I think the best way to learn something is doing
trying to teach helps a lot...but doing, testing, comparing...this helps much more.
My 50 cents.
regards,
Carlos
trying to teach helps a lot...but doing, testing, comparing...this helps much more.
My 50 cents.
regards,
Carlos
bacxk to the subject current mirrors can reduce distortion and more precisely set bias currents. The extra gain out of LTP and VAS stages can then be used for more local feedback (emitter degeneration) wich decreases the total amount of global feedback needed to decrease these stages distortion (which is good, no?) Now does this only maters if your OPS distorion is low enough? I dont know, but decreaseing the distortion of any stage cant hurt can it? The only negative to current sources I have read is they add noise. Dont know how much.
I do not know those things.... i know how they sound only
What is good and what is no good to my ears.
If some book say they are good i wish book be happy listening.
ahahahha!
Carlos
What is good and what is no good to my ears.
If some book say they are good i wish book be happy listening.
ahahahha!
Carlos
Just some food for thought........
I have been digging in a old box I have of papers related to JLH. Since my teens with an interest in audio I collected everything I could from this designer as he was what I would call my silent teacher. It comes as a slap in the face me not paying more attention to these papers. Too much running after skirts at that time. I thought I had learned all I could from him but I should have paid more attention. This man was ages before his time.
Looking at them I come to realise many so called new insights into circuits are actually old news if anyone dared at that time to try out his designs. Im not gonna use blameless name anymore, JLH had this exact circuit all worked out back in 1979, and its even better in my view as it features phase lead, miller comp. Apart from the compensation and different resitor and cap values the circuit is identical to blameless. He also explains with some good maths all his design decisions. Now when I look at Self s book I have to really wonder ..............
He goes further and later in that year he shows some improvements that can be made. These include all kinds of cfps for the ltp ( BJT*FET,FET*BJT to name a few), cascode vas,cfp vas and some outputstages (bjt*mosfet cfp s with voltage gain) I have never come across here or in books.
This man was (is) awesomely creative. Nearly 30 years later we are biting each other and proposing topologies and all sorts of tricks he had figured out then. 😀 😀 😀
These papers are so old they tear some as I take them out of the box. He looked at other topologies too altough I can see he favoured the Lin by the amount of examples. In some of the letters to him the writers actually critise him for trying some of these,as they call it,outrages designs.
I have a lot of restoring and reading to do. First I ll try get some info on his life.
I have been digging in a old box I have of papers related to JLH. Since my teens with an interest in audio I collected everything I could from this designer as he was what I would call my silent teacher. It comes as a slap in the face me not paying more attention to these papers. Too much running after skirts at that time. I thought I had learned all I could from him but I should have paid more attention. This man was ages before his time.
Looking at them I come to realise many so called new insights into circuits are actually old news if anyone dared at that time to try out his designs. Im not gonna use blameless name anymore, JLH had this exact circuit all worked out back in 1979, and its even better in my view as it features phase lead, miller comp. Apart from the compensation and different resitor and cap values the circuit is identical to blameless. He also explains with some good maths all his design decisions. Now when I look at Self s book I have to really wonder ..............
He goes further and later in that year he shows some improvements that can be made. These include all kinds of cfps for the ltp ( BJT*FET,FET*BJT to name a few), cascode vas,cfp vas and some outputstages (bjt*mosfet cfp s with voltage gain) I have never come across here or in books.
This man was (is) awesomely creative. Nearly 30 years later we are biting each other and proposing topologies and all sorts of tricks he had figured out then. 😀 😀 😀
These papers are so old they tear some as I take them out of the box. He looked at other topologies too altough I can see he favoured the Lin by the amount of examples. In some of the letters to him the writers actually critise him for trying some of these,as they call it,outrages designs.
I have a lot of restoring and reading to do. First I ll try get some info on his life.
Do you know where I can find some of those John Linsley Hood papers,
homemodder
Much all stuff I know is from the great Class A site:
The Published Articles of John Linsley Hood
http://www.tcaas.btinternet.co.uk/jlharticles.htm
But just having a list of his articles wont help me.
I wont learn much by only looking at one list, will I 😀
Neither will I benefit any from you tellling how good he is/was.
What we need is to see what he actually can teach us! 😎
So bring it on .. unless you regard it as your own secrets.
Like some do.
Just to be able to 'float above', pretending to know more ... and not sharing.
Regards, Lineup
homemodder
Much all stuff I know is from the great Class A site:
The Published Articles of John Linsley Hood
http://www.tcaas.btinternet.co.uk/jlharticles.htm
But just having a list of his articles wont help me.
I wont learn much by only looking at one list, will I 😀
Neither will I benefit any from you tellling how good he is/was.
What we need is to see what he actually can teach us! 😎
So bring it on .. unless you regard it as your own secrets.
Like some do.
Just to be able to 'float above', pretending to know more ... and not sharing.
Regards, Lineup
Lineup, what I have is in paper form and its in bad condition due to moisture and age. It has travelled with me to europe 12000 km or so by ship and is around 22 years old now. A lot of it isnt even on that class A site and a lot that is there I dont even have. Its magazine articles, letters etc. The paper with the blameless type design is called ultra fidelity something, theres a damm watermark on the spot, dated 1979, I think I can make out ETI Canada if that means anything. I am hoping to be able to make photocopies and then get it into electronic form.
I was wondering about his whearabouts but I guess I dont have to anymore after seeing that web related page. Geoff Moss is a very friendly helpfull guy, he has sent me some of those papers he has on my request through this forum so I think Ill be contributing to that list of his sometime. If you want some of those papers maybe he could help you. JLH sure has a lot of papers, an audio great too I would say.
Its not secret Lineup, he published all, between all the members at diy i think most of his ideas have been tested or used, keep in mind some of these circuits are nearly 30 years old.
But just in case I think Ill keep one with some notes with interesting component combinations and greek to me output configurations for myself. 😀 😀 This one he didnt publish but was sent to the professor of electronics at the varsity where I studied. The prof was kind enough to make me copies when I attended his classes and he found out I had a interest in audio.
The prof is retired but still alive and because its addressed to him I wouldnt put it out there for everyone in any case without his permission.
I was wondering about his whearabouts but I guess I dont have to anymore after seeing that web related page. Geoff Moss is a very friendly helpfull guy, he has sent me some of those papers he has on my request through this forum so I think Ill be contributing to that list of his sometime. If you want some of those papers maybe he could help you. JLH sure has a lot of papers, an audio great too I would say.
Its not secret Lineup, he published all, between all the members at diy i think most of his ideas have been tested or used, keep in mind some of these circuits are nearly 30 years old.
But just in case I think Ill keep one with some notes with interesting component combinations and greek to me output configurations for myself. 😀 😀 This one he didnt publish but was sent to the professor of electronics at the varsity where I studied. The prof was kind enough to make me copies when I attended his classes and he found out I had a interest in audio.
The prof is retired but still alive and because its addressed to him I wouldnt put it out there for everyone in any case without his permission.
Guys,
I might have some of those papers............
.............. the man was way, way ahead of his time.
Jam
I might have some of those papers............
.............. the man was way, way ahead of his time.
Jam
Alex,
You got it. JLH is one of my favorites, and I try to read him widely. He gave me several ideas, notably phase lead, which I now use routinely. I've gone on to separate current and voltage amplification functions in the VAS, and used his compensation idea to great advantage.
Some of his work on quasi complementary circuits was very good too. Interesting, the JLH 1969 Class A circuit, a classic and much written about by Geoff Moss, does not measure that well yet sounds astonishing. I remember hearing Paul Desmond's 'Summertime' in 1971 on a JLH Class A, something of an ephiphany.
Cheers,
Hugh
You got it. JLH is one of my favorites, and I try to read him widely. He gave me several ideas, notably phase lead, which I now use routinely. I've gone on to separate current and voltage amplification functions in the VAS, and used his compensation idea to great advantage.
Some of his work on quasi complementary circuits was very good too. Interesting, the JLH 1969 Class A circuit, a classic and much written about by Geoff Moss, does not measure that well yet sounds astonishing. I remember hearing Paul Desmond's 'Summertime' in 1971 on a JLH Class A, something of an ephiphany.
Cheers,
Hugh
I also appreciate JLH Hugh... and i have build some amplifiers
And i have built the 1969 model that was strongly appreciated, i have visited a good friend and the JLH gone with me.... was installed into his home and beated his brand new, fully digital Sony Home Theater Receiver with a lot of features.... both adjusted to 4 watts RMS no chance for the Sony modern unit.
That amplifier, the 1969 JLH used a capacitance multiplier suggested by Rodd Elliot into DOZ..... was a heavy metalic case and very hot because class A..... was nice till i have assembled my first Aksa 55 down 2004.... the 55 smashed the JLH in such a way i have felt ashamed as i made a lot of noise into my audio group of friends and have travelled to Paulinho's home to show him the JLH magnificence.... so smashed, so hardly beated,
almost deleted, desintegrated and erased from my life since the first moment Aksa 55 played the first tones having the same speakers and the same power (adjusted) and the same audio source.
Was a big problem..friends were excited and almost ordered me to build Aksa for them.... i remember i have asked you and you said no.... i have lost some of those friends... was a great and awfull moment to me.... to decide to be fair with you or fair with them.
I really felt sorry about myself, about JLH and my strong appreciation on your circuit started that moment and it is still alive till those days, as the best sounding amplifier i have listened (exception was a valve, a tube old Macintosh...but a tube only.... not a solid state).
I think, not only me, but many other guys that have Aksa products, the 55 is the better one...maybe not perfect for measurements..but i have found audio quality.... soft and pleasant audio reproduction, with nice treble and present voices.... i do not like the bass end... the bottom bass reproduction is week.
Those last monthes i have tried one class A, a DOZ from Rodd Elliot... again Aksa smashed the unit... the quality difference was so big that i started to laugh... a little bit steric laughing because i felt pitty about Mr. Hood.... the smashed legend.... made in peaces by a very clever genius...but an English Teacher by main profession... a military too, and officer..... but poor JLH...he was one of the "masters of the universe".... at least he deserved to be beated by Doctor Self or someone with dozen degrees...ahahaha... was not that way..... teached me also that people does not need degrees to produce special quality amplifiers...the opposite, if people has not degrée has more freedom as have not to answer questions from his coleagues producing psychological pressure on them to use CCS, mirrors and all that auxiliary stuff...this sometimes increases audio quality but sometimes destroy.... if all those modern enginnering features, special differential, special CCS, current sinks and all those things.... if was really good...the chip amplifier would be unbeatable..and they are not unbeatable!
You know what i mean....Mr. John Hood would feel more confortable to loose to Mr. Douglas Self or other famous guys....but came from Australia, a huge man that made the job to send his design to the trash box....beated!
regards,
Carlos
And i have built the 1969 model that was strongly appreciated, i have visited a good friend and the JLH gone with me.... was installed into his home and beated his brand new, fully digital Sony Home Theater Receiver with a lot of features.... both adjusted to 4 watts RMS no chance for the Sony modern unit.
That amplifier, the 1969 JLH used a capacitance multiplier suggested by Rodd Elliot into DOZ..... was a heavy metalic case and very hot because class A..... was nice till i have assembled my first Aksa 55 down 2004.... the 55 smashed the JLH in such a way i have felt ashamed as i made a lot of noise into my audio group of friends and have travelled to Paulinho's home to show him the JLH magnificence.... so smashed, so hardly beated,
almost deleted, desintegrated and erased from my life since the first moment Aksa 55 played the first tones having the same speakers and the same power (adjusted) and the same audio source.
Was a big problem..friends were excited and almost ordered me to build Aksa for them.... i remember i have asked you and you said no.... i have lost some of those friends... was a great and awfull moment to me.... to decide to be fair with you or fair with them.
I really felt sorry about myself, about JLH and my strong appreciation on your circuit started that moment and it is still alive till those days, as the best sounding amplifier i have listened (exception was a valve, a tube old Macintosh...but a tube only.... not a solid state).
I think, not only me, but many other guys that have Aksa products, the 55 is the better one...maybe not perfect for measurements..but i have found audio quality.... soft and pleasant audio reproduction, with nice treble and present voices.... i do not like the bass end... the bottom bass reproduction is week.
Those last monthes i have tried one class A, a DOZ from Rodd Elliot... again Aksa smashed the unit... the quality difference was so big that i started to laugh... a little bit steric laughing because i felt pitty about Mr. Hood.... the smashed legend.... made in peaces by a very clever genius...but an English Teacher by main profession... a military too, and officer..... but poor JLH...he was one of the "masters of the universe".... at least he deserved to be beated by Doctor Self or someone with dozen degrees...ahahaha... was not that way..... teached me also that people does not need degrees to produce special quality amplifiers...the opposite, if people has not degrée has more freedom as have not to answer questions from his coleagues producing psychological pressure on them to use CCS, mirrors and all that auxiliary stuff...this sometimes increases audio quality but sometimes destroy.... if all those modern enginnering features, special differential, special CCS, current sinks and all those things.... if was really good...the chip amplifier would be unbeatable..and they are not unbeatable!
You know what i mean....Mr. John Hood would feel more confortable to loose to Mr. Douglas Self or other famous guys....but came from Australia, a huge man that made the job to send his design to the trash box....beated!
regards,
Carlos
Heck seems I am the only one never built or heard that JLH class A amp, due mostly to the inefficiency of class A.
Hugh, my so called version of blameless is based on JLH s design with beefed up outputs. I also got idea of phase lead from him as he uses this in combination with Miller in 95 percent of his amps. Back in 1992 I was building all kinds of kits, mostly japanese design, and throwing this feature in with good effect. Many amps went up in smoke till finding the right values, as a student I had no measuring equipment. My favourite amp then was called KWMOS250, not japanese though, 250watt monster with 2sj50 2sk135s output mosfets, which sounded tremendous with this feature.
Carlos I have some notes here on improving that JLH circuit, improvement in open loop gain and input impedance with the addition of one more tranny and bootstrap circuit. These things have to be tested to see if they work offcourse, its dated 1973. It seems he rarely just gave out full schematics with values but rather a discription of area he felt improvement was due with a small schematic and the maths to be done. BTW later on from around early 1980s he uses curent mirrors and even before that his circuits feature current sources although he strongly favours the two transistor ones using very low cob devices. He mentions the cob for the mirror too and even back then he mentions that one is wasting his time if looking for good sound and not using the lowest cob transistors available for the vas.
With quasi complementary output configurations he seems to like intergrating bootstraps but these papers on this I have are barely readible, should kick myself for not taking better care of them.
Ill make a drawing of a output stage he recommends to the prof to be used with one of his frontends for all to see. Nothing special, except the idea. Maybe someone has tried this already I have experiment some with similar circuit. It features a bjt mosfet cfp in class AB. He recommends this for listening to classical music and says it has tube like sound.
Jam, his papers certainly warrant a second read, Ive moved away from The lin topology, their are other topologies which have merit although Im also inclined to say the well executed Lin is very very good.
Comes down to matter of taste.
Hugh, my so called version of blameless is based on JLH s design with beefed up outputs. I also got idea of phase lead from him as he uses this in combination with Miller in 95 percent of his amps. Back in 1992 I was building all kinds of kits, mostly japanese design, and throwing this feature in with good effect. Many amps went up in smoke till finding the right values, as a student I had no measuring equipment. My favourite amp then was called KWMOS250, not japanese though, 250watt monster with 2sj50 2sk135s output mosfets, which sounded tremendous with this feature.
Carlos I have some notes here on improving that JLH circuit, improvement in open loop gain and input impedance with the addition of one more tranny and bootstrap circuit. These things have to be tested to see if they work offcourse, its dated 1973. It seems he rarely just gave out full schematics with values but rather a discription of area he felt improvement was due with a small schematic and the maths to be done. BTW later on from around early 1980s he uses curent mirrors and even before that his circuits feature current sources although he strongly favours the two transistor ones using very low cob devices. He mentions the cob for the mirror too and even back then he mentions that one is wasting his time if looking for good sound and not using the lowest cob transistors available for the vas.
With quasi complementary output configurations he seems to like intergrating bootstraps but these papers on this I have are barely readible, should kick myself for not taking better care of them.
Ill make a drawing of a output stage he recommends to the prof to be used with one of his frontends for all to see. Nothing special, except the idea. Maybe someone has tried this already I have experiment some with similar circuit. It features a bjt mosfet cfp in class AB. He recommends this for listening to classical music and says it has tube like sound.
Jam, his papers certainly warrant a second read, Ive moved away from The lin topology, their are other topologies which have merit although Im also inclined to say the well executed Lin is very very good.
Comes down to matter of taste.
If you have interest homemodder..then go ahead and publish
those ideas about.... the informations you have and also your thougths about.
But better to use the old JLH thread we already have or open a new one about last updates made.
There are sites too... Jeff ... or Jeoff has a site about JLH also.
So... those informations you have, if you want to share them, we have many options.
I do not feel it is a good idea to publish here...because thread seems (i have to read it once again, do not remember exaclty the purpose of this thread) to me is not about JLH...but as i told..i have to read it once again since the begining to see what we had as threads are very dinamic..sometimes start about one amplifier and closes talking about another one.
If i can remember this one was about the nic topologie used by Hugh Dean, the bootstrapped circuits and this nice three stage using darlington into emitter follower into the output.... also i have used this same idea, that born into the seventies used by tenths of factories... i have used into the Dx Amplifier, the Dx Standard too...also the HRII uses bootstrapp... the best one, the DHR Turbo also uses bootstrapp and the old style circuit.
My amplifiers does not sounds so good as Aksa 55...but does not loose by an enormous ammount... the subcircuits Aksa use makes the difference, a respectable difference, but nothing to smash my "babies"
I am able to beat Aksa into the very low end..ahahahahah..only that...but this is something!
regards,
Carlos
those ideas about.... the informations you have and also your thougths about.
But better to use the old JLH thread we already have or open a new one about last updates made.
There are sites too... Jeff ... or Jeoff has a site about JLH also.
So... those informations you have, if you want to share them, we have many options.
I do not feel it is a good idea to publish here...because thread seems (i have to read it once again, do not remember exaclty the purpose of this thread) to me is not about JLH...but as i told..i have to read it once again since the begining to see what we had as threads are very dinamic..sometimes start about one amplifier and closes talking about another one.
If i can remember this one was about the nic topologie used by Hugh Dean, the bootstrapped circuits and this nice three stage using darlington into emitter follower into the output.... also i have used this same idea, that born into the seventies used by tenths of factories... i have used into the Dx Amplifier, the Dx Standard too...also the HRII uses bootstrapp... the best one, the DHR Turbo also uses bootstrapp and the old style circuit.
My amplifiers does not sounds so good as Aksa 55...but does not loose by an enormous ammount... the subcircuits Aksa use makes the difference, a respectable difference, but nothing to smash my "babies"
I am able to beat Aksa into the very low end..ahahahahah..only that...but this is something!
regards,
Carlos
hello.......
dear carlos and all,
i am back....hmm....i missed you all lots. lets read first all those threads ar posted in past. Dx-turbo is still working without any problem.
dear carlos and all,
i am back....hmm....i missed you all lots. lets read first all those threads ar posted in past. Dx-turbo is still working without any problem.
I was missing you Space... i am happy your amplifier is still fine
When time passes we go observing, listening, and we always find something not perfect...well... at least happens with me...i always found something not perfect.
They are not perfect... amplifiers and speakers not perfect, and some of them behaves good others not so good... and i always perceive something that should be better..could be better.
I am happy you still love your amplifier.
regards,
Carlos
When time passes we go observing, listening, and we always find something not perfect...well... at least happens with me...i always found something not perfect.
They are not perfect... amplifiers and speakers not perfect, and some of them behaves good others not so good... and i always perceive something that should be better..could be better.
I am happy you still love your amplifier.
regards,
Carlos
Re: If you have interest homemodder..then go ahead and publish
Start a new thread for all the "unpublished" JLH stuff otherwise it will get burried in an old thread and be lost again.
Andy
destroyer X said:
Start a new thread for all the "unpublished" JLH stuff otherwise it will get burried in an old thread and be lost again.
Andy
Yep...you have your opinion....i think a little bit different
JLH is some kind of reference into this forum..considered good by a lot of folks...and it is really very good..no doubts about that.... but not unbeatable as i could see.
Was JLH the amplifier that made me perceive Aksa 55 value... was the first one "eated into the breakfast" by the 55 in my home... a fair comparison was made and folks were called to evaluate..also children and women too.
So.... there is a connection, in my life a historical connection between them.... also this thread talks about Aksa, the circuit that uses that topologie i think as the best one... with more nice sound....so... things are interconnected...if he decided to post here, at least the thread openner will not be bothered.
Not the very best solution...but a reasonable good solution to post it here too..all that stuff are interconnected.
I use to write too much because i do not know how to write in english..so, i have to explain into long texts..also verbs forms i do not have made texts longer...i am sorry folks.... i know they are big and i will try to make them shorter.
regards,
Carlos
JLH is some kind of reference into this forum..considered good by a lot of folks...and it is really very good..no doubts about that.... but not unbeatable as i could see.
Was JLH the amplifier that made me perceive Aksa 55 value... was the first one "eated into the breakfast" by the 55 in my home... a fair comparison was made and folks were called to evaluate..also children and women too.
So.... there is a connection, in my life a historical connection between them.... also this thread talks about Aksa, the circuit that uses that topologie i think as the best one... with more nice sound....so... things are interconnected...if he decided to post here, at least the thread openner will not be bothered.
Not the very best solution...but a reasonable good solution to post it here too..all that stuff are interconnected.
I use to write too much because i do not know how to write in english..so, i have to explain into long texts..also verbs forms i do not have made texts longer...i am sorry folks.... i know they are big and i will try to make them shorter.
regards,
Carlos
Hi Carlos, you might wanna take a look at this, one can listen to your spice simulation, link provided by aparatusonitus
http://www.ltspicelabs.blogspot.com/
😱 😱
I have to wonder whats next..........
BTW, congrats Brasil gave portugal a good hiding last night, a shocker. The words eated into the breakfast are very appropriate here too
http://www.ltspicelabs.blogspot.com/
😱 😱
I have to wonder whats next..........
BTW, congrats Brasil gave portugal a good hiding last night, a shocker. The words eated into the breakfast are very appropriate here too
I do not know about that "eating" happened... maybe football
or soccer to UK folks and Aussie guys....I do not listen Radio, or Brazilian TV channels, only International channels into different language.
Here we have too much corruption, blood and bad things beeing shown.... i hate the local television... so...i do not know what is going on here.
The last new i had was that our Government and People were mad about Spain that was creating problems to tourists visiting..sending them back.
During the eigthies we had the same problem with Portugal, was boys and girls from Brazil going to nigth clubs...you know... sex and dance and i found Portuguese Government correct to kick their AS-- out from the country.
regards,
Carlos
or soccer to UK folks and Aussie guys....I do not listen Radio, or Brazilian TV channels, only International channels into different language.
Here we have too much corruption, blood and bad things beeing shown.... i hate the local television... so...i do not know what is going on here.
The last new i had was that our Government and People were mad about Spain that was creating problems to tourists visiting..sending them back.
During the eigthies we had the same problem with Portugal, was boys and girls from Brazil going to nigth clubs...you know... sex and dance and i found Portuguese Government correct to kick their AS-- out from the country.
regards,
Carlos
- Status
- Not open for further replies.