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1970s Design Indulgence
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jul 2022 at 12:09pm
For those wondering if the amplifier has finally reached a dead end, it hasn't.

Many pages back I said I wanted to establish design rules for the single HT a.c. coupled amplifier - seeing as nobody else did!

Yes, I guess it could have been a trade secret kept worldwide by every manufacturer, and if so, why weren't most of them any good?!

There may be one or two people on planet earth interested in really learning exactly how such amplifiers work, and how to obtain the absolute best performance from them.

Then again, it is a throw away world that cannot make its mind up about the right to repair, whilst complaining from its armchair.

So, the manual about the amplifier has had to grow to explain absolutely everything I've discovered, the design rules, how every component in relation to every other component, works, and why. Including all the maths and formulas, in an ordered and organised way.

Right now I'm grappling with the output interface, such as the Zobel (which Mr Self has problems in explaining, calling it enigmatic instead), but apart from that and a lot of tidying up, index pages, more illustrations and photos etc. It isn't far off.

A few more weeks could see it through.
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Fatmangolf View Drop Down
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Points: 8989 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jul 2022 at 5:48pm
Thank you very much for sharing your findings about this type of amplifier and your expertise Graham.
Jon

Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Bi-wire View Drop Down
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Points: 284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Bi-wire Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jul 2022 at 3:41pm
Originally posted by Fatmangolf Fatmangolf wrote:

Thank you very much for sharing your findings about this type of amplifier and your expertise Graham.

I would like to second Jon's sentiment here. I started reading this thread a while back, not really sure if it was for me. It has since drawn me in and I've learnt a great deal thanks to Graham's generosity in sharing his expertise. I'm looking forward to the completion of this 'journey' after so much effort on Graham's part.
Peter

Satisfied user of: Revelation M, PSU1-Enigma, Solo SRGII and lots of CuSat50
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jul 2022 at 7:20pm
I just have to tie up loose ends such as complying with CE and UKSA legislation, and being able to present it in a technical information file to show that the relevant standards have been applied.

4kV CE test input bandpass
(Maybe the Audio Science Review would like to comment?!)

It might be a 68kHz low pass to the EN 61000-4-2 test probe, but to EN 61938 which allows an output impedance of 2k2 to the source, it falls to 40kHz.

So, what about tubes? Sorry, CE and UKSA has moved on...

(Maybe the Audio Science Review would like to try and rubbish me again?!)


Edited by Graham Slee - 26 Jul 2022 at 7:25pm
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jul 2022 at 10:15pm
A stitch in time...

Everybody knows that the time constant of 68kHz is 2340ns and not 1170ns.

If not then try 1/2πƒ

1/2π 68,000 = 0.00000234

But the single positive, or negative pulse of the ESD test gun, is not cyclic, it is the equivalent of a half cycle, and half of 2340ns is 1170ns.
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jul 2022 at 10:22pm
What I'm doing is writing the design and technical information manual for constructors of the Conclusion-P power amplifier (a fitting name I thought).

Free with every parts kit and pre-built amp (watermarked PDF), or otherwise I might try and get it on Amazon Kindle at a price.
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Graham Slee View Drop Down
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Points: 16298 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 26 Jul 2022 at 11:32pm
I just love this "rationale" from EN 61000-4-2 (8.3.2.e)

Many connector ports are designed to handle high-frequency information, either analogue or digital, and therefore cannot be provided with sufficient overvoltage protection devices. In the case of analogue signals, bandpass filters may be a solution. Overvoltage protecting diodes have too much stray capacitance to be useful at the frequencies at which the EUT is designed to operate.

(thank you to whoever wrote it) Wink
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