Tape Guide (Aug. 1980)

Unequal Gain

Q. The left channel of my cassette deck records louder than the right channel, both on phono and FM. I would appreciate your help.

-Dale Holiday, Willard, Ohio.

A. It appears that either (1) recording gain is higher in the left channel, or (2) playback gain is higher in this channel. You can tell which is the case by playing a tape that has been re corded on another deck (such as a prerecorded tape or one made on a friend's deck). If the problem remains, it is playback gain which is at fault.

Some decks have internal controls for adjusting record gain and playback gain so as to balance the channels. If your deck does have these controls, it is a simple matter for a technician to make the necessary adjustment. If there are no such internal controls, it is still relatively easy for a competent technician to replace an appropriate resistor in order to balance the gain.

If the adjustment has to be made in the record amplifier, one must be careful that record gain is adjusted so as to result in an appropriate indication by the record level indicator. For example, if the deck has a true VU meter, record gain is adjusted so that the meter reads about 0 VU at a recording level that results in about one-percent harmonic distortion for a signal in the range of 333 to 1,000 Hz.

EQ and Bias Settings

Q. I own a large number of re-recorded reel tapes, many from the '60s. They still sound excellent, and most are in good physical shape. I would like to use some of them for recording but am at a loss as to what recording bias and recording equalization to use. Can you come up with a rule of thumb as to what is best to use?

-Helmut Kranz, Philadelphia, Pa.

A. Probably the lowest bias setting and the highest record equalization setting of your deck will give best results in recording these old tapes. However, the best test is by ear: Record a tape of a phono disc, play the tape and disc in synchronization, and compare the two. The best settings of bias and equalization are those which, to the ear, give flattest response. If you find that more than one bias setting gives satisfactorily flat response to your ear, use the highest of these bias settings, thus assuring lowest distortion. Similarly, if more than one record equalization setting gives satisfactory results, use the setting which produces least treble boost.

Excessive Bias Current

Q. I have a nagging problem with my cassette deck: Ferric oxide tape sounds brighter than chrome tape does! My audio dealer said chrome tape should sound brighter and told me to bring in my deck. The bias was slightly adjusted and I was told my heads were almost ready for replacement, but there was no improvement.

I brought my deck in again. The bias was adjusted once more, and the dealer said it sounded fine. He also suggested that I try recording at a higher level. The higher recording level did not help, and the second bias adjustment not only failed to improve chrome performance but made ferric oxide performance worse. Is it normal to have to use treble boost with chrome tape, but not with ferric oxide tape?

-Dennis Galletta, Erie, Pa.

A. No, it isn't normal to have to increase treble when using chrome tape. It appears that your tape deck is sup plying excessive bias when the bias switch is in the chrome position. Apparently, since the dealer's second bias adjustment, your deck is also supplying excessive bias in the ferric oxide position. Too much bias current causes treble loss. I suggest that you look around for another place to have your deck serviced--one with a good reputation. Before taking your deck home again, ask for a bench check; that is, have the shop demonstrate how well your deck is working with both kinds of tape.

Cassette Alignment

Q. I notice that when inserted into my deck, the cassette sits at an angle of about three degrees rather than parallel with the face of the deck. Does this affect the pinch roller and tape heads in any way, or the sound for that matter?

-Tracy Ching, Sacramento, Calif.

A. Even though the cassette is not parallel with the face of the deck, what counts is whether it is in proper position with respect to the transport mechanism. Usually these mechanisms are engineered so that they will not operate unless the cassette is in correct alignment. Therefore, it is likely that matters are all right.

However, you should visit your local audio dealer to see whether other units of the same model have a similar offset. If they don't, then it might be a good idea to have your deck checked out by an authorized service representative. Incorrect alignment will affect high-frequency output, and even the way the tape pack sits in the cassette shell has an effect here.

CrO2 Abrasivity

Q. Will I damage the heads in a tape machine if I use chromium-dioxide tape?

-Richard Bailey, Lynchburg, Va.

A. It is not nigh-universally accepted in the audio industry that chrome tape is no more abrasive than other tapes. Some, in fact, claim that chrome tape is less abrasive.

Recording With Dolby Circuits

Q. When taping from one Dolby deck to another, is it better to record with both Dolby circuits on or to leave both off? Leaving both off means one would use the Dolby circuit on the second deck to process the Dolby signal produced by the first deck

- John Clelen, Portland, Ore.

A. In theory it is best to "record with both Dolby circuits on," as you put it. This tends to insure flattest frequency response. In practice, however, good results--at least acceptable to the ear--are sometimes obtained by leaving both Dolby circuits off; that is, by playing the original tape with Dolby off and recording the copy tape with Dolby off. You might try it both ways and let your ears decide which is bet ter. While theory provides a general rule (keep both Dolby circuits on), practice occasionally provides a useful exception.

(Audio magazine, Aug. 1980; Herman Burstein )

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