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Old 13th January 2004, 09:00 AM   #1
kenlow is offline kenlow  Malaysia
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Default NDFL amplifiers

hello everyone,

anyone out there built a NDFL amp from E. Cherry's NDFL design/article which appeared in an edition of ETI UK back in the early 80s?

it seems that the Cherry received a patent for his NDFL concept which he subsequently sold to Pioneer Japan.

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Old 13th January 2004, 09:02 PM   #2
tomzss is offline tomzss  Canada
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Default NDFL amplifiers

I built a 60watt version as it appeared in the Canadian edition of "Electronics Today International" back in the 70's or early 80's.

It used the same output transistors and power supply as a SWTPC Tiger Amp that I had. So I rebuilt the Tiger into an NDFL. There was a major improvment in quality.

I still have the amp and sometimes still use it when I need dual 60 watts. I have both the construction articla and the accompanying theory article.

The amp also had compesation for the feedback cap that kills the DC gain. It can pass a low frequecy square wave intact. Cherry mentions that this feature can be used on any amp but I have never seen any one else use it.
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Old 25th April 2007, 12:35 AM   #3
smithy666 is offline smithy666  Australia
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I built a pair of these back in the 80s, which served me well for many years. They were 60W modules which featured 2 nested differentiating feedback loops designed by Professor Cherry. The article appeared in the the Australian version of ETI as well....if I can find it I will post the schematic for interest.

From memory, they were pretty good at the time (I still have them but haven't pulled them out for a long time)
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Old 25th April 2007, 01:27 AM   #4
Leolabs is offline Leolabs  Malaysia
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Any example???
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Old 25th April 2007, 03:15 AM   #5
jcx is online now jcx  United States
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apparently not hobbyist's favorite design, but you can search for commentary

try "nested differentiating" in exact phrase or various dr/prof/ed Cherry searches
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