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steph_tsf 17th August 2011 09:39 AM

Borbely-Lender True Symmetry
1 Attachment(s)
From "High Performance Audio Power Amplifiers"
Written by Ben Duncan.
Published by Newnes - An imprint of Butterworth-Heinemann Ltd Linacre House, Jordan Hill, Oxford OX2 8DP.

See attached jpg.

When came the original publications or schematics by Borbely and by Lender ? Can we access the original texts ?
Are there DIY amplifiers available nowadays using such topology ?
What are the results ?
I have no interest in Lin, Blameless or Circlotron. Please don't try selling me these in this present thread ;-)


buzzforb 17th August 2011 10:13 AM

Check out A75 article at Passdiy.

steph_tsf 17th August 2011 11:44 AM

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Radio Plans n403
True Symmetry
Buffered Darlington output
June 1981

steph_tsf 17th August 2011 11:46 AM

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Radio Plans n434
True Symmetry
Vertical MOSFETs output
January 1984

steph_tsf 17th August 2011 11:58 AM

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Originally Posted by buzzforb (
Check out A75 article at Passdiy.

You mean this all MOS implementation dating back from 1992 (Audio Amateur) ?

leapcat 17th August 2011 12:04 PM

The thread, solid solid state power amplifier, by PMA might be of some interest.

steph_tsf 17th August 2011 12:08 PM

More about Erno Borbely
This is a "must read".
Next exercice is to analyze the Hafler DH200 schematic.
Then, analyze the Millennium power amp schematic.

wahab 17th August 2011 12:30 PM

1 Attachment(s)
1977 CC2 Audionics , whose schematic was taken from a manufacturer
app note.(was it Fairchild.?)...

This the 1979 version.

steph_tsf 17th August 2011 12:33 PM

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Hafler DH-200
Designed by Erno Borbely

see attached .jpg

wahab 17th August 2011 12:42 PM

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Another ancestor, that might well be the first such design
is the Motorola design published in REL 12/1973.

Notice the output stage topology.

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