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On Tue, 10 Aug 2010 18:01:57 -0700, Arny Krueger wrote
(in article ): "Audio Empire" wrote in message On Mon, 9 Aug 2010 17:05:12 -0700, Arny Krueger wrote (in article ): "Audio Empire" wrote in message On the playback end, it was D/A converters that were not able to do a full 16-bits linearly (early Philips players (Magnavox) didn't even try. They used 14-bit D/A converters and the little Magnavox FD-1000 sounded MUCH better than the Japanese 16-bit units of the day). The above account ignores the fact that oversampling was used to obtain 16 bit performance from 14 bit parts. For all practical purposes, the converters were 16 bit. No, the D/A converters were 14-bit. They were in an oversapling configuration. This is well known. The objective of the oversampling was a trade off of speed which was in abundance, for linearity which was costly. They used 14-bit converters because Philips believed (and rightly so) that the then current 16-bit DACs weren't very linear. In 1972 (ten years earlier) I worked with 16 bit, 200 KHz DACs that had 1/2 bit linearity and monotonicity. The only problem with 16 bit DACs was their price before the CD player market ramped up production. Yes, so the ones used by many CD manufacturers weren't very linear, and those which were were more expensive than mass-market manufacturers wanted to spend. In the early days, numerous things were tried to get around this problem, lower bit D/As, over sampling, single bit D/As that used the same bit for everything (insuring the steps were absolutely the same, and therefore linear) etc. Eventually, the D/As got better (laser trimming, etc.) and the sound of CD players improved. Today, they're pretty close to "perfect". The fact that they used 4X oversampling to achieve 16-bit resolution is irrelevant to my statement. Your statement was false because of the false claims that it included including "..the little Magnavox FD-1000 sounded MUCH better than the Japanese 16-bit units of the day). In fact they both were sonically transparent or very nearly so to the extent that they absolutely blew away the analog equipment of the day, given proper source material to play which was readily available from the onset. My experience tells me otherwise. Sorry about that. The claim that there was a signficant and large audible difference has been investigated with DBTs and found to be yet another audiophile myth. Sorry. I had both the Sony CDP-101 and The Philips-Maganvox FD-1000, and I beg to differ. The Sony sounded awful (still does) and the little Maggie was much more listenable (and still is). I ended-up giving the Sony to a friend - he didn't like it either. I don't believe that we have ever been treated to your technical measurements or the results of proper statistically-analyzed, time-synched level, matched comparisons of them. The extant well-controlled listennig tests involving them tell a different story - both units were eminantely listenable given that they were in good working order. Nor have we been treated to your test results and technical measurements or the results of proper statistically-analyzed, time-synched level, matched comparisons of them, either. They also had really crude multi-pole anti-alaising filters and produced, what would be considered today, unacceptable levels of quantization error. As a rule there are no anti-aliasing filters in playback devices. Aliasing is only possible in ADCs and resamplers. Nyquist requires that the upper frequency response limit of the reconstructed waveform (the Nyquist frequency) be half of the sampling rate and the signal at the sampling rate must not have sufficient amplitude to be quantifiable. This means that the reconstruction filter must be very steep to avoid there being significant signal at 44.1 Khz. Now you've had a chance to review the relevant technical material and change your story. The filters are now properly identified as "reconstruction filters". Yet you present this all like its a correction to my statement which was correct all along. I was just using the standard parlance as I explained above (and you "conveniently" snipped the part where I SAID THAT YOU WERE RIGHT, but that these reconstruction filters are commonly called anti-alaising filters, even though that term is not strictly correct. I'm not just addressing you in this thread, you know? And if you're going to debate with me, I'd appreciate it if you would try to be a little more honest in your snippage, OK?). Meaning that above the Nyquist frequency (in this case 22.05KHz) cutoff needs to be as absolute as possible leading to designs of filters with as many as six poles (before the advent of cheap digital filtering, that is). If you think that the origional CD players had 6 pole filters, then you are again not telling it like it was. If memory serves there were about 15 inductors and 15 capacitors per channel in the reconstruction filters of the CDP 101. This was pretty typical. Any second year engineering student knows that filters like these have about 30 poles (in pairs). Even worse. I had forgotten and memory "didn't serve". It's been a long time, so what? |