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Pass ACA Class A Power Amplifier Review

BDWoody

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The purpose of an amplifier is not to produce a chart on an audio analyzer. It is to render enjoyment to a listener.

I thought that was that the music was for...

I don't think of my microwave as rendering enjoyment...it just heats up the food, which is where the enjoyment comes from.

Not sure why I'd want my microwave to throw a handful of salt into my food as part of the process because that microwave designer REALLY likes salt.
 

MediumRare

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There are ten thousand posts in the ACA thread at diyaudio.com. Measured objectively, the ACA is providing thousands of man-hours of enjoyment to someone for some reason. The hand wringing evident in this thread on ASR is not a good look.
There are millions of hot dogs happily consumed in this country every day. What conclusion am I to draw from that with respect to their quality?
 
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amirm

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Our brains do not objectively transcribe auditory stimuli into perceptual experiences
I am always curious of such statements. Have you conducted your own research into how our brain works in this matter? Or can cite research papers that have led to such knowledge? Or is it lay intuition and assumptions?
 

LTig

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The former. The purpose of an audio system is to create a sensory experience in the mind of the listener. The notion of using a set of microphones to capture sound pressure level measurements in real time, that are mixed down to two channels and played back via a pair of loudspeakers in a listening room is an engineering solution to that problem. It depends on the inability of our ears to discriminate a great deal of information in the sound field, which, if we could perceive it, would destroy the audio illusion. Defining the role of the amplifier as a perfectly linear voltage multiplier is a constraint that simplifies the solution and renders it workable in practice. It's reasonable to leave the tailoring of the sound to the recording engineers, who can work under the assumption of a standardized playback environment.

If you were to plot in real time the vector soundfield that exists in a hi-fi listening room and compare it to that at the original performance, certain parameters would correlate, but many would not even come close. It's both a limitation and a marvel that our ear/brain reconstructs the illusion of live sound in a 3D space from such wildly distorted perceptual stimuli. The real science behind audio engineering has to do with characterizing the response of listeners to these stimuli to optimize their subjective response in their minds. It is an assumption, though arguably not necessary nor sufficient, that the components in the signal chain are accurate with respect to linearity and frequency response. The perceptual processing that happens in our brains is phenomenally complex. To try to predict subjective experience from a few crude objective measurements is to narrow the scope of investigation to the point of triviality.
I think I begin to understand your point of view. You expect measurements to show whether a specific amplifier is a good match to one's personal speakers, the room they are in and their position. I fear this is not possible. You cannot expect an amplifier to correct frequency response errors in a specific room setup or to manipulate delays and phases such that one gets the illusion to listen to a live recording. Much has been written about why it's impossible to do this with a limited number of channels so please spare me to repeat it here.

However there are means to partially fix said problems, but it's not the amplifier:
  • Room EQ can improve FR at the listening position
  • Tone controls can improve bad recordings
  • A Stereo widener can improve width of the soundstage if the recording sounds too narrow
  • Many AVR offer algorithms to improve immersion in the sound field
I use the first three means in my main system if required.
Nothing I'm saying is controversial. Hi-fi as we know it is a compromise. Certain distortions (whether linear or non-linear) will be picked up as cues by the ear/brain that enhance the subjective perception that the sound is "lifelike." Other distortions may render the sound less lifelike but more pleasing. The conventions we have for audio design are the product of decades of research into the best tradeoffs between perceived sound quality, practicality, and economics. The ACA, and Pass's designs in general, exist to explore the limits of these tradeoffs. It's no surprise they succeed on some levels and fail on others.
The correct place to intentionally add distortion is on line level before the amplifier. NP himself made a device which created a fixed amount of 2nd oreder distortion and offered it freely for a number of people to try it between source and amplifier. Better yet use a processor with controls which can add just the amount and kind of distortion you prefer.

The task of the amplifier is to amplify what's given. If one expects an amplifier to add just the amount of distortion one prefers one shall have a hard time to find an amp matching ones personal taste.
My personal feeling about the ACA is that it's a cute little tech demonstrator that has garnered, maybe, more interest than it deserves. But I see a lot of good overall in the contribution Nelson Pass has made, and continues to make, to the DIY community. His design philosophy is controversial, but he's managed to keep his business going over the years, through many changes, while other very respectable manufacturers have gone by the wayside. He is clearly designing and selling products that challenge conventional wisdom. His amplifiers are arguably overpriced and underperforming when assessed against mainstream standards. But I've never seen Nelson Pass write disparagingly of conventional amplifier technology. He does his own thing, he seems like a content, generous, smart fellow, he's making a lot of people happy, and he's keeping the lights on and the doors open at Pass Labs. Unlike the folks selling ten thousand dollar power cords, he's not trying to trick anyone. He's completely transparent and unusually generous in sharing the detailed technical reasoning behind his designs, as well as his intellectual property. One could do much worse.
NP made very good designs before he entered into his own business. Using very simple gain stages with lots of power consumption and high distortion values is a dead end. A very lucrative one for sure, but a dead end. There is nothing to be learned from, except that either people are unable to detect high THD values or that they prefer them. But as I wrote there are better devices to manipulate sound.

Real progress in amplifier technology is what Benchmark did with the AHB2. Although I think that very few people are able to distinguish between an AHB2 and any other decent power amp in a level matched blind test nevertheless reducing distortion is something good. Adding distortion not.
 
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amirm

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That's fine, Amir. You have a point of view.
I have a point of view I can demonstrate using research and professional experience in this field. Surely you are not equating to anyone having any opinion.
 
D

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There are millions of hot dogs happily consumed in this country every day. What conclusion am I to draw from that with respect to their quality?

I would conclude that hot dogs make people happy, and if I were in the business of making hot dogs, I'd try to figure out how to make my hot dogs the ones that make people the most happy of them all.

About the microwave oven analogy, you can put a frozen turkey in a microwave or in a conventional oven. You can cook both of them until a thermometer reads exactly 170 degrees. But they won't taste the same. And what does temperature mean anyway? Is it the temperature in the meat of the thigh, or is it the average temperature throughout the whole turkey? Is it desirable for the temperature to be uniform everywhere, or will it taste better if it reaches a higher temperature in some places than in others? It's not so simple.
 

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I would conclude that hot dogs make people happy, and if I were in the business of making hot dogs, I'd try to figure out how to make my hot dogs the ones that make people the most happy of them all.
Having been involved with developing new food products for over 20 years, I can confirm that would be a good start. Then someone in finance would tell you that your perfect hot dogs cost $2 each to produce and the competition costs $0.30 each, and, while everyone could tell the difference, most are not willing to pay the difference.

So the conclusion I take away is it is just fine to have mass-market performance at mass-market pricing. That will, in fact, make the greatest amount of "happiness". Yet it has zero to do with measurable quality. Remember, most people CAN tell the difference. At least with a little training.

I think what got people worked up here is the disconnect between the implied promise that an NP product would be pretty darn good, and yet it is measurably not so good. Demonstrably worse than a lot of cheaper products. And for the price, it could be considerably better and still meet the DIY brief.
 

rdenney

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I can't agree with you. The purpose of a bridge is to support a load. The purpose of a traffic signal is to regulate traffic. These things can be measured objectively. Ah, but consider the following. Traffic jams are stressful. Stressed people become agitated and distracted and this leads to traffic accidents. Perhaps one measure of the utility of a traffic signal network is the extent to which drivers subjectively perceive traffic to be smooth-flowing, and whether or not the delays they encounter are fair. How do you measure that with a meter? This reminds me of the social engineering theme park designers do to make long waits in line tolerable to their guests.

The purpose of an amplifier is not to produce a chart on an audio analyzer. It is to render enjoyment to a listener....

Two things you've said here. On the first one, I have professional expertise, so I will address that (maybe not so) briefly. First, the purpose of a bridge beam is not just to support a load, but to support that load within a range of parameters, including deflection, resonance (vibration), size, weight, and cost. If a bridge beam supports the load but sags too much, or not enough, the traffic on it will bounce along. Very embarrassing. Yes, it happens more often than you think. Lawsuits often result. Even worse is when the structure looks great until the vibration causes the joints to fail or be damaged, or until the vibration scares people on the bridge, or until the vibration sets up an uncontrolled resonance that tears the bridge apart (the poster-child example for this, of course, is the Tacoma Narrows bridge disaster).

And, bravo (no sarcasm--I mean it!), you have identified two main objectives for traffic signal timing: In a network, smooth flow, and at an intersection, fair distribution of green. That puts you ahead of a lot of people responsible for signal operation. (Those two objectives don't work in the congested regime, but that's been one of my specialties.) How do we measure smooth flow and fairness? We listen to citizens, of course, and do so very carefully. But we are doctors and they are telling us where it hurts. We certainly do not assume their diagnosis is correct, nor do we accept their suggested treatment at face value. Then we measure. It is true that measurement used to be a highly trained traffic engineer making observations on the street, because that's the best sensing analysis we had, and this led to all sorts of disagreements at all sorts of levels. These are not subjective measurements even if they are qualitative (there is a difference) and anecdotal (there is a difference there, too). The engineer is looking for specific features based on understanding cause and effect. But in the last decade or two we have learned how to use data far more effectively for performance measurement. For example, I can measure smooth flow using a Purdue Coordination Diagram (Google it). I can measure fairness using degree of saturation on each approach, or lack of fairness by looking at the reason the signal controller terminated the greens for the movements at the intersection. There is a vast body of knowledge there, and the science of it is absolutely based on careful measurement and data. That science may be theoretical--I studied under Robert Herman, who developed a basic theory of town traffic called the Two Fluid Model--or it may be empirical. Let's just say that traffic guys at the more advanced levels paid attention during statistics classes.

And, believe me, I have heard about where it hurts. For the time I was in local government, I personally answered something like 12,000 citizen complaint calls about signals in the large city where I was in charge of their operation. (I believed the guy in charge should explain the decisions, not some poor call-taker who has no idea.) Traffic engineers have to understand "preference" as much as "operation", and how they are different. They also should understand the difference between objectives and measurements.

On your second paragraph that I quoted, the purpose of an amplifier may not be to transparently enlarge the signal. But lots of amplifier designers claim that this is their goal, but that achieving their goal requires stuff the plain measures of transparency don't capture. So, they are claiming something mystical, and cry crocodile tears when detailed and careful measurements refute their claim. Is Nelson Pass claiming this? I don't think so, and Amir's tests indicate that his measurements are completely consistent with the specifications Pass claimed. No, it's not a refutation of Nelson--he designed a fun project that teaches some things, including that a home-made distortion box might still sound pretty good within the very limited context of its operation. But his followers have expanded that claim to include that the design actually sounds better. For that to be true, high levels of distortion must be favorable to music reproduction, yet the artist and the producers have already added all the distortion they wanted to add. Is it the amp's job to add more? If Nelson presented this as, "This little project will demonstrate high distortion--see if you can hear it" then we wouldn't be having this conversation. If he said "This little project will demonstrate that distortion makes some recordings sound better to me" then we might disagree but that really is in the domain of preference. If he says everyone prefers it, then we would want to see preference testing. But even then it would be advice to producers, and the home equipment should transparently reproduce the distortions added by the producer and artist as a result of that preference testing. But that's not what I see--I see a bunch of people saying this little amp represents something better, and defending that point of view when measurements challenge it.

But it's like most specialized fields: Only the specialists in the field really understand how much engineering and measurement there really is. Untrained users often run into things they don't understand, assume the wrong causal relationship subjectively, and then draw the incorrect conclusion.

Rick "guess what I do for a living" Denney
 

peng

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I have heard ultra expensive and impeccably designed products that produce fantastic numbers on the bench tests but I did not think they sounded very good. And I have heard mid-fi products that did not measure as well that I believe sounded fantastic.

Assume that is true, then how do you think designers should design their amps, I mean what would be the goal, if not minimum distortions, noise and flat FR aside from high DF, wide bandwidth etc.? What could they do so that the mid-fi products that did not measure as well would sound fantastic to you? And if they could actually do that, how would they know the amp would sound fantastic to others?

The thing is, amps are products based on science, designers who try to produce amps that generate certain distortions may please some individuals may disappoint many other potential buyers. Also, if such amps exist, bench tests should be able to identified the distortions or other characteristics. If not, it is more likely that people heard something that the amp itself is not responsible.

Below are from Passlab's website, Nelson Pass said:

"I have built many examples of simple 2nd and 3rd harmonic “types” of amplifiers over the last 35 years. When I say “types” I mean that they used simple Class A circuits described as “single-ended” versus “push-pull” and so tended to have a 2nd harmonic versus 3rd harmonic in the character of their distortion, but were not made to deliberately distort.
Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both. Customers have also been known to change their mind over a period of time.
However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” – the example in figure 3. It’s worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn’t ordinarily display.
Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don’t think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn’t quite hold up.
The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do particularly well with simple musical material, and 3rd order types generally seem to be better at more complex music."

It doesn't look like he believe in deliberately designing for higher distortions and since not everyone prefer the same kind of distortions, it makes sense to aim for minimum distortions and if people want to hear certain types of distortions they can buy Nelson's harmonic adder, or if they prefer non flat FR, there are all kinds of ways to EQ, tone control etc.

So I would stay away from amps that don't measure well even if those were deliberately designed that way for reasons Nelson Pass mentioned, if nothing else.
 

NTK

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Assume that is true, then how do you think designers should design their amps, I mean what would be the goal, if not minimum distortions, noise and flat FR aside from high DF, wide bandwidth etc.? What could they do so that the mid-fi products that did not measure as well would sound fantastic to you? And if they could actually do that, how would they know the amp would sound fantastic to others?

The thing is, amps are products based on science, designers who try to produce amps that generate certain distortions may please some individuals may disappoint many other potential buyers. Also, if such amps exist, bench tests should be able to identified the distortions or other characteristics. If not, it is more likely that people heard something that the amp itself is not responsible.

Below are from Passlab's website, Nelson Pass said:

"I have built many examples of simple 2nd and 3rd harmonic “types” of amplifiers over the last 35 years. When I say “types” I mean that they used simple Class A circuits described as “single-ended” versus “push-pull” and so tended to have a 2nd harmonic versus 3rd harmonic in the character of their distortion, but were not made to deliberately distort.
Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both. Customers have also been known to change their mind over a period of time.
However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers usually have lower total distortion. Third harmonic usually appears with a negative coefficient, resulting in what we think of as “compressive” – the example in figure 3. It’s worth noting that odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone -something a distortion analyzer doesn’t ordinarily display.
Audiophiles have been accused of using 2nd or 3rd harmonic distortion as tone controls to deliberately alter the sound. I suppose that there are people who like it that way, but I don’t think this is generally the case. For reasons which will become clearer when we talk about inter-modulation distortion, high levels of any harmonic become problematic with musical material having multiple instruments, and the argument that 2nd or 3rd adds “musicality” doesn’t quite hold up.
The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do particularly well with simple musical material, and 3rd order types generally seem to be better at more complex music."

It doesn't look like he believe in deliberately designing for higher distortions and since not everyone prefer the same kind of distortions, it makes sense to aim for minimum distortions and if people want to hear certain types of distortions they can buy Nelson's harmonic adder, or if they prefer non flat FR, there are all kinds of ways to EQ, tone control etc.

So I would stay away from amps that don't measure well even if those were deliberately designed that way for reasons Nelson Pass mentioned, if nothing else.
Very curious. Why isn't there any mention of intermodulation distortion? Don't HD and IMD go together? Why hide the IMD? The term "IMD" puts people off?
 
D

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I am always curious of such statements. Have you conducted your own research into how our brain works in this matter? Or can cite research papers that have led to such knowledge? Or is it lay intuition and assumptions?

Have you ever listened to "Yanny/Laurel?" I'm sure you have. There are many such auditory illusions you can try, e.g., on YouTube. They are amusing and confounding.

I would never claim to be a perceptual scientist nor a philosopher. But I believe it is established by science, and self-evident with a little thought and experimentation, that the internal state of mind that we experience as reality is only a rough mapping of our raw physical perceptions. We do not "hear" every sound that reaches our ears, and what we hear subjectively is hardly a one-to-one exact mapping of the time/frequency variations that impinge on our eardrums. So, for instance, you hear a tone and a series of harmonics as having the pitch of the fundamental, and not a collection of separate notes. You perceive a change in frequency response as altering the spatial localization of the sound sources. You are sensitive to reflections that arrive with certain delay times, but not to others. You perceive multiple sound sources in a sonic image when there are only two loudspeakers making sound, and so on.

Have you read "Quining Qualia" by Daniel Dennett? I'm not going to say how relevant it is to our discussion, but I mention it to give you an idea where I'm coming from. Philosophically, the relationship between what our senses detect and what we perceive is a gigantic can of worms.

I wonder if you're attached to a point of view and don't want to hear, as it were, what I'm saying. Maybe the following will satisfy you:
  • By any conventional measure, the ACA is a very low-performance amplifier, and a poor value at over three hundred dollars if conventional hi-fi reproduction is your goal.
  • In the standard hi-fi systems architecture, it is desirable for the electronic components in the chain to have noise and distortion so low as to be imperceptible, and, all other things being equal, lowering noise and distortion can't hurt (though it may not help).
  • It is difficult or impossible to define a narrow threshold of performance that cleanly separates "perfect" from "imperfect" sound. Therefore, it makes sense to engineer our components to be as perfect as possible.
  • Having established a "blameless" (to quote Douglas Self) signal chain, we can turn to the recording engineers and purpose-built effects boxes to tune the sound to suit our preferences.
  • Pursuing objective perfection is an interesting technological exercise in its own right.
Where I get uncomfortable with your methodology is the implication that your findings establish a sliding scale of "goodness" or suitability to purpose. I believe you would admit that the differences you measure in most cases are imperceptible. So why bother publishing the scale at all? Well, the answer is that it's interesting. But of limited value, IMHO. Where is the dividing line between ok and not-ok performance?

I will claim there are people on this forum who are looking to affirm some sort of us-versus-them tribal instinct or something. I know, you disagree. But there exists the perception, not only mine, that ASR cultivates a segment of members who are, dare I say, sneeringly condescending toward their subjectivist colleagues. Hi-fi is necessarily subjective because the product is subjective. I'll say again: no one listens to a distortion graph.

Where I applaud ASR is where you shine an uncompromising light on flat-out snake-oil. But if you are a scientist (I don't believe you have ever worked in pure science, but forgive me if I'm wrong) then you know you cannot prove the null hypothesis. If you were doing real science here, you would be running experiments to show that audible differences are provably perceptible among imperfect components, and characterizing the distortion mechanisms that are responsible for the differences. Instead... I'm not sure what you're doing. Basically, the sum total output of this exercise seems to be that all components sound the same -- except the ones that don't. And there is no actual end-user testing to back it up, no information given to help predict whether or not a component is "good enough."

I know it's career limiting at ASR to argue with the boss. I hope you will recognize I'm trying to be honest and rigorous here. I've been thinking about this problem for forty years.

To get back to the subject, and maybe to conclude my arguments (nah, I can never resist replying), I have to agree the ACA seems over-hyped. But enough people seem to like the amplifier that I can't dismiss their opinions. Something about it appeals to them. I absolutely believe you listened to it and found it intolerable. But I sensed a certain amount of "hate" (I use the term colloquially) going on in this thread and I have to disagree with that. Lots of people seem to be having good fun with the ACA, and I think that's great.

As for Nelson Pass, yeah, you can definitely criticize him for promoting a snake-oil shtick. I guess I cut him some slack because he's completely open about what he does. And anyone who is interested in circuit design, as I am, can find some value in his methodologies. He establishes the lower boundary of how badly an amplifier can perform and still create subjectively pleasing sound.

If you would like to discuss the specific details of ultra-low distortion circuit design with me, Amir, feel free to reach out. I'm designing a new headphone amplifier now. It's quite conventional (there are no new circuits) but I am open to suggestions.
 
D

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Two things you've said here. On the first one, I have professional expertise, so I will address that (maybe not so) briefly...

Thank you. That's very interesting, especially the description of how traffic studies have improved with technology.

We can all agree there's an enormous amount of bullshit in hi-fi. I believe in subjectivism because at the end of the day it's the sound I listen to. I don't believe in sighted, uncontrolled subjectivism. And I definitely don't believe in snake oil. I just happen to think the interface between subjective performance and technical performance is complex and murky and not as pat-and-dry as this forum makes it seem sometimes.

You know, if I listen to some music and I think to myself, "Hey this sounds really nice!" then that's an objective report of a subjective experience. You can't take it away from me. Does it mean anything "real" with respect to the technical performance of the equipment? Maybe. Who knows?

As I said, I listened to the Aleph 3 and it sounded really, really nice. That happened. It's real. The fact that there are better-measuring amplifiers doesn't change anything. As long as I don't try to explain my experience with faulty technical reasoning, I'm a hundred percent entitled to my impressions.

You're right, Nelson Pass is walking a fine line and you could argue he's promoting a bad solution, that amplifiers should be linear and effects left to effects boxes. The day I turn on the news and discover that climate change has been solved, the COVID pandemic is over, war and injustice have been eliminated, and the entire world is happy and peaceful, I will immediately join the campaign to stamp out hi-fi snake oil.

-Henry
 

LTig

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We can all agree there's an enormous amount of bullshit in hi-fi. I believe in subjectivism because at the end of the day it's the sound I listen to. I don't believe in sighted, uncontrolled subjectivism. And I definitely don't believe in snake oil.
I fully agree.:)
I just happen to think the interface between subjective performance and technical performance is complex and murky and not as pat-and-dry as this forum makes it seem sometimes.
Well, a lot of this is already covered by some 80 years of psycho acoustic research.
You know, if I listen to some music and I think to myself, "Hey this sounds really nice!" then that's an objective report of a subjective experience. You can't take it away from me. Does it mean anything "real" with respect to the technical performance of the equipment? Maybe. Who knows?
Nobody here disputes that you experienced what you, well, experienced. How could one? And nobody wants to take this away. But claiming that such personal subjective experiences have any worth (without proper controlled conditions) is difficult here, that's true.;)
As I said, I listened to the Aleph 3 and it sounded really, really nice. That happened. It's real. The fact that there are better-measuring amplifiers doesn't change anything. As long as I don't try to explain my experience with faulty technical reasoning, I'm a hundred percent entitled to my impressions.
Absolutely correct. OTOH if folks here think that ones experience is not based on audio alone because science tells us otherwise, and then ask for proof one should not see this as an attack to ones integrity.
 
D

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But claiming that such personal subjective experiences have any worth (without proper controlled conditions) is difficult here, that's true.;)

I think some people would dismiss my experience as delusional, based only on measurements. And if they listened themselves and had a similar reaction, they would dismiss their own experience. If you study the mind-body problem and the philosophy of consciousness (I only dabble; it's too arcane for me, really) you will realize nobody has any clue what it's "like" to be another person -- or a bat, LOL. We are all locked away in our own minds, and I think this is one reason why there's so much controversy over the sound of hi-fi.

Absolutely correct. OTOH if folks here think that ones experience is not based on audio alone because science tells us otherwise, and then ask for proof one should not see this as an attack to ones integrity.

As far as I can tell, I made no claims requiring proof. In the end, my only purpose was to defend the ACA and Nelson Pass against what I thought was, in some posts, overzealous criticism. And to encourage people to take a little broader view of the whole objectivist-subjectivist thing.
 

MediumRare

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You know, if I listen to some music and I think to myself, "Hey this sounds really nice!" then that's an objective report of a subjective experience. You can't take it away from me. Does it mean anything "real" with respect to the technical performance of the equipment? Maybe. Who knows?
Sorry you're playing with words there. It's just one data point of a subjective experience. That's not what objective means. It's, in fact, the opposite.

On the other hand, if you said you participated in a properly conducted DBT and selected "Option A" 80% of the time out of 20 tries, then you could say you objectively prefer Option A with a confidence of X%

It also doesn't mean that what you prefered is any good, just that it's better than Option B.

It can be difficult to judge absolute quality without a reference. To give a simple example, an opinion "hey this sounds really nice" might change entirely when presented with the same setup properly EQ'd.
 

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Crazy I thought Pass Labs amplifiers were some of the best design!! I guess not
 

BDWoody

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About the microwave oven analogy, you can put a frozen turkey in a microwave or in a conventional oven. You can cook both of them until a thermometer reads exactly 170 degrees. But they won't taste the same.

Right..and all of those issues are in the realm of art creation. The Chef makes the choice, not the oven. All the oven does in my example is raise the temperature. The artistic decisions have been made...except that extra handful of salt my microwave designer thinks I need in every plate it sees.

Analogies break down obviously, but it's still the chef and the raw material that renders the eventual joy. The oven is critical, but not individually important.
 
D

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Sorry you're playing with words there. It's just one data point of a subjective experience. That's not what objective means. It's, in fact, the opposite.

I may not have been clear. It's an objective fact that I thought the Aleph 3 sounded good, subjectively. I didn't say that implies anything about the objective performance of the amplifier, or how others would rate it subjectively. I hope this clears up the confusion.
 
D

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Right..and all of those issues are in the realm of art creation. The Chef makes the choice, not the oven. All the oven does in my example is raise the temperature. The artistic decisions have been made...except that extra handful of salt my microwave designer thinks I need in every plate it sees.

Analogies break down obviously, but it's still the chef and the raw material that renders the eventual joy. The oven is critical, but not individually important.

I get your point. Chefs can do their jobs better if ovens all work the same, every time. But there are many kinds of ovens, each of which is designed to impart a different flavor to the food. For instance, have you ever eaten pizza cooked in a wood-fired oven, or hamburgers grilled over charcoal? Those ovens do add flavoring to the food. LOL, nothing is simple.
 
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