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Class A?  Really?
Class A?  Really?
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Old 16th September 2021, 11:40 AM   #101
Jazz Man is offline Jazz Man  Wales
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IIRC Nelson Pass mentions how the degree and type of distortion can give a sense of increased depth in his H2 article.
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Old 16th September 2021, 12:12 PM   #102
phase is offline phase  United States
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Quote:
Originally Posted by mocenigo View Post
The future for class D for critical listening is now. In fact, it has been that future for a few years now.
That has not been my experience however!
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Old 16th September 2021, 12:33 PM   #103
andyr is offline andyr  Australia
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Quote:
Originally Posted by Jazz Man View Post
IIRC Nelson Pass mentions how the degree and type of distortion can give a sense of increased depth in his H2 article.
Aah, thank you, JM - that makes a lotta sense.

(The amplifier delivering the greater sound stage depth was a well-regarded Class A tube amp - with, obviously, a much higher level of H2 than a Purify Class D amp.)

Andy
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Old 16th September 2021, 01:24 PM   #104
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by mocenigo View Post
The future for class D for critical listening is now. In fact, it has been that future for a few years now.
Quote:
Originally Posted by phase View Post
That has not been my experience however!
It really depends on what “class D” you’ve been listening too. Not all class D is created equal - some of it is far worse than others.

My experience is that you *can* eliminate the TYPE of distortion that people who hate class AB object to with well designed class D. You CANNOT do this (safely) at very high power levels, as it requires switching frequencies approaching a megahertz and dead times of 10 nanoseconds. And a lot of filtering. This requires “electrically small” components - wavelength-wise, and kilowatt amplifiers tend to violate this. This kind of limits it to power levels that are appropriate for class A (but eliminates the heat, of course). If you’ve been listening to Behringer iNukes, some cheap Chinese kit, or something in a price-point receiver - they are not near as good as class D is intrinsically “capable” of.
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Old 16th September 2021, 01:39 PM   #105
mocenigo is offline mocenigo  Germany
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Quote:
Originally Posted by andyr View Post
Quote:
Originally Posted by mocenigo View Post
So they are balanced? push pull?
No, they do not have a balanced topology - RCA inputs.
Ok, there is some confusion here. You can have RCA inputs only and a balanced design, or a push pull, and so on. I was also a puzzled when you said "no SE, because I have +V and -V". Mmmm.

Quote:
I am afraid I am no expert; I know they are 'Class A' (so the NPN and PNP Mosfets never turn off) - but whether this is defined as 'push pull' ... I have no idea.
What is the design you build? (link please :-) )
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Old 16th September 2021, 01:41 PM   #106
mocenigo is offline mocenigo  Germany
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Quote:
Originally Posted by andyr View Post
Aah, thank you, JM - that makes a lotta sense.

(The amplifier delivering the greater sound stage depth was a well-regarded Class A tube amp - with, obviously, a much higher level of H2 than a Purify Class D amp.)

Andy
I definitely need to return to coding my filter to add various type of distortion in the digital domain...
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Old 16th September 2021, 04:11 PM   #107
mocenigo is offline mocenigo  Germany
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Quote:
Originally Posted by phase View Post
That has not been my experience however!
Then have not listened to the right Class D amplifiers. And/or you mistake euphonic distortion for a "better" prerequisite for critical listening.
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Old 16th September 2021, 09:32 PM   #108
andyr is offline andyr  Australia
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Quote:
Originally Posted by mocenigo View Post
Ok, there is some confusion here. You can have RCA inputs only and a balanced design, or a push pull, and so on. I was also a puzzled when you said "no SE, because I have +V and -V". Mmmm.

What is the design you build? (link please :-) )
Yes, it is not your average Class A. It sounds absolutely wonderful, though! I built 2 of the 4R version, as they needed to power the 3ohm mids and 2 ohm ribbons of my active Maggies.

Here's the link: Alpha Nirvana 39w 8ohm Class A Amp - diyAudio

Andy
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Old 17th September 2021, 12:54 AM   #109
bimo is offline bimo  Indonesia
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Quote:
Originally Posted by mocenigo View Post
Actually good AB and D is various orders of magnitude measurably better than class A. T
No. Push pull amplifier of Class AB and class A, the different is only bias current of output transistors. The measurement different is only harmonic profile of the distortion. If you compare class AB and class A with different topology (not only bias current change), of course they will measure different.
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Old 17th September 2021, 01:04 AM   #110
bimo is offline bimo  Indonesia
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Quote:
Originally Posted by andyr View Post
1. a Purify 452 (I think the model is) stereo amp.
2. A pair of Audio Research 250SE tube monoblocs.

#2 produced a deep soundstage, from the plane of the spkrs to waaay back.
#1 had a flat soundstage.

This difference was easy to hear ... I'm curious to know what measurements would explain the difference we heard.
Sound stage is about matching phase and gain in two channel, and no (or small) phase distortion in each channel.
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