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Old 5th January 2010, 05:30 AM   #31
gootee is offline gootee  United States
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Quote:
Originally Posted by danielwritesbac View Post
I loved your comment.

Now, I don't have a boom car, but just happened to think that maybe, with loud rap, it could be the case of replay exactly as the artist intended.
Wow, I wish I had thought of that! Good one! It's probably the truth, too.
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Old 5th January 2010, 12:10 PM   #32
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Chip amps vs class D amps?
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Old 5th January 2010, 12:42 PM   #33
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Oh ROTFLMAO, audiophiles are a slowly dieing bread. People come over to my house and look at my huge Infinity BETA's and racks of equipment and ask my wife how she stands all that "crap".
And yes I totally agree I do not want to close my eyes to perfection in reproduction, but how do you open others?
It started with advertising, louder sells, then radio, more compression more volume more attention. Quality has gone out the window for who can make the loudest CD, because that's what the masses expect.
What happened to creativity, and talent?? in this day and age of sampled, digitized, sound when anybody with a computer can make "music" .......
I think it all comes down to schools, we have leveled the playing field for students, stifled creativity, and all but removed most art programs. With no reason to excel students wont.
How do you create Mozart's, and Einstein's when everybody is "joe". No reward no gain.
In our quest not to alienate anyone we have stifled creativity, and neutered our education system.
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Old 6th January 2010, 03:35 AM   #34
gootee is offline gootee  United States
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Originally Posted by tiltedhalo View Post
Oh ROTFLMAO, audiophiles are a slowly dieing bread. People come over to my house and look at my huge Infinity BETA's and racks of equipment and ask my wife how she stands all that "crap".
And yes I totally agree I do not want to close my eyes to perfection in reproduction, but how do you open others?
It started with advertising, louder sells, then radio, more compression more volume more attention. Quality has gone out the window for who can make the loudest CD, because that's what the masses expect.
What happened to creativity, and talent?? in this day and age of sampled, digitized, sound when anybody with a computer can make "music" .......
I think it all comes down to schools, we have leveled the playing field for students, stifled creativity, and all but removed most art programs. With no reason to excel students wont.
How do you create Mozart's, and Einstein's when everybody is "joe". No reward no gain.
In our quest not to alienate anyone we have stifled creativity, and neutered our education system.
(You should see the several tons of electronic test equipment in my basement!)

So you WERE in there, all along! At first I wasn't sure if anyone was home. Nice tactic, though. (Or was it just genuine cynicism?) But now you're speaking my language. So I guess I was preaching to the choir, as they say. (By the way, have you ever seen the movie "Idiocracy"?)

It's not only audiophiles that are a dying breed, my friend. I probably _really_ shouldn't get started on "violently agreeing" with you (and perhaps even on a lot with which you won't agree), but...

It's all been so-tragically dumbed-down, probably past "the point of no return", and certainly to the point of a very long, slow return, at best. The "culture wars" were lost, long ago, and the lowest common denominator is now king (or el Presidente, as it were).

Much of great value has been lost or prevented, that might never be recovered or rediscovered. The trajectory of our potential has been aborted by "mission control" and the previous potential apogee seems now to be unattainable, with the current vehicle and flight path. (We are now either sub-orbital or stuck in a low and decaying orbit. Either way, we will most-likely crash and burn, or experience "catastrophic loss of vehicle", and, of course, "our lives".)

And, literally, feedback control loops have been installed that doom our society's future. Idiots, using YOUR money to buy votes and build alliances with other idiots, have perpetrated much of it. With their "social" programs, they have initiated positive feedback loops with inexorably increasing gain factors. Mathematically, that is guaranteed to be "unstable" (even without the increasing gain; even with any gain > 0), meaning that something will eventually smack into either the 0V or the V+ rail, or whatever hard limit is appropriate to the system in question (unless there is no hard limit and it skitters off toward some empty infinity, or spirals into some inescapable black hole...).

Along the way, they murdered Freedom and are doing their best to make sure that no one can hope to be justly rewarded if they excel, and no one can be allowed to think that they might be, or be able to be, "better" (or more wealthy) than anyone else. The idiots apparently took the meaning of "all men are created equal" literally, instead of realizing that it only meant "...equal under the law".

Meanwhile, our adversaries on the other side of the globe are educating something like an order-of-magnitude more engineers per year than we are, which just by itself is a deficit that we can not recover from for at least two or three generations, already. And that's assuming that we somehow changed to a perfect course immediately, which appears to have been pre-empted long ago, per the above (and below), which is all only a pebble compared to the Everest that a full accounting would be. (And yes, advertisers have taken full advantage of the more-and-more-stupid masses, and have helped to encourage both their ignorance and their stupidity. And the shill media idiot-alliance collaborators are at least as bad as the commercial advertisers.)

Where are OUR Einsteins and Mozarts?? They are here! But in most cases neither they, nor we, will ever know it! It breaks my heart. It all reminds me, somewhat, of the poem that is called, I think, "Eligy in a Country Churchyard". Please excuse my faulty memory. I only read it once, when I was in class, in eighth grade, at age thirteen or so. And I am now fifty-two. It was about unfulfilled human potential, and the poet was musing about the difference between how the achievements of people, versus their potential, were affected by their environment, i.e. the society and culture around them, and how tragic it was that perhaps some of the long-dead people in the country church's graveyard could have achieved greatness (and contributed greatness), had they only been born in a large city and had the educational and cultural opportunities that existed there, but, instead, had lived their lives as country bumpkins.

And now, to my horror, "the adversaries within" have practically institutionalized similar ignorance (and the means to perpetuate and enhance it), to the point where it is celebrated. And intellect, ambition, and "the truth" are openly derided (and even that derision is celebrated)! We have already entered a higher-tech version of The Dark Ages. I only hope that a new Enlightenment (probably generations from now at best) has not somehow already been precluded. Maybe we need modern versions of the ancient monasteries, and of the Irish who stole the books from Rome when it was sacked, to help preserve higher culture and higher civilization until we are ready (and worthy) to embrace them again.

In a practical and more-immediate sense, I do have one faint glimmer of hope, which is that, possibly, the political and cultural pendulum was swung too far, too fast, such that it might now swing far-enough the other way to at least make it possible to begin to correct our course, before too much is irrevocably lost. But that's assuming that there are still enough good people left...

Tom

Last edited by gootee; 6th January 2010 at 04:03 AM.
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Old 6th January 2010, 03:59 AM   #35
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Well........ I can only say, so true, so very very true. I just did not want to put it right out there. I am worried about getting slapped for turning this into a social political debate.
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Old 6th January 2010, 05:08 AM   #36
gootee is offline gootee  United States
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Quote:
Originally Posted by China_Vincent View Post
Chip amps vs class D amps?
Quite right. My apologies for seeming to stray so far off-topic.

The point of some of the previous seemingly-off-topic posts was that, if executed well-enough, no one should be able to tell the difference in the resulting sound reproduction between any two types of amplifiers, including chipamps and Class D amps (along with points pertaining to the quality of sound reproduction, in and of itself, and related topics).

So if the debate is centered on a potential theoretical difference in optimal sound-reproduction quality between Class D amps and chipamps that were all executed "well-enough", then there can not be much of a debate.

However, with chipamps, we are still at the mercy of the chips that are available, and so potentially might not be able to "execute well-enough", unless or until there are already chips that have been executed well-enough.

Therefore, with Class D, it might be the case that we could, theoretically, come closer to executing both a design and an implementation well-enough, in the above-described sense, than we could with currently-available chipamp chips, since we could use discrete components instead of being limited to basing a design around one of the "Class D chips" that are available. As such, DIY Class D potentially offers a richer realm of possibilities (and technical complexities and challenges) and rewards for a DIY designer (not to mention the listener).

So, now that that's settled, how about a new topic that's arguably much more important? Maybe a better topic would be "Shouldn't we worry much more about speakers than about amplifiers?", since speakers are typically much worse at doing their job than amplifiers are at doing theirs.

On the other hand, there are still many other pros and cons that have not been discussed or compared, in this thread, for chipamps versus Class D amps.

Efficiency/power-dissipation/heating is a big one, and is very-much in favor of Class D amps:

Class D amps can be small and light weight, yet have high power-output capability (as chipamps also can), but typically require much less cooling, and give off much less heat, than a comparable-power chipamp (or a comparable-power discrete-component non-Class-D transistor amp).

That's basically because the main power-handling components are essentially switches, and the solid-state switching components (transistors) are almost always either Off, generating no heat, or fully-On, and (and this is the key point), having been selected to have very low resistance when fully on, dissipate very little power as heat even though they might be carrying very large currents, because their dissipated power is the current squared times their resistance, and the resistance is extremely small when they are fully swithed on, so the dissipated power is (relatively) small.

To achieve the very low power dissipation during switching operation, the time spent BETWEEN the on and off states must also be kept very short, because the resistance in that state is NOT extremely small, and spending much time there would heat the device in the same way that transistors in a non-Class D amp are heated. (So high-speed gate-drive circuit design and proper implementation become very important, and perhaps challenging.)

On the other hand, in a non-Class D amplifier (including chipamps), the transistors are basically never operated in the fully-on state, meaning that they basically always have a significant resistance, and so for high output currents they will always dissipate relatively-significant power as heat. And so for the same average output current as a comparable Class D amp, a chipamp or non-switching-type "analog" transistor amplifier's transistors will dissipate significantly-more power as heat.

Note, too, that the power that is dissipated as heat is, also, literally, wasted power. So a Class D amplifier will virtually always be significantly more efficient than a comparable-power non-Class-D transistor amplifier.

Tom

Last edited by gootee; 6th January 2010 at 05:28 AM.
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Old 9th January 2010, 08:05 AM   #37
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Quote:
Originally Posted by gootee View Post
. . . So a Class D amplifier will virtually always be significantly more efficient than a comparable-power non-Class-D transistor amplifier.

Tom
Virtually? But not in practice?

Given an equal effort, then the efficiency difference is small. But, who works towards making hyper-efficient linear?

Advertisements include datasheets, and there is such a big difference in efficiency, because of their approach. . .

Its usually true that the Class D amplifiers are efficiency optimized in their support circuits as listed in their datasheets.
Unfortunately, its also true that the Class B (or class AB) chip amplifiers rarely (if ever) have optimized support circuits listed in their datasheets (and the examples are usually quite bad).

For example, TDA7294: The datasheet circuit is really horrible with muffled audio and it gets hot. Instead, if you treat it like a discrete amplifier, using a sane power circuit (small size signal grade power caps at the amplifier board and other differences), then it is 4 ohm stable and barely gets warm.

Howabout U2501B (a radio with a class B audio section) running fairly loud for 10 days nonstop on 4 of AA size rechargeable batteries? Efficiency difference? Bunk!!
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Old 9th January 2010, 03:32 PM   #38
gootee is offline gootee  United States
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Quote:
Originally Posted by danielwritesbac View Post
Virtually? But not in practice?

Given an equal effort, then the efficiency difference is small. But, who works towards making hyper-efficient linear?

Advertisements include datasheets, and there is such a big difference in efficiency, because of their approach. . .

Its usually true that the Class D amplifiers are efficiency optimized in their support circuits as listed in their datasheets.
Unfortunately, its also true that the Class B (or class AB) chip amplifiers rarely (if ever) have optimized support circuits listed in their datasheets (and the examples are usually quite bad).

For example, TDA7294: The datasheet circuit is really horrible with muffled audio and it gets hot. Instead, if you treat it like a discrete amplifier, using a sane power circuit (small size signal grade power caps at the amplifier board and other differences), then it is 4 ohm stable and barely gets warm.

Howabout U2501B (a radio with a class B audio section) running fairly loud for 10 days nonstop on 4 of AA size rechargeable batteries? Efficiency difference? Bunk!!
Hi Daniel,

You are comparing apples to oranges and I stand by all of my original statements.

Yeah, "virtually always" might have been a poor choice for the "weasel words" I was trying to find (For accuracy's sake, I tend to worry that there might be some "pathological case" that I didn't consider). So I'll boldly modify that statement and just say "ALWAYS", every time, no matter what. And, further, the efficiency ratio (between well-executed comparable-average-power-output Class D and non-Class D transistor power audio amplifiers) will never be small, when they are operating with any significant average output power.

It's NOT the "support circuits" that are "efficiency optimized" in Class D amplifiers! It is in the very nature of the main power-amplification devices, combined with the way that they are used.

In Class D, the power devices almost never have a significant resistance with high current through them. And with non-Class D, the power devices basically always have a significant (or at least much higher) resistance with high current through them. For any significant average output power, the effect of that, alone, on the overall efficiency of the amplifiers, will swamp all other effects.

Tom

Last edited by gootee; 9th January 2010 at 03:38 PM.
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Old 11th January 2010, 06:02 AM   #39
Steve M is offline Steve M  Australia
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If I could perhaps turn this discussion around slightly, yes I kind of agree with Tom that given a perfect world and perfect electronic design and execution - all of the amplifier topologies would probably sound the same.

However, the current status of play is that that to my ears at least there appears to be some sonic differences between Class D vs. Chip amps. I have owned or have in my possession a dozen or so Class D and chip amps, and to answer the original posters question my anecdotal conclusions of the sound differences would be:

a) Class D ~ is airy, detailed, fast, extended treble with good bass, but a little laid back in the midrange (doesn't quite light up the mids like valves). Digital amps can run out of steam at extreme head banging levels, the power outputs quoted are a bit fudged up IMO. For example an ICE250 or ICE500 module supposedly @ 250w/ch & 500w/ch doesn't have as much drive as a Krell KSA100 or for that matter even a KSA50 (this is from owning Krells and ICE/Tripath/Bel Canto/Nuforce/Panasonic Equibit digital amps).

b) Chip Amps ~ are detailed and fast sounding too, they have a clarity and grip in the midrange that is superior to Class D to my ears, bass is nice tonally but IMO, only just adequate, they are not amplifiers for playing at high volumes or into low impedence spkrs where they have a tendency to lose control and sound mushy (this from owning various chip amps including LM3876/3875/4870).

Of course all dependent on your own implementation of Class D or Chips and all system dependent ...

Regards,

Steve M.

Last edited by Steve M; 11th January 2010 at 06:11 AM.
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Old 11th January 2010, 09:50 AM   #40
Ltralus is offline Ltralus  Denmark
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Originally Posted by tiltedhalo View Post
Blathering is good I think you are missing my point. What is truth in the performance or the recording or the reproduction of the recorded performance? A persons personal taste, that is the only truth. Is an over-modulated 112db recorded bass heavy distorted rap track true reproduction, yes to those who think it is. Take a person with there 1KW car amps huge bass drivers resonating car body parts and put them infront of my Infinity IRS Beta's listening to the Jennifer Warrens Bird On A Wire, they will pick there rap performance and car audio system over mine time and time again, even playing the same material.
Personal tastes, personal preference is the only truth.
Truth in musical reproduction would be the accurate reproduction of anything played with 100% truth, but even then someone will prefer there i pod, you know it just sounds better.
They may very likely hate your musak, but if you reserve the questions to the system itself, and even tried your musak on their system and vice versa, you may find if you're honest, it is you who ends up humbled, and they do have ears.

Their systems are likely as purpose built as your own, with an exacting intent of what will get played on it and how it will be played. In practice that is alright as long as expectations for it are never exceeded. In practice that's never really the case either because "truths of perception" are fleeting, so such a system is a designed let-down for everything other than its given intent.

Personal taste should not be mistaken for "truth". Truth needn't be redefined to fit our personal perceptions for if that's the case, then it by default is not truth. How could we possibly enjoy music as a group if that were the case? How could it unite rather than divide? Clearly there is truth to music well beyond the personal taste of our fleeting perceptions, but it doesn't serve industry to think so. If you perceived your date as beautiful but only after half a case of beer, will your perception at the time hold as truth by morning? Would the baby produced be as beautiful as the night before or the morning after? Only to the mother?

Look at metallica's last album, nobody would fault that crowd with an audiophile amongst them, and yet there was a petition with some 30k signatures going around to have it remastered. They consider it unlistenable given the level of hard clipped distortion it has. This is clearly a case with preferences and perceptions at odds.
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