rfg@hound.UUCP (R.GRANTGES) (03/19/85)
I would like to hear from some of the more Au-eared among us who have heard the alleged superiority of the oversampling systems (4x-14 bit) and vouch they are much better than brick wall 16 bit - who have also heard the recently introduced 2x oversampling, 16 bit system available on several units. the Sony CDP-102 is one such. They even specify the phase linearity to 20 khz. (+ or - 10 degrees, I seem to recall). Well, is it audibly superior or not? Have we approached Nirvana more closely or not. Careful! you may be toying wityh MY pocketbook if you are persuasive. There is a review in the current issue ofDigital Audio of theCDP-102, but its not by any Au-ear I recognize. Phil Rastocny, go out and hear this one and tell us about it, please. -- "It's the thought, if any, that counts!" Dick Grantges hound!rfg
bhs@siemens.UUCP (03/19/85)
Well, here we go again... Categorically, the oversampling technique is superior to brickwall, analog filters. However, the question of wether one can hear any difference is not answered as easily as that. One componenet frequently introduced by the analog filters is ringing, which is caused by the capacitors used. Another is the phase shift which you mentioned. The digital filtering used with quadruple oversampling does not introduce any frequency dependent phase shift. It also severely reduces ringing. It can not entirely eliminate it, as there is still an analog filter in the system, in order to filter out the high-frequency switching transients from the D-A converter. What is most critical in the analog filters is how meticulous the filters have been designed- leafing through a very technical report on various CD players available on the German market, it was quite revealing to see the differences in output code coming from the various analog filters used in the various players. Comparing even the best of the analog filters with an oversampling machine showed quite clearly the advantage of the digital filters. But, I notice that I have not yet answered your question. I believe that you can hear a difference between a player incorporating oversampling and one with analog filters. Analog filters tend to create a sound which is slightly crisper, sometimes harsher and colder, than that put out from digital filters. I atribute this to the relative lack of high-frequency ringing. This feeling is confirmed by my observations comparing my Magnavox 2020 with my brother's Technics SL-P8. Mine is more mellow, without sacrificing any of the clarity or high-end sound. Ah, well, this is of course a matter of taste. An additional caveat- I do not think that, after listening to several players, you would definitively be able to state which ones had analog filters and which ones had oversampling. You are not comparing Chevettes to Corvettes. However, you are comparing slightly better machines with slightly-less-better machines. Oh, and I do not see why going for oversampling will kill your budget. The people who built the first oversampling CD player also are quite inexpensive. Philips and Sony co-developed the standard. Sony concentrated on building a machine with fancy remote control and good programmability, while Philips sat down and designed the better signal processing- quadruple oversampling, digital filtering. Somehow, I bought my player for it's sound, not for it's programmability. I have a VAX at work for that. And- it cost me $299. The newer Magnavox players have remote control and improved programmabiltity, but I give mine the edge in styling. Oh, an added bonus- what is sold here as the Magnavox player is identical to the Philips players- they are all built in Belgium. Bernard H. Schwab Siemens RTL, Princeton NJ
greg@olivee.UUCP (Greg Paley) (03/21/85)
This isn't really an answer to Dick Grantges' article, but rather a commentary on some of the further complications involved in choosing between CD players and their diverse technologies. Of course, the sound quality is vitally important. "Digital Audio", while not convincing me 100% with some of their reviews, at least command my respect by being one of the few U.S. publications to acknowledge differences in the sound quality of CD players and provide some commentary on this in their reviews. This has forced me to try and obtain copies from friends travelling to Europe of German audio publications, since German "Audio", "Stereoplay" and, to a lesser degree, "Fono Forum" comment extensively not only on the sound, but always end their reviews with a judgement as to the unit's performance relative to its price. So far, test reports in both their "Audio" and "Stereoplay" magazines have consistently ranked the sound quality of the various 14-bit/4x-Oversampling machines (including all of the Philips units) as "ausgezeichnet" (outstanding) in both sound and value. I have not seen their tests of the Sony 102 or 302 (same sound, more features), but their previous tests of Sony units have ranked the sound as "durchschnittlich" (average) and have ranked other 16-bit, single-DAC, 1x sampling units as, at best, "ueber durchschnittlich" (above average). Their articles have, however, hastened to point out that even gross differences in ranking translate into relatively subtle audible differences when compared to most other equipment. Another area where the 14-bit/4x-Oversampling machines score significantly higher and consistently so is in error correction. Is it a coincidence that most of these machines are European made and that European manufactured CD's have a significantly higher defect rate? It seems as if the Japanese machines are designed with the expectation that the disks themselves will be near-perfect, as most of the Japanese-manufactured CD's themselves seem to be. The problem comes with the greater frequency of European CD's and, now, American CD's coming onto the market. Unfortunately, I found no mention in the "Digital Audio" review of the Sony 102 of its error-correction performance. I have heard quotes on the Sony for as low as $329. The bottom- of-the-line Magnavox can be purchased locally for - you guessed it - $329! The actual frequency response curves given for the Sony are flatter at the top than those of the Magnavox, but the reduced phase shift caused by the use of the single DAC in the newer Sony is still greater than that produced by the dual DAC's in the Magnavox. The answer should, I guess, be "listen for yourself". The difficulty in this is finding a dealer who has both of the units you're interested in and who also has the capacity to demonstrate them through associated equipment that you know and trust. I've been fortunate in having friends who've let me do extensive listening on their equipment and who've let me take their units home (my home system includes Hafler 110/220 and Vandersteen 2C's), but those units are the Revox, NEC and NAD - all of which now seem more expensive than I feel is now necessary to pay for a good unit. The further problem is predicting how the better sounding unit will do in handling less than perfect disks. As I said, no answers but just more questions. - Greg Paley