John Curl's Blowtorch preamplifier part II

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#86,321
memory

The context of SY's remark was (EDIT: in 86303), however, the reliability of aural memory for level differences separated by a time interval. Despite the fact that in very-short-term comparisons we are usually very good at noticing level changes, with sufficient time between comparisons we are probably pretty lousy.

This reminds me of a recording session from many years back, where I had the daunting task of emulating a shakuhachi on alto flute. Prior to that, a hired top-notch string section came in to record some things which would wind up being used via the PA system at the concert, to augment the paucity and weakness of the official group's live players. The string section donned headphones to hear the synchronizing background track, but one of them quipped that another of them didn't need to hear this, as he had "perfect click".

It would be another interesting dissertation topic to study the memory effect based on the particular aural modality. I didn't grow up with a piano in the house and thus lack "piano pitch", which is far more common than so-called "perfect pitch"; but I have trained myself to get closer to absolute pitch perception. What I tend to find is that, if I imagine hearing a given piece in my head, I am often flat by about a semitone.
 
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#86,322
bcarso said:
Actually the subjective testing tends to reinforce long-developed conclusions by many about frequency response and directivity. It's not as if a group of listeners prefers something, which is then used as input to the product development process.

What has been happening more recently is that simulation tools are maturing and do a steadily better job of predicting the loudspeaker's response on axis and the polar pattern, and physical models are then measured in the anechoic chamber with a sophisticated system, the so-called Spinorama. Out of this one develops a product which is then verified in the subjective testing.

If a competitor's speaker did anomalously well in subjective testing and didn't look very good in the Spinorama, this would be of great interest. So would the reverse situation. Where it got interesting was when the sighted tests showed a large effect that tended to raise the score of the large and attractive speakers compared to the smaller and less-impressive-looking ones.

Actually, the anomalous results tend to come most when professional audio reviewers are used. I don't know offhand what the correlation is with their many-times idiosyncratic hearing (all are subjected to a standard hearing test), but in addition to having rather odd preferences in many cases, the scatter in the data is also generally larger.
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That only applies to speakers.
 
#86,323
Destroyer, thank you for putting to bed the relative (un)importance of amplifiers and line-level stuff, beyond mid-priced levels where things tend to work well, by highlighting that this applies for speakers, which have variations orders of magnitude greater than amps. I knew you'd get there! 😀
 
#86,325
bear said:
For example, maybe, at Harmon, it did not matter which amplifiers they used?
Of course out of their own, but then why would it matter if it was theirs or another brand?
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In all loudspeaker testing facilities I have been, folks were very casual about amplification, cables, interconnects, what have you, and very fuzzy about the room. There are even standards for those.

Good enough is good enough. Guys, it is like building a bridge. It is not easy. Many things have to be considered, many things can go wrong, many alternative approaches are possible. But in the end, it all boils down to solid engineering to build a bridge that stays up, or an amplifier that doesn't cause audible artifacts.
 
#86,327
DPH said:
Destroyer, thank you for putting to bed the relative (un)importance of amplifiers and line-level stuff, beyond mid-priced levels where things tend to work well, by highlighting that this applies for speakers, which have variations orders of magnitude greater than amps. I knew you'd get there! 😀
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No, I didn't mean they're unimportant. I just meant measuring waterfalls, polar patterns, etc, is for speakers. We tend to know what people like for speakers, or what they won't like. With electronics it's a mixed bag in many ways... we know lots of people love loads of 2nd harmonic distortion... and yet marketing and claims also exist for low distortion being favoured, or class A, or tubes, or.... on and on and on. I honestly have trouble understanding why people here are interested in homogenizing everything into 'the one truth of DBT proven low distortion electronics'; it's a little hive-minded and boring. Even if some very poorly made stuff is out there, I like to appreciate that there's a broad spectrum. And I think most gear sounds bad...

But then again who wouldn't be pumped about living out the rest of their days repackaging Hypex products 🙄
 
#86,328
vacuphile said:
In all loudspeaker testing facilities I have been, folks were very casual about amplification, cables, interconnects, what have you, and very fuzzy about the room. There are even standards for those.
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If speaker are your thing, ya, you probably don't obsess over the electronics, especially if you don't know much about them. Vice versa too... N. Pass has some big *** horns he drops different fullranges into, instead of elaborate flagship speakers and such that his amplifiers power all day everyday.

It's not a statement of true value in the field of audiophilism, to find that an engineer of one thing isn't concentrating on every other thing. It's not like microbiologist is also a microscope developer because he uses them in his lab; nor would he be as carried away in the ultimate performance of one.
 
#86,330
DPH said:
Yeah, this is why I try to avoid calling X better than Y, since I generally lack definitive proof, and just enjoy playing with all this stuff (which hits at my ultimate "fun" goal).

In the meantime, I try to be a pain in the rear of those who do try to call X better than Y without any sort of definitive proof. 😀
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Derfy,

When I listen to a sound system, it usually takes just seconds of listening to some to decide they have issues. There really are many underperforming systems.

One of my better learning experiences was tuning a system In an independent Baptist built Akron plan church. Adjusting the frequency response to get a flat line on the analyzer, in theory correcting for the room response, produced sound quality I found unacceptable. The rich room resonances left in clearly belonged.

There just might be a reason thousands of Akron plan churches were built and are stil in use today. As is the same sound system after 30++ years. Although the electronics have been changed.
 
#86,331
morinix said:
Here is the RDH.
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I think that was referring to mono. Stereo may have stricter demands.

Chris Hornbeck said:
I cannot agree with this. It's a useful conjecture, but needs to be proved in context, and that's difficult. I'm uncertain if you would actually believe this of yourself. I don't of myself, depending greatly on context and import.
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You don't believe that long-term auditory memory is unreliable? In particular, you find it difficult to believe that anyone might doubt his own long-term memory, and you don't doubt your own one? Is this really what you are saying?

To put it another way: must we accept an obviously flawed test methodology because anything else is too difficult? Sometimes, yeah. But sometimes butts get bitten. My interpretation of the current situation is that the difficulties in making a proper test are really serious ones.
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What is "obviously flawed" about the idea that a test of what can be heard should only involve hearing? Is it that such tests give the 'wrong' outcome? This reminds me of the way that some people object to "difficult texts" in some Scriptures; they find them difficult to accept but have to pretend that they find them difficult to understand.

morinix said:
This is very telling about you. Because this has nothing to do with listening to/evaluating tonal and harmonic content of sound reproduction. Total gain is one of those more gross evaluations verified by even just a fluke meter.
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Perhaps you missed SY's point? Something relatively easy to distinguish (level) has to be done with only a short time lag to have any hope of getting it right; it is reasonable to conclude that something harder to distinguish has even greater need of short time lags. Let us be clear: the question is not "do I like this", but "can I tell X and Y apart?". If I can't, then questions of which is 'better' are meaningless.

I get the feeling that this ABX stuff, as academically important as it is, is being used by many as a replacement for repeated, long term, listening and experiencing of the real thing.
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I'm not sure what you are arguing here. Hi-fi people don't like music? (Not true). Musicians and recording 'engineers' are the best judge of sound? (Not true, in my opinion - although there may be a few exceptions).

My view is that the best test of hi-fi is 'how well does it reproduce sound?'. That means that the sound it reproduces must have existed as a sound; otherwise there is nothing to compare the reproduced sound to. That means acoustic instruments e.g. a violin and a pair of speakers behind a curtain. When the audio chain sounds like the violin (i.e. people can't easily distinguish them) then we know we have achieved hi-fi.

Listening to an audio system and thinking "that sounds like the violin I heard yesterday" may help, but the real test is "that sounds like the violin I heard 30 seconds ago". Such tests have been done, and that is how we have some numbers to aim at. Further such tests may refine those numbers. This will, of course, be irrelevant to those with different musical tastes or different acoustical tastes - but they are not pursuing hi-fi but instead want a sound which pleases them.
 
#86,333
simon7000 said:
Derfy, When I listen to a sound system, it usually takes just seconds of listening to some to decide they have issues.
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That's just normal..... 😉

There really are many under performing systems.
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That's just normal.....



There just might be a reason thousands of Akron plan churches were built and are still in use today.
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Yes, a good sounding room is a good sounding room...there has been a millenial history of building 'passive' eq/reverb/amplification spaces, long before electronics popped up.

Iirc, you made mention recently of sending out gear that measures the same but sounds better....what did you do ?.


Dan.
 
#86,335
auplater said:
Hi SY...

So far, so good... 3 mo. scans still NED, so @ 2 years post resection moving to 4 mo. intervals for another year, then hopefully biennial [love the time in the MRI ;-( ]



John L.
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My thoughts and wishes are with you for continuing good results. Just completed my first year of less serious but similar thing, recently had fist op where I was clear and no resection required, was on top of the world.
Take care.
Marc
 
#86,336
DF96 said:
<snip>
"Better" can be confused with 'prefer', but even then it is useful to know whether someone can actually tell the difference between what he professes to prefer and what he does not. If I say I prefer chocolate icecream to vanilla icecream it might be useful to check whether I can tell the difference when I can't see the icecream; otherwise the truth might be that I prefer brown icecream to yellow icecream.
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Must be a misunderstanding. If you execute a preference test and as a result a preference is established then by definition it is a confirmation for a perceivable difference. (all said wrt probablities)

jan.didden said:
And that John is an honest account of what we are trying to tell. The preamps sound so much alike that your ears only cannot determine any differences so your brain is at a loss, and consequently you are confused.

Your brain can tell you which is playing at any one time when your eyes can see it, or a buddy tells it, or whatever additional non-auditory clues are present.

Jan
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That is a plausible hypothesis but you can´t present it as a fact, as you didn´t test your hypothesis. 😉


scott wurcer said:
Fair enough, to outline a cable test the way I might like to do it would combine the Pear and Carver challenge. Take the $7000 speaker cable and have the challenge be pick an amp and speaker and let me take the cable and make a substitute out of stock Belden wire and maybe even a passive or two at the speaker end using any measurements I want.

As I said I was actually surprised at how low on the usual nonsense the Pear site was, but that being said even though triboelectric, DA, etc. effects are real I don't think they matter here. IMO the R/L/C/G, length matter and little else.

EDIT - Though DBT in this case 😉
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Sorry, i didn´t realize that we were still discussing the pear anjou (Randi/Fremer) event.
According to Dave Clark´s review (that gave rise to Randi´s ranting) the Pear guys claimed a capacitance of 114 pF/ft(L= 0.025 microH/ft, no data for R) and Clark used a cable 4 feet long.
So it could be an interesting experiment but what hypothesis do you want to test (or confirm)?
 
#86,337
Jakob2 said:
Must be a misunderstanding. If you execute a preference test and as a result a preference is established then by definition it is a confirmation for a perceivable difference. (all said wrt probablities)
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My point was that if I say I prefer a particular taste (chocolate vs vanilla), it might be useful to check whether in reality I actually prefer a particular colour (brown vs yellow). It is even more important to check, if I am an ice cream manufacturer who always tells his customers that chocolate is the best ice cream. My unscrupulous rival down the road might be fobbing off his customers with brown ice cream labelled as chocolate - or I might be doing that.

I saw a TV programme a few days ago which showed how people's perception of crunchiness (and hence freshness) of potato crisps depends as much on what they hear as what they feel in their mouth.
 
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