low distortion measurements and forcing opamps to class a

mlloyd1 · 1st July 2009, 08:40 PM

i haven't seen this link posted or discussed and thought it might be of a little interest.

New Technique Accurately Measures Low-Frequency Distortion To <-130 dBc Levels

although the distortion measurement stuff is interesting enough, the real reason i posted the link is the discussion and test results (later in the paper) on forcing an op amp output stage higher into class a.

well, have it ...

mlloyd1

mlloyd1 · 2nd July 2009, 10:36 PM

i guess either everybody's still reading or "measurements" is a bad word ...

and i meant to say "have at it" in my previous message.

mlloyd1

stinius · 2nd July 2009, 10:45 PM

mlloyd1

It was a good link and a very interesting document, sorry to see that nobody responded to your post, to be honest I didn’t respond because I was sure that a lot of others would do that.

KSTR · 3rd July 2009, 12:05 AM

I think the conclusion is a rather bad one:

All manufacturers should provide this data (the optimum class-A current) already in their datasheets for opamps, if an improvement is found. Or somebody with precision measurement capabilities should volunteer to test many typical audio opamps this way and publish the results. A general overview using the same test setup throughout would be really nice to have.

At least now we know a good value for the OPA690. Won't help JC for the AD797, though.

- Klaus

1st July 2009, 08:40 PM	#1
mlloyd1 diyAudio Member Join Date: Feb 2001 Location: illinois	low distortion measurements and forcing opamps to class a i haven't seen this link posted or discussed and thought it might be of a little interest. New Technique Accurately Measures Low-Frequency Distortion To <-130 dBc Levels although the distortion measurement stuff is interesting enough, the real reason i posted the link is the discussion and test results (later in the paper) on forcing an op amp output stage higher into class a. well, have it ... mlloyd1

2nd July 2009, 10:36 PM	#2
mlloyd1 diyAudio Member Join Date: Feb 2001 Location: illinois	wow ... i guess either everybody's still reading or "measurements" is a bad word ... and i meant to say "have at it" in my previous message. mlloyd1

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2nd July 2009, 10:45 PM	#3
stinius diyAudio Member Join Date: Oct 2008	mlloyd1 It was a good link and a very interesting document, sorry to see that nobody responded to your post, to be honest I didn’t respond because I was sure that a lot of others would do that.

3rd July 2009, 12:05 AM	#4
KSTR diyAudio Member Join Date: Jul 2007 Location: Central Berlin, Germany	I think the conclusion is a rather bad one: All manufacturers should provide this data (the optimum class-A current) already in their datasheets for opamps, if an improvement is found. Or somebody with precision measurement capabilities should volunteer to test many typical audio opamps this way and publish the results. A general overview using the same test setup throughout would be really nice to have. At least now we know a good value for the OPA690. Won't help JC for the AD797, though. - Klaus