Class AB vs D

[oldschool4me 10+ year member]

i did my own lil study a long time ago on amps. i used an audio art car amp on two orion xtr 12s. awesome sound by the way. and i took a home reciever and ran extension cord to the car and ran the subs with it. the home reciever ran the subs a good bit more efficiently. you cant say there is no audible difference between a thd of .05% and .0008%. same for 1% to .05. if you guys have the equipment try this out.

 

[joetama 5,000+ posts]

Who said they all sound the same?

No one did, but a lot of people think they do. It was just a comment that is all.

Which ones cannot? Sound quality is not subjective, sorry.

SQ is subjective. For example, go to your local HT store and listen to every speaker they have. They are all going to sound different. Person A might think B&W sounds the best. Person B might think MartinLogan sounds the best. Person C might think Thiel or Focal or Paradigm sounds the best. A users experience is what makes sound quality totally subjective. I personally like a clear but relaxed presence range while still being slightly bright with an exact high frequency and a dry tight bass. Many others think the optiumum sound quailty is a full midrange with a full presence range with a slight roll off of high frequency and a strong thick bass. My definition of SQ varies from someone elses, so SQ is subjective. Measurement equipment can not tell me these parameters, my ear does. There for SQ is subjective, becuase it depends on the subject listening.

You cannot hear an amp, you can only hear a speaker. Listen to any speaker you want and move your head by 2" and it will sound different, even though it may have not objectively/physically changed. Ears are necessary to perceive sound. Sound itself doesn't exist in a world without ears...waves are waves.

Sound exists without hearing. Sound is sound and you are right waves are waves. But, everything you put in a signal line affects the total sound. If I put an EQ inline with my system and take 1K out it is affecting the sound coming out of my speaker, so you hear the EQ in a mannor of speaking. If an amplifier tends to be bright it affects the sound coming out of the speaker by making it brighter, so essentually you hear the amplifier. A frequency sweep of the amplifier might look perfectly flat. But, when factoring in reactance with input devices and reactance with output devices you might end up with a bright sound. Circuits which are made differently react differntly to inputs and outputs. Since most circuits are not coppied but redesigned for a particular goal most will act differently in different situations. Many times this is not audible, but people shouldn't fool themselves into think this doesn't happen.

Anyway, I think I have gotten off point.

This guy should go Class D, simply because of the heat, power, and quality factors. That is all.

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[n2audio 5,000+ posts]

i did my own lil study a long time ago on amps. i used an audio art car amp on two orion xtr 12s. awesome sound by the way. and i took a home reciever and ran extension cord to the car and ran the subs with it. the home reciever ran the subs a good bit more efficiently. you cant say there is no audible difference between a thd of .05% and .0008%. same for 1% to .05. if you guys have the equipment try this out.

this is so vague it has no relavence whatsoever.

There is a listening test on bcae1.com dealing with distortion.

It starts with a 2khz @ 0% THD, a few seconds in it adds 1%, then 5%. It's very difficult to hear 1%, 5% fairly obvious.

Even with 5% though - if that were mixed with music it would be very difficult to differentiate between something less than 1%.

To discern

 

[n2audio 5,000+ posts]

Oh man here we go...

I can sum this up in 3 points:

1. Some amps might have a different sound, it might be marginal but it is there.

2. Not all audible parameters can be measured.

3a. Most people either can't hear the difference

3b. or don't have a good enough system to hear the difference.

Most people are going to fall into 3b.

1) Marginal as in "inaudible"? yes.

2) That's just wrong. An amp is not a work of art. Everything about them can be measured to a degree far beyond audibility.

3) Ahh, the golden ears' mantra -- Either you're not as gifted, or not as rich as me. And from the golden ears' perspective -- probably both.

 

[FoxPro5 5,000+ posts]

SQ is subjective. For example, go to your local HT store and listen to every speaker they have. They are all going to sound different. Person A might think B&W sounds the best. Person B might think MartinLogan sounds the best. Person C might think Thiel or Focal or Paradigm sounds the best. A users experience is what makes sound quality totally subjective. I personally like a clear but relaxed presence range while still being slightly bright with an exact high frequency and a dry tight bass. Many others think the optiumum sound quailty is a full midrange with a full presence range with a slight roll off of high frequency and a strong thick bass. My definition of SQ varies from someone elses, so SQ is subjective. Measurement equipment can not tell me these parameters, my ear does. There for SQ is subjective, becuase it depends on the subject listening.

You've made an argument for personal preference, that's all. Quality is absolute an doesn't change when we go to measure it. Our interpretation, may however.

Sound exists without hearing.

No, it doesn't. It's sensory perception which lies within the organ that's sensitive to it (ie your ears) and your brain that interprets it. Same thing as color and eyes. There is nothing in 440hz that says it's the color red, is there? What is in a 110 hz wave that tells you it's a males voice or a distorted guitar? Nothing. It is in your head, that is a fact.

 

[rc10mike 10+ year member]

No, it doesn't. It's sensory perception which lies within the organ that's sensitive to it (ie your ears) and your brain that interprets it. Same thing as color and eyes. There is nothing in 440hz that says it's the color red, is there? What is in a 110 hz wave that tells you it's a males voice or a distorted guitar? Nothing. It is in your head, that is a fact.

So if a tree falls in the woods and nobody is around to hear it, does it still make noise?

 

[n2audio 5,000+ posts]

So if a tree falls in the woods and nobody is around to hear it, does it still make noise?

Since we know it would move the air and a person would HEAR it if they were there we would say yes, but in reality - if there is not a sound sensing organ or instrument present to listen noise is just motion.

 

[FoxPro5 5,000+ posts]

So if a tree falls in the woods and nobody is around to hear it, does it still make noise?

No. Noise is something ears hear. There is nothing that can tell the difference between 40hz from your sub and 40hz from a diesel engine except ears. If you were deaf, you could still feel the impact of the airwaves hitting you, though....but it's not sound.

Yea, it's picky but it's true. Human senses are very easily fooled all the time. For example, stereo sound is a complete trick on our ears...it's an illusion.

If you want to make an argument for timbre, a quality of sound, then that's completely different. Timbre is the difference between those 40hz waves. But, to know timbre you have to rely on memory. It's a mess, but it's real science.

 

[oldschool4me 10+ year member]

this is so vague it has no relavence whatsoever.
There is a listening tests on bcae1.com dealing with distortion.

It starts with a 2khz @ 0% THD, a few seconds in it adds 1%, then 5%. It's very difficult to hear 1%, 5% fairly obvious.

Even with 5% though - if that were mixed with music it would be very difficult to differentiate between something less than 1%.

To discern

just a study i did on my own and this thread reminded me of it. maybe you could explain why there was such an audible difference then. try it if you have say a 200watt home stereo and a 200watt car amp. its not a small barely noticable difference. it a good bit of difference actually. just a fun experiment. i already stated my opinion of class a/b and d amps. you pay for what you get period. i just say dont be foold by what manufacturers say the amp puts out and set your self up to think your getting a true 1000w amp and its $200 new and when someone with a good 200w amp blows yours away you feel like a rere boy. not so much of a difference in classes of amps then quality of the amp. but i do think on average you can hear the difference between class a/b and d. but a good class d you probably wouldnt notice it.

 

[Beerdrnkr 5,000+ posts]

I definately don't have as much experience or knowledge as a lot of you in this thread but maybe the difference or non difference is also the fact that a lot of the people that say they like a/b over d are usually talking about old school a/b amps, which were usually overbuilt in the U.S. and with high quality components. I honestly haven't heard better sounding (while getting loud) systems recently, then from some friends I had back in the day using old school class a/b amps. I don't know if it's that 100wrms back then was more like 150wrms or what. Maybe the reason no one can tell a difference now between class a/b and d is because class a/b amps aren't made as stout and with quality parts as they used to be. If class D was so much better than a/b I don't understand why manufactures/engineers/amp designers would still be making class a/b amps? Obviously everyone has their own opinions so chalk up another "draw" to this same thread that has been debated over and over again.

 

[n2audio 5,000+ posts]

maybe you could explain why there was such an audible difference then. try it if you have say a 200watt home stereo and a 200watt car amp. its not a small barely noticable difference. it a good bit of difference actually.

Because w/o level matching to an acceptable degree of accuracy there was no comparison going on at all other than one being louder than the other.

Not to mention - a home amp/reciever is typically designed to power an 8 ohm load. If you hooked it up to 4 ohm speakers who knows how much power it was producing.

 

[n2audio 5,000+ posts]

If class D was so much better than a/b I don't understand why manufactures/engineers/amp designers would still be making class a/b amps? Obviously everyone has their own opinions so chalk up another "draw" to this same thread that has been debated over and over again.

because regardless of all the proof in the world there are still a/b purists that will only buy a/b amps. Mfg's are well aware of this so they'll continue to build them.

you have to stop and realize that we the enthusiasts are only a small segment of the consumer market. Millions and millions of dollars come from those who have no idea what a class D amp is vs a class a/b, and that's just scratching the surface of the "drive-by" car audio customer's ignorance.

A/b's are here to stay, and it has nothing to do with any shortcomings from high efficiency full range amps.

 

[oldschool4me 10+ year member]

wasnt just louder, it ran the sub alot more efficiently as well.

 

[joetama 5,000+ posts]

1) Marginal as in "inaudible"? yes.2) That's just wrong. An amp is not a work of art. Everything about them can be measured to a degree far beyond audibility.

3) Ahh, the golden ears' mantra -- Either you're not as gifted, or not as rich as me. And from the golden ears' perspective -- probably both.

//content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

I guess if you don't hear it you won't hear it. That is it. That does not mean others don't experience something different. You are completely right about just about everything being measured. However, to completely measure everything would be so totally impractical it is almost never done. There is only a certain degree to which we can measure with impunity. A speakers reactivity and consequent impedance is almost infinitely variable can you measure two amplifiers with an infinite number of reference points? No you can't with machines; but guess what can? Your ear! BTW, some people's hearing is better than others, which is a fact. But, women statistically have better hearing than men and how many women are in this hobby? Not many, so really the point is to hear something better you have to train yourself. I know people with much better hearing than myself but they don't notice some of the things I do. I am by no means calling myself a mythical magic ear god, but no one can make me think what I hear is wrong. Sorry.

You've made an argument for personal preference, that's all. Quality is absolute an doesn't change when we go to measure it. Our interpretation, may however.


No, it doesn't. It's sensory perception which lies within the organ that's sensitive to it (ie your ears) and your brain that interprets it. Same thing as color and eyes. There is nothing in 440hz that says it's the color red, is there? What is in a 110 hz wave that tells you it's a males voice or a distorted guitar? Nothing. It is in your head, that is a fact.

Well what is the scientific idea of quality? How would you describe quality? What is quality?

Something that has the lowest distortion? Highest dampening factor? Flattest frequency response to 100kHz? A system that most accurately reproduces sound?

Which begs the question, do we listen for scientific numbers and for machines? Or do we listen for our own enjoyment and the satisfaction of our brains?

I've seen amplifiers with rather impressive statistics putter out sound that is utterly unlistenable. Is that quality? The problem is quality can't really be defined without the human element. But, when you enter the human element you add a completely non objective source of observation.

So, I guess you guys can listen for machines. I'll listen for my ears. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[squeak9798 5,000+ posts]

No you can't with machines; but guess what can? Your ear!

Your ear/human sensory of sound is a horribly inaccurate measurement device. Indisputable.

BTW, some people's hearing is better than others, which is a fact.

My dad is a mechanic, has been for 35+ years. One day my car was making this odd high-pitched squeaking noise (not wear indicators on the pads). I took my dad on a drive in my car so that he could hear the noise, when it occurred, etc to try to troubleshoot it. So we get out on the road, a few miles into our drive, and he says...."So it must not be making the noise now, huh?". //content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif "What the hell are you talking about, you can't hear that god awful noise?" I say. "Nope, I don't hear a thing."

All those years working with power tools and loud engines, his high frequency hearing is shot! //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Moral of the story....Your right; human hearing is inaccurate and a horrible device with which to measure sound.

Well what is the scientific idea of quality? How would you describe quality? What is quality?

The output that most closely matches the input. Not that difficult. Personal perception and subjectivity can be left at the door. Which you most "prefer" is completely irrelevant, to this discussion at least.

Which begs the question, do we listen for scientific numbers and for machines? Or do we listen for our own enjoyment and the satisfaction of our brains?

Accuracy is not measured with our ears or brains. That simple.

Set up your system how you prefer, what you think sounds subjectively better, if you wish. That's certainly up to you. But don't try to argue that because you prefer it, it must be most accurate. That would be a fallacy to say the least.

I've seen amplifiers with rather impressive statistics putter out sound that is utterly unlistenable. Is that quality? The problem is quality can't really be defined without the human element.

See above. Subjectivity and personal preference does not in any way equate to accuracy and/or quality.

Accuracy is 100% objective. No two ways around it. You might not prefer it. You might subjectively think that non-accuracy "sounds better". Fine. Whatever.

But you liking it does not equate to accuracy/quality. People "enjoy" and subjectively prefer some pretty horrendous things as far as accuracy is concerned......bass 40+db louder than the rest of the system, distortion well into the double digits, etc.

But, when you enter the human element you add a completely non objective source of observation.

Exactly.

So, I guess you guys can listen for machines. I'll listen for my ears. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Fine. Just don't call it "accurate" or higher "quality".