What will you be buying this year? A new survey by the Institute of High Fidelity, official organization of the hi-fi components industry, attempts of focus on major buying trends for 1979. Here are some highlights:

While receivers in the over-100 watt class will sell no less than they did last year, a large increase in sales is expected for receivers in the under-100 watt class.

Speakers under $150 show a light sales increase over last year, but speakers over $150 are expected to sell very strongly.

Separate tuners, preamplifiers and power amplifiers will do as well as, or a little better than, last year. Sales of integrated amplifiers over $300 will increase; sales of integrated amplifiers under $300 will be slightly off.

Notable increases are seen ahead for sales of single-play turntables, with the lion's share going to the direct-drive models. No gains are seen for record-changers. Sales of phono cartridges will be up sharply.

Headphones are expected to do well.

A fairly big rise is seen in the sales of equalizers, and somewhat less of a rise for noise-reduction devices and expanders.

Some decline is seen in open-reel tape deck sales, but substantial gains are expected for cassette models, especially in the under $300 price class, although the costlier units are close behind. Blank tape is expected to become one of the year's best-sellers. And another major sales upswing is anticipated in accessories. Car stereos will continue to expand.

Bob Carver (Carver Corporation), who recently introduced his unprecendented M400 "magnetic field" amplifier (200 watts per channel from a really small, cool-running unit priced at about $300), also has something he calls a "sonic hologram." Comparing its role in sound to that of a visual hologram for pictures, Carver claims his device creates an image that appears to be located precisely where it is beamed. When the sonic hologram is switched on (it is built into a Carver preamp, model C-4000), the music is "freed" from the speakers and appears to be "in every nook and cranny of your living room."

The first "consumer model" of a digital audio processor seems more important for its implied tie-in with video cassette recorders than it does as a potential major-selling item for home music systems. Be that as it may, the unit is the Sony PCM-1 priced at $4,400.

This device encodes a live sound source, and converts it to pulses which in turn can be recorded on a video cassette recorder, such as Sony's Beta Max, U-Matic, or other NTSC-standard models. The PCM-1 weighs less than 16 pounds, and is 9 inches wide, 7 inches high, and 18 inches deep. Response is rated at 20 Hz to 20,000 Hz with a dynamic range of 85 dB. Such problems as wow and flutter, distortion, tape hiss and speed deviation are claimed to be "virtually eliminated" from the recording process.