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Old 29th October 2018, 05:32 PM   #781
ivanlukic is online now ivanlukic  Serbia
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Does that mean that ODNF is some kind of feedforward error correction?
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Old 29th October 2018, 05:34 PM   #782
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by vzaichenko View Post
Hi Gareth,

This is a variant of ODNF (Only Distortion Negative Feedback).
The idea is that he subtracts the input signal from the output signal, resulting in the error signal, normalizes its amplitude (U2), and then subtracts the error signal from the total (input + error) signal (U1), reducing the distortion.
Thanks Valery ! - after all these years I finally find out the secret

Is it like Class S ?
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Last edited by Bigun; 29th October 2018 at 05:40 PM.
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Old 30th October 2018, 09:16 AM   #783
Machina is offline Machina  Poland
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TY Guyz you are awsome!
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Old 30th October 2018, 03:51 PM   #784
vzaichenko is offline vzaichenko  Russian Federation
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Quote:
Originally Posted by ivanlukic View Post
Does that mean that ODNF is some kind of feedforward error correction?
Hi Ivanlukic,

If we look at it from the overall concept point of view - ODNF is still the kind of a feedback, not feedforward.

You can also look at it in the following way:
- Initially, we've got an amplifier with no global feedback loop, gain = 29db, providing some level of distortion (low enough).
- As soon as we add ODNF circuit, we increase the gain by +18db (small signal distortion increase is low) and then kill that additional 18db gain with 18db global feedback, together with the overall level of distortion, decreasing the overall output impedance by that volume as well.

As a result, we preserve the initial amplifier's character (distortion profile), decreasing the absolute level of distortion by the global feedback loop gain (almost), provided by ODNF circuit (18db in my implementation).

The thing works well if the initial amplifier is linear enough by itself so that the ODNF loop gain is not too high (say, 20db or so).
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Old 30th October 2018, 03:58 PM   #785
vzaichenko is offline vzaichenko  Russian Federation
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Quote:
Originally Posted by Bigun View Post
Thanks Valery ! - after all these years I finally find out the secret

Is it like Class S ?
Well, it's similar nature in a way that there are some [higher-quality / small signal / low power] and [lower-quality / big signal / high power] amplifiers and they assist each other

Although, ODNF mechanism is different from the one for class S.
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Old 8th February 2019, 06:21 AM   #786
Unique is offline Unique  Greece
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Originally Posted by alex mm View Post
........ I have layout one of many great design of Dr.Bora J , T REFERENCE AMPLIFIER for people who intend to build .
Alex.
Is there a mistake on this pcb? At the schematic, there are two 1uF input capacitors ( which equal to 2uF, understood ) but at the pcb layout there are two 1uF caps in parallel on the left of the input pin and another two in the place of the 2.2uF cap, which are in parallel too, but not connected to the input path on the right side ( where the single 2.2uF would sit and make contact ). Am I missing something?
One more thing, what would be the value of the output coil?
Thanks in advance.
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Old 10th February 2019, 08:40 PM   #787
Machina is offline Machina  Poland
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You can use what you want, in schematic there is 2x 1uF
So much place to use one big good 2,2uF, like jantzen cap MKT/MKT or something like that
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Old 11th February 2019, 08:53 AM   #788
Unique is offline Unique  Greece
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Of course I would of used either the top two 1uf caps or the one spot for the 2.2uF but it was kind of funny the indication of two 1uf caps in the place of the 2.2uF with them not being connected to the input, so I wanted to be sure if there is a mistake or the pcb designer had something else in mind. Anyway, I will erase the unnecessary tracks on the 2.2uF spot.
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