What are the reasons to choose Class A/AB/H over D in this day and age?

[Lambda]

144dB is the goal!

, given that the better amplifiers are already better than human hearing.

Researchers found a balloon inflated to rupture peaks at 168 decibels (dB).

So i don't know any commercial Amp with over 160dB dynamic...

Are there some new upcoming amp designs of totally new conceptual technology?

With GAN fests been able to switch Mhz-Ghz at high voltages in the near future a Multi Phases DSD like Class D with over 144dB dynamic would be theoretically possible.

 

[tmtomh]

So i don't know any commercial Amp with over 160dB dynamic...


With GAN fests been able to switch Mhz-Ghz at high voltages in the near future a Multi Phases DSD like Class D with over 144dB dynamic would be theoretically possible.

I'm all for improvements in the technology, but I don't agree with @anphex that 144dB is the goal, and I don't see the relevance of the fact that sounds as loud as (and I'm sure much louder than) 168dB can be generated in the world.

For the former - the supposed 144dB goal - it would appear that figure has been chosen simply because it's the max S/N ratio of 24-bit, undithered PCM. But if 24-bit PCM's noise floor is below the threshold of human hearing (which we are told is -115-120dB), then 144dB would seem to go beyond the goal, and by an arbitrary amount. We could, for example, say that if -115-120dB is the human hearing limit, then we should be conservative and go with -120dB, and then we could even say we should add a "safety margin" of another 10dB, resulting in -130dB. Personally I don't think even -130dB is necessary, but a least that would be a figure that has a clear connection to the limits of human hearing, and whose assumptions ("let's use 120dB as baseline"; "let's add a round 10dB for safety margin") could be interrogated and debated.

For the latter - the 168dB balloon pop - the difficulty I see there is a version of the "reproduce a live performance" fallacy: IMHO the point is not for a home hi-fi system to reproduce the full volume range of real-world sounds, because beyond a certain point it is dangerous (even fatal if you go loud enough) for anyone to actually listen at those levels. Now, if someone really wants an amp with a -170dB noise floor so they can lock themselves into totally sound-proofed room and listen to a recording of silence followed by a full-volume 168dB balloon pop, I'm not going to stop them from doing that. If they want to destroy their hearing that's their business. But I am going to insist that that is not a rational or feasible use-case with which to set a standard or goal for amplifier S/N performance.

 

[jruser]

Has anyone put a higher end class-D amp on an oscilloscope and looked at the sine wave? The last I had seen, class-D always had the carrier frequency visible in the sine wave, but I haven't seen this done on any of the higher end models of the last few years.

 

[Frgirard]

I'm all for improvements in the technology, but I don't agree with @anphex that 144dB is the goal, and I don't see the relevance of the fact that sounds as loud as (and I'm sure much louder than) 168dB can be generated in the world.

For the former - the supposed 144dB goal - it would appear that figure has been chosen simply because it's the max S/N ratio of 24-bit, undithered PCM. But if 24-bit PCM's noise floor is below the threshold of human hearing (which we are told is -115-120dB), then 144dB would seem to go beyond the goal, and by an arbitrary amount. We could, for example, say that if -115-120dB is the human hearing limit, then we should be conservative and go with -120dB, and then we could even say we should add a "safety margin" of another 10dB, resulting in -130dB. Personally I don't think even -130dB is necessary, but a least that would be a figure that has a clear connection to the limits of human hearing, and whose assumptions ("let's use 120dB as baseline"; "let's add a round 10dB for safety margin") could be interrogated and debated.

For the latter - the 168dB balloon pop - the difficulty I see there is a version of the "reproduce a live performance" fallacy: IMHO the point is not for a home hi-fi system to reproduce the full volume range of real-world sounds, because beyond a certain point it is dangerous (even fatal if you go loud enough) for anyone to actually listen at those levels. Now, if someone really wants an amp with a -170dB noise floor so they can lock themselves into totally sound-proofed room and listen to a recording of silence followed by a full-volume 168dB balloon pop, I'm not going to stop them from doing that. If they want to destroy their hearing that's their business. But I am going to insist that that is not a rational or feasible use-case with which to set a standard or goal for amplifier S/N performance.

A Power amp is used to reproduce music with a dynamic range between 5 dB and 80 dB.
144 dB is not enough for the cachalot orchestra : 230dB.

 

[NTK]

Has anyone put a higher end class-D amp on an oscilloscope and looked at the sine wave? The last I had seen, class-D always had the carrier frequency visible in the sine wave, but I haven't seen this done on any of the higher end models of the last few years.

This plot gives much more information than a simple oscilloscope trace. Would have been nicer if the output level and load is given (but I assume the data is from the 1kHz 5 W @ 4 ohm test).

 

[pjug]

Has anyone put a higher end class-D amp on an oscilloscope and looked at the sine wave? The last I had seen, class-D always had the carrier frequency visible in the sine wave, but I haven't seen this done on any of the higher end models of the last few years.

They all have residuals from the switching. The Devialet scheme is pretty free of it but even that has something like 6mV noise wideband so not entirely eliminated.

 

[MakeMineVinyl]

Has anyone put a higher end class-D amp on an oscilloscope and looked at the sine wave? The last I had seen, class-D always had the carrier frequency visible in the sine wave, but I haven't seen this done on any of the higher end models of the last few years.

We do that all the time. If there is a switching frequency residual, it is far out of the audio band and is attenuated by the output inductor / filter. For testing purposes, an AES-17 low pass filter is used ahead of the Audio Precision analyzers to filter this out. The presence of this residual is inconsequential for 99.99999% of speaker setups out there and certainly is not audible.

If this situation bothers you, there are other classes of amplifier which work extremely well.

 

[tmtomh]

A Power amp is used to reproduce music with a dynamic range between 5 dB and 80 dB.
144 dB is not enough for the cachalot orchestra : 230dB.

Please direct us to a recording of that orchestra that has a 230dB dynamic range.

 

[ZolaIII]

Please direct us to a recording of that orchestra that has a 230dB dynamic range.

Vulcan Royal orchestra.

 

[tmtomh]

Vulcan Royal orchestra.

So the recording has a 230dB dynamic range? That's a neat trick: at 6.02dB per bit, it would have to be a 39-bit recording.

So please give us a link to the recording.

 

[ZolaIII]

So the recording has a 230dB dynamic range? Link to the recording, please.

That whose a joke as Vulcans (Star Trek and Alien). Not only that something like that doesn't exist but there's no recording equipment (mics, ADC) that will pass 150 SINAD line (and even that much only theoretically).

 

[Eggs Ackley]

So please give us a link to the recording.

Would only be of interest to sperm whales anyway.

 

[tmtomh]

That whose a joke as Vulcans (Star Trek and Alien). Not only that something like that doesn't exist but there's no recording equipment (mics, ADC) that will pass 150 SINAD line (and even that much only theoretically).

D’oh! Sorry for not catching that!

 

[Bob from Florida]

Nice article from Yamaha.

What Is Dynamic Range, and Why Does it Matter? - Yamaha Music - Blog

In this article, we explore the concept of dynamic range and explain why it is so important to the enjoyment of listening to recorded music.

hub.yamaha.com

Read the article and exercise your comprehension. To summarize: 90 db is the range of human hearing, 120 is at the pain limit, music recordings are compressed to typically between 6 and 32 db of dynamic range. So, any talk about greater than 120 db - pain level - is bullshit. Even with a 32 db dynamic range recording going to 120 db peaks would have soft passages at 88 db! Which is already insanely loud.

Much of what is being discussed is way deep in "It just doesn't matter" territory.

Back to the original question. You buy whatever class amp works for your speakers, aesthetically pleases you, and fits your budget.

 

[MaxBuck]

Traditional class A and A/B amplifiers tend to be more interesting as objects in their own right, and thus lend themselves to audio as a hobby. This is doubly true of vacuum tube amplifiers. Class A and A/B amplifiers are relatively (or literally) massive and you can clearly see the technology in action. The sheer presence of these amplifiers is the point; pride of ownership is part and parcel for these amplifiers. They are the logical complement to beautifully finished and imposing loudspeakers.

Class D amplifiers are more like appliances, and its difficult for me to view them as an object of fascination. They are more for the person who wants efficiency in a box which does its job to near technical perfection and otherwise gets out of the way. They are for people who are more interested in the end product - the music or movie sound - and less interested in the bits which are making it possible.

Myself, I'm firmly in the class A / A/B camp, and almost exclusively vacuum tube. I can sit and be fascinated by the glowing tubes while enjoying the music they are enabling. A class D amplifier holds about as much fascination for me as my toaster or lawn sprinkler controller.

Very articulately stated. Since my interest is primarily in hearing the music reproduced as the artist and/or recording engineer intended, modern Class D is kind of obvious for me. For other people whose interest is primarily in the reproduction equipment itself, other priorities may very well prevail.

 

[antennaguru]

Nice article from Yamaha.

What Is Dynamic Range, and Why Does it Matter? - Yamaha Music - Blog

In this article, we explore the concept of dynamic range and explain why it is so important to the enjoyment of listening to recorded music.

hub.yamaha.com

Read the article and exercise your comprehension. To summarize: 90 db is the range of human hearing, 120 is at the pain limit, music recordings are compressed to typically between 6 and 32 db of dynamic range. So, any talk about greater than 120 db - pain level - is bullshit. Even with a 32 db dynamic range recording going to 120 db peaks would have soft passages at 88 db! Which is already insanely loud.

Much of what is being discussed is way deep in "It just doesn't matter" territory.

Back to the original question. You buy whatever class amp works for your speakers, aesthetically pleases you, and fits your budget.

Wikipedia says 100 dB dynamic range for human hearing, so your referenced article's estimate is a whopping 10 times lower than that!

Dynamic range - Wikipedia

en.wikipedia.org

Furthermore:

78 rpm records have 40 dB dynamic range.
33.33 rpm records have 55 - 70 dB dynamic range.
Magnetic Tape has 60 dB dynamic range, without Dolby NR.
CD has 96 dB dynamic range.
A dynamic microphone has 140 dB dynamic range.
A condensor microphone has 125 dB dynamic range.

 

[H-713]

The numbers for dynamic and condenser microphones does vary a bit. Some condensers ca clear 140 dB, though it's rare.

Fact of the matter is, however, that power amplifiers have been a "solved problem", at least from a linearity perspective, for about 40 years now. Doesn't stop some of us from playing with them, but I genuinely do not care about harmonics that are below -90 dB.

As hard as it is for this forum to hear, the only real thing that the Topping PA5 brings to the table over a Hafler DH220 or GFA-545 from the 1980s is a moderate reduction in size, weight and power consumption. Oh, and a volume control (not that anyone cares about volume controls on power amps).

 

[Bob from Florida]

Wikipedia says 100 dB dynamic range for human hearing, so your referenced article's estimate is a whopping 10 times lower than that!

10 db is 10 times the intensity but we perceive that as half volume if going down 10 db or double the volume if increasing 10 db. This also correlates to 10 times the amplifier power to double the perceived volume.

 

[Lambda]

. We could, for example, say that if -115-120dB is the human hearing limit,

Why would you say this?
the lower limit is per definition 0dB SPL
the upper limit is ?
well over 160dB since we all have heard balloon pop for example.

the point is not for a home hi-fi system to reproduce the full volume range of real-world sounds

This is literly the goal of HiFi faithful reproduction of sound.
Short and low Frequency pulses are not at all harmful.

Educate yourself abut dB and dBA used for exposure limits:

Also who said everything must be save?!

120 is at the pain limit, music recordings are

This is all verry frequency and depend
1 cycle 18Hz at 120dB is not alt all painful!
And again who said music cant be Painfully loud dangerous and damaging?

A dynamic microphone has 140 dB dynamic range.
A condensor microphone has 125 dB dynamic range.

 

[antennaguru]

The numbers for dynamic and condenser microphones does vary a bit. Some condensers ca clear 140 dB, though it's rare.

Fact of the matter is, however, that power amplifiers have been a "solved problem", at least from a linearity perspective, for about 40 years now. Doesn't stop some of us from playing with them, but I genuinely do not care about harmonics that are below -90 dB.

As hard as it is for this forum to hear, the only real thing that the Topping PA5 brings to the table over a Hafler DH220 or GFA-545 from the 1980s is a moderate reduction in size, weight and power consumption. Oh, and a volume control (not that anyone cares about volume controls on power amps)

I agree!

Well designed Class AB amplifiers sound equivalent to well designed Class D amplifiers, and they don't appreciably use any more power as proven in my earlier posted kWh measurements. There is nonetheless a preference on this forum for Class D amplifiers because they measure better for SINAD, and are therefore ranked higher by SINAD, and the misbelief they are appreciably more energy efficient - which is simply not true. Audibly, all well designed amplifiers sound equivalent regardless of Class of operation and SINAD measurement.

WRT your example of a Hafler DH220, I built the kit version almost 40 years ago and incorporated all of the Musical Concepts "mods", the most significant of which was increasing the bias current a bit. It still sounds nice today and has certainly stood the best of time. It is also very serviceable. I highly doubt that Class D amplifiers can meet these same product life and serviceability standards, as from what I have seen they are designed to be throw-away modules.