"Official" All amps sound the same thread - Page 6

Well, you seem to want to make unsupported claims on Internet forums. If you had done a real, level-matched comparison, then your claims would actually have been supported!

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Because cooler air usually contains more moisture - humidity - sound does travel better in cool air. Another factor is the density, at higher elevations the thin air acts as a dampener on sound. Not likely that you will be able to ascertain the differences in your LR unless you live at 15K feet. You may be more concerned with breathing than listening.

Well actually the higher the humidity the less dense the air and so sound will not propagate as well. I know it seems counter intuitive, but its true. You are right though that cold air does transmit sound better, it just isn't because of humidity. In cold air the particles aren't moving around as fast so they can pack in tighter.

I agree though, I don't think it would really matter when we are talking about home theater.

I would be interested in reviewing the results of tests that support your claim.

FAIL.

That isn't the argument.



Here's perhaps a more fundamental question: since sighted listening is fraught with chances for error, why should we accept at face value your sighed comparison testimony that the two states sound different, much less that one sounds worse?

But if you can hear a difference, it is measureable. Why don;t you follow Chu's advice and ask Crown why your amp/speaker combo might be distorting audibly in one state but not the other?

Audio cable manufacturers, other than the folks from Belden, are not typically the 'go to' for straight talk on audio difference, much less difference between amps.


Be still my beating heart. Jjust for giggles, in what form did you pose the question to him? Did you ask 'Do amps ever sound different?' or was it a question that WASN'T a strawman?


"et cetera." Let's see some data that those differences are ROUTINELY above audible threshold.


And this is a ******** argument, because amps don't have to be 'perfectly linear' to be audibly indistinguishable, and a difference can be 'meaningful' in objective terms (if, for example, a certain design target is to be met) but be irrelevant in audible terms. What's required is that their linear and nonlinear distortions remain below thresholds of audibility.



Under what conditiosn, pray tell?


Gee, that's nice, but no one is arguing about tube vs SS amps



Instead of bothering people like 'our friend Kurt', how about reading the E. Brad Meyer article I linked to? It laid out the potential causes of difference in layman's terms quite nicely, some 20 years or so ago.

I understand that if you drive a speaker too hard, it's output will be limited by its range of excursion. The dynamic range of say the woofer, may be limited compared to the tweeter, resulting in a form of compression, and a loss of overall balance.

I'm sure mine does, too, as well as many others here. But remember, 16K to 20K is only a fraction of an octave of very subtle -- though of course important-- sound.

Do re mi fa so la ti do--the musical scale of one octave. If lower "do" is 10K, then 16K is probably between "so" and "la". upper "do" is 20K, as each octave doubles or halves the grequency.I don't know the exact math here, anybody jump in if you can correct me.

But my point is loss at 16K is probably not the end of the wor
ld musically, though of course all the way to 20 would be preferable. Just a little optimistic perspective for those of us who ain't getting any younger.

So which did you prefer?

(Bear with me please, if this has already been asked--just found this thread and I'm still on page 3).

So I'm guessing your answer is no.

The best summary I can point you to is Tom Nousaine's old review of amp tests. Here's his conclusion:



See also the Meyer article that Krabapple linked to earlier.

And if you doubt that people really hear differences where none exist, Nousaine did a paper on that, too.

I dunno. What was the question?

Well, we (not Steve) don't know what this 'worse' was when the amp was run bridged. Personally I suspect Steve did notice a problem. Crown might ask for clarification of the term worse, the measured impedance of the sub, crossover questions, etc. For all I know, distortion/noise rises appreciably when bridged and may further rise or go into some sort of oscillation if the impedance over the frequency range drops. But, that's pure speculation on my part. To not avail yourself of a free phone call to get some insight from the actual manufacturer and have the ability to speak to engineers, that just doesn't make sense to me.

There are lots of people who have a vested interest in not believing anything in particular. This can cut both ways.

However, there seem to be far more people who have a vested interest in believing that the last purchase they made was fully justified by sound quality. And then there are the purchases they made before that.

Furthermore, there are many reasons why equipment comparisons will come out as being positive for audible differences, listener bias notwithstanding. Poor level matching is probably the most common.

See post #125.

Nice tacit admission that you have a strong vested interest in the idea that all amps sound different. If they didn't, you have wasted a lot of time and money.

60 Hz is a pretty strange choice of single frequency to match levels. Most technically savvy people would pick 1 KHz or 400 Hz. Furhtermore, matching levels at just one frequency leaves the doors open for a ton of level match differences due to frequency response.



That statement has been made and debunked a great many times. The same argument has been made for CD pens. Do you want to go there?


More to the point, why should an amp sound worse bridged unless it was incompent when driving low impedance loads?

If it an amp is incompetent to drive a low impedance load then the most common symptom would be clipping, and that is one of the conditions that it has been said again and again to cause audible differences.

The only question I see in post #125 (unless you want to know if I remember Bob Carver) is this one:

There are multiple posts in this very thread where people describe doing exactly what I referred to. They're my examples. Also, if you'd actually comprehended anything I've written here, you would know that I do not believe that "there is no way for an amp to sound different."

Personal opinions and experiences:
1. There may be several forms of sound distortion that are not currently measured, or even formally recognized.

2. On prejudices and expectations: I have heard many different examples of all audio product types and my judgments were not as expected, nor consonant with reviews I had read prior to experiencing.

3. In comparing products memory is not a factor if you write down your impressions at the time and compare them.

4. You are a major variable. The same record on the same system can be very annoying after a bad day, or conversely transcendant when relaxing late at night after a bad day.

5. For me, emotional response to the music is far more important than any measurement. The best equipment ($$,$$$ per piece) does it, the rest not nearly as much. Unfortunately I live with the rest ($,$$$ per piece).

6. In my system humidity has a very noticable effect on the sound of a system. If high (summer, > 60% or so) the sound is dull, lifeless as compared to usual 40% or so. Temperature is fairly constant year around. This has to be taken into consideration when judging a products overall performance.

7. Since I don't normally listen in a blind environment I really don't care about such.

When bridged there is a lack of control over the low frequencies (below around 35hz). It's a mute point for two reasons, firstly because a single channel from the crown is more than enough power for all but ear damaging, lets see how loud this thing will go testing. Secondly I'm now using a BGW 750C amp bridged to power the sub. It's a 55lb class a/b mid 80's beast that is still going strong (750 watts into 8ohms bridged). Touch wood it doesn't fail and send DC to my VC any time soon .

edit: measured impedance of the driver is here - nothing below 5.8 ohms

http://www.bcspeakers.com/PDF/PRD/15PS100.pdf

Arny, I think he ran 60Hz because it was a sub.

I used 60hz because I was too lazy to bypass my AVP's crossover. I used my laptop and REQ as a signal generator. If it's level matched at 60hz it's level match everywhere - unless of course bridging the amp alters the FR.

DBT is not the be all end all. A DBT could be devised to prove or disprove a difference by being selective with program material and subjects. If you do manage to achieve a positive correlation of 80% or greater with a DBT then you've proven something! But on the other hand if you get less than 80% then you may have just proven than you picked the wrong set of test conditions.

The crown is rated to 1140watts (yeah right!) into 4 ohms in a bridged configuration. The clipping LED's did not come on.

But that's still more than you've proved by doing a sighted comparison.

Unicorns may exist too. But if you propose them as an explanation for something, it's your job to provide the evidence. And 'I heard it' isn't good enough, unless you run standard controls; we *already* have explanations for why you can 'hear' the audio equivalent of a unicorn. You need to rule THOSE explanations out, first, before putting any weight on novel distortions.


Biases need not be conscious.


Limitations of audio memory remains a factor in any comparison, whether the impressions are written down or not. These limitations suggest the use of quick switching protocols to optimize your powers of discrimination. Without it, the written record can simply end up as an example of GIGO -- garbage in, garbage out



True. Which should give audiophiles pause before they confidently assert that the difference they heard was because they changed the *gear*.


If that's so, wanna bet some of that 'emotional response' isn't coming from the *music* at all?


Consider also your physiological state in humid weather.


Which is basically saying, you don't care if something's real or not. High-end snake-oil makers LOVE guys like you.

Odd, then, that DBT is the method of choice for scientists.

If a DBT 'proves' the difference , then there's probably an audible difference under those conditions. A 'negative' result means that the hypothesis of difference was not supported under those conditions. Nothing more or less.

Sighted comparison, on the other hand, allows NO conclusion either way.



No, you haven't, unless you've set "80%" as your confidence level. Typically it's "95%" or better (actually it's evaluated in terms of p value, the probability that you made the *wrong* conclusion. "95%" in this instance means you accept a 5% chance of being wrong. For a difference that is a priori quite unlikely -- like, say, an audio unicorn -- one could well demand a p of < 1%).



Meanwhile, sighted comparison is *always* the wrong set of test conditions, scientifically speaking.

Posturing I guess. Thats fine.

What I do know is that you seem to think that if an amp does sound different from another, one must be malfunctioning.

I have read several reviews by a well repected audio journalist who believes that he hears differences in amplifiers. He also hears differences in cables, even power cables. So for you and 1 or so other posters to not even be able to acknowledge that it is possible speaks volumes.

It's not so much a difference of opinion, it's you and your buddy inferring that someone who disagrees with you is either an idiot or a liar. Nice job.

Your findings then suggest that the Crown XLS 402D, when bridged, has problems with your sub. Like you said, it ought to have had no issues making the usual assumptions. The 402 has gone through several iterations and originally it wasn't spec'd for bridged 4 ohm operation. Me, I'd arrange for Crown to service it if it's under warranty.

Well respected by whom? Certainly not anybody in the scientific community, where audio "journalism" is regarded as a bad joke. Put a cloth over (most of those) things, and I guarantee you he won't be able to tell them apart to save his life. And when he can, we'll be able to point to a simple measured difference that can explain it.

Look, you want to believe in unicorns, that's your business. You want to buy magazines written by people who believe in unicorns, that's your business, too. But make no mistake: Most of the people out there writing about audio today believe in unicorns.

Not necessarily. Large output impedance, noise levels, one or both driven past its capabilities, instability, and more come to mind.


I know a well respected journalist that says the same thing. He also hears differences when he turns a power distribution center upside down or on its side, when he replaces fuses, if he puts a ferrite bead on a power cord, etc. He also is practices Reiki -interaction with our energy auras by a waving of the hands - and holds periodic gatherings where he & other spiritually attuned folks focus their psychic energies to heal people. Some people you know are just nuts, but they write well.

Tell that to the whole pharmacological industry... relying on those all the time... And try to tell that to your mom's doctor when he will need to choose the proper cancer medication to give to her...