Tape Guide (Dec. 1979)

Tape Guide Policy

Q. I am considering the purchase of brand X, brand Y, or brand Z tape deck. Please help me decide which one is best for my needs.

-John Q. Public, Main St., U.S.A.

Q. I have about $600 to spend on a tape deck. Please advise me which one is the best for the money.

-Jane Q. Public, Elm St., U.S.A.

A. It is again necessary for me to issue my periodic reminder that the policy of Audio prohibits The Tape Guide column from recommending specific brands and models of audio equipment (except in unusual cases where there is only one of a kind on the market).

The first step in making a purchase decision is to make oneself knowledgeable about the subject mat ter. One way to do so is by reading the equipment reviews of tape decks that appear in Audio and other periodicals.

Consult the tape deck directory that appears annually in Audio's October issue to become familiar with the comparative features and specifications of the decks you are considering. Check with your audio store or library for a readable book on the subject of tape recording. LISTEN to the decks you are considering. Using a phono disc of good quality, notice how faithful a copy each of the tape decks can make and how faithfully they can reproduce inter-station FM noise. See what parts and service warrantees come with the decks; find out how far it is to the nearest authorized service agency. Try to find out which tape decks come in least frequently for service relative to the number sold.

Armed with all this information, determine your priorities regarding specifications and special features.

Consider the amount of money you can afford to spend and also where to spend it--i.e., look around for a store whose reputation you can trust and whose personnel seem both knowledgeable and helpful. Then decide which brand and model offers you the most value.

Taping Multiple Turntables

Q. I am looking for an uncomplicated method of connecting two turn tables so that both are "live" simultaneously. The purpose is to be able to cross-fade stereo albums and record them with a tape deck. My aim is to imitate actual broadcast techniques, especially those of the "top forty" AM radio stations, and record the result on stereo tape. If I wanted to add micro phones for the purpose of disc jockeying, to what component would they be properly connected?

-Steven Cohen, Philadelphia, Penna.

A. I think you are looking for a mixer that will, accept two turntables and several microphones. The output of the mixer would be fed to your tape deck. I suggest that you visit local audio dealers to find a mixer suitable for your needs.

Erase Fader

Q. Enclosed is a photocopy of the schematic for my tape deck. I want to install a potentiometer into the erase circuit to fade the erase head in or out.

As I am not able to determine the necessary circuit for this modification, I wonder if you might be able to suggest such a circuit. I suspect that some form of L-pad or T-pad might be the answer, but I just don't know what values to use.

- Ron Streicher, Elk Grove, Cal.

A. I am sorry, but I cannot give you a specific answer because this would involve more time--to design and check out the required circuitry--than the Tape Guide is able to devote to one question. You might try putting a variable resistor is the path between the bias oscillator and the erase head.

As a very rough guess, it should have a power rating of at least two watts, and its resistance should be in the area of 100 ohms. Keep in mind that as you diminish the amount of bias current taken by the erase head, you increase the bias current supplied to the record head, with a consequent decline in amount of treble signal recorded on the tape. Hence, as your letter recognizes, an L-pad arrangement would be better to present a constant load to the bias supply. Unless the pad presents a perfectly uniform impedance in con junction with the erase head, you may still be changing the amount of bias going to the record head, although less than before. I do not know what value of L-pad to use. Check your ser vice manual regarding the impedance of your erase head at the bias frequency, and try an L-pad (if available) with the corresponding ohmic value. If .the service manual does not give the impedance, consult the manufacturer.

All the above may be academic, however. For fade in and fade out the loss and/or gain in treble may be inconsequential, provided that bias to the record head is ultimately correct when erasing full strength. Hence, you might find a simple variable resistance quite satisfactory.

Buzzing Tape

Q. I have a problem with my tape deck. At 1 7/8 ips there is a sound resembling speaker buzzing on transients.

This appears on the tape itself, and I am sure it is not the fault of my speakers.

-Kenneth Karasek, Maple Heights, Ohio.

A. The buzzing may be due to over loading the tape, i.e., excessive signal applied to the tape. At 1 7/8 ips there is a good deal of treble boost in the record amplifier (in order to overcome the great magnetic losses of high frequencies on the tape); this increases the tendency toward overloading. Try re cording at a lower level.

Effects of Power Supply Fluctuations

Q. I am stationed at a remote Air Force radar installation. Our power supply fluctuates between 59 and 63 Hz. Does this have any adverse effects on a Dual 1219, ReVox A-77, or Heathkit AR1500?

-Anders Bastman, APO Seattle, Wash.

A. The ReVox A-77 maintains correct speed independently of changes in line frequency. I doubt that changes of the magnitude you describe would have any significant effect on the Heathkit's performance. If the turntable has a synchronous motor, its speed would change with variations in line frequency.

(Adapted from: Audio magazine, Dec. 1979; Herman Burstein)

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