Tape Guide (Q and A) (Mar. 1975)

Tape Deck Options

Q. I have a KLH Model 41 tape deck which has been modified to use the Scotch Dynarange series of tapes.

This was done according to factory specifications by a qualified technician. The deck works perfectly with Dynarange tape. My question is: What other tapes will it work equally well with, if any? I am particularly interested in your opinion about how it would perform with the new BASF low-noise, high-output tape, TKD-SD tape, and Sony SLH-180. Do all of these tapes require approximately the same bias setting? Is it the same setting I now have after the Modification for DynarangeP. I realize the real test is to try them, but that can get expensive.

-E. W. Hodges; Newark, Del.

A. Conventional tapes of various brands require very nearly the same bias for optimum performance.

Similarly, low-noise tapes require nearly the same bias as each other, although somewhat different bias than conventional tapes (low-noise tapes require somewhat more bias). In order for one manufacturer to compete with others making the same general kind of tape, he cannot afford to require substantially different bias. On the other hand, for fine adjustment of a tape machine in order to extract the most out of it in terms of good performance (flat frequency response, high signal-to-noise ratio, and low distortion), bias may have to be adjusted slightly from one brand of tape to another. In other words, for a given kind of tape, one setting should do pretty well for most brands of tape.

High Frequency Loss

Q. I have a Uher 24 Special (Model 9000 in America, I believe). I have played it an average of 5 to 10 hours per month over a four-year period, and have cleaned the heads about every two months with isopropyl alcohol. However, I never demagnetized the heads until very recently.

During the past year I have noticed a loss volume and a loss of high frequencies, usually in one channel, but sometimes in both. I again cleaned the unit, which didn't help; then I checked the circuitry and the alignment instructions accompanying the recorder, which didn't help either. Finally I decided that demagnetizing was the factor that I had overlooked. Furthermore, l read about "wet demagnetizing" with tape head cleaner and decided to try that.

The results were marvelous. But, alas, these good results were very short lived. On repetition of cleaning and demagnetization, I found that the improved sound quality would last only about 10 to 30 seconds before deterioration again set in.

-Stephen R. Snow; Eugene, Or.

A. It may be that you are operating your machine too soon after cleaning your heads, so that the still-wet heads are picking up tape oxide. The resultant slight spacing between the tape and the heads (specifically the playback head) causes high frequency loss. More likely, the problem lies in a worn head, with too wide a gap.

Therefore head replacement is indicated. You should take your machine to an authorized service, agency, unless you have the technical competency and necessary test instruments yourself.

(Source: Audio magazine, Mar. 1975; Herman Burstein)

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