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Old 12th November 2007, 01:30 PM   #21
bwaslo is offline bwaslo  United States
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Nico Ras :
Quote:
This has also been proven over and over.
Can you give examples when this has been proven over and over?

PMA:

It's easy to show that energy "exists" out to any frequency you want. What matters is (1) how much the energy is relative to other lower frequencies and (2) what hearing sensitivity is at the high frequency. I work with devices that depend on acoustic energies at over 1GHz (1 BILLION Hz). That doesn't mean or even imply anyone could ever hear it (I'd be interested in any evidence that they do -- evidence, not merely claims, of course!).

Another bit of inconvenient reality is that recordings are usually made with a strong emphasis on dynamic range, so "large capsule" microphones are what is often used to keep noise down (and also because people like the sound of them). Large capsule (1 inch or more diameter) mics have low resonance frequency, above which their response drops rapidly and their pattern becomes very beamy. These mics struggle to get to 20kHz, much less 50kHz. It is hard to find even a quarter inch microphone that has decent response beyond 20kHz. Toward higher frequencies, hearing sensitivity is rapidly dropping, mic sensitivity is radpidly dropping, phono cartridge sensitivity is dropping, tweeter sensitivity is dropping (and when not, it is so directional that it may as well not exist), are none of these factors significant?
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Old 12th November 2007, 04:57 PM   #22
PMA is offline PMA  Europe
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... but none o them gets brickwall. Brickwall is only good when no frequency component above its Fc exists. Which is not true. If exists, brickwall makes the worst possible influnce in time domain.
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Old 12th November 2007, 04:58 PM   #23
PMA is offline PMA  Europe
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Even 12kHz -20dB/decade filter is more acceptable than 22kHz brickwall. Engineers failed to realize this.
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Old 12th November 2007, 05:30 PM   #24
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It sounds like there maybe many things in affect here. I agree with Nico that cymbals rarely sound like cymbals on recordings. But this could be the fault of the recording process, like microphones used or the speakers used to make the sound, but I can't see the standard cd format doing much to help this at all. Do you not have to capture all the energy and all harmonics for the original sound to be recreated properly? We supposedly have tweeters that can run up to 40-50kHz and amplifiers have been able to go higher than this easily, so why haven't we been able to resolve higher frequencies than the standard cd format?

If we want high fidelity reproduction I would think this would have to be done. Something like a cymbal has a high energy sound coming out of it and it is so week and minuscule in recordings.

Not that I entirely care, cause I will listen to anything as long as its energetic and fun, but like to have things as best as possible if able to.
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Old 12th November 2007, 05:40 PM   #25
PMA is offline PMA  Europe
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That is why I gave this link to similar thread:

http://mixonline.com/mag/audio_resolution_project/

Just try it.
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Old 12th November 2007, 07:15 PM   #26
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Quote:
Originally posted by bwaslo
Nico Ras :


Can you give examples when this has been proven over and over?

South African Broadcasting Corporation - New recording and playback equipment was evaluated for various new studios and listening tests performed on a large number of musicians and conductors during the selection and installation phases. I was one of the technical consultants.
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Old 12th November 2007, 07:57 PM   #27
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On the other hand, I must confess, it is a bit late in life to slate CDs. We all have them and there are some advantages to be had that does enhance listening pleasure and that is the absence of surface noise, clicks, pops, etc.

Furthermore, you do not have to spend much in the tools and rituals of playing LPs, the sauce that is smeared, the counterweigths, the settling of tracking error, and all those good things that was synonymous with the hi-fi fanatic. Playing a single cut on an LP could take five minutes of ritual before the stylus actually hits the groove and then only to observe a curl of gundge being scraped out the groove by the stylus.

I do not promote that the sound quality of LPs are superior to CDs, that is totally debateable and probalbly has been for as long as CDs exist.

However, no recorded material actually surpasses live sound - again I must substantiate the claim; instruments that is not connected to a wire not passing though op amps, fuzz boxes, zener clamps and the like, but accoustic instruments that you can hear without it being plugged into a wall socket.

CDs cannot be faulted for electronically generated music as there is no-one on earth that can tell what it should sound like.
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Old 13th November 2007, 12:39 AM   #28
percy is offline percy  United States
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Quote:
Originally posted by Nico Ras
it is a bit late in life to slate CDs.
All's not lost. If I am not wrong, master recordings are done at a much higher bitrate than CDs before they are downsampled to 16/44. I think its 24bit/96Khz ? or 192Khz ?

Maybe they will see the light of day, someday ?

I also recall some online services offering high bitrate original master recording downloads/purchases.
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Old 14th November 2007, 02:49 AM   #29
bwaslo is offline bwaslo  United States
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Quote:
... but none o them gets brickwall. Brickwall is only good when no frequency component above its Fc exists.
Maybe when no frequqncy component you CARE about above fc exists. Surely you don't suggest that a brickwall cutoff at 10MHz would be significant? Because everything else, including hearing, have long fallen out by that freq.

An FIR near-brickwall still has perfectly linear phase up to cutoff. Has no effect on frequencies below cutoff. Yes, a scope with bandwidth beyond the cutoff will show squarewaves with Gibbs ripples, but filter the scope to cut out before the brickwall and they go away.

Anyway, all of those rolloffs (mic, ear, speaker, anti-aliasing filter) are tapering the response down (and a LOT, in practice) before the nyquist cutoff, so the actual system response is actually smoothly rolled off, not brickwalled. Excess concern about one piece of the chain that is effectively already in the stopband of many other pieces just makes no sense, I think.

__

In the link to the Resolution Project, I see they did some recordings with a custom made high rate/res system and believe high cutoffs are important; and some testimonials are quoted. But I don't find any actual data there -- no evidence that shows this making a difference, in objective terms, no tests to see if this can be heard when people aren't already told what they are listening to. I could be wrong, I'd be happy to re-read, can you point it out to me, or is there more on this project where actual tests were done rather than just the initial impressions and demonstrations? That report seems kind of preliminary. I have AES journals, was this project made into an academic study?
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Old 14th November 2007, 06:03 AM   #30
PMA is offline PMA  Europe
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Quote:
Originally posted by bwaslo


Maybe when no frequqncy component you CARE about above fc exists. Surely you don't suggest that a brickwall cutoff at 10MHz would be significant?
I hoped this was obvious. There is no problem with brickwall for audio when sample rate is 192kS/s.

2 example of the same music.

First - recorded at 24bit/96kHz
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