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In Reply to: Technical question about vinyl posted by mike_decock on November 18, 2002 at 14:58:41:
There is a fundamental difference between analog and digital which makes this an apples to oranges comparison.That being said one often overlooked part of digital audio is that as implemented it cannot exactly recreate the original analog signal. The theory allows taking samples at discrete time intervals of a band limited signal and recreating the original analog signal exactly (sampling thereom) assuming you can make a perfect low pass filter. For all this to work the samples have to be continuous and not discrete. 16 bit quantization of the samples is the main thing preventing the realisation of a better rendition of the original signal (you would like an inifinite number of bits). I think high-res audio has the potential to sound a lot more like analog because of the bit resolution more so than the sample rate. You get 256 times closer to "continuous" samples with 24 vs 16 bits. Higher sample rates allow you build low pass filters that are not necessarily ideal but very close to ideal in the audible band. This has been exploited for a long time with oversampling.
There is no sample frequency or amplitude quantiziation in analog, except that at some point the molucules which control the movement of the stylus are discrete, in terms of digital audio you could think of the amplitude of the signal being represented by a number of bits approaching inifinity and infinitely small time sampling (allowing unlimited bandwidth).
It would be interesting to have a format which was discrete time sampled but used a stylus instead of a DAC to have a continuous "sample" level based on molecular bits. In essence, high rez digital formats are trying to emulate that type of situation in a more convenient (and less error prone) format.
That being said, I just got a Music Hall MMF-7 turntable and there is something so magnetic about the sound of vinyl I have a hard time listening to CDs now.
Follow Ups:
Sorry, analog system noise levels are far, far above the ultimate imposed by molecular dimensions of vinyl or lattice dimensions of diamond, and even far above the thermal noise limit of the pickup.If you don't like the sound of your CD player, then get a new CD player and enjoy all the music encoded on your discs as well as the treasures in your vinyl library.
I realise noise is always a big issue in any of this stuff, and yes analog systems do suffer from a lot of it. I was just trying to draw the analogy of analog to digital without considering such things. Any good digital system will also have a lot of noise.One of the major differences though is that digital systems introduce noise that is correlated to the actual signal (due to quantization of the sample amplitudes) and correlated noise in the clocking also creates a non-random type noise. This may explain the qualitative differences people hear bewteen analog and digital. Granted most turntable produce an inner groove distortion which can be quite annoying as well. And wow/flutter of the platter can also contribute to correlated noise, especially with servo controlled motors.
I am not giving up on CDs... I have too much invested in them. I find that even big clicks or pops in vinyl don't ruin the illusion of the music - I assume because they are completely uncorrlated to the music your brain treats them as separate sounds. "Hey, someone is popping popcorn on my speakers" but it doesn't ruin the illusion of an orchestra playing in my room. Crappy CD players do ruin the illulsion of the orchestra playing in my room - even with 110dB S/N ratio. Why is that?
I'm not qualified to evaluate your statements about correlated noise, but you may be right about the reason some people do not like digital sound.In my experience, those who claim to hate all digital simply do not like the sound of the particular CD playback equipment they own. Even if it is very expensive, based on what I've heard when visiting them, I have to agree with them. There are better and worse CD players just like in everything else. I have and enjoy the Wadia 861. It has a very strong analog output stage, which IMHO contributes to its good performance. Crappy CD players have crappy output stages and power supplies contaminated with correlated and noncorrelated digital grunge. Did you ever experiment with the Radio Shack CD3400? That device demonstrated clearly how a well-regulated supply could clean up the sound.
The WOW distortion from playback of LPs with off-center holes makes it impossible for me to believe there is a real performance going on in the room, regardless of how well the pickup and phono stage reproduce the sound. This distortion is very annoying to me, and I hear it on most LPs. I'm sure I had been trained to ignore it back in the days before CDs, just as I'm sure I'm well trained now to ignore whatever correlated noise the Redbook CD playback method produces, even with good equipment.
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