Disc recordings far outsell tape recordings ("prerecorded tapes") but the latter are still regarded by aficionados as the best available program material to enjoy over a high-quality playback system. Tapes have better channel integrity for stereo, and there are no engraved grooves to become worn out or dirty. Assuming the tape machine is kept in good condition, a tape recording will retain its high-frequency sparkle and lifelike tonality longer than a disc recording.

Tape is not without its problems, of course. One is the difficulty of cueing up to a given spot on a tape as readily as you can with a disc. And, in addition to periodic cleaning of tape heads, the owner also must guard against "print-through" (whereby the signal from one wrapped layer of a tape reel is transferred to an adjacent layer). This is mostly a matter of remembering not to store a tape in fast-wind mode.

Tapes also cost more than equivalent discs, largely because they are made in less quantity and by a more tedious process. That is, discs are turned out in large numbers by stampers, whereas prerecorded tapes must be duplicated on "slave" recorders. Even though the copying is done at high speed, the entire program must be played through, which takes time.

For all this, prerecorded tape-and especially open-reel, which is still the best sounding-has become something of a connoisseur's item with a loyal but limited following. Even so, it appears to be growing. According to industry sources, sales of tapes last year incresed by about 70 percent, while disc sales rose only by 20 percent for the same period.

In addition to catering to "selective tastes," tape producers point with pride to their unusually high quality control. As compared to discs, there are very few customer complaints against tapes.

It must be emphasized that this applies to open-reel and to the better cassettes. It does not apply to 8-track cartridges, which for one reason or another have rolled up a discouraging track record for sound track record for sound quality and for durability.

Among cassettes, the highest regarded for some four years now have been the releases in Advenths CR-70 series. The catalog now numbers 65 titles; it started with 28. Advent's tapes are chromium dioxide and use Dolby-B noise reduction. A full list is available on request to Advent Corp., 195 Albany Ave., Cambridge, Mass. 02139.

One of the recording labels in Advent's repertoire-Connoisseur Society-recently licensed a new tape company to issue cassettes of music not included in the Advent series. The new label is called In-Sync. These cassettes also use chrome tape and Dolby-B. Their catalog also is free on request to In-Sync Laboratories, 2211 Broadway, New York, N.Y. 10024.

The mecca for open-reel tape has become Barclay-Crocker, 11 Broadway, New York, N.Y. 10004, which produces stereo and some four-channel tapes using masters from many well-known recording labels. With only a handful of retail dealers, Barclay-Crocker is mostly a mail-order operation. Its catalog-which is regarded as the "Schwann" of open-reel tapes-costs $1. For best results, these tapes should be played through a Dolby-B system, either incorporated in the deck or in the form of an outboard accessory.

Q: The other night I recorded my wife singing while a friend accompanied on the piano. I used cardiod microphons placed about two feet in front of the piano. The tapes sounded good except for an echo-like quality over the music that we were not aware of during the performance. Any ideas on this?

A: Microphones will often pick up sonic effects (for better or worse) that you may not have been aware of during the live rendition. For one thing, there is the normal "ambience" of the room, its natural reverberation. For another, there are the sounds that are reflected from walls and objects in the room, which tend to become "magnified" when recorded. This problem has concerned all recordists, including professionals. One answer is to experiment with placement of the microphones prior to making the final recording. What seems to be the right spot or irientation for a microphone may turn out to be wrong. Another is to use highly directional microphones that reject sounds other than those in a direct line from them. Yet another is to use an octave equalizer that can "tune out" certain room resonances. Even more elaborate would be to record the room resonances on a seperate track and then mix, very carefully, with the basic performance itself for the final tape. Have fun.

Q: I hooked up the Pioneer TV tuner to listen to improved sound from TV shows and to record some. On most channels I hear a definite imporvement, but on one channel I hear a loud-pitched hum through the Pioneer that I do not hear from the TV set. Why?

A: Don't blame the Pioneer device. It is pulling in everything that the TV station is sending out, including some obviously unfiltered low-frequency noise. You don't hear this on your TV set probably because that set's own low-frequency response just does not extend as far down as that of the wide-range Pioneer device, especially if the Pioneer is playing through a hi-fi amplifier and speakers. You might write to that TV station and ask them about their hum.