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Old 11th July 2008, 07:05 PM   #1381
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Quote:
Originally posted by audiorob
Why there?
Because it IS positive feedback ?

Suppose you run a topless bar and it's full. To have all the seats taken, no empty ones and no standing eye-ballers, instead of controlling the in-flow at the entrance you can control the sucker-flow at the exit.
(in the restaurant business they make you wait an hour for the bill if the place isn't fully booked)

If the gain is higher than it should be, there's more current flowing through the feedback resistors, the JFET will see the one below it (R1 or R2) as a virtual higher resistance=> result is less gain.
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Old 11th July 2008, 07:32 PM   #1382
estman is offline estman  Estonia
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This amp has positive feedback only from listeners !
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Old 11th July 2008, 08:07 PM   #1383
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Thumbs up In-flow Out-flow

Dear Jacco,

You have such an amusing way of explaining
things.
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Old 11th July 2008, 09:49 PM   #1384
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Yeah well, i've always wanted to be an academic sleaze, or was it a sleazy academic, let's just stick to a sleaze.

Feedback of a regular non-inverting amp is also only NFB when it's fed to the inverting side of the input differential pair.
The real beauty of this thing is the split feedback, a single polarity feedback signal from the output simultaneously corrects both sides of the complementary input pair.
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Old 11th July 2008, 10:00 PM   #1385
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by jacco vermeulen
Yeah well, i've always wanted to be an academic sleaze, or was it a sleazy academic, let's just stick to a sleaze.

.....

you're sayin' that manu is academic sleaze .......... ?

naah .........


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Old 11th July 2008, 10:21 PM   #1386
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Nope, he's the sleazy academic, seen his legs ?
Which academic regards showing naked body parts as proper decorum ?
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Old 12th July 2008, 01:27 AM   #1387
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Default Re: In-flow Out-flow

Quote:
Originally posted by Dennis Hui
Dear Jacco,

You have such an amusing way of explaining
things.
We call them Tata's over here
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Old 12th July 2008, 10:01 AM   #1388
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Last time i googled for a TaTa-bar i ended up at a car shop in India.

What's puzzlin me is whether the dual-pump action is less intrusive than a single NFB loop, or still be looked at as a single gain block with error feedback. Intuitively it feels like the first, when you slice the F5 down the middle it's a symmetrical balanced system.
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Old 12th July 2008, 06:02 PM   #1389
KSTR is offline KSTR  Germany
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Those two loops interact, they aren't independent.

BTW, in simulation when I change the feedback network from its "rhombus" or "bridge" style to an equivalent "cross" (8.2R source-R's, 8.2R to GND, 41R feedback) which represents a traditional "current feedback" single loop hookup, thus running the same DC bias points for all parts and the same overall gain, the circuit performance is practically identical for a variety of test conditions I have used, the original version being slightly better on the order of 10% or so, the harmonic distribution is overall very similar in magnitude and phase (original has slightly better even order cancelling). Maybe Nelson will enlight us what exactly made him choose the split hookup?

- Klaus
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Old 12th July 2008, 08:07 PM   #1390
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I have two reasons.

Reason #1, I don't choose to discuss at this time.

Reason #2, It is novel enough to make you guys speculate about it.

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