For those that are interested in seeing what the outside of the integrated kit version of the amp looked like, I just spotted one for sale on the UK ebay site (item 300071961271) called 'John Linsley Hood Stereo Amplifier (1970)'. I've attached one of the images. Other images show the three settings for the bass turnover freq.
Sure looks pretty long in the tooth. I wonder if JLH was responsible for the entire circuit design (phono stage, tone controls etc) or just the power amp?
Hmmm....I'd be more interested if I was about 20,000km closer!
Sure looks pretty long in the tooth. I wonder if JLH was responsible for the entire circuit design (phono stage, tone controls etc) or just the power amp?
Hmmm....I'd be more interested if I was about 20,000km closer!
Hi Geoff
Thanks very much for the link.
I've done a couple of JLH class A amplifiers, the last one from your
site. This one is sensacional and is a must for my ESL built almost four years ago. Still running.
But I've been lookiong for a quasi amplifier for quite some time as I've
got so many NPN good quality transistors and I couldn't find any
design that merit the term HiFi. Perhaps this one you sent me, is it
that good? The schematic looks promising though.
Thanks again
Thanks very much for the link.
I've done a couple of JLH class A amplifiers, the last one from your
site. This one is sensacional and is a must for my ESL built almost four years ago. Still running.
But I've been lookiong for a quasi amplifier for quite some time as I've
got so many NPN good quality transistors and I couldn't find any
design that merit the term HiFi. Perhaps this one you sent me, is it
that good? The schematic looks promising though.
Thanks again
jmateus said:
Well, the Cyrus 1 and Cyrus 2 (basically the same circuit, the 2 had slightly higher rail voltages and beefier output transistors) were commercial amps that were quite highly regarded in their time. They were referred to as 'budget' audiophile amplifiers in some reviews.
PS. I'm pleased to hear that you are enjoying your JLH Class-A!
jmateus said:
Geoff said:
The Cyrus One ( http://www.cyrusaudio.com/ )
looks interesting.
http://www.tcaas.btinternet.co.uk/cyrus1pwr.gif
Has got some 'extras'.
Like for example the input stage solution with double transistors.
And the limiting capacitors C49 / C50.
We can see it is an amplifier done with care for best performance.
-------------------------------------------------
Questions for Geoff :
Cyrus One is not a Class A, right?
You don't happen to know where to find parts list?
I mean it would be good to see what Transistors were used?
Even if we of course, can use good upgrade/replacement devices, today.
Regards, lineup
ACD - Audio Circuit Denmark
Another fantastic Collection of Amplifier Schematics
is done by a member from Denmark, ACD
This schematics resource is Well Worth a Visit, jmateus!
Amplifier Schematics list:
http://www.audio-circuit.dk/Schematics.html
ACD - Audio Circuit Denmark - Home:
http://www.audio-circuit.dk/
As example, here are two legendary Nelson Pass amplifiers:
Treshold_800A.pdf
Threshold_S-Series.pdf
A couple of minimalistic old Dynaco power amps:
Dynaco_120a.pdf
Dynaco_ST80.pdf
Dynaco_150.pdf
Regards, lineup
Another fantastic Collection of Amplifier Schematics
is done by a member from Denmark, ACD
This schematics resource is Well Worth a Visit, jmateus!
Amplifier Schematics list:http://www.audio-circuit.dk/Schematics.html
ACD - Audio Circuit Denmark - Home:
http://www.audio-circuit.dk/
As example, here are two legendary Nelson Pass amplifiers:
Treshold_800A.pdf
Threshold_S-Series.pdf
A couple of minimalistic old Dynaco power amps:
Dynaco_120a.pdf
Dynaco_ST80.pdf
Dynaco_150.pdf
Regards, lineup
Hi Geoff
Our conversation about the quasi complementary schematic reminded me a bunch of old papers(very yellow already) from the
magazine Hi/FiNews and Record Review, March 1980, in which John
Linsley Hood published an article in three parts describing "a simple 30 watt integrated amplifier". And I found them after a while!
This was the first amplifier from JLH I got in contact with. I built it
(just the power amp) and the thing sounded unbelievable. Over the
years I kind of lost contact with this amplifier (I do not remember if I gave it to a friend or else) the truth is, I wanted to build the amplifier again years later but the idea of having an elect. cap at the
output told me not to build even though I knew it sounded really
good. That's when I got aquainted with your site and familiar (more
familiar I should say) with the most known amplifier from JLH.
So I decided to build that one aimed for ESL's with two pairs of MJ 15003.
I still look with a certain nostalgia to these sheets from Hi Fi News
that had a power amp and a preamp, everything really detailed for
the novice to build.
Among other reliques I still kept the article from JLH to remind me
how good he was designing electronic circuits. Actually I have
all the pages I could get at the time from his designs, including
in the ETI magazine. Good old times!
Our conversation about the quasi complementary schematic reminded me a bunch of old papers(very yellow already) from the
magazine Hi/FiNews and Record Review, March 1980, in which John
Linsley Hood published an article in three parts describing "a simple 30 watt integrated amplifier". And I found them after a while!
This was the first amplifier from JLH I got in contact with. I built it
(just the power amp) and the thing sounded unbelievable. Over the
years I kind of lost contact with this amplifier (I do not remember if I gave it to a friend or else) the truth is, I wanted to build the amplifier again years later but the idea of having an elect. cap at the
output told me not to build even though I knew it sounded really
good. That's when I got aquainted with your site and familiar (more
familiar I should say) with the most known amplifier from JLH.
So I decided to build that one aimed for ESL's with two pairs of MJ 15003.
I still look with a certain nostalgia to these sheets from Hi Fi News
that had a power amp and a preamp, everything really detailed for
the novice to build.
Among other reliques I still kept the article from JLH to remind me
how good he was designing electronic circuits. Actually I have
all the pages I could get at the time from his designs, including
in the ETI magazine. Good old times!
Dynaco ST-80 Classic
See my attachment.
Dynaco ST-80 is a minimalistic old Classic amplifier.
It uses Quasi Complementary output stage = Two NPN Power transistors.
I am quite sure I would be able to to make something very nice of this one.
With some small modifications, naturally.
I will try to simulate and work with it, when get time.
The circuit, in its idea, is good. And well known from those days.
It is bit in Nelson Pass spirit: Simple but Good!
Regards, lineup
See my attachment.
Dynaco ST-80 is a minimalistic old Classic amplifier.
It uses Quasi Complementary output stage = Two NPN Power transistors.
I am quite sure I would be able to to make something very nice of this one.
With some small modifications, naturally.
I will try to simulate and work with it, when get time.
The circuit, in its idea, is good. And well known from those days.
It is bit in Nelson Pass spirit: Simple but Good!
Regards, lineup
jmateus said:
I too have a (poor) copy of this article.
Well, as with the original 1969 Class-A, the 30W amp could easily be modified to run off dual supply rails thus obviating the need for an output capacitor. However, it would suffer from a similar problem of output dc offset drift between switch-on and normal operating temperature.
I quite agree!
jmateus said:
The very old ( 1969 ) Dynaco STEREO 80, uses two 2N3055 for output.
I was lucky to find a complete article by a guy here:
Dynaco Stereo 80 Power Amplifier
Schematic:
http://home.indy.net/~gregdunn/dynaco/components/ST80/schem.jpg
Parts List:
http://home.indy.net/~gregdunn/dynaco/components/ST80/parts.jpg
jmateus,
As there are 'generations' between year 1969 Dynaco ST-80 and Cyrus One,
no question, Cyrus One is the better amplifier.
I am more interested in simplicity, so I want to try to explore Dynaco ST-80
and see if that amplifier circuit model can be used and improved.....
------------------------------------
I am glad I found the parts list for Dynaco, though.
Now I can set up the original for simulation
and go from there - trying to improve!
Regards, lineup
Yes, Geoff good old times!
Lineup, a few years ago I bought on Ebay an ST80, burned up to
the bones, I fixed it and had it playing. What a deception! I don't
know what it was, the new transistors used, the coupling caps or else,
the truth is I couldn't bare the bad quality of that amplifier, so I disassembled it and built in that chassis the what is today the JLH for ESL. BIG heatsinks, regulated capacitance multiplier supplies (two),
the works....
I think I still have somewhere the list of components you are looking for
it's just a matter of looking for it but that will take some time, it must
be buried in all my papers.
Lineup, a few years ago I bought on Ebay an ST80, burned up to
the bones, I fixed it and had it playing. What a deception! I don't
know what it was, the new transistors used, the coupling caps or else,
the truth is I couldn't bare the bad quality of that amplifier, so I disassembled it and built in that chassis the what is today the JLH for ESL. BIG heatsinks, regulated capacitance multiplier supplies (two),
the works....
I think I still have somewhere the list of components you are looking for
it's just a matter of looking for it but that will take some time, it must
be buried in all my papers.
jmateus said:
Yes, I have seen, now when searching, someone say the same:
"In original this amp was not very good or reliable."
But have also seen one saying the Dynaco ST-80 amplifier can be modified into being good.
He has rebuilt several.
--------------------
I managed to find a very good picture of inside of Cyrus One
http://content.answers.com/main/content/wp/en/f/f4/MissionCyrus1-2.JPG
This picture is : 1956x1309 pixels and 1.4MB !!!!!!!
Of course i feel happy to see good friends joined together here
Not my thread, but i had published something and friends jumped to join me...i thank you all.
Dear Sheldon
My old friend Mr. John Mateus
Kimbo
Geoff
Line up
Cobra2
Jonathan Brigth
Pingrs shown a good image..thanks for that.
Also Doctor John Ellis, of course.
Serve yourself in our conversation room...fine...good...i love that!
Roger on that folks!
Carlos
Not my thread, but i had published something and friends jumped to join me...i thank you all.
Dear Sheldon
My old friend Mr. John Mateus
Kimbo
Geoff
Line up
Cobra2
Jonathan Brigth
Pingrs shown a good image..thanks for that.
Also Doctor John Ellis, of course.
Serve yourself in our conversation room...fine...good...i love that!
Roger on that folks!
Carlos
The image is more than we can see in our computer monitor.
Line up
They normally have 1000 by 800 (or something alike).....800K pixels maximum i suppose.... more than that will not result better images...software will schrink it to fit into the computer screen.
I have made some comparison.... and really...nothing better withing bigger data images.
Bigger data images will be needed if you want or need to zooming in....well...to crop or to produce some image processing.
Watch the image with lower resolution and see that the losses are not so big...the noise are result of my processing..they can be removed or avoided.... watch the big one and the reduced one fitting into the monitor screen...because zooming in we will need 600 Megapixels and stereoscopic vision because our eyes.
Was nice to watch big images...to zoom in too.
regards,
Carlos
Line up
They normally have 1000 by 800 (or something alike).....800K pixels maximum i suppose.... more than that will not result better images...software will schrink it to fit into the computer screen.
I have made some comparison.... and really...nothing better withing bigger data images.
Bigger data images will be needed if you want or need to zooming in....well...to crop or to produce some image processing.
Watch the image with lower resolution and see that the losses are not so big...the noise are result of my processing..they can be removed or avoided.... watch the big one and the reduced one fitting into the monitor screen...because zooming in we will need 600 Megapixels and stereoscopic vision because our eyes.
Was nice to watch big images...to zoom in too.
regards,
Carlos
Re:
Thanks for editing that biggy image, Carlos
I think maybe your friend jmateus will go for Cyrus One....
And for him that image can be good to study .. in small details.
I have started a new topic about my Dynaco ST-80 clone and the modification + simulation of it.
This thread is of an interesting JLH amplifier.
I do not want to disturb too much here ... only a little bit.
Something like 1-2.5 topics per thread maybe is ideal.
Otherwise we can start call it threadjacking
lineup
destroyer X said:
Thanks for editing that biggy image, Carlos
I think maybe your friend jmateus will go for Cyrus One....
And for him that image can be good to study .. in small details.
I have started a new topic about my Dynaco ST-80 clone and the modification + simulation of it.
This thread is of an interesting JLH amplifier.
I do not want to disturb too much here ...
only a little bit.Something like 1-2.5 topics per thread maybe is ideal.
Otherwise we can start call it threadjacking
lineup
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