TAPE GUIDE (Jan. 1994)

Head Life

From time to time, a number of readers have asked about the life expectancy of cassette deck heads. The question is not easy to answer in precise terms; information on the subject is difficult to obtain. I have heard that cassette deck heads may have a life as short as 1,000 operating hours and as long as 10,000 or even 20,000 hours. Heads for which manufacturers claim very long life may be inferior with respect to saturation and to preservation of a very narrow and very straight gap.

Head wear depends on at least three factors: Material of the head (such as perm alloy, Sendust, ferrite, etc.); quality of the tape, with respect to smoothness and lubrication of the magnetic coating, and pres sure of the tape against the head, which is determined not only by the pressure pad but also by the tension exerted by the take- up and supply reels. (At least one manufacturer, Nakamichi, moves the pressure pad out of the way and depends on tape tension for good tape-to-head contact.) Premium tapes from well-known manufacturers are apt to cause less head wear than other tapes, particularly tapes of unknown origin and quality.

Head wear is not as bad with cassette decks as it used to be with open-reel decks, because the much slower tape speed of cassette decks reduces wear per hour of use. Cassette decks normally operate at the standard speed of 1 ips, whereas open- reel decks have a standard speed four times as great, namely 7 1/2 ips. While open-reel decks often offer the 3 speed as an option, best performance from them usually requires the 7½-ips speed, or even 15 ips.

Azimuth By Ear

Q. Azimuth, that's my problem! I own a good dual-well deck, but have noticed a big difference in treble response with a prerecorded tape on each well I recorded from a CD onto a tape in well B and played this tape back in both wells A and B; treble suffered in well A. Therefore, I broke the head seals in an attempt to fix the azimuth myself I took a blank tape to an audio store and recorded it on their best cassette deck. The test tape sounded good on this and other decks. Next I used the tape to adjust azimuth of the heads in my deck, judging by ear as to when I achieved correct azimuth. Amazingly, both wells of my deck now sound equal when playing a tape. This attempt to make my own test tape and adjust azimuth by ear took hours and hours. Am I crazy?

A. Yes, you are crazy. Like a fox. Just as the proof of the pudding is in the eating, the test of audio is in the listening. Kudos to you. I recall a very respected audio engineer who designed a number of highly regarded audio components; he refused to adjust azimuth by instruments (test tape and meter or oscilloscope). Instead, he set azimuth by ear.

The audio dealer who let you spend considerable time in his shop making a test tape and trying it out deserves a vote of thanks.

What Price More Treble?

Q. I recently purchased my first cassette deck; its frequency response for Type II tape is rated 2 kHz higher than for Type I. But a test report in a leading consumer magazine indicated that Type I tapes are better than Type IL Is the extra 2 kHz in response worth the degradation in tape performance?

A. First, I question the general statement that Type I tapes are superior to Type II. At one time, Type II was generally considered better, but then some Type I tapes began to catch up and even surpass some Type us. Today, whether Type I or II is better depends on the specific brand and grade of tape you buy.

Now let's consider whether an "extra 2 kHz in response" is worthwhile. This depends on the reference frequency. If you are talking about 2 kHz above 10 kHz, yes, this is probably quite worthwhile. If it's 2 kHz above 12 kHz, it may be worthwhile. Above 14 kHz, the improvement is open to question. The answer depends on your hearing ability. Most adults hear little above approximately 13 kHz. The same may be true for many young people whose hearing is impaired by frequent exposure to the sound levels prevalent at rock concerts and in clubs.

Hi-Fi VCR Tape Speed and Audio Quality

Q. I have a Hi-Fi VCR. Someone told me there is little sound degradation between SP (fastest speed) and LP or EP (slower and slowest speeds). Is this true? If not, would reducing VCR speed by half (going from SP to LP) degrade the sound as much as cutting the speed of an open-reel tape deck in half (say, from 7½ to 3 3/4 ips)?

A. Very good audio recording can be achieved with a Hi-Fi VCR at the LP and EP speeds. Results at these slower speeds are often indistinguishable to the ear from those at SP. To verify this for yourself, tape the same material-for example, a good CD--with your VCR at each of its speeds. Let your own ears determine whether a significant sacrifice results from going to the slower speeds. Sound degradation from reduction in tape speed is probably greater with open-reel (or audio cassette) recording than with Hi-Fi VCR recording.

Data-Compressed Signals and Amps

Q. I am writing about the Digital Compact Cassette. From what I understand about data compression, the inaudible portions of an audio signal are removed, which permits a lower bit-per-second rate. Does this mean that an amplifier will have an easier job when a DCC is playing than when the same music is being played from a DAT? Will this affect the power produced by the amplifier?

A. The data-compression schemes of DCC and other digital media will not significantly affect the signal presented to an amplifier or the power presented by that amplifier to the speakers.

(adapted from Audio magazine, Jan. 1994, HERMAN BURSTEIN)

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