Testing or Listening? :|: Split from Blowtorch II

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When you haven't got a working definition of an ideal amplifier (or preamplifier) to compare a real one to....anything goes.

This is nonsense. It rather reminds me of the notion that we need targets to aim for - which has been explained away in the writings of (for example) Hubert Dreyfus.

And engineering goes too.....right out the window. Hello tinkering.

But all along this thread you've been using your own humpty dumpty version of the word 'engineering' so how is this relevant to the rest of us? Tinkering is not at odds with engineering as I know it, rather its a way to optimise a working design.
 
When you haven't got a working definition of an ideal amplifier (or preamplifier) to compare a real one to....anything goes. And engineering goes too.....right out the window. Hello tinkering.

After the tube amplfier is bought and the speakers still sound thin and shrill, that's when they go shopping for magic wires....with high resistance and high series inductance or shunt capacitance. After that it's magic stones, intelligent ICs, pet rocks, mood rings, or whatever else comes along. That's why they call it a cult.

First you ask me, than you reply, in the same message, while your reply is inapplicable to my case.

So be it.
 
Its a little hard to follow, and looks to me like you're confusing experiential knowing with perception - direct experience is not an illusion, whereas perception is not knowing and most definitely does have illusory nature.

I prefer not to discuss my website here, in this forum. It's way off topic.
You can email me directly if you wish to discuss it.
 
If anyone is at all confused what audio engineering is, at its heart and soul, then just look through the JAES 1953-1960, as I did, over the last few days. What you will find are the formidable problems presented by phono playback, analog tape recorder design, and even the first efforts at solid state design. You will find what it is all about, there. Looking at the problem, attempting to measure it, finding approaches to fix it, that are as true today, as they were more than 50 years ago. Check it out, all serious designers.
 
As soundminded, crudely tried to point out - I'm from Ireland (don't know where Trolls are from?) & part of the Irish mythology is that we aren't English :D

I believe that and I suppose that the Scotch-Irish aren't Irish either (BTW: I know that it's supposed to be Scots-Irish).

That is, unless it's an Irishman that's had a lot of Scotch that afternoon.:D

Best Regards,
TerryO
 
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Lots of interesting posts on perception! I agree fully that the perception that is experienced is a construct of the mind, using bits and parts from many sensory inputs as well as past and (expected) future ones.
One thing I'm not seeing/reading which I think is important.

It is worthwhile to remember that even, say, identical music played by identical amps over identical speakers, to the same person, may give different perceptions in different circumstances and at different times.
Because the inputs to the brain construction process may all be different even if that one input, the air vibrations on your ears, are identical.

jan didden
 
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I was just reading in the BT II thread about that Stereophile article comparing 4 different phono preamps. Maybe better to comment Here than There?

The way they did it was recording a musical section played through each of the DUTs to a CD-R and then listening to the differences between the tracks.

Then I thought, wait a minute! Is Stereophile now endorsing CD-R replay as having such good resolution, resolving power, detail, realism etc that it can be used to hear the suble differences between phono preamps replaying vinyl??
Or should I not take Stereophile too seriously on this? ;)

jan didden
 
I agree its such a complete break with the established methodology used in Stereophile - I went back to check the date, which is March and not as seemed possible, April. Why CD-R of all things when a recording could have been done at 96 or even 192kHz? And given the outputs were in digital form, there's no excuse at all for omitting measurements of frequency response and distortion. Also did the Peak LE5 program do the downconversion to 44k1? If so, what are its characteristics (dither, filter response). JC seems so convinced of the necessity for beyond 20kHz response and he's content to see his baby reviewed through an unknown brickwall filter?:headbash:
 
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"Science is not as collection of facts, any more than opera is a collection of notes. It's a process, a way of thinking, a method based on a single insight - that the degree to which an idea seems true has nothing to do with wheter it is true, and that the way to distinguish factual ideas from false ones is to test them by experiment"

Timothy Ferris, "Not Rocket Science", The new Yorker (July 20, 1998, p5).

Underline and italics mine.

We seem often to confuse the question as to whether something is true or not, with the question of whether something can be enjoyed or not or preferred or not. I am sure my audio system has many flaws, some of which I am aware, probably some I am not even aware. Yet I greatly enjoy it. That's one side of reality.

Then there the other side of the reality, for instance whether a change in a certain component makes the amplifier more or less transparent. That is a factual question that needs experimental tests to find out which it is.
There are several ways to design such a test. For instance, you can do a battery of measurements that are related to how transparent the signal goes through the amp. Or you can design some controlled subjective listening tests to find out if there is an audible difference in transparency.

Whatever you do, remember that: to establish a fact needs experimental verification, and that is completely independent of whether you can enjoy your equipment, have preference for this or that speaker, that sort of thing.
Two different things.

So, it's pretty nonsensical if someone says: I prefer speaker X over speaker Y, and someone else says: but that's impossible because X has a frequency response that is less flat than speaker Y. Apples and oranges.
Also pretty nonsensical if someone says: amplifier X has less THD than amplifier Y, and someone else says: can't be because I prefer the sound of amp Y. Pears and olives.

jan didden
 
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And what does transparent mean?

Well I use the term in what I believe is the most original one, namely that what goes in comes out unaltered (except for level of course).
So transparent for me means that nothing gets added to, nothing gets taken out of, the sinal.
I realize in Real World that's not 100% possible but in designing an audio component we should try to get as close as possible.

{I do realize that some designers purposefully manipulate the signal like adding some extra bass because it sells better but that's no concern for me as a designer}.

jan
 
But it's kind of a tautology, isn't it? How do we know what goes in, except by measuring it. How do we measure what goes in except by playing it through some device? So which device are we measuring the one that measures it or the one that plays it back?

It's a bit like Stereophile using pieces recorded to CDR to listen to the replay from different DUTs - what's being listened to here the original sound, the CDR recording device, the CDR media, the CDR replay chain, etc?
 
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But it's kind of a tautology, isn't it? How do we know what goes in, except by measuring it. How do we measure what goes in except by playing it through some device? So which device are we measuring the one that measures it or the one that plays it back?

It's a bit like Stereophile using pieces recorded to CDR to listen to the replay from different DUTs - what's being listened to here the original sound, the CDR recording device, the CDR media, the CDR replay chain, etc?

I don't know of any other way for testing for transparency than testing for difference between input and output. I don't think you can do that by listening, as far as I know.

There's basically two problems in transparency testing:
- How do you measure under circumstances that are close enough to actual use with music to be relevant for music reproduction?
- What parameters do you measure that let you judge transparency?

I believe the first one has been solved. For instance, my AP can test equipment linearity with a signal composed of a spectrum of 31 (or more) different frequencies; and then by cleverly spacing these frequencies, test for the individual harmonics per frequency and all the myriad intermodulation results of all the frequencies. It is possible to set the individual levels such that it exercises the amp much heavier than any musical signal ever would, so I believe this is a relevant test and test signal.

I'm not sure about the second issue because it involved settling the question what levels of 'non-transparency' can safely be assumed to be non-audible.

One exciting solution to both questions is Bill Waslo's AudioDiffmaker that lets you compare actual music signal segments difference between input and output and is VERY sensitive. For instance, he demostrated two musical signal excerps that differed such that one had a complete Sousa-band 'buried' in the signal at -60dB IIRC. Most people (as far as I know, all so far who tried) cannot even tell in which signal the Sousa band is. Yet if you listen to the difference signal you just hear that Sousa-band clearly.

So I believe we're getting there, even if we're not there yet.

jan
 
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