Home |
Search |
Today's Posts |
#1
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
Does anyone have a schematic for a Luxman SQ38D? I mostly require info
on the tone amp section. The one I have has been modified and I need to restore it to standard. TIA -- Trevor Wilson www.rageaudio.com.au |
#2
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? A long series of " SQ38 " amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. ..... Phil |
#3
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/13/2012 11:11 AM, Phil Allison wrote:
"Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? **I REALLY do have one of them. In pristine nick too. This being the beastie in question: http://www.thevintageknob.org/luxman-SQ38D.html A long series of " SQ38 " amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. **Some were. I have a half a filing cabinet drawer full. Mostly solid state though. A legacy of being a major service agent for the product from 1980 'till Interdyn let go of the product. In fact, I have a few doubles if you need anything. -- Trevor Wilson www.rageaudio.com.au |
#4
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"Trevor Wilson" Phil Allison wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? **I REALLY do have one of them. In pristine nick too. This being the beastie in question: http://www.thevintageknob.org/luxman-SQ38D.html ** Where do you get 6RA8 output triodes these days ?? Luxman schems were always near impossible to obtain - certainly so here in Australia. **Some were. I have a half a filing cabinet drawer full. Mostly solid state though. A legacy of being a major service agent for the product from 1980 'till Interdyn let go of the product. ** Luxman was sold and supported by L&G Hoskins in NSW through the 70s and 80s. They also sold Alpine cassette decks and Celestion speakers. They adopted the name "Quality Hi-Fi" in 1976 and are still trading under it. http://www.qualityhifi.com.au/files/about_us.html I was alluding to them when I said schems were impossible to get - there was more chance of getting blood from a stone than having Gordon Hoskins part with a schematic for any of his products. What a Neanderthal. ..... Phil |
#5
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"Phil Allison" ** Where do you get 6RA8 output triodes these days ?? ** Found some he http://www.ebay.com/itm/6R-A8-6RA8-N...em3c cbd573cd Not cheap ... ..... Phil |
#6
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/13/2012 1:22 PM, Phil Allison wrote:
"Trevor Wilson" Phil Allison wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? **I REALLY do have one of them. In pristine nick too. This being the beastie in question: http://www.thevintageknob.org/luxman-SQ38D.html ** Where do you get 6RA8 output triodes these days ?? **Buggered if I know. The ones in the amp I have are OK (admittedly, a very short test). Luxman schems were always near impossible to obtain - certainly so here in Australia. **Some were. I have a half a filing cabinet drawer full. Mostly solid state though. A legacy of being a major service agent for the product from 1980 'till Interdyn let go of the product. ** Luxman was sold and supported by L&G Hoskins in NSW through the 70s and 80s. They also sold Alpine cassette decks and Celestion speakers. **Actually, I believe Interdyn was the importer of Luxman since the 1960s. I think they had an exclusive with Hoskins 'till the early 1990s for NSW. I could be wrong though. I recall trying to obtain information from Hoskins during the 1980s. It was almost impossible. They adopted the name "Quality Hi-Fi" in 1976 and are still trading under it. http://www.qualityhifi.com.au/files/about_us.html I was alluding to them when I said schems were impossible to get - there was more chance of getting blood from a stone than having Gordon Hoskins part with a schematic for any of his products. **Difficult, but not impossible. I did some service work for them for a few years last century. I can probably still obtain a manual if I need one. The trick is knowing who to talk to. What a Neanderthal. **You got that right. -- Trevor Wilson www.rageaudio.com.au |
#7
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"Trevor Wilson" Phil Allison wrote: "Trevor Wilson" ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? **I REALLY do have one of them. In pristine nick too. This being the beastie in question: http://www.thevintageknob.org/luxman-SQ38D.html ** Where do you get 6RA8 output triodes these days ?? **Buggered if I know. The ones in the amp I have are OK (admittedly, a very short test). ** The amp you have is not a 240V model, is it ? More like 100V, straight from Japan via Ebay ?? What a Neanderthal. **You got that right. ** LOL :-) .... ..... Phil |
#8
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/13/2012 1:47 PM, Phil Allison wrote:
"Phil Allison" ** Where do you get 6RA8 output triodes these days ?? ** Found some he http://www.ebay.com/itm/6R-A8-6RA8-N...em3c cbd573cd Not cheap ... .... Phil **Thanks for that. If I need them, I know I can probably buy them. Fortunately, the amp is worth a couple of grand (I'll be selling it after re-building), so a few hundred for new valves is worth it. -- Trevor Wilson www.rageaudio.com.au |
#9
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/13/2012 2:06 PM, Phil Allison wrote:
"Trevor Wilson" Phil Allison wrote: "Trevor Wilson" ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? **I REALLY do have one of them. In pristine nick too. This being the beastie in question: http://www.thevintageknob.org/luxman-SQ38D.html ** Where do you get 6RA8 output triodes these days ?? **Buggered if I know. The ones in the amp I have are OK (admittedly, a very short test). ** The amp you have is not a 240V model, is it ? More like 100V, straight from Japan via Ebay ?? **Nope. Genuine 240VAC 50Hz/60Hz label on the back. An ancient Australian mains plug on the lead too. AFAIK, it has probably been owned by the original purchaser for many decades. What a Neanderthal. **You got that right. ** LOL :-) .... .... Phil **FWIW, I was speaking to one of the guys down at Interdyn a few weeks back. He was ****ed off. Management instructed them to dispose of many filing cabinets full of old service manuals and boxes of old spare parts. Many were Luxman items. Idiots. They could have sold it all for good money. -- Trevor Wilson www.rageaudio.com.au |
#10
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of them ? A long series of *" SQ38 " *amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. .... *Phil What's wrong with Trevor? All he has to do is sit there for awhile and draw the schematic from what he sees, and then work out how it works, or should work, bearing in mind any mods he should be able to see, and then, once he understands what he's doing, he can properly check the darn thing out. Even with a schematic, a good tube tech draws the schematic anyway, and completely familiarizes himself where everything is on the schematic. Its all so much more logical than trying to draw a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a fix, one had 6868, and they were so expensive in 1995 that I replaced them with EL34 & sockets after making the case taller. The next had some strange OP tetrode but had two blown OPTs, so its still here after 12 years. The next can with strange 12 pin tubes with 50V heaters and a missing OPT which another tech had lost, so the OPT musta fused. It stayed awhile, then I reused the chassis for something far better of my own design with 2 x EL34, and some better wound-in-Oz PT and OPTs. I reused a choke. Below Trev says he want to sell the Luxman for $2,000 after paying hundreds for new rare tubes unlikely to be available when the next time comes arounf for replacement. What's anyone got for 2 grand? Just another lack lustre tube amp, with maybe very used/traumatised OPTs after possible episodes of overheating tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura" but I don't see it. I get a number of ancient POS amps coming here for singing lessons and quit-smoking therapy. All very sacred old brands, but not one is a sacred cow, so I usually gut the lot and start all over again. Just finished a pair of POS Jadis SE300B amps. No other way to make 'em behave. Patrick Turner. |
#11
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/13/2012 7:29 PM, patrick-turner wrote:
On 13 Nov, 11:11, "Phil Allison" wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? A long series of " SQ38 " amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. .... Phil What's wrong with Trevor? **Nothing wrong with me. Using a published schematic (if available) is MUCH quicker and expedient that re-engineering an amplifier that has been modified by a third party. I simply wish to restore the amp to it's original spec in readiness for sale. The amplifier has been modified by another tech such that it no longer performs as it did when first made. I can certainly make some educated calculations about the appropriate component values and choices, but it is much easier to use the original components. All he has to do is sit there for awhile and draw the schematic from what he sees, **And again: The tone amplifier stage has been substantially modified. It no longer resembles the original topology. Drawing out what is there would be a waste of time. and then work out how it works, or should work, bearing in mind any mods he should be able to see, and then, once he understands what he's doing, he can properly check the darn thing out. Even with a schematic, a good tube tech draws the schematic anyway, and completely familiarizes himself where everything is on the schematic. Its all so much more logical than trying to draw a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a fix, one had 6868, and they were so expensive in 1995 that I replaced them with EL34 & sockets after making the case taller. The next had some strange OP tetrode but had two blown OPTs, so its still here after 12 years. The next can with strange 12 pin tubes with 50V heaters and a missing OPT which another tech had lost, so the OPT musta fused. It stayed awhile, then I reused the chassis for something far better of my own design with 2 x EL34, and some better wound-in-Oz PT and OPTs. I reused a choke. Below Trev says he want to sell the Luxman for $2,000 after paying hundreds for new rare tubes unlikely to be available when the next time comes arounf for replacement. What's anyone got for 2 grand? Just another lack lustre tube amp, with maybe very used/traumatised OPTs after possible episodes of overheating tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura" but I don't see it. I get a number of ancient POS amps coming here for singing lessons and quit-smoking therapy. All very sacred old brands, but not one is a sacred cow, so I usually gut the lot and start all over again. Just finished a pair of POS Jadis SE300B amps. No other way to make 'em behave. Patrick Turner. **Whether the amp is good, bad or indifferent, is not the issue and I don't much care either way. It is a desirable object for many people. Kinda like a Model T Ford. Try and explain to a T Ford owner that a 2012 Ford Mustang is a vastly superior vehicle in every way. You'll get nowhere fast. -- Trevor Wilson www.rageaudio.com.au |
#12
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 14 Nov, 06:42, Trevor Wilson
wrote: On 11/13/2012 7:29 PM, patrick-turner wrote: On 13 Nov, 11:11, "Phil Allison" wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of them ? A long series of *" SQ38 " *amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. .... *Phil What's wrong with Trevor? **Nothing wrong with me. Trevor, you are such a great big fukken dope, you don't know that you are one, and its been like this all the time I've known you. I can't and won't help you. Go fix your amp like I've had to fix dozens, all without schematics. Just do it. Patrick Turner Using a published schematic (if available) is MUCH quicker and expedient that re-engineering an amplifier that has been modified by a third party. I simply wish to restore the amp to it's original spec in readiness for sale. The amplifier has been modified by another tech such that it no longer performs as it did when first made. I can certainly make some educated calculations about the appropriate component values and choices, but it is much easier to use the original components. * All he has to do is sit there for awhile and draw the schematic from what he sees, **And again: The tone amplifier stage has been substantially modified. It no longer resembles the original topology. Drawing out what is there would be a waste of time. * and then work out how it works, or should work, bearing in mind any mods he should be able to see, and then, once he understands what he's doing, he can properly check the darn thing out. Even with a schematic, a good tube tech draws the schematic anyway, and completely familiarizes himself where everything is on the schematic. Its all so much more logical than trying to draw a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a fix, one had 6868, and they were so expensive in 1995 that I replaced them with EL34 & sockets after making the case taller. The next had some strange OP tetrode but had two blown OPTs, so its still here after 12 years. The next can with strange 12 pin tubes with 50V heaters and a missing OPT which another tech had lost, so the OPT musta fused. It stayed awhile, then I reused the chassis for something far better of my own design with 2 x EL34, and some better wound-in-Oz PT and OPTs. I reused a choke. Below Trev says he want to sell the Luxman for $2,000 after paying hundreds for new rare tubes unlikely to be available when the next time comes arounf for replacement. What's anyone got for 2 grand? Just another lack lustre tube amp, with maybe very used/traumatised OPTs after possible episodes of overheating tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura" but I don't see it. I get a number of ancient POS amps coming here for singing lessons and quit-smoking therapy. All very sacred old brands, but not one is a sacred cow, so I usually gut the lot and start all over again. Just finished a pair of POS Jadis SE300B amps. No other way to make 'em behave. Patrick Turner. **Whether the amp is good, bad or indifferent, is not the issue and I don't much care either way. It is a desirable object for many people. Kinda like a Model T Ford. Try and explain to a T Ford owner that a 2012 Ford Mustang is a vastly superior vehicle in every way. You'll get nowhere fast. -- Trevor Wilsonwww.rageaudio.com.au- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - |
#13
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 11/14/2012 10:57 AM, patrick-turner wrote:
On 14 Nov, 06:42, Trevor Wilson wrote: On 11/13/2012 7:29 PM, patrick-turner wrote: On 13 Nov, 11:11, "Phil Allison" wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" was released in Japan in 1965 - do you really have one of them ? A long series of " SQ38 " amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. .... Phil What's wrong with Trevor? **Nothing wrong with me. Trevor, you are such a great big fukken dope, you don't know that you are one, and its been like this all the time I've known you. I can't and won't help you. Go fix your amp like I've had to fix dozens, all without schematics. Just do it. Patrick Turner **Thanks for your input Patrick. I'll ask you one question: How would YOU go about ascertaining the original values of the components in a tone amp stage, without access to the original schematics, parts lists, or even the original parts from the amplifier? If it makes you happy, continue with your innane insults. For my part, I asked a reasonable question. I even received a reasonable response from PA. Your response is nothing short of insane. -- Trevor Wilson www.rageaudio.com.au |
#14
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 14 Nov, 11:12, Trevor Wilson
wrote: On 11/14/2012 10:57 AM, patrick-turner wrote: On 14 Nov, 06:42, Trevor Wilson wrote: On 11/13/2012 7:29 PM, patrick-turner wrote: On 13 Nov, 11:11, "Phil Allison" wrote: "Trevor Wilson" Does anyone have a schematic for a Luxman SQ38D? I mostly require info on the tone amp section. The one I have has been modified and I need to restore it to standard. ** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of them ? A long series of *" SQ38 " *amps were released including the "SQ-38D" in 1998. http://www.onahighernote.com/luxman/?c=5&id=45 Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones uses regular 6BQ5s. Luxman schems were always near impossible to obtain - certainly so here in Australia. .... *Phil What's wrong with Trevor? **Nothing wrong with me. Trevor, you are such a great big fukken dope, you don't know that you are one, and its been like this all the time I've known you. I can't and won't help you. Go fix your amp like I've had to fix dozens, all without schematics. Just do it. Patrick Turner **Thanks for your input Patrick. I'll ask you one question: How would YOU go about ascertaining the original values of the components in a tone amp stage, without access to the original schematics, parts lists, or even the original parts from the amplifier? If it makes you happy, continue with your innane insults. For my part, I asked a reasonable question. I even received a reasonable response from PA. Your response is nothing short of insane. Trevor Wilson is an idiot, and one who has always hated having people tell him he is what he calls others, ie, insane. Since I began discussing audio tech matters with this idiot in 2002 or therabouts he has never ever displayed any capability to really understand basic amp design issues generally, and has never ever designed and built any amplifier from what he knows alone. Trevor has always paraded his gross mental disabilities especially when dealing with anything with a vacuum tube in it. He complains I insult him, but I merely point out the inconvenient truth about the man. Trevor has always been extremely stubborn and unable and far too lazy to understand that one really has to analyse properly when schematics of gear are unavailable, and also when they are. He fails dismally to be willing or able to draw up the schematic of a tube amp properly and confidently and fully, and then make intelligent mods or repairs, and in conjunction with measuring all voltages and currents and plotting graphs of F response. AFAIK, there is absolutely nothing at his website to prove he knows much. Last time I discussed anything at aus.hi-fi or anywhere else it alsways ended in acrimony because he would not accept that the CEO ME solid state amps should have been and should be far more forthcoming with full schematics required for these very over complicated amps made in Oz until they went broke. Trev would have needed the schematics because he'd have no idea how to otherwise proceed. I have fixed a number of SS amps without schemas, after careful analysis. But I now won't provide any repair service for any SS amps, because I am rather slow compared to a couple of very rare good SS techs who are so much better and faster and cheaper than Trevor will ever be, and besides, I have a huge pile of tube gear to fix, many speculative projects done for the sake of doing them, and I have officially retired. So I don't need to learn any more than I have about SS junk. I won't be explaining again to Trevor about how to suck eggs. Once is a enough. Its like explaining to a gum tree how to be a ballerina. I refuse to assist him in answering his questions while he refuses to think and consider things himself, in his time, not mine. All his questions so far are very easy for a good tube amp repairist to answer. Tube amps are far simpler and easier to understand than most SS. I refuse to spoonfeed Trevor, but if he travels to a store selling kitchen gear I am sure he'll find a nice big wooden spoon to feed himself with, while furiously studying RDH4 and many other books he should have bought and read. There are umpteen websites out there full of info for Trevor. He could do a lot worse than read my website about what's needed in a good tube amp but interpolating my info into a Luxman without becoming well be-fuddled would probably not be possible. I might add its amazing to see that PA has gained some notably worthy control over his past habits of demolishing stupid ideas and arguments put forward by Trevor - ad-nausem, or by anyone else, and over many years. Fact is, many demolitions were very justified and correct because PA knows far more than most others who have ever stepped a foot inside this joint. He frightened so many wannabes who liked to jarg the jargon, with ignorance. As people soon learn here, while I have little time for fools, I am not perfect, and cannot be perfect, and I don't mind that I fukkin ain't perfect. I admit mistakes and my limitations, and with this attitude the tantrums ppl chuck don't work with me, and nor will petulant whinging. I will only give credit where its due, and statements of facts need to be supported, and I can only respect diligence in others as I might respect it in myself. I would suggest I won't change until I am laying on a slab somewhere looking like a very nice corpse, ready for a warm trip uppa chimney someplace. Patrick Turner. -- Trevor Wilsonwww.rageaudio.com.au- Hide quoted text - - Show quoted text - |
#15
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"Trevor Wilson" **Thanks for your input Patrick. I'll ask you one question: How would YOU go about ascertaining the original values of the components in a tone amp stage, without access to the original schematics, parts lists, or even the original parts from the amplifier? If it makes you happy, continue with your innane insults. For my part, I asked a reasonable question. I even received a reasonable response from PA. Your response is nothing short of insane. ** The Turneroid has never quite been the same since he fell for British audio designer Susan Parker. http://www.susan-parker.co.uk/ http://www.audiophonics.com/index.html He lost his cool completely when I dubbed her "Dopey Sue" for making a fundamental error regarding power mosfets. Since Sue married her long time girlfriend a few years back - Pat has been all but inconsolable. ..... Phil |
#16
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
On 15 Nov, 14:14, "Phil Allison" wrote:
"Trevor Wilson" **Thanks for your input Patrick. I'll ask you one question: How would YOU go about ascertaining the original values of the components in a tone amp stage, without access to the original schematics, parts lists, or even the original parts from the amplifier? If it makes you happy, continue with your innane insults. For my part, I asked a reasonable question. I even received a reasonable response from PA. Your response is nothing short of insane. ** The Turneroid has never quite been the same since he fell for British audio designer Susan Parker. http://www.susan-parker.co.uk/ http://www.audiophonics.com/index.html He lost his cool completely when I dubbed her "Dopey Sue" *for making a fundamental error regarding power mosfets. Since Sue married her long time girlfriend a few years back - *Pat has been all but inconsolable. .... * Phil Yes, broke my heart it did, but we remain excellent friends, a far better arrangement than having to work around a lady's unpredictble emotional condition. I'd not want to wonder very long about who you may be married to, but i'd not be surprised if it was Ms Handandfingers. I find that sue has some excellent ideas about transformers and about simplicity. But she's been unable to focus much on her audio hobby interests because of her heavy committments to well paying job at a university. Is the **** about mosfets the only thing you're cranky about today? Patrick Turner. |
#17
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
"patrick-turner" "Phil Allison" "Trevor Wilson" **Thanks for your input Patrick. I'll ask you one question: How would YOU go about ascertaining the original values of the components in a tone amp stage, without access to the original schematics, parts lists, or even the original parts from the amplifier? If it makes you happy, continue with your innane insults. For my part, I asked a reasonable question. I even received a reasonable response from PA. Your response is nothing short of insane. ** The Turneroid has never quite been the same since he fell for British audio designer Susan Parker. http://www.susan-parker.co.uk/ http://www.audiophonics.com/index.html He lost his cool completely when I dubbed her "Dopey Sue" for making a fundamental error regarding power mosfets. Since Sue married her long time girlfriend a few years back - Pat has been all but inconsolable. Yes, broke my heart it did, but we remain excellent friends, a far better arrangement than having to work around a lady's unpredictble emotional condition. ** IME - working around unpredictable female emotions is a hazard for all. I find that sue has some excellent ideas about transformers and about simplicity. ** Simple, even elegant but very far from inexpensive. But she's been unable to focus much on her audio hobby interests because of her heavy committments to well paying job at a university. ** The uni's workshops must be where she gets all that nice metalwork and cabinetry done. Foreign orders anyone ?? ..... Phil |
#18
Posted to rec.audio.tubes
|
|||
|
|||
Luxman SQ38D
But she's been unable to focus much on her audio hobby
interests because of her heavy committments to well paying job at a university. ** The uni's workshops must be where she gets all that nice metalwork and cabinetry done. * * Foreign orders anyone ?? I doubt it. Unfortunately, perhaps you don't know Susan as well as I do, and bearing in mind your own difficulties with females and your sprinklings of negativity I can only smile at your comments, and I hope in that in the fullness of time you would find a wealth of personal pleasures to be had where you wouldn't dream of dissmissing so many people because you can gain access to their wit, their determination to genuinely discuss things, and other wondrous facets of human bevaiour so that you benefit as they might, without duress, or verbal scaldings of boiling oil when there are inevitable dissagreements, as indeed there must be for any of us to attain wisdom. Well you may complain about the costs of building a minimamlist amplifier with just an input tranny and output tranny and 2 N mosfets in source follower mode and class A. Ah, but the cost you say - hopeless silly effort. Indeed cost is high, but all hobbies are all a waste of time and money when that time and money could be put towards fine charitable causes, or medical research, or R&D for a company wanting to make 1 square metre solar panels that are 50% efficient for $2 each, with lightweight batteries to go with them. Surely the persuit of listening to music with valve amps is a true monumental waste of human resources, and you'd prefer them all to beat a path to your door to get advice on how to make an amp for $3, weighing less than 100 grams and 99% efficient. Of course that's exactly where the audio industry had headed with PWM amps fed by digital audio signals, so the world beat you to it. Its another huge tragic waste that the world wants 6.1 home theatre, with screens 10 feet wide and suburban houses which compete with those owned by Louis IXV, and of course everyone needs 2 cars each and they want to each eat enough to feed a family of 16 Africans, and only vote for parties that give out yet more Guvvy assistance. They then spnd hundreds of thousands on expensive messy acrimonious divorces, and while learning nothing, repeat it all. So I see your point in complaining about the cost of Susan's minimalism approach. Don't worry, she more than compensates by not having children and living a very simple life while owning a push bike, while battling on in a maddening world. I'm left wondering also about what became of your website? Where has it gone? But then it dawned on me that perhaps you never got around to inviting the world to your mind, so they may see how good audio could be achieved. Was it all too vain and selfish to make a website? That's a real pity considering you have vast knowledge. Nobody I know, except possibly someone who might be your twin, would frown on having a website. In 1990 I frivolously built a pair class A amps with 4 mosefts with an OPT. Mosfets are driven by LTP with 2 garden variety bjts in LTP and one for a CCS. It has cap coupling, and works just fine, and gives 40 Watts in class A with THD 0.3%. I've never found anyone to say it sounds worse than a tube amp with 4 x EL34 etc, and one may wonder why I made these things but I enjoyed the experience and it taught me more. One of these days I may convert it to Circlotron and have a pair of EL84 as input/drivers, but I may never find the time. Susan's amp has a step up input tranny with 600 ohms impedance. The 2V input must be raised to roughly 30V output for gate to gate drive, and to get input Z = 600r, the sec load must be 136k, and if Sec C load = 100pF, then Cin at Pri = 0.022uF. I'm guesstimating here but HF roll off would trouble many people unless thay had a very low drive source powering the IPT and if they didn't have a decent IPT. Sue just uses a power mosfet as source follower to drive the IPT. The lower the drive source Z, the less the characteristics of IPT and OPT will cause distortions. Of course many say its a waste, but it matters not, and the status quo is stained by productions governed by accountants, and anything other than what mainstream industry does becomes invalid. Anyway, using a pair of EL84 in triode with Ra = 2k5 to drive perhaps 50pF of input C at gates seems a reasonable solution. Having mosfets in circlotron with simple OPT means you have matching devices, and if Vds on each mosfet is 20Vrms, then gate drive = about 10.5Vrms Vg-0V, and the amp Rout is low enough and because class A, and ß = 0.5 and open loop mosfet A = about 20, then THD is low, bandwidth vert wide, and so you get hi-fi, fairly simply, without GNFB, or an IPT. The OPT is probably best if an auto tranny, and can have 8 ohms input end to end for 50 Watts of output with 20Vrms. If OPT core = 50mm stack of 50mm tongue E&I with partial air gapping for µe = 3,000, then wire size is large and its quite easy to wind. On each side of PP circuit I think a good load is 32 ohms for each of 4 class A mosfets, so that all four drive the OPT primary of 8 ohms. Taps for 4 ohms and 2 ohms are easy but I'm still not sure of HF performance because with say 2 ohms, using 1/2 the total auto tranny turns, the leakage inductance affects the HF pole. I'm trying to figure out a decent winding set up that allows many Z combinations so as RL is lowered, the class A action remains and the amp doesn't move into class AB. There doesn't seem to be very much online about making audio auto- trannies with very low winding losses and HF losses for Z range between say 1 ohm and 64 ohms. Having an auto tranny which gave say 64 ohms to 4 ohms would be a boon to owners of tubed OTL amps. They tend to become dissolutioned by OTL tubes suffering bias failure from overheating due to the inevitable very poor load matching even with multiple 6C33c output tubes. The load line analysis I've done on 6C33c indicates good class A is available if Ea = +160V and RLa = 250r, and Pda = 60W with Ia at around 370mA. 4 such tubes in class A can give 40Watts, and OPT primary RL can be 62.5 ohms. To my mind, this is superior to using the same tubes hooked directly to 8 ohms and forcing tubes on each side of PP circuit with low bias, and in class AB2, to each produce say 1.4 amp peak current. 40W into 8 ohms is 3.15 peak amps, so at least 6 x 6C33c are wise, and Pda with continuous signal invites smoke, and things get worse with 4 ohms. Auiophile say they like the transparency of OTL, but all OTL I've seen have a very large amount of NFB applied, and its NFB that improves the sound, rather than the absence of OPT. But I digress. I hope Trevor has by now worked out what is the best tone control with tubes, IMHO, ( apart from scrapping tone control completely and loudness function ). It is achieved with cathode follower input driving a Baxandal type R&C circuit within a unity gain shunt FB network So at least 2 halves of 12AX7 are needed for 1 channel. Usually such unity gain tone control stages do not color sound and nobody I know can tell when they in the circuit and not being bypassed. Such circuits may be left in circuit un-bypassed and they provide a low Rout drive to volume control pot immediately before power amps. But line stage gain and power amp gains need careful study. Most ancient amps have high sensitvity because line-in source levels were 200mV, or less, like Leak, with 100mV, because ppl hated paying more the extra tube needed to get phono amp output higher when using a lone EF86 per channel, etc. Lord knows what might be in the SQ38D Luxmam, but typical tone control circuits in 1960 used 1 x 12AU7 to raise signal by 22dB, then feed that to a passive high value R log pots and C etc with very little overall gain. Such old amplifiers with such tone controls usually suffered C value drift and pots became noisy, and 12AU7 has no NFB so it puts in 2% THD, and I am no fan of ancient stuff this way and they are best reformed with unity gain with FB and linear pots. It means gutting and re-wiring, and many hours of work. Usually the rest of all such Old Junk amps also need gutting, re-designing, then re-wiring. I have several here awaiting My Treatments. One has to end up doing what bean counters dissallowed in 1960. Such old junk then sounds at its possible best, which can be "brilliantus maximus", with quite low THD and noise, with both channels having equal gain and phase shift so image is good. Its very rewarding work to do. I used to re-engineer some SS amps, eg, Phlame Linear, but after awhile it seemed like cleaning toilets, I dunno why, but at least I reduced the Phlame factor and smoke. I have a pair of ancient 30 Watt RCA amps in the pile, 2 x EF86 + 2 x KT66. Hmm, a delicious opportunity to make 'em much better, but I don't know whay they were parked by owner 30 years ago - maybe new OPTs are needed! Trevor would be unable to persue me for a better mission plan than the one I might use myself - Draw up the existing schematic, think about it for a couple of days, decide what to change, check available space for parts left out in 1960, draw up everything properly, leave room for flexibility for changes during the process. Pay attention to switches on front panel. Typical 1960 amps were riddled with Do-Dah switches for tape monitor, hi-lo cuts, and pahse of signals. These are all best omitted from the new design, and often I have had to make a new front panel with less stuff&junk on it. Often more tag strips need installing, plus far better electros and new Si diodes to replace tube rectifier/s. Often IEC socket plugs are wise plus all new speaker terminals allowing 4mm banana plugs, and all RCA sockets need changing. The list of things needing to be done would fill a couple of screen fulls. No wonder I found I could not earn much as an audio tech on this type of work for owners loathe to pay a socially just wage. But for me, since I took deep interest in audio maters in 1993, it was about the wonderment rather than the dollars. Because I worked my arse off when young, I have escaped paying rent, or upkeep of ex-wives etc, and i could afford change from the building trade to audio trade. Its no wonder that so few ppl try to fukkabout commercially with tube amps, but I didn't fancy learning about computers, or fixing toasters. Patrick Turner .... * Phil- Hide quoted text - - Show quoted text - |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
FS: Luxman CL-40 | Marketplace | |||
Luxman lv103 | Vacuum Tubes | |||
Luxman SQ 65 ? | Vacuum Tubes | |||
Luxman DZ-92 Remote | Tech |