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Old 2nd April 2013, 02:46 PM   #37651
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IF you are happy with an IC based design, PMA, good for you! You have done what I have not yet done. Of course, I can make an IC based design. The JC-3 is an IC based design.
Perhaps the far future is in IC's almost exclusively. However, the NEAR FUTURE, and most of the rest of MY life is going to be with jfets. Almost all the companies that I consult for, and my direct competitors in the audio field, (you know, the guys who usually share the A ratings with me), have reasonable to vast stockpiles of jfets yet to use up.
It would be just like having a large vacuum tube stockpile and being an expert in tube design, being told that you are 'obsolete' and you that should switch to discrete transistors, let's say, 40 years ago. There is 'Marketing Hype' for you. You know: Solid state is better than tubes, IC's are better than discretes, and finally 'Perfect sound forever' with digital. '-)
More than 45 years ago, Dyna shifted from the Stereo 70 (tube) to the Stereo 120 (solid state), the PAS 3 (tube) to the PAT 4 (solid state), later, McIntosh stopped making the C22 (tube) and the 350 (tube), some of the best equipment in the world at that time, and replaced it with solid state 'schlock'. Those designs were EMBARRASSING, because the designers were forced to move prematurely to solid state, when: Really good parts were not available, the resident designers had little experience with solid state, and pre-made designs that were useful for the military-industrial complex, were NOT really that successful processing audio. It took us years of quiet development, behind the scenes, to make the complementary differential input stage, (45 years ago), complementary differential jfet input stage (40 years ago), mosfets weren't even designed yet, and this took another decade, and finally the Japanese took to making exquisite to exotic complementary components for audio, just as a point of pride, to show off their design and fabrication skills, starting about 35 years ago.
We have had a good run, especially with the Japanese parts, but of course, they are being discontinued. Good luck everybody with what is available to you in the future! '-)

Last edited by john curl; 2nd April 2013 at 02:56 PM.
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Old 3rd April 2013, 08:23 AM   #37652
gk7 is offline gk7
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Just want to note that Toshiba still makes low noise FETs (only n-channel and smd though): 2SK880, 2SK208, 2SK209. And they are cheap...
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Old 3rd April 2013, 09:12 AM   #37653
coresta is offline coresta  France
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Quote:
Originally Posted by john curl View Post
IF you are happy with an IC based design, PMA, good for you! You have done what I have not yet done. Of course, I can make an IC based design. The JC-3 is an IC based design.
Perhaps the far future is in IC's almost exclusively. However, the NEAR FUTURE, and most of the rest of MY life is going to be with jfets. Almost all the companies that I consult for, and my direct competitors in the audio field, (you know, the guys who usually share the A ratings with me), have reasonable to vast stockpiles of jfets yet to use up.
It would be just like having a large vacuum tube stockpile and being an expert in tube design, being told that you are 'obsolete' and you that should switch to discrete transistors, let's say, 40 years ago. There is 'Marketing Hype' for you. You know: Solid state is better than tubes, IC's are better than discretes, and finally 'Perfect sound forever' with digital. '-)
More than 45 years ago, Dyna shifted from the Stereo 70 (tube) to the Stereo 120 (solid state), the PAS 3 (tube) to the PAT 4 (solid state), later, McIntosh stopped making the C22 (tube) and the 350 (tube), some of the best equipment in the world at that time, and replaced it with solid state 'schlock'. Those designs were EMBARRASSING, because the designers were forced to move prematurely to solid state, when: Really good parts were not available, the resident designers had little experience with solid state, and pre-made designs that were useful for the military-industrial complex, were NOT really that successful processing audio. It took us years of quiet development, behind the scenes, to make the complementary differential input stage, (45 years ago), complementary differential jfet input stage (40 years ago), mosfets weren't even designed yet, and this took another decade, and finally the Japanese took to making exquisite to exotic complementary components for audio, just as a point of pride, to show off their design and fabrication skills, starting about 35 years ago.
We have had a good run, especially with the Japanese parts, but of course, they are being discontinued. Good luck everybody with what is available to you in the future! '-)
Yep, especially with RoHS directive (unleaded) and whiskers growing up as the size of SMDs is ...downsizig, metal can transistors (dissipation) , RN65 resistors , disapear ... i stock for my future
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Old 3rd April 2013, 01:40 PM   #37654
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Well since things are quiet, I'll post a few more interesting power supply measurements.

This is the AC line noise that passes through a power transformer. I find the self limiting resonance most interesting.

ES
Attached Images
File Type: jpg Noise DST LP.JPG (613.1 KB, 211 views)
File Type: jpg Noise R core and Toroid.JPG (678.5 KB, 207 views)
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Old 3rd April 2013, 05:13 PM   #37655
PMA is offline PMA  Europe
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Cheap shots (not you, Ed).
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Old 3rd April 2013, 05:27 PM   #37656
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Originally Posted by PMA View Post
Cheap shots (not you, Ed).
Thanks, I am two years in on this power supply thing and think I can finish the article.

I found it interesting how much distortion just comes from the transformer even before you add rectifier noise.

Attached transformer distortion with an AC load resistor or not and then with a rectified load. BTY the first graph has a 26 db attenuator in circuit.

So far I have shown transformer distortion, rectification distortion and line noise pass through.

Next I might even show the effects of filtering with big C versus distributed RC.
Attached Images
File Type: jpg 14A 60 hz.JPG (106.7 KB, 177 views)
File Type: jpg Ripple PC-24 DST LP-24-1000.JPG (504.8 KB, 174 views)

Last edited by simon7000; 3rd April 2013 at 05:31 PM.
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Old 3rd April 2013, 05:34 PM   #37657
SY is offline SY  United States
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Quote:
Originally Posted by simon7000 View Post

Next I might even show the effects of filtering with big C versus distributed RC.
Make sure you have the Cathode Ray (Scroggie) article on this. He may have scooped you by 50 years or so...
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Old 3rd April 2013, 05:37 PM   #37658
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Make sure you have the Cathode Ray (Scroggie) article on this. He may have scooped you by 50 years or so...
I am writing a tutorial. Just showing pictures of current products and how they actually behave. I don't think PC mount flatpack transformers were around 50 years ago. (Close though.)

But if you have a cite...

The new stuff is on how to get rid of DC type effects on transformer primaries.
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Old 3rd April 2013, 05:41 PM   #37659
SY is offline SY  United States
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Originally Posted by simon7000 View Post
But if you have a cite...
He also does a mathematical treatment of the general case, so you can plug in whatever frequency you like. I am involuntarily separated from my library at the moment, but if you have a copy of Valve Amplifiers, it's cited in there, and there's scans floating around the intertubes.
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Old 3rd April 2013, 05:50 PM   #37660
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He also does a mathematical treatment of the general case, so you can plug in whatever frequency you like. I am involuntarily separated from my library at the moment, but if you have a copy of Valve Amplifiers, it's cited in there, and there's scans floating around the intertubes.
Math! Nobody does math any more. It would screw up opinions, require you to think and know what a pencil and paper are used for.

The thing that popped out was that the transformer uses up 60 degrees of the cycle actually charging, pretty much no matter what the load.
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