gregr@tekig4.UUCP (Greg Rogers) (06/10/85)
I should know better by now but .... >> I have Telarc LPs and CD ...... In each case the LP came out on top. > This is an interesting comment, since all the Telarc recordings (at > least in the last several years) are digitally recorded. This implies > that somehow putting digital information onto an LP in the recording > studio and then playing the LP gives a more listenable result than > playing that SAME digital information directly. Well ..... This is not quite accurate. The Telarc recordings, both CD and LP's, are made on a Soundstream Digital Tape Recorder with a sample rate of around 48 Khz ( or 50 Khz, I can't remember the exact number someone else can supply it, but it definitely isn't the 44.1 Khz sample rate of CD's). For LP's the signal is reconverted to analog by D/A converters, etc and then undergoes the usual disk mastering processes with their inherent limitations and distortions to produce an LP. Clearly there is alot of degradation to the audio signal in this process, including uncorrectable nonlinearities (distortion of miscellaneous types and names) as well as correctable (or at least partially correctable) minimum phase frequency response (meaning phase and amplitude) distortions as well. So as implied in the response to the original article a truly accurate reproduction system will have to reproduce a poorer version of the original signal than the Soundstream's digital output converted directly to analog, i.e. a perfect turntable cartridge would reproduce all the errors of the LP mastering process. HOWEVER, the digital output of the Soundstream is not the SAME digital information as on the CD as stated in the last sentence of the reply above. The frequency must be converted to the CD standard by a sampling frequency converter the Studer SFC-16 which Telarc uses. This is entirely a digital process but nonetheless introduces an opportunity for some anomilies to be introduced. While I feel that any effects do to this frequency conversion are less problematic than the disk mastering process, I felt it was only fair to point out this additional digital processing step. For what its worth: My own experience is that higher end cartridges SOMETIMES do sound better than lower end cartridges but OFTEN are actually less accurate reproducing devices. That is they introduce frequency response errors that may partiallly offset the errors created in the mastering or analog recording process. This makes perfect sense if you followed my discussion above. Of course frequency response isn't the only parameter at work here. However one of the most accurate cartridges available, no matter what parameter you wish to use, still SUBJECTIVELY to my ears sounds worse than several "golden ear" audiophile cartridges that are in fact far less accurate absolutely. Hence if you want the final output of your system to sound its "best" with LP records you may choose a less accurate cartridge (some "audiophile cartridges" qualify). The catch is that different LP's may exhibit different errors, due to different analog recorders or different mastering setups, or different recording engineers trying to compensate for all this themselves (or not caring and trying to produce a record that will sound more "spectacular"). Hence you will need different cartridges for different records. Isn't it easy to see why this is referred to as an art rather than a science? With all these errors to try and compensate for, and the human judgements and tradeoffs balancing this entire system from microphone to speaker becomes one giant compromise. Digital tape recorders, producing CD disks offers a way of removing many of the worst of these problems and compromises. Its no secret that many CD disks sound poor that were made with analog recorders, analog equalization, and microphone setups that were used to help compensate for the problems in the LP process. It will take several years for recording engineers to break old habits, learn new techniques, and quit "fixing" the CD disks like they have LP's. Some of you must have some of the original stereo recordings. They were ghastly for reasons having nothing to do with the fidelity of the new stereo equipment. Anyway there are just enough great CD recordings around to convince me that any limitations in CD's are much more in the recording techniques than the playback equipment. Greg Rogers Tektronix