watchnerd
Grand Contributor
- Thread Starter
- #101
Thank you, I am in the same direction in my multichannel multi-amplifier project...
Good lord.
How do you have time to work on all that?
Thank you, I am in the same direction in my multichannel multi-amplifier project...
I don't doubt that. However, a high Class AB bias point does not provide the lowest distortion. That may not have been the point of the A51 design either. Many times marketing needs prevail over engineering optimizations in commercial products.My Parasound A51 claims something like this I think. It is a great sounding amp.
Actually, it is quite easy to study (but admittedly harder to fully understand). I highly recommend Douglas Self's article series in Wireless World about distortion in audio amplifiers. It's 7-8 articles throughout a year in the mid-1990s. The articles later became his book on Audio Power Amplifier Design. He walks you through the various distortion mechanism in a power amp, including the impact of output stage biasing. You get the lowest distortion in an emitter follower output stage when one thermal voltage (Vt = kT/q) is present across each emitter resistor.Push-pull class A easily transits to class AB. It is all about idle current and load impedance. No mysteries here. There may be variable bias as well, or class A+. Marketing x user's education, as always. Study, though it is not easy.
Good lord.
How do you have time to work on all that?
And, I really like your title of this thread "Class A vs AB -- Do They Really Sound Different?", where you did not say "Class A vs AB -- Do They Really Measure Different?"
I do hope all of you would please stay safe and enjoy music during the holiday season and (hopefully towards happy) new year.
If anyone wants to do a Foobar ABX, I can do a couple of level matched (electrical, at the speaker terminals, low level for crossover distortion detection- straight into the A/D of say a focusrite 2i2v2) short recordings of my big Marantz PM-95 Mosfet in Class A and then in Class AB.
This puppy:
https://audio-database.com/MARANTZ/amp/pm-95-e.html
View attachment 100584
http://www.thevintageknob.org/marantz-PM-95.html
If anyone wants to do a Foobar ABX, I can do a couple of level matched (electrical, at the speaker terminals, low level for crossover distortion detection- straight into the A/D of say a focusrite 2i2v2) short recordings of my big Marantz PM-95 Mosfet in Class A and then in Class AB.
This puppy:
https://audio-database.com/MARANTZ/amp/pm-95-e.html
View attachment 100584
http://www.thevintageknob.org/marantz-PM-95.html
If anyone wants to do a Foobar ABX, I can do a couple of level matched (electrical, at the speaker terminals, low level for crossover distortion detection- straight into the A/D of say a focusrite 2i2v2) short recordings of my big Marantz PM-95 Mosfet in Class A and then in Class AB.
This puppy:
https://audio-database.com/MARANTZ/amp/pm-95-e.html
View attachment 100584
http://www.thevintageknob.org/marantz-PM-95.html
What the heck was that used for, given it would have a ceiling of about 16 kHz in the audible range?
I acknowledge that I have visual biases but it does not account for the subtle but obvious differences I hear with Class A amplifiers.What's to be sorry about?
After having done a lot of level-matched ABX testing, I'm just acknowledging my limitations and propensity for sighted bias.
I acknowledge that I have visual biases but it does not account for the subtle but obvious differences I hear with Class A amplifiers.
please do not assume to understand what and how i hear.You don't know that because you haven't done the basic experiment.
uh huhplease do not assume to understand what and how i hear.
i have been to many audio shows over the years and can usually spot a class A amp the minute i walk in to a room regardless if i am aware of the particular amplifier's topology or not.
Undeniable fact: class A/B amplifiers can exhibit crossover distortion, and class A amplifiers cannot.I acknowledge that I have visual biases but it does not account for the subtle but obvious differences I hear with Class A amplifiers.
I acknowledge that I have visual biases but it does not account for the subtle but obvious differences I hear with Class A amplifiers.
Undeniable fact: class A/B amplifiers can exhibit crossover distortion, and class A amplifiers cannot.
I know the scientists here will scream about correctly designed class A/B being 'perfect' and 'that problem was solved' yada, yada, yada.
please do not assume to understand what and how i hear.
i have been to many audio shows over the years and can usually spot a class A amp the minute i walk in to a room regardless if i am aware of the particular amplifier's topology or not.
Undeniable fact: class A/B amplifiers can exhibit crossover distortion, and class A amplifiers cannot.
I know the scientists here will scream about correctly designed class A/B being 'perfect' and 'that problem was solved' yada, yada, yada.
But class A is not automatically a cure to all distortion issues.