Was a $1000 CD Player Better than a $150 one? My view. - Page 9

Ok, gotcha. I figured that would be your answer (the first paragraph, anyway).

DT, do you have a link to the forum thread that talked about the results? I found the synopsis that you linked to a bit hard to follow. Rather a pity don't you think that the cable that seemed louder didn't result in measurement of output levels from the amp for all three. Also, it didn't seem as if there was any randomization. But I'd like to read the forum thread while I'm on the crapper.

Can any design be objectively transparent? They all measure differently to varying degrees. The claim you are making is the differences cannot be audible when the amps are driven below clipping.

So why do you need to know what they are then?

BTW, I have heard small differences between other receivers amps too...it's just the JVC was the most distinctly different one I've heard. For example, prior to the DG1000, I was using a Sony DA5ES. It had a softer but deeper low end than the DG1000. Tonally they sound pretty much the same. The JVC by comparison sounded harsher and had a distinctly different tonal quality than both the Sonys.

According to you, hearing these things isn't possible. Are you willing to put your money where your mouth is and bet? Because I absolutely am.

Which, in terms of audibility, would make them transparent.

I don't need a lecture - I'm under no illusions. To prove that I can hear a difference requires that I pass a well designed double blind test.


I'm 99% sure I can do it with the JVC amp. Of course I can never be 100% certain until I've actually done it.


Give me a break. I'm not claiming anything like that.

No. But it is far easier to be sonically transparent - transparent as evaluated by ear.


Yes they do, and so does each channel of stereo or multichannel analog equipment. How much do you worry about that?

All analog equipment has noise and distortion which cannot be improved beyond a certain degree.

Measurable noise and distortion can be reduced to be as small as desired by staying in the digital domain.


Right, and audibility is simple. If you keep all forms of noise and distortion 100 dB or more down, there is no chance that an audible change will result. In fact, 80 dB usually suffices.

I'm not referring to distortion or noise. I don't doubt they are usually below audible levels.

Please can someone provide links to the peer reviewed studies that indicate that sound quality of amplifiers cannot be distinguished from one another. Unfortunately I am not privy to these studies but would like to read them. (I did browse thru the previous links provided but these did not appear to be peer reviewed studies.)

Do those who believe amps all sound the same are simple products to design?
Just curious how many people have heard of SPICE and its use for amp design, even then there is a bit of disagreement on how accurate/valued it can be beyond the initial design reference model.

Cheers
DT

Sorry Chu you will need to do a bit of hunting on their forum if it is not linked to the article.
And your right it is best to read it while on the loo, probably also good as a replacement for the loo roll
The test was blind ABX with no guarantee a cable was replaced and repeated with different music, not sure how that is not random, apart from one very important difference to other tests stated by some - nothing else in the chain so it excludes those comparator boxes.

Now this is a pet bugbear of mine (nothing to do with you Chu), I find it annoying that some on this forum state changing manually the interconnects even when done properly can change the sound and yet all other aspects of circuitry design and technology has no effect.
It does raise the point though, if changing interconnects manually changes sound, then how is it possible to accurately identify the interconnect consistently when cables are swapped often, because if the sound changed then it would not be possible for a listener to match it in the following repeats, in fact by their argument AB and X would all sound different.
Just saying this as I know some have stated this in the past (sure this will start the arguments up again).

Edit:
Chu, the cables had no attenuation so while they said it was perceived more mute/dulled/quiet it is not possible that the voltage could be changed in a way that you may be inferring.
Also bear in mind that the cynics still did not manage a high accuracy, while only the believers did so the result was not consistent for all four listeners although there was a trend highlighting better accuracy from believers.
What gets me though is that cable was provided by one of the cynics

LOL Chu you slacker the link for the forum discussion is at the bottom of that page, shows one message and can click the link for the other 600, probably 500 of those are arguing like here

Cheers
DT

It was late when I posted that. I was un-trojanning my son's laptop. BTW, when I want random, I flip a coin.

Yeah I agree, glad you clarified as some may also think of the randomised comparator boxes.
Still, the choices were identical for all four listeners, so if the trend is that one group are successful and the other fails it shows that it was effective.

I cannot remember if they used a coin, although the test was done with no guarantee a cable would be replaced so it was possible they would get AAX, which they did once.
So as far as the listeners were concerned it was not just a flip of the coin for A or B, but also the added pressure that there was no change to the setup, which removes their assumption that there are always differences for each test.

Bear in mind though that I was using the link not to say there is definitely differences between cables, just to put a balance on the statements/assumptions by others saying there are no differences and all tests show this.

Cheers
DT

What else is there that affects sound quality of an audio signal besides distortion and noise?

AFAIK there are no peer reviewed studies that say which specific amplifiers can't be distinguished.

The articles would have to be specific, because of course the world is full of substandard amplifiers that do in fact sound different.

High end audiophiles seem to gravitate towards amplifiers that sound different.

Peer reviewed articles about audio gear generally avoid mentioning specific makes and models.

However, there are peer reviewed articles that support the use of ABX and other DBT listening methodologies for this purpose and say that procedures that lack sufficient controls are to be avoided.

Of course nobody who is sensible believes that all ampliifers sound the same, because obviously anybody can make one that sounds different with very little effort.

But, if you are asking whether or not it is reasonbly easy to design amplifiers with inaudible noise and distortion, then the answer is yes.


Virtually everybody in the business of designing electronics has heard of Spice. Most design engineers under the age of 55or so probably used it or something like it as part of their university training.

Certainly everybody who is serious about audio design at least knows about it.


So what? Designing audio power amps is not rocket science any more. Hasn't been for at least 40 years.

There are enough canned designs in manuals provided by semiconductor manuals that coming up with a transparent audio amp is pretty easy.

For example, one of the power amps that we tested in the early days of ABX was an exact model built from a design in a early-1970s RCA Semiconductor manual. It was indistinguishable from a straight wire with gain.

The same basic design showed up in a goodly number of second and third generation SS amplifiers and receivers.

This sounds as if your saying there is no differences in amp designs or any differences are simple due to following semiconductor manual.
Sorry if that is the case then there would be no need for SPICE or those with exceptional knowledge/experience of amp designs.
Just my take on it, which I appreciate is at the other end of the spectrum to you.
Those on this forum have a great knack of simplifying technology to the point where any product becomes trivial in most discussions here.

Cheers
DT

Do you read in any language but hyperbole?

No colors or even shades of gray?

I did not say that there are *no* differences. Nor did I put any constraints on what differences might exist.

I simply said that even many of the semiconductor manual designs are very effective and sonically transparent.


Grouping SPICE and exceptional knowlege/experience is very strange, because the use of circuit analysis programs is very common, and the various flavors of SPICE are very well known and widely used.

Again, *no* need is a very strong statement. I would say that there is often no critical need for exceptional knowlege or experience.

IOW, you don't need to be Nelson Pass to build a typical home audio power amp that is sonically transparent. By typical I mean 400 wpc or less, 4 ohm or higher speaker loads, reasonable but not exceptional price/performance.

AFAIK, both Nelson Pass and John Curl are familiar with/experienced users of SPICE, but so are most fresh EE graduates.


Non-switchmode home audio power amp technology has been around in its present general form for over 40 years. If it isn't fairly trivial to execute by now, technology isn't doing its job.

The challenging development area in audio power amp design is switchmode. Building one economically that is as clean as a linear design and not an EMI generator remains at least challenging.

To know whether they were or not in your particular case. You say there was an audible difference between those two receivers. If there really was, substantial FR differences would most likely be the cause.


If you think that, then you need to learn how to read for comprehension.


No one who understood human hearing would be 99% certain of anything they heard.

Not directly. Believe it or not, the audibility of amplifiers is not considered a worthwhile subject of scientific evaluation. What scientists study is human perception of sound; they're rather indifferent to how the sounds are produced.

So psychoacoustics can tell us what magnitude the differences have to be in order to be audible. And measurements can tell us whether the differences between two amps exceed those magnitudes. That's how we know what we know.

That said, there have been many tests published in the popular press, and Tom Nousaine did a "literature review" for an AES convention back in the 90s. You should be able to find the abstract on the AES Web site. And I'll try to dig up something from a psychoacoustics textbook on the subject.

Arny my grouping SPICE and exceptional knowledge/experience is not strange if over the years you have followed and discussed this with designers such as John C and Pass, also other very good designers.

JC and a few others do not use SPICE but do know it very well, while others do not start a design without going through SPICE 1st.
In fact it is fair to say JC is very critical of SPICE.

What you state is in contradiction to my experience of reading what those designers say and others on one forum they belong to; www.diyaudio.com

It seems your saying (apologies if taking it out of context/mistakenly) that it is not that difficult to design an amp, but that is if you have the blueprint to begin with, if your think I am wrong then sorry your disagreeing with a lot of people who have tried this at diyaudio, not just EE DIY fans.

You could say any audio product is simple as long as the blueprint is available to follow, but once you start to deviate from this then it no longer becomes trivial.
And yes not all modern amps stick to the old blueprints that exist, same goes for other audio gear, including speakers (as an extreme) where there are many blueprint designs.

Cheers
DT

These are individual preferences, and of course people are free to exercise their preferences. We should only judge results.


I'm aware of that, but my impression that this is an informed opinion, and that he has hands-on experience with SPICE. I was speaking to whether or not he was familiar with SPICE.


Curl and Pass have their little corner of the world, which is big enough to allow them to survive and thrive a little. But, its not the mainstream.

They seem to have staked their fortunes on the idea that they can create "better sounding" amplifiers ad infinitum. This is an idea that does not do well when investigated in a scientific manner.

Again, there is no requirement that everybody do everything in a scientific manner. I've got my own pet beliefs, too. Just not so much about audio.

We call ideas that are based on tradition and intuition, but cannot be affirmed by scientific means, by certain words that I will not use here because we all know them, and some find them offensive.


The difficulty of the design depends on the nature of the goals. I mentioned an area (switchmode) where generally interesting and useful work continues.

If the goal is to obtain a farily typical, farily durable, fairly economical home audio power amp with power up to about 400 wpc into 4 ohm typical speaker loads, that is effectively a straight wire with gain, then exceptional talents are simply not required. There's no reason to use any talents at all other than product selection and purchasing. The amp of your dreams is available from a number of competitive sources.


I don't think that there are many people who put diyaudio.com over and above all other technical sources as an audio authority. I don't believe that they make any claims about formal peer review, or even use of the same kind of evaluation techniques as peer-reviewed publications demand.


That's true as long as the deviations are significant. In this day and age power amps are essentially commodity building blocks of systems that are interesting for reasons other than the details of the power amps that they include.


There are many reasons that power amps deviate from evaluation board and application note designs, but improved sound quality of the power amp circuit itself are rarely among the reasons why.

As I said, a great many people using rigorous scientific means determined that at last some evaluation board and application note designs were capable of sonically transparent operation while driving typical loudspeakers, 30 or more years ago.

The need for new power amp designs did not evaporate at that point, but improved sound quality ceased to be a major concern. Since then costs, power levels, size, and suitability for various specific applications (e.g. mobiile) have improved greatly.

Is JC making anything these days? Whenever I read him, he tends to come across as a bitter, old man.

I don't get it then. The whole point is amps do have frequency response differences...some more than others. The ones with bigger differences in FR are the ones likely to sound different. Uh...that's the whole point.

What two, off the top of your head have such large disparities in FR differences? Let's leave out relatively high output impedance tube based amps.

Apparently not.


Well, at least you get this much. What you don't get yet is that, by and large, modern solid state amps do not exhibit FR anomalies that large. That's why they sound alike.

Now, let's look at your particular case. You say you heard a difference. Broadly speaking, there are three possible explanations for this:

1) One of the amps was clipping (unlikely given your speaker load)

2) FR anomalies (unlikely for modern solid-state amps, but possible if something else is going on in the receiver, "analog direct pass-through" notwithstanding)

3) Your perception was influenced by non-sonic factors (highly likely, by process of elimination)

That's where we are. Either measurements or an objective listening test would tell us more.

What is the point then of discrediting claims people have of hearing an audible difference between this or that amp if you don't know the measurements?

Well, I'm prepared to bet a pretty good amount of money that I could pass such a listening test with several different amps - not just the JVC. If Richard Clark ever gets back to me and he lives within a reasonable distance, I'm willing to take the "challenge." Frankly though, the whole thing smells like a scam to me.

Because the claims are based on nothing. They didn't listen in a way that could tell them anything.

Besides, as I keep saying (and you keep missing), the overwhelming majority of modern SS amps measure flat enough to be audibly transparent. We're on really safe ground in predicting that you won't be able to tell any two of them apart in a real test, if you ever bothered to do one.

Let's say that they're suspicious because the claims aren't qualified in any particular way leading one to give as one possibility that one of the amps had run out of power. By qualified, I mean things like
what they were listening to (gives an idea of frequency distribution)
the distance from the speakers
speaker sensitivity, nominal impedance, etc.
the nominal SPL level at the listening position
was the room lively or treated
how the comparison was made
how often
was it sighted

etc.

Plenty have said when they replaced one amp (not receiver) with another, both with pretty close to the same wpc and all that they heard differences. But without more qualification and a bit more rigor, they might not be so sure why they heard differences. If one amp just wasn't capable (clipping occasionally) and the other was, then all that means is that the sonic differences were due to that and not to anything unique.