Tape Guide (Q and A) (Apr. 1973)

Tape Length

Q. I am writing you in regard to the different lengths of cassette tape. I use a Sony TC-160 cassette deck to record music, and was wondering if using a C-120 or C-90 cassette is advisable. I have been told that when using these cassettes the tape speed will slow down and the speed will be irregular, causing excessive wow and flutter. Can you advise me as to the best tape length to use?

-Chuck Thurwachter, Lathrup Village, Michigan

A. Cassettes can hold more tape only by using thinner tape. With thinner tape come problems, such as squeal, print-through, and possibly increased wow and flutter (particularly flutter). For anything like good results, 1/2-mil tape is generally not recommended.

My suggestion is that you try each of the tape lengths (tape thicknesses) and listen for appreciable differences, if any.

Guitar Recording

Q. I would like to make some sound on sound guitar recordings. Since I don't want any side-noise, I connected my guitar directly to the tape recorder input. This works, except that I cannot change the tone of my guitar while recording; it always comes out with too much bass and too little treble. Is there any unit I can build or buy which I can insert between the guitar and tape recorder to permit me to change the tone of the guitar?

-Walter Weeler, Commack, N.Y.

A. In general, an audio preamp (without power amps) would meet your problem. Such preamps, with a good deal of bass and treble control, are still available. You can find a number of these described in the audio directories that periodically appear in Audio.

1 7/8 ips vs 3 3/4 ips

Q. In your opinion, does the Tandberg at 1 7/8 ips provide as good performance as other moderate quality tape decks do at 3 3/4 ips?

-K. L. Ecton, APO San Francisco

A. So far I have seen no open-reel home machine which performs as well at 1 7/8 ips as do "moderate quality tape decks" at 3 3/4 ips. On the other hand, some machines (such as the Tandberg)

do remarkably well at 1 7/8 ips.

Matching Outputs

Q. I want to use two tape recorders with a Dolby unit and need to match their outputs. Unfortunately, neither one of these recorders has an output control. Can you suggest a simple attenuator network that will not cause impedance matching problems?

-Mac Fitzsimmons, Shreveport, Louisiana

A. To reduce output of a machine without an output gain control, you could install such a control. Connect a pot across the output, and take the signal off the arm of the pot. The value of the pot should correspond to the load impedance recommended by the machine's manufacturer. If he does not supply a recommended load impedance, you might try a value that is about 10 times the rated output impedance of the machine. For example, if the rate output impedance is 2,000 ohms, use a pot of about 25,000 ohms.

Magnetized Head

Q. Recently I wanted to see what the signal coming right off the playback head of my deck is like so I could have something to compare against should I at some future date suspect the head of having gone bad I connected the leads of my a.c. VTVM right across the head output without disconnecting the head from the machine's electronics. I then ran an Ampex alignment tape and I immediately noticed a very loud, gurgling hiss on the track that the meter was hooked to. By allowing the tape to run to the end, I managed to wipe out an entire (quarter) track of the tape. I ran a piece of scrap. tape and noticed the same noise, so I degaussed the heads, and this cured the problem. One thing I didn't mention is that while the tape was running, one of the clip-leads slipped and momentarily shorted one of the head leads to the shell of the head. It seems that I somehow caused the head to become magnetized, and I'm hoping you can tell me why.

-Harvey Geminder, West Orange, New Jersey

A. A sudden current change, particularly a strong one, can magnetize a head. My guess, and it is merely a guess, is that this happened when one of your clip-leads slipped and shorted one of the head leads.

(Audio magazine, Apr. 1973; Herman Burstein)

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