Technics Class A Biasing - Page 3

atiq19 · 10th January 2009, 11:52 PM

you could try this website for generic info on cross-over error:

http://www.angelfire.com/ab3/mjramp/pagetwo.html

jkeny · 11th January 2009, 12:26 AM

Thanks atiq19,
This site shows Dynamic crossover distortion well & this is what is eliminated in the biasing scheme you asked about. Seems like a worthwhile improvement to me but Andrew & Bob both seem to criticise it because it's not class A according to Andrew (so what) & it still leaves static crossover distortion according to Cordell.

I'm just trying to get Bob Cordell to say how important this static distortion is in the scheme of things? For instance, I understand that it's not frequency dependent which is a good thing as the ear can easily accommodate itself to some level of distortion which doesn't vary (with frequency, etc).

So is the bias scheme being criticised unfairly? Do we need to operate purely in highly wasteful Class A to eliminate a minor non-issue?

atiq19 · 11th January 2009, 12:37 AM

I haven't got holistic knowledge about this static + dynamic cross-over distortion phenomenon and their relations to signal variations. this is the first time I have seen such a distinguished answer from Mr Cordell. Best of my knowledge, this area hasn't been investigated with stringent measurement techniques, so far but I may be wrong.

Anyway have a look at the original site:

http://www.angelfire.com/ab3/mjramp/index.html

I think Mr Renardson is not relying only on flimsy non-switching criteria rather he devised some improved feed-forward error correction technique originated in Quad Current Dumping amps.

The whole issue needs to be revisited, I believe.

Cheers

atiq19 · 11th January 2009, 12:46 AM

sorry,

my poor writing skills.

I meant, 'such a distinguished/decisive answer from Mr Cordell on this matter'.

I wouldn't bother about class A, B, AAB etc. Class A is class A. I am a low carbon consultant by trade. I wanted to see some innovative solutions to class A amps whereby efficiency could be improved without much compromising to sonic performance. I thought it has already been done so many years gone passed for Hi-fi R&D.

andy_c · 11th January 2009, 01:04 AM

Quote:

Originally posted by atiq19
The whole issue needs to be revisited, I believe.

Hi atiq,

I have the AES preprint article on this topology by Danyuk and Renardson. I can email it to you if you wish. I have only glanced at it and not read it in detail.

atiq19 · 11th January 2009, 01:07 AM

yes please.

cheers

jkeny · 11th January 2009, 01:09 AM

Thanks atiq,
I'm reading the Renardson site as I post - very interesting - any others built this circuit yet, I wonder? Are you tempted to purchase some pcbs?

atiq19 · 11th January 2009, 01:10 AM

I dropped a line to Renardson.

Waiting for response.

atiq19 · 11th January 2009, 01:17 AM

Jkeny,

I believe this man has done some some work on Renardson amp:

http://petrh.org/web/renardson.aspx

Mind you this was based on early days design from Renardson. He has refined his toplology to date.

You need google translator to read (?) this page written in Czech.

Also look here:

new Renardson amp

cheers.

andy_c · 11th January 2009, 01:24 AM

Quote:

Originally posted by atiq19
yes please.

You have mail

.

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10th January 2009, 11:52 PM	#21
atiq19 diyAudio Member Join Date: Jun 2007	you could try this website for generic info on cross-over error: http://www.angelfire.com/ab3/mjramp/pagetwo.html

11th January 2009, 12:26 AM	#22
jkeny Banned Join Date: Feb 2007 Location: Dublin	Thanks atiq19, This site shows Dynamic crossover distortion well & this is what is eliminated in the biasing scheme you asked about. Seems like a worthwhile improvement to me but Andrew & Bob both seem to criticise it because it's not class A according to Andrew (so what) & it still leaves static crossover distortion according to Cordell. I'm just trying to get Bob Cordell to say how important this static distortion is in the scheme of things? For instance, I understand that it's not frequency dependent which is a good thing as the ear can easily accommodate itself to some level of distortion which doesn't vary (with frequency, etc). So is the bias scheme being criticised unfairly? Do we need to operate purely in highly wasteful Class A to eliminate a minor non-issue?

11th January 2009, 12:37 AM	#23
atiq19 diyAudio Member Join Date: Jun 2007	I haven't got holistic knowledge about this static + dynamic cross-over distortion phenomenon and their relations to signal variations. this is the first time I have seen such a distinguished answer from Mr Cordell. Best of my knowledge, this area hasn't been investigated with stringent measurement techniques, so far but I may be wrong. Anyway have a look at the original site: http://www.angelfire.com/ab3/mjramp/index.html I think Mr Renardson is not relying only on flimsy non-switching criteria rather he devised some improved feed-forward error correction technique originated in Quad Current Dumping amps. The whole issue needs to be revisited, I believe. Cheers

11th January 2009, 12:46 AM	#24
atiq19 diyAudio Member Join Date: Jun 2007	sorry, my poor writing skills. I meant, 'such a distinguished/decisive answer from Mr Cordell on this matter'. I wouldn't bother about class A, B, AAB etc. Class A is class A. I am a low carbon consultant by trade. I wanted to see some innovative solutions to class A amps whereby efficiency could be improved without much compromising to sonic performance. I thought it has already been done so many years gone passed for Hi-fi R&D.

11th January 2009, 01:07 AM	#26
atiq19 diyAudio Member Join Date: Jun 2007	yes please. cheers

11th January 2009, 01:09 AM	#27
jkeny Banned Join Date: Feb 2007 Location: Dublin	Thanks atiq, I'm reading the Renardson site as I post - very interesting - any others built this circuit yet, I wonder? Are you tempted to purchase some pcbs?

11th January 2009, 01:10 AM	#28
atiq19 diyAudio Member Join Date: Jun 2007	I dropped a line to Renardson. Waiting for response.

11th January 2009, 01:17 AM	#29
atiq19 diyAudio Member Join Date: Jun 2007	Jkeny, I believe this man has done some some work on Renardson amp: http://petrh.org/web/renardson.aspx Mind you this was based on early days design from Renardson. He has refined his toplology to date. You need google translator to read (?) this page written in Czech. Also look here: new Renardson amp cheers.