copp@petrus.UUCP (09/27/85)
It appears from the advertising (am I too gullible?) that the tape manufacturers are almost continuously improving their product, at least the high end response. On one hand this sounds great; on the other hand, would you applaud if speaker, cartridge, amp, etc., manufacturers kept boosting the highs by an additional db every six months? If nothing else, doesn't this ever-increasing high-end response play havoc with Dolby tracking?
rentsch@unc.UUCP (Tim Rentsch) (09/30/85)
In article <7000007@petrus.UUCP> copp@petrus.UUCP writes: >It appears from the advertising (am I too gullible?) that the >tape manufacturers are almost continuously improving their product, >at least the high end response. On one hand this sounds great; >on the other hand, would you applaud if speaker, cartridge, amp, >etc., manufacturers kept boosting the highs by an additional db >every six months? If nothing else, doesn't this ever-increasing >high-end response play havoc with Dolby tracking? The issue of being gullible arises not out of whether the claims of the manufacturers (with regard to frequency response etc.) are true, but out of accepting these consequent "improvement" at face value. (It should be said that most people are gullible in this respect.) Tapes certainly have gotten better in the sense that they have more dynamic range, wider frequency response, better signal to noise ratio, and so forth. The question is, does this "improvement" make the tapes sound better? Other things being equal, of course, the answer is yes. Equally of course, however, other things are *not* equal. (Which other things? I'm glad you asked....) For one thing, wider dynamic range means the tape is more sensitive to magnetic fields -- has to be, to record the weaker magnetic fields of the weaker signals. Unfortunately, this means more sensitive to stray magnetic fields as well, which may cause print-through or other problems. For another thing, the recording tape of today uses more tightly controlled particle size than, say, tape of twenty years ago. While the *average* signal-to-noise ratio is better, the more uniform particle size means the resultant hiss will tend to have a characteristic frequency, and so may actually be louder in the frequency range in question, even though the average s/n ratio is better. [Pesons who would argue that these are good reasons to do digital rather than analog recording are kindly invited to step into the next room and keep their comments to themselves. I also think that digital recording is the way to solve these problems, but not at 50kHz, thank you very much but no thanks all the same.] Notice that I have *not* said that this makes the tapes sound worse. This may be true, or it may not be, depending on the listener. Whether or not the sound is "worse" depends on how you weight the various influences. If your ears have a big dip at 14-16kHz, and this happens to coincide with the characteristic hiss frequency, then obviously this will be less important to you than to some other person whose ears have a rise in the same range. And so forth. Are tapes better? By some measurements, yes; by all measurements, no. Let your ears decide. And remember, contrary to manufacturing hype, 'progress' doesn't always result in 'improvement'.
rdp@teddy.UUCP (10/01/85)
In article <7000007@petrus.UUCP> copp@petrus.UUCP writes: >It appears from the advertising (am I too gullible?) that the >tape manufacturers are almost continuously improving their product, >at least the high end response. On one hand this sounds great; >on the other hand, would you applaud if speaker, cartridge, amp, >etc., manufacturers kept boosting the highs by an additional db >every six months? If nothing else, doesn't this ever-increasing >high-end response play havoc with Dolby tracking? Not so. What is normally being improved is the high frequency response at high recording levels. The low-level response (normally measured at something like -20 db re 200 nW/cm, which I believe use to be the Dolby 0 reference level) remains pretty much unchanged. If this changed, this would not only play havoc with noise reduction, but would then screw up general high frequency response. Normally, when a deck is set up, the playback amp frequency response is adjusted by playing back a reference tape. The adjustment is made in essentially a tape formulation independent manner (that is, the playback EQ is, for normal iron-based tapes, fixed, and only adjusted to meet an agreed upon standard. For reel-to-reel decks, there is the NAB and the IEC playback EQ standards). Now, inorder to ensure as linear an input to output transfer function as possible, it is the record EQ that is diddled with to ensure the signal that finds its way onto the tape matches this playback standard as closely as possible. This ensures that people can exchange tapes from one machine to another. Now, most of this adjustment is done at a fairly low record level (see above) at higher levels, two things come into play. First, the ability of the tape to linearly record signals at high frequencies and high levels is limited. The tape can only record so much signal, and trying to exceed that results in a "soft" clipping effect, and reduced high frequency information. Secondly, note that whatever signals are recorded at these levels, the noise reduction system (Dolby, DBX, ANRS) does not function at these levels because it does not need to. The signals are high enough to mask any noise present. The noise reduction effects are only present at lower levels. The above is, admittedly, a gross oversimplification, so I hope that the cognizetti out there don't start flaming accordingly. Dick Pierce t