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Old 10th November 2007, 05:35 PM   #11
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You should try harder.
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Old 10th November 2007, 06:59 PM   #12
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Well, I'm just not seeing what you're seeing in those graphs. The FFT maybe, but it could as easily be distortion products that far down and that high up. LPs are anything but clean in a pure technical sense. If you really want to get a baseline for what's needed, play some notes or find someone to do so, and record that. Do same analysis. Look at the filtered reconstructed signal, not the data files. Getting from what you see in a waveform, back to why something sounded a certain way, is fraught with problems; I keep my confidence level on such matters purposely very low.
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Old 10th November 2007, 08:19 PM   #13
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Quote:
Originally posted by Conrad Hoffman
[B If you really want to get a baseline for what's needed, play some notes or find someone to do so, and record that. Do same analysis. [/B]
This has been already done many times, e.g. here:

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

The main problem of 16/44.1 is the low cuttoff frequency of the brickwall filter, which is necessary for proper digital signal processing to cut aliases and mirrors, and unfortunately affects natural musical signal.

I did look at the reconstructed filtered signal, I hope you got it. I sampled the CD output analog signal at about 50 - 100 x higher rate than is the original sampling frequency. What I saw is that the output signal bears a signature of brickwall filters used (Fs/2), and this indicates to unsufficient sampling frequency, which is the main problem of the CD format.

Can you transform signals from time domain to frequency domain? If not, then do not say that you do not see in the graphs what I do see.
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Old 11th November 2007, 11:37 AM   #14
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Spectral analysis is an averaging method, the bigger set of samples, the more averaged. It hides transients. I am sure that we must do not only spectral analysis, but analyze time domain as well.
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Old 11th November 2007, 01:32 PM   #15
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Now that (transients) I agree with, but keep in mind that time domain measurement have provided little hi-fi enlightenment over the last 50 odd years, and everybody went to spectral analysis hoping to do better. It hasn't really happened, and consensus on what's audible is still sadly lacking. IMO, you need both, but once you've presented data, some correlation with audibility is needed. The bottom line is that so far the differences between well recorded 16/44.1 and higher bit rates/depth, have proven minimal. Not zero, but not the great improvement everybody hoped for. Everybody's looking for the "X factor", but there's a huge body of evidence that says it doesn't exist, and audio quality can be summed up with very conventional thinking, and within the normally accepted hearing band of 5-20 Hz, up to maybe 20 kHz, depending on the individual. That applies if you're under 30 or so. If you're older and can hear 16 kHz, you're doing well, and as someone in another post mentioned, response typically drops off like a stone off a cliff. Dozens of dB in a few hundred Hz. If I were a bat, I'd starve.
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Old 11th November 2007, 05:01 PM   #16
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Sadly I must say, if you hear a cymbal crash and it does not contain all the harmonics with the right ampliftude, then it does not sound like a cymbal but like a shoe box. with 44.1 kHz sample rate you hardly have two samples of 20 kHz and it may not have been taken at the right instance so you may only have two samples of 10kHz if you are lucky.

This has been a problem all along with CD, people who play real accoustic instruments have a problem resolving the charater of the instrument. This has also been proven over and over. Although 24 bit has a higher amplitude resolution and dynamic range, the sample rate fails dismally.
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Old 11th November 2007, 05:08 PM   #17
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Quote:
Originally posted by PMA
Spectral analysis is an averaging method, the bigger set of samples, the more averaged. It hides transients. I am sure that we must do not only spectral analysis, but analyze time domain as well.
Both spectrum analysers (frequency domein) and oscilloscopes (time domein) sample the input, besides just the sweep rate represents is a typical sample. The higher the resolution band width, the lower the sweep rate. Modern spectrum analysers can resolve 1 Hz and lower.
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Old 11th November 2007, 05:17 PM   #18
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Nico,

this is just the case of us who are familiar with live acoustic, unamplifyied instruments and concerts. The people who know only reproduced electronically amplifyied and recorded music do not understand the issue and often come with trivial engineering attitude. The further case is just commercial - MP3 and 16/44.1 is enough then.

Regards,
Pavel
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Old 11th November 2007, 05:42 PM   #19
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Quote:
Originally posted by Nico Ras


Modern spectrum analysers can resolve 1 Hz and lower.
The frequency resolution of spectrum analysis is sampling frequency divided by number of samples in the record. So, for 96kHz sampling and 64K samples you get resolution like 1.46Hz. But you need those 64K samples, and there can be few transients between them. 64K samples of 96kHz sample rate takes 0.68s of time, this is a long time, and FFT is averaged in this time interval. You can have several fast transients during this interval, that are "hidden" in FFT, but can be easily captured in time domain.
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Old 12th November 2007, 08:53 AM   #20
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Horn on vinyl:
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