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Review and Measurements of NAD T758 V3 AVR

BDWoody

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There is already significant number observations for which tests do not exist.

Right now, it is like if someone claims that they see green men, force them participate in a test to see whether they can see blue men and claim they cannot.

If you look at the history of science, models emerge to explain observations, sometimes from scientists in controlled situations, some from regular people in uncontrolled situation. In the latter case, you devise a test to see if the observations can be replicated in a controlled setting, not demand that the regular folk create their own controlled tests before they can report observations. Of course, you need some reasonably credible observations to start with.

But we already have some from the spreading DRC systems. For example, many AVRs give you choice to select from a flat target or some “reference” target curve to do their corrections to. Both smooth the resonances etc but they affect tonal balances. There is clear evidence in all the forums for these equipment that people have preferences for one or the other. Heck, even family members differ in their preference in the same equipment. Other than saying, they are subjective preferences, there is no science based explanation for it. You can either claim that such a subjective preference does not really exist if the test was controlled or have a theory that explains the correlation between what someone prefers and the FR curve that makes it pleasing for that person. So, you are not accounting for experience in real world at all in that case.

So, a valid enquiry is whether they will able to reproduce that preference in a controlled test. For example, play the sounds for each of the curves using the same equipment in a fully controlled test in a random repeating sequence between the two and see if they can pick the one they prefer correctly in a statistically significant way.

If they don’t, then that preference was illusory. If they do, then it needs a theory for why that is the case and it is easy to extend that into why people might prefer one unit over another. Not because of distortion numbers.

As far as I know, none of the existing studies or tests do that exactly. Denying those anecdotal observations because the typical consumer cannot do the controlled test to the level needed to establish the reality is not a defensible position.
You are kind of all over the place...mixing areas where subjective preferences have perfect validity, and where they have none. I'll leave most of that without comment...

The typical consumer you mention not only isn't going to care about any of this, they aren't really who this forum attracts. If someone is so convinced the current measurement and psychoacoustic science doesn't capture what they hear, then the first step is to actually demonstrate that you can hear it, not just claim you can. It doesn't matter how many people make the claims, anecdotal evidence just doesn't convince those of us who have actually gone through the exercise of blind, matched tests. It is hard to have patience with those who just refuse to do it.

If you can hear it, you can measure it. Show otherwise, and claim the Nobel...
 

audimus

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“Knowing the numbers” tells us that a system is measurably accurate within the bounds of audibility. “Failing to tell the difference in a blind AB test” tells us that there is nothing else that is being missed by the measurements. It all comes down to the blind AB test. You probably have to take one before you can become a true disbeliever. And disbelieving will set you free.

Someone in this forum likes to say: “if you can’t hear it without peeking, it’s not real”. I’m going to add that to my sig if I can properly attribute it.
I am not sure why you would assume one has not taken a blind test for this discussion instead going into the religious mantra of converting people to be free.

It is actually the principle of the blind test that is being proposed. The blindness or peeking also includes not knowing the distortion numbers for listening tests. If you don’t agree with that, then you have not understood the principle behind the “unsighted” test.

So, you take a test in which you do not know if a piece of equipment is altering the sound or not. Say your hearing acuity is low in bass frequencies. Hypothetically, one of the headphones boosts the LF in a way that what you hear is closer to the EQ of the original recording. The other reproduces it perfectly but because of your hearing, feel the music lacking and prefer a musician that EQs for louder low frequencies. In which case, have you heard exactly what the artist intended?

The above is essentially what the DRCs attempt to do but for room characteristics. Why wouldn’t the same apply to one’s hearing characteristics if that can be done or that is the basis on which one prefers equipment.
 

audimus

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You are kind of all over the place...mixing areas where subjective preferences have perfect validity, and where they have none. I'll leave most of that without comment...
I am going to leave it at that since we are communicating past each other. Dogma is not a monopoly of religion.
 

digicidal

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As far as I know, none of the existing studies or tests do that exactly. Denying those anecdotal observations because the typical consumer cannot do the controlled test to the level needed to establish the reality is not a defensible position.
I think it's a completely defensible position - or more accurately one that needs no defense in the first place. There are as many variables in the "how an individual perceives a particular element in the signal" as there are individuals multiplied by the number of elements. You don't test for that as the applicability is virtually zero. You test what is repeatable and consistent, with the knowledge that a single application may (indeed will) be affected by other factors. The idea is to reduce the sampling noise as much as possible - not factor as much of it in as possible.
 

BDWoody

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I am not sure why you would assume one has not taken a blind test for this discussion instead going into the religious mantra of converting people to be free.

It is actually the principle of the blind test that is being proposed. The blindness or peeking also includes not knowing the distortion numbers for listening tests. If you don’t agree with that, then you have not understood the principle behind the “unsighted” test.

So, you take a test in which you do not know if a piece of equipment is altering the sound or not. Say your hearing acuity is low in bass frequencies. Hypothetically, one of the headphones boosts the LF in a way that what you hear is closer to the EQ of the original recording. The other reproduces it perfectly but because of your hearing, feel the music lacking and prefer a musician that EQs for louder low frequencies. In which case, have you heard exactly what the artist intended?

The above is essentially what the DRCs attempt to do but for room characteristics. Why wouldn’t the same apply to one’s hearing characteristics if that can be done or that is the basis on which one prefers equipment.
Missing the point.

It's about what device most accurately recreates an analog signal, not which one alters it to someone's taste. I can do that for myself with filters and dsp... If I'm mixing up a bunch of what are effectively custom synthesizers, who knows what I'll end up with. Give me an objectively measured clean signal, and I'll take it from there and season to MY taste.

I am going to leave it at that since we are communicating past each other. Dogma is not a monopoly of religion.
No, I'm getting what you are saying, I just don't agree. You seem to think if you just explain it differently, or just...again...it will make a difference.

I'm sorry if I'm communicating past you.
 

audimus

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I think it's a completely defensible position - or more accurately one that needs no defense in the first place. There are as many variables in the "how an individual perceives a particular element in the signal" as there are individuals multiplied by the number of elements. You don't test for that as the applicability is virtually zero. You test what is repeatable and consistent, with the knowledge that a single application may (indeed will) be affected by other factors. The idea is to reduce the sample noise as much as possible - not factor as much of it in as possible.
Going into science terminology, there is a difference between data points and independent variables that affect the perception. You want to control and limit the data points to representative and statistically significant levels. But in modeling reality you cannot limit the number of independent variables just because it is not convenient otherwise. The different target curves proposed in DRC is precisely the attempt to arrive at a manageable set of values each of which fits a cluster of data points of how things are “heard” (not just room resonance). No single curve fits all but it isn’t unmanageable in number of values either.

There is significant applicability to the hypothesis that the FR as “heard” by individuals is an independent variable in determining what sounds good. It does not have to be necessarily customized to each person but there may be a couple of best fit solutions that appeal to different groups.
 

audimus

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Missing the point.

It's about what device most accurately recreates an analog signal, not which one alters it to someone's taste. I can do that for myself with filters and dsp... If I'm mixing up a bunch of what are effectively custom synthesizers, who knows what I'll end up with. Give me an objectively measured clean signal, and I'll take it from there and season to MY taste.
This is why we are communicating past each other. You are not addressing the point I actually made. Let us agree to disagree on that.
 

MrGoodbits

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There is a problem with that. Our ears are not perfect microphones and their ability to react to different frequencies even vary with time. So, in a way, NOBODY hears (or to be more precise perceives) what is exactly on the recording or even what the musician (or the recording engineer) him/herself hears in these things even if all of them were using the same equipment. So I would claim that goal is illusory.
Yet, with headphone EQ and good electronics we can approach a measurably neutral system and it sounds flat-out amazing on well-engineered recordings. Don't fall for the "everything is perception so why strive for accuracy" argument. There's probably a vendor near the entrance to the Louvre Museum selling rose-colored glasses.
 
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So, you take a test in which you do not know if a piece of equipment is altering the sound or not. Say your hearing acuity is low in bass frequencies. Hypothetically, one of the headphones boosts the LF in a way that what you hear is closer to the EQ of the original recording. The other reproduces it perfectly but because of your hearing, feel the music lacking and prefer a musician that EQs for louder low frequencies. In which case, have you heard exactly what the artist intended?

The above is essentially what the DRCs attempt to do but for room characteristics. Why wouldn’t the same apply to one’s hearing characteristics if that can be done or that is the basis on which one prefers equipment.
I actually like the idea, even if it would be difficult to implement for more than one person. But how cool would it be to take a personal hearing test (with headphones) then the room EQ would attempt to compensate for both your electronics and your hearing.

A smart company could even charge a small monthly fee for new versions that would be needed as your hearing changed.
 

Blumlein 88

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I'm not saying my methodology for subjectively testing AVRs myself is perfect, but this is what I've done in the past and it's been effective for making my own personal decisions...

When comparing AVRs I only use the front two channels (swapping all the surround channels and subs is too complicated and time consuming).
The front 2 channels are on Banana Plugs.
I leave both receivers plugged in and powered on.
I connect my Oppo either over S/PDIF or HDMI into a 1x2 splitter (I have both a S/PDIF and HDMI one).
This means that my Oppo is connected to 2 AVRs at once.
I then just move the 4 banana plugs back and forth (carefully making sure that I put the AVR in standby while swapping)... only takes about 10 seconds and it helps if you have a helper.

...I know that my method is far from perfect, but I've been shocked how much of a difference there is between AVRs in "Direct mode" without room correction that I've subjectively tested like this. I'm confident that the drastic audible differences I hear wouldn't show up as noise in an objective test.

To my possibly broken ears/brain... There's more too how these Pre/Pros & Receivers sound than a test can show and I think that its because the way these DACs are implemented can result in very different sound signatures. I have no idea how you can test or prove this aside from just experiencing it and most people don't typically have multiple receivers/processors lying around.

Regardless, these test results are very interesting and it only benefits consumers if these manufacturers up their game in terms of how these devices objectively test.
Do you match levels in these tests? I know it is cliche, and should be. If you don't match levels that right there is the reason for your shocking sound differences.
 

amirm

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There is clear evidence in all the forums for these equipment that people have preferences for one or the other.
Forums? Why would you look to forums for such scientific research?

The topic has been studied and it shows that most of us have similar preferences. We can't push that to 100% because music itself is not standardized so you can't pic a target response and say it is good for everything and every person. But otherwise, most of us prefer similar things in EQ and Speaker target response in a room. See the second section in this article I wrote: https://www.audiosciencereview.com/...s/target-room-response-and-cinema-x-curve.10/
 

amirm

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So, a valid enquiry is whether they will able to reproduce that preference in a controlled test. For example, play the sounds for each of the curves using the same equipment in a fully controlled test in a random repeating sequence between the two and see if they can pick the one they prefer correctly in a statistically significant way.
That is exactly what has been done and published:

The Subjective and Objective Evaluation of Room Correction Products, Olive, Sean; Jackson, John; Devantier, Allan; Hunt, David, AES Convention 127, October 2009
 

amirm

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Not to me. The owner has not heard back from them either but is making progress communicating with them indirectly.
 

MrGoodbits

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So, you take a test in which you do not know if a piece of equipment is altering the sound or not. Say your hearing acuity is low in bass frequencies. Hypothetically, one of the headphones boosts the LF in a way that what you hear is closer to the EQ of the original recording. The other reproduces it perfectly but because of your hearing, feel the music lacking and prefer a musician that EQs for louder low frequencies. In which case, have you heard exactly what the artist intended?
You are mixing preference and perception. But in your example, my perception is essentially what the artist intended because I'm used to hearing everything that way. I would still perceive a bass-heavy mix as bass-heavy, etc.
 

MrGoodbits

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I actually like the idea, even if it would be difficult to implement for more than one person. But how cool would it be to take a personal hearing test (with headphones) then the room EQ would attempt to compensate for both your electronics and your hearing.

A smart company could even charge a small monthly fee for new versions that would be needed as your hearing changed.
I have wondered about this too! But I fear though that our brains accommodate our minor hearing deficiencies pretty well. It probably would not sound "right". I know that my hearing past say 13 kHz sucks, but when I use parametric EQ to boost that even a little it sounds hopelessly bright.
 

LTig

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I don't think anyone is saying none will. But so far they have been disappointing.
I' d like to disagree in case of the Classé. THD, noise and jitter performance seems to be better than the rest of the pack. But maybe this is just the bias of its proud owner ... or my measurements with the RME are not as reliable as with @amirm's AP.
 

LTig

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The time it takes to switch one AVR for another is huge. As such, there is no scientifically valid audio comparison with two AVRs done that way. Our short-term memory is not remotely that long.
Its easier with AV prepros if you use stereo only. When I compared two AV prepros I connected the SPDIF Toslink output of my CD player to the first and the SPDIF Coax to the second, so they would paly the same signal in parallel. Then a 2 channel XLR switch is sufficient to switch the outputs of both AV prepros to the power amp (or active speakers). I have to admit that I have no such switch and changed cables manually which took me about 5 sec.
 

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