John Curl's Blowtorch preamplifier part II - Page 1049 - diyAudio
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Old 3rd March 2011, 03:50 PM   #10481
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Default Don't Ask An Idiot A Difficult Question....

I have repaired thousands of amplifiers in my time, and once they are working I listen to them before sending them back to their owners.
I listen in a familiar environment, on the same speakers, using the same cd player and the same familiar music tracks.
I have no attachment to any of these amplifiers, and no expectations.....I run them up and just listen.
Over the range of consumer, audiophile and pro amplifiers is a whole range of sounds.
Within this range, there are many amplifiers that are subtly dirty, disturbing, irritating etc, and every now and then there are amplifiers that sound 'right'.

I think everybody here concedes that amplifiers sound different, so what is this big deal about not being able to tell them apart ?.

When it comes down to essentially distortionless (blameless) amplifiers it does become more difficult to tell them apart, and this is where listening to nuances is the key, like how cymbals are reproduced, or how bass notes are distinct or blurred, or how realistically vocals are reproduced etc for example.
This can come down to repeated listening to particular cymbal hits, or particular bass chords, or particular vocal words or phrases to define amplifier sonic characteristics.
Distinguishing amplifiers (or sources, or speakers) is very much dependant on the listening skill of the listener, and this comes with practice and experience.
Blind test subjects need to pass a listening skills test before being included in any DB survey.

Dave.
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Old 3rd March 2011, 03:51 PM   #10482
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Well said, Dave.
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Old 3rd March 2011, 04:12 PM   #10483
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Originally Posted by janneman View Post
You have no way to know this. Your visitors don't know it themselves, and you don't know your own prejudices and expectations.

jan didden
Jan, your reasoning is just academic, as usually. You do not know me personally, we have never met, and you have no right to judge my approach and my intentions, as well as my prejudice or expectations.
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Old 3rd March 2011, 04:14 PM   #10484
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Originally Posted by soundmeister View Post
Blind test subjects need to pass a listening skills test before being included in any DB survey.

Dave.
I have conducted a number of tests to determine sound system speech intelligibility. The listener panel is always given practice tests in a small room without a sound system. This is both to train them as the scores do rise a bit with some practice and to eliminate those with hearing difficulties. I use the ANSI standard from 1971 (as I recall). This is best done with a live person reading the list. The scores are a bit lower replaying it from a recording and that is acknowledged in scoring the final results.

As a result of this practice I am better able to identify problem areas before the test is conducted.

What I found interesting is that if the issue arises as to if the sound system is working for speech after witnessing or participating in the test just about everyone accepts the results. (The folks who complain they can't hear are correct... they can't hear! It is not a problem with the sound system.)

Now the test is not a double blind test as the tester knows the word list. What is interesting is virtually every listener believes they got every test word right, until they see the actual word list. (I don't recall anyone ever scoring 100% though!)

None of this is new information. I f I need to convince someone else of the speech quality a formal test is useful. If I want to satisfy myself I do not need a formal test, practice and experience get me into the ballpark, stadium or Arena.

For those about to raise the objection, yes there are times when my ear says the system is not adequate!
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Old 3rd March 2011, 04:15 PM   #10485
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Thank you John.
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Old 3rd March 2011, 04:22 PM   #10486
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I said nothing about my method, therefore all assumptions about what it includes and it doesn't include are baseless speculations.
True, in the sense that if I claim I have a perpetual motion machine but I'm not going to show it to anyone or explain its operation, one can't speculate that I'm mistaken or lying.
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Old 3rd March 2011, 04:26 PM   #10487
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Jan, your reasoning is just academic, as usually. You do not know me personally, we have never met, and you have no right to judge my approach and my intentions, as well as my prejudice or expectations.
My only assumption is that you are a pretty normal human being. If I'm wrong there, please correct me .

jan didden
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Old 3rd March 2011, 04:30 PM   #10488
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ISO900x certification is meaningless in the context of limited production and fashion. Conformance to ISO900x boils down to documenting procedures and following them ("Document what you do, then do what you document"). You can make absolute doo-doo and still be ISO certified- it means that everything you make is doo-doo, and the same kind of doo-doo day in and day out. And it means you paid a LOT of fees for auditors, consultants, and the rest of the ISO racket.



Considering that Jerry Garcia died in 1995, that's a safe statement. And I would dare say that most people around here listen to live music on a regular basis- it's impossible to avoid.
Do you think Jerry Garcia is grateful to be dead?

What ISO9000 means is that the one YOU get when you plunk your money down is likely to perform like the one you saw and heard as a demo and thought you were getting. If you are spending a lot of money on something manufactured, I think that's the least you should expect. Of course a garage operation can't offer that. Basically you are rolling the dice when you buy.
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Old 3rd March 2011, 04:38 PM   #10489
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if I claim
Speaking of which, i ordered one from you, but for some reason i can't seem to find the turn-off switch.

(i know it's been ages after the factory warranty expired, but can you still help me out ?)
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Old 3rd March 2011, 04:39 PM   #10490
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Now, just last week I was asked by Jack Bybee to attend a live performance of the Vienna Philharmonic at Zellerbach hall, doing Schubert, etc. Jack was adamant that he go, even though he had a major operation on his knee, just 2 days before. He went, with another mutual colleague of ours, and I declined. Had they done music I was into, I would have attended gladly.
I don't think "Friend of the Devil" or "Hell in a Bucket" is in the Vienna Philharmonic's repetoire.
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