformers to the wife, when there exists bills to pay? Who are you to judge? If on the other hand, the individual really does have a low income, why should he deny himself the right to having some fun with tube audio equipment just because his transformers don't meet Mr. Turner's spec? I for one would much rather see a person spending his free time lashing together a simple amplifier out of the cheapest bottom end Hammond products, and some used parts salvaged from old radios and TVs, than see him throw up his arms and buy a Sony home theatre receiver. Maybe he will learn the limitations of his modest setup, and then move on to bigger and better things once he has the funds in place. Or, maybe he'll decide tube equipment is not for him... if so, then so what? Patrick Turner. Just my $0.02 Max |
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