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

[Bob from Florida]

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.

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?!


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?

Hearing a 160 db balloon pop does not mean you can differentiate between 120 db and 160 db. Think about it.

 

[Kal Rubinson]

Why would you say this?
the lower limit is per definition 0dB SPL

No, it is not. 0dB SPL @ 1kHz was chosen as a reference but it is solid science that humans have 4-5dB lower thresholds in the 3-4kHz range.

the upper limit is ?
well over 160dB since we all have heard balloon pop for example.

Untrue and poor logic. We would hear that sound as long as it exceeds our minimum threshold and that depends on frequency.

 

[Lambda]

Untrue and poor logic. We would hear that sound as long as it exceeds our minimum threshold and that depends on frequency.

sure, but i don't get your argument.
of causes it depends on frequency. that's the point we need lots more dB for low frequency to sound loud

So what is the Maximum level we can hear?
i'm sure there is no hard cut off but a point it starts becoming highly non linear.

 

[tmtomh]

sure, but i don't get your argument.
of causes it depends on frequency. that's the point we need lots more dB for low frequency to sound loud

So what is the Maximum level we can hear?
i'm sure there is no hard cut off but a point it starts becoming highly non linear.

Here's an interesting link:

The loudest sound in mankind's history

Krakatoa is believed to be the loudest sound produced on the surface of the planet -- in human history, that is.

www.zmescience.com

The linked article includes this:

"A note on the loudest possible sound in air

"Strictly speaking, the loudest possible sound in air, is 194 dB. The “loudness” of the sound is dictated by how large the amplitude of the waves is compared to ambient air pressure. A sound of 194 dB has a pressure deviation of 101.325 kPa, which is ambient pressure at sea level, at 0 degrees Celsius (32 Fahrenheit). Essentially, at 194 dB, the waves are creating a complete vacuum between themselves.

"You can go louder than 194 dB, but that’s not technically a “sound” anymore. The extra energy starts distorting the entire wave, and you end up with something that’s more a shockwave and less a soundwave. At that level, sounds don’t pass through air — they push the air along, producing pressurized burst (shockwaves).

"But for the sake of the argument (and because let’s face it, no one wants to be overly pedantic), we will consider anything over 194 dB as sounds — just know that that’s not an exact phrasing."

So depending on temperature and elevation/atmospheric pressure, there is a point at which sound ceases to be sound in any meaningful sense of the word.

Beyond that, it's a question of practicality and safety. It is important to note that the NIOSH chart you have shared is not about duration of exposure per instance - it's duration of exposure per day, and it assumes that you are in a generally quieter environment for the rest of the day, and that you are not exposed to that level of noise at all for 2 days a week. The government also explicitly adds three important notes:

1. These charts are not a recommendation for advisable hearing levels outside of occupational settings - they are, rather about maximum allowable levels in environments where loud noise is unavoidable.

2. These guidelines are meant to protect against hearing loss "substantial enough to make it difficult to hear or understand speech" - a level of hearing loss that is way, way worse than any standard people would want to use for music listening or even just sound exposure in normal everyday life.

3. Even with these guidelines, "NIOSH acknowledged that approximately 8% of workers could still develop hearing loss. In order to protect the most sensitive 8% of the population, NIOSH recommends that hearing protection be worn whenever noise levels exceed 85 dB(A) regardless of duration."

So if you put all that together, it does not make sense to aim for 168dB work of dynamic range - or 144dB - in audio equipment. And it's not very wise to consistently listen above even 85dB unless a 1-in-12.5 chance of permanently damaging your hearing over time is odds that you feel comfortable with.

It would be an interesting engineering and technology exercise to see if sound-recording and sound-reproduction equipment could eventually be made that could equal the approx. 194dB range of human-detectable sound. But it would only be an exercise, as there is no good reason to mass-produce hi-fi gear that can reproduce the 1883 Krakatoa eruption at full volume. Not to mention you couldn't really even test whether or not such equipment could actually reproduce a sound that loud, as the Krakatoa sound wave reportedly circled the earth four times and instantly destroyed the hearing of sailors on ships as far as 40 miles away from the volcano.

 

[Kal Rubinson]

So what is the Maximum level we can hear?

Just less than the level that destroys the auditory cilia.

 

[Lambda]

1. These charts are not a recommendation for advisable hearing levels outside of occupational settings - they are, rather about maximum allowable levels in environments where loud noise is unavoidable.

2. These guidelines are meant to protect against hearing loss "substantial enough to make it difficult to hear or understand speech" - a level of hearing loss that is way, way worse than any standard people would want to use for music listening or even just sound exposure in normal everyday life.

3. Even with these guidelines, "NIOSH acknowledged that approximately 8% of workers could still develop hearing loss. In order to protect the most sensitive 8% of the population, NIOSH recommends that hearing protection be worn whenever noise levels exceed 85 dB(A) regardless of duration."

All right and i never sated the opposite.
this is just as reference.
We do a lot of things that are not healthy like drinking and smoking. or driving fast.
i don't want to be limited by how fast the designer of the car thinks is responsibly save but by how fast i want to go even if there is a higher danger.

who said a hobby needs to be save and healthy?

Again how loud and how dangers do you think a halve wave of 18hz would be with an peak of 160dB?!
not at all because:

The ear operates as an energy detector that samples the amount of energy present within a certain time frame. A certain amount of energy is needed within a time frame to reach the threshold. This can be done by using a higher intensity for less time or by using a lower intensity for more time.

Especially if stapedius reflex is allred triggerd

Just less than the level that destroys the auditory cilia.

And what level would this be at 18hz and for a single pulse?

 

[tmtomh]

All right and i never sated the opposite.
this is just as reference.
We do a lot of things that are not healthy like drinking and smoking. or driving fast.
i don't want to be limited by how fast the designer of the car thinks is responsibly save but by how fast i want to go even if there is a higher danger.

who said a hobby needs to be save and healthy?

Again how loud and how dangers do you think a halve wave of 18hz would be with an peak of 160dB?!
not at all because:

Especially if stapedius reflex is allred triggerd


And what level would this be at 18hz and for a single pulse?

A hobby doesn't need to be safe and healthy (although it kind of does need to be safe - see the legal point below). If you want to listen at 168dB and if you want to work on making audio equipment with a corresponding -168dB noise floor, go for it!

Just don't expect any manufacturer - whether it's a mass-market brand, a dedicated amp-module maker, or a audiophile discrete-component boutique operation - to make such equipment. For one thing, it's unnecessary, as 99.9+% of potential buyers have no interest in playing sound at 168dB, and 99.9% of that tiny fraction that do want to play it that loud do not care whether or not the equipment's noise floor remains at 0dB when the volume is turned up to 168dB. Moreover, if someone damages their hearing - or the hearing of others, or their kids turn it way up and damage their hearing in the process - the manufacturer cannot use the "this equipment was never intended to be used that way" defense if it was in fact designed to be able to play that loud without degrading its noise performance.

So for practical, legal-liability, and safety reasons, you're on your own with this quest of yours. But again, go for it if you want! Just make sure no one is within a hundred or more feet of you when you do.

Oh - and if you want to listen to actual, you know, music with 168dB peaks in it, then while you're making your 168dB dynamic range amp, be sure to save some money to totally sound-proof your room, because if you play such a recording at real-life volume on such equipment and you are in a normal, quiet residential room, you're going to have to turn the 1dB sounds on the recording up about 20-25dB in order to be able to hear them above the ambient noise of your room, and so that 168dB peak sound will become 188-193dB and you'll likely go deaf instantly (and at that volume deafen most of your neighbors).

Of course, even if you are in a totally quiet room, the sound of your own breathing averages about 10dB. But if you play songs that are shorter than the amount of time that you can hold your breath, then I guess you could eliminate that problem.

 

[Lambda]

Sure sure
So point was. there are relay loud things in this world we all experienced and we have not had hearing damage from them.
Balloon popping is an easy example because i think we all can relate to this?!

As long as the Frequancy is low and duration is short it is by far not as harmful as you all seam to think.
but safety was never the point.

Point is we are far from having DACs or Amps capable off reproducing the absolute limits of hearing.
How can someone make this statement without defining the upper limit?
I have never said we will soon have 160dB SPL home hifi systems.

I'm just saying even the best systems don't have the dynamic to faithfully reproduce what we all have experienced live.

 

[Kal Rubinson]

And what level would this be at 18hz and for a single pulse?

Lots of data on this but here's some helpful graphs.

 

[clearnfc]

The reason, for me, is availability.

Sadly, the traditional technologies are what's widely available in some product segments (AV receivers, for example), from major vendors.

That said, I've enjoyed class D in car audio (for more than a decade), home theatre subwoofers, and studio monitors for quite some time (product segments where Class D is readily available).

IMHO, one of the main reason why hifi industry is slow in adapting new technologies is low demand. Not that many people are into hifi. Casual listeners are probably more keen in gadgets and lifestyle products like bluetooth speakers, soundbars rather than bookshelf speakers and amps.

This means factories are not "churning" out amps and speakers unlike gadgets and devices like phones, computers, tablets etc. Companies need to recover their investments. If they put in alot of money into development of new technologies but the demand is low, then there is little incentive for them to do so.

 

[Jim Matthews]

Vulcan Royal orchestra.

Anvil chorus, with 'splosions?

 

[rcstevensonaz]

That whose a joke

That is why the smiley was invented: https://www.cs.cmu.edu/~sef/sefSmiley.htm

As a side note: my only "claim to fame" in life is that I was a student at CMU at that time, and was reading the sequence of posts about the "burning candle vs. mercury in a free-falling elevator" as the thread was unfolding. The burn marks in the elevator (from the candle's flame) are still slightly visible nearly forty years later

 

[tmtomh]

Sure sure
So point was. there are relay loud things in this world we all experienced and we have not had hearing damage from them.
Balloon popping is an easy example because i think we all can relate to this?!

As long as the Frequancy is low and duration is short it is by far not as harmful as you all seam to think.
but safety was never the point.

Point is we are far from having DACs or Amps capable off reproducing the absolute limits of hearing.
How can someone make this statement without defining the upper limit?
I have never said we will soon have 160dB SPL home hifi systems.

I'm just saying even the best systems don't have the dynamic to faithfully reproduce what we all have experienced live.

I don't know if that's correct. The loudest rock concert in history (or at least in the Guinness Book of World Records) is a 1976 Who show that was clocked at 120dB.

Now, I would assume that there have been musical performances with peaks louder than 120dB. The first likely example that comes to mind would be a performance of Tchaikovsky's 1812 Overture that used real cannons.

But whatever the SPL of a cannon, the audience is not listening to it at anywhere near the 1 meter standard distance for SPL ratings. Instead, the cannon is fired at a safe distance from the audience so that it will be very loud and impactful, but not painful and potentially deafening. So the 1-meter SPL equivalent of that cannon fire would almost certainly be less than 120dB.

I know you think that I and some others are missing your point, but we are not. Instead, we are saying that what you think is the point of audio equipment design is not actually the point of it. As I noted in a prior comment, if you yourself want to design, build, or try to pay someone to build equipment that can reproduce the actual volume of, for example, standing 1 meter away from a cannon as it's fired, go for it. But that is not the benchmark for hi-fi audio design. This is why I wrote earlier in this thread about the "live performance" fallacy. For most recordings there are many other factors besides sheer volume that make them impossible to convincingly reproduce in your or my listening space. And conversely, the recordings that are probably most likely to be reproducible in a convincingly "live" manner are small acoustic ensemble recordings, or something like solo piano and voice, close mic'd - and for those recordings you usually don't need to worry about massive, 120dB-and-louder dynamics.

You can want what you want and that's fine - but when it comes to using the experience of standing right next to a balloon that is inflated until it pops as a standard for audio equipment design and performance, you're barking up the wrong tree.

 

[Momotaro]

I don't know if that's correct. The loudest rock concert in history (or at least in the Guinness Book of World Records) is a 1976 Who show that was clocked at 120dB.

Now, I would assume that there have been musical performances with peaks louder than 120dB. The first likely example that comes to mind would be a performance of Tchaikovsky's 1812 Overture that used real cannons.

But whatever the SPL of a cannon, the audience is not listening to it at anywhere near the 1 meter standard distance for SPL ratings. Instead, the cannon is fired at a safe distance from the audience so that it will be very loud and impactful, but not painful and potentially deafening. So the 1-meter SPL equivalent of that cannon fire would almost certainly be less than 120dB.

I know you think that I and some others are missing your point, but we are not. Instead, we are saying that what you think is the point of audio equipment design is not actually the point of it. As I noted in a prior comment, if you yourself want to design, build, or try to pay someone to build equipment that can reproduce the actual volume of, for example, standing 1 meter away from a cannon as it's fired, go for it. But that is not the benchmark for hi-fi audio design. This is why I wrote earlier in this thread about the "live performance" fallacy. For most recordings there are many other factors besides sheer volume that make them impossible to convincingly reproduce in your or my listening space. And conversely, the recordings that are probably most likely to be reproducible in a convincingly "live" manner are small acoustic ensemble recordings, or something like solo piano and voice, close mic'd - and for those recordings you usually don't need to worry about massive, 120dB-and-louder dynamics.

You can want what you want and that's fine - but when it comes to using the experience of standing right next to a balloon that is inflated until it pops as a standard for audio equipment design and performance, you're barking up the wrong tree.

Sadly (or thankfully, depending on your perspective) Guinness BoR apparently don't run that category now. AC/DC are reputed to have played at 130 dB for a while, as were My Bloody Valentine. The latter provided ear plugs so devotees could safely endure a full-body shoegaze sonic sandblasting.

But back to the balloon. You've covered distance, but people often ignore the related characteristics of potential sonic excess, amplitude and duration. The effective power and related damage of a sonic event depend on both. It's an area-under-the-curve thing. A tall thin wave may wet the windows of a skyscraper, a tall fat wave may bowl it over.

 

[antennaguru]

I believe OSHA requires hearing protection be used by employees working in an environment with 88 dBA SPL for 40 hours per week. I first noticed this when flying on Turbo-prop planes and the flight attendant would put in earplugs before we took off. After seeing that I started wearing them myself as a passenger.

 

[antennaguru]

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).

Wow, 50 mW at 500 MHz. Sounds like a medium wave exciter/transmitter (+17 dBm)! The speaker leads will radiate like a dipole so this must be a Part 15 device (FCC).

 

[ebslo]

Wow, 50 mW at 500 MHz. Sounds like a medium wave exciter/transmitter (+17 dBm)! The speaker leads will radiate like a dipole so this must be a Part 15 device (FCC).

kHz, not MHz.

 

[dc655321]

The loudest rock concert in history (or at least in the Guinness Book of World Records) is a 1976 Who show that was clocked at 120dB.

System of a Down, Open Air Festival, Chicago 2019 ( I think?). We were 30m back from stage. F'ing loud. Great show!

 

[antennaguru]

kHz, not MHz.

Thats what I meant, sorry for the typo. Medium wave transmitter, will bother AM radio reception. Needs Part 15 Type Acceptance without an output filter.

 

[DanielT]

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.

Maybe so, or it's like this. Class D based on Texas Instruments (for example Aiyima A07, Topping PA5):

It is also worth repeating that TI has never intended the TPA325x series to be used for pure hi-fi amplifiers. They (TI) undoubtedly understand that performance is not really enough. The distortion increasing with frequency is a problem, but especially without PFFB you also get far too large frequency deviations for a normal speaker (typically one or a couple of dB) over about 10 kHz due to the impedance of the output filter.

Between the thumb and forefinger, this distortion is halved with PFFB, so Topping.... . This is of course very good for a class D construction, even if it is far from what a better class AB construction can handle.

PA5 is not a bad amplifier, but it would surprise me greatly if the high frequency distortion was not audible. However, this may not be the way to look at it all, but instead you should use PA5 to obtain good amplification in a small size and at a low price for desk systems and the like.

faktiskt.io • Visa tråd - Topping PA5 lysande test resultat