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-   -   Class i (http://www.diyaudio.com/forums/solid-state/222133-class-i.html)

Bonsai 24th October 2012 04:07 AM

Class i
 
Class i discussed here by Kendall Caster-Perry:-

The Class i low-distortion audio output stage (Part 2) | EDN

Main benefit is a 'purely resistive' output impeadance. Includes a formal analysis of the circuit - might be an interesting one to explore in a future design, but I dont know it it is suitable for really high powers.

Bonsai 24th October 2012 11:39 AM

Any takers?

ingenieus 24th October 2012 12:19 PM

The article goes into the theory but does not present much by way of an actual circuit.

Part one does present the following as a starting point:

http://www.eetimes.com/ContentEETime...fig2_large.jpg

http://www.edn.com/design/consumer/4...h-pull-outputs

Putting the theory into practice would be a significant effort.When do we get started? :D

dadod 24th October 2012 12:41 PM

There is other thread about Class i and siblings http://www.diyaudio.com/forums/solid...-siblings.html

jcx 24th October 2012 10:10 PM

lots of promises in the 1st part write up but I'm not seeing yet how this isn't just another local feedback error correction scheme
mixing output stage local linearizing feedback with a "non-switching" bias scheme has also been done

jan.didden 14th November 2012 03:46 PM

3rd part of the article.

jan

Struth 16th November 2012 02:13 AM

Hi Guys

Although one benefit is a resistive output impedance, I believe the "main" benefit is elimination of crossover distortion and related low-level nonlinearities.

Have fun
Kevin O'Connor

Edmond Stuart 18th November 2012 08:45 PM

Main benefit ???
 
Quote:

Originally Posted by Bonsai (Post 3213284)
...
Main benefit is a 'purely resistive' output impedance.
...

Hi Andrew,

It's not as 'purely resistive' as you might think, rather it is Zo + Re, where Zo is about the output impedance of any other (regular) EC OPS. Moreover, we have two Re's, the top and the bottom one. If they aren't exactly equal they create another source of distortion (except in case of class-A operation, of course). I wouldn't see this as 'beneficial' feature of class-I.

See: http://www.diyaudio.com/forums/solid...ml#post2826537
and also: http://www.diyaudio.com/forums/solid...ml#post2852220

Cheers,
E.

Bigun 18th November 2012 08:51 PM

Quote:

Originally Posted by Struth (Post 3243296)
Although one benefit is a resistive output impedance, I believe the "main" benefit is elimination of crossover distortion and related low-level nonlinearities.

We've seen very low distortion available from ClassAB for a long time now - why would Class i be of any interest other than intellectual ?

Edmond Stuart 18th November 2012 09:02 PM

Nevertheless, even 'academic curiosities' are worth a closer look. ;)


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