Tape Guide (Q and A) (Feb. 1970)

by HERMAN BURSTEIN

Q. I am striving for a high-quality system of music reproduction via phono records. I have been told that the thing to do is record the first play of a high-quality disc with a professional-type tape recorder and with the finest disc playback equipment. In doing this I will have the same fine sound as the record and will not have the loud tape hiss characteristic of many prerecorded tapes. Is this information correct? If so, must I stick to 1 ½ mil tape to minimize print through? Or would I have better sound if I just spent the money for a good turntable, arm, and cartridge, and replaced the disc every 25 plays or so?

-David E. Sosin, New Haven, Conn.

A. The information given you how to get a hiss-free recording is correct.

I think that if you went to 1mil tape you would be unlikely to find print through a significant problem unless you employed excessive recording levels. If your purpose in acquiring a tape machine is only to copy phono discs, you might be better off by not buying the tape machine and instead putting your money-probably a lesser sum-into a first-rate record player, arm, and cartridge. Using a top-flight cartridge that permits tracking at 1 1/2 grams or less, you are unlikely to scratch the record, especially if you use a cueing device.

Reports have it that when a disc is played with good equipment, it can last with little loss of quality for 100 plays, 200 plays, and perhaps more.

If you have anything of a record collection, the chances of playing the same record more than 200 times or so seem small.

It is only fair to add that owing to technological improvements, pre-recorded tapes are getting better in various respects, including hiss. Hence you may want to review the entire situation in terms of the pre-recorded tapes now available.

Q. I have developed the following problem with my tape recorder. During a stereo recording my machine will record properly on the right channel, but only very slightly on the left. So when I play back the tape it will only play the right channel. But if I play a pre-recorded tape, both channels reproduce 100%. I have tried adjusting the bias control to supply more bias to the tape head, but this does not help. I have also tried trouble shooting with a VTVM and comparing the voltages for the right channel (good) and the left channel (poor), but I am still unable to solve the problem. The tape head is a combination one, having all three functions (erase, record, and playback) in one head. I am wondering if this might be the problem.

-James David Gorr, Philadelphia, Pa.

A. Your tape machine combines a record-playback head and an erase head in one casing. Inasmuch as your machine functions correctly in playback, this appears to eliminate the head as the source of trouble. The difficulty, then, seems to lie in the electronics. Apparently the bias oscillator circuit is o.k. inasmuch as you are recording satisfactorily on the right channel. Perhaps not enough bias current is reaching the left channel. Your machine has separate bias-adjust controls for the left and right channels.

Did you adjust the correct one? If insufficient bias is not the trouble, then some electronic fault in the left channel, involving such elements as resistors and capacitors, would be responsible.

Expert troubleshooting should reveal the culprit.

Q. For the past year and a half it has been necessary for me to store all my pre-recorded tapes while I was away. Before I left, I packed them on edge in their boxes, firmly but not tightly in corrugated cartons, and placed the cartons in a closet where the temperature and humidity would not be expected to vary a great deal.

Last month I returned, only to find that a number of my tapes now suffer from rather pronounced edge warp or fluting at regular intervals during the first couple of hundred feet. Although this physical distortion does not appreciably affect the music quality, it is disturbing to me, and I am anxious to correct the condition if possible and to avoid similar problems in the future.

Almost all of the damaged tapes are reel tapes, most of them full-reel twin packs. The culprit therefore seems to be either the brand's tape or reels. I suspect the reels, since they are solid plastic except for one long notch, and the tape nearest the notch seems to be the most badly fluted. I hesitate to blame my tape machine for faults in winding tension, etc., since I have a very good unit which I have serviced and adjusted regularly. Is there anything I can do to correct the tapes already damaged and to prevent similar damage in the future?

-Roger C. Anderman, Dayton, Ohio

A. One step is to avoid in the future your mistakes of the past. This means using those brands of tapes and those types of reels which have given you least trouble, and making sure to rewind or replay your tapes every few months. I have never been able to get a misshapen tape back into condition.

Some claim to have obtained an improvement by winding and rewinding the tape several times. I guess their degree of success depended on how badly warped or fluted the tape was.

Are you perhaps storing your tapes after rewinding them at high speed? Tapes are best stored after having been wound at normal operating speed (such as 7.5 ips) rather than after high speed winding. Also (including from the point of view of minimizing print through) it is desirable to store tapes tail-out, namely with the last part of the recording at the outside of the reel; and then rewind the tape just before playing it.

It may be of some point to mention that using good tape and good reels, I have stored some recorded tapes flat rather than on edge, in extremes of temperature (well over 100° and below freezing) and humidity (close to 100); and that they have shown little if any signs of physical deterioration after several years under such conditions.

Too Much Bass

Q. Not long ago I bought a ---- tape recorder and noted a short time afterward that recordings on it are extremely bossy, especially when played hack on other recorders. The sound is otherwise excellent. I found out later that this is true of all ---- recorders of the same model. Unfortunately I have been unable to find another recorder to suit my purpose, even in higher price brackets. The man at the repair shop said he could make a bass cut if he had a wiring diagram. 1 wrote the company for one and for instructions for making the correction. Instead of sending what 1 asked for, they sent me literature on various products I have no use for; no wiring diagram was included. My tape recorder has no tone control, but according to several books a bass cut can be introduced into the microphone circuit. However, they don't mention how it is done. How is such a bass cut made?

-John F. Martin, APO San Francisco, Calif.

A. It may be that the bassy characteristic of you tape recorder was deliberately introduced to cover up its otherwise hissy characteristic.

Apparently you wish to introduce bass cut in recording, and in the microphone circuit. If yours is a piezoelectric microphone (crystal or ceramic), this can be done very simply by reducing the load resistance into which the microphone feeds. This is equivalent to placing a resistance across the microphone leads. I cannot tell you exactly what resistance to use. You will have to find this out experimentally. Try something like a 500,000 ohm resistor to start. If bass is still excessive, successively try values such as 250,000 ohms, 120,000 ohms, etc. If yours is not a piezoelectric microphone, you can achieve bass cut by feeding the hot lead of your microphone through a small capacitor. Again the value must be determined experimentally.

You might start with a value of about 2,000 or 3,000 pf. If bass is still excessive, use smaller values of capacitance.

That Rattle!

Q. I own a ---- tape recorder.

In all modes of operation and even when free-spinning, the right reel spindle makes a continuous rattling or crunching noise. The recorder has been to an authorized service station twice, but the noise is still present.

Please, if you can, tell me what my problem is.

-Ernie J. Caine, Lee's Summit, Mo.

A. The drive mechanisms of tape machines differ appreciably from one to another, and it is therefore difficult to supply a general answer likely to fit your problem. Is it possible that it is not the reel spindle that is rattling, but the reel itself? These do rattle sometimes. Another possibility is that what you think is the spindle rattling is actually noise produced by a drive belt. In this case, belt replacement is of course in order. The only other suggestion I can make is that you locate another authorized service agency and have better luck than with the first one.

Surface Noise

Q. I have become quite interested in dubbing some of my disc recordings onto tape. My problem is essentially this: Although my discs are as clean as I can get them using the best of commercial dust and static removers, I still get some surface noise. Of course my tape recorder picks these noises up faithfully, along with the music. Perhaps I am a hit too much of a perfectionist, but I would like to eliminate the surface noise from the disc when dubbing it onto tape, without having to edit each pop or click.

How can this be done with my existing equipment? The "high filter" on my amplifier only operates on playback and has no effect on recordings made through the "recorder out" outputs. Does any company that you know of make a relatively simple, switchable filter that can be connected between the outputs of my amplifier and the inputs of my tape recorder?

-David C. Cumming, Blythe, Georgia.

A. I know of no such filter commercially available that I can suggest to you, although quite some years ago, when 78 rpm records were still with us, some companies did make "dynamic noise suppressors." If you wish, you could consult the early Audio Anthologies for articles on such circuits. However, I must warn you that these are quite complex. I doubt that you will find a circuit that is truly effective for the occasional pop or tick you get on today's quality phono discs.

Tape Editing

Q. I have a ---- tape recorder hooked up to my receiver for recording and playback. I want to hook up a second tape machine to my system for playback only, to be used for editing. This arrangement works fine if I use the auxiliary outputs for the second machine. However, I want to use the auxiliary outputs for TV sound. There are outputs for a tape aleck which I would like to use, but neither tape machine will work in these outputs, nor will the TV sound.

Is there any way to utilize the tape head outputs by modifying the tape machine or the TV set? If there is no way to do this, what type or make of tape mechanism could be used in the outputs?

-William J. Zinn, Hanover, Ontario, Canada.

A. In referring to `outputs," such as the "auxiliary output," I take it that you really mean the inputs of your receiver. One way of handling your problem is to connect the signal directly from the playback heads of your second machine to the tape head inputs of your receiver. Alternatively, you could modify the tape head input so that it will accept a high-level signal, such as that from the playback electronics of your second machine.

This involves decreasing the gain of this input and removing tape playback equalization; this can perhaps be most easily done by bypassing the first playback stage. Another possibility is to connect both your tape machines' output cables to the same input of the receiver, using a Y-connector. There is some chance, but less than 100%, that this will work satisfactorily; it depends on how the two machines interact with each other. Still another possibility is to purchase an audio mixer, with the outputs of the second tape machine and the TV set going into the mixer, and with the output of the mixer going into the auxiliary input of the receiver.

(Audio magazine, Feb. 1970; Herman Burstein)

= = = =