Three similar products from different manufacturers may not add up to an industry trend. But they do suggest the rebirth of the compact open-reel tape deck at a price competitive with the best cassette decks -- and with features and options beyond what the cassette format can offer.

The three are the Pioneer RT-707, which has been available for about two years now, and two recent entries: the Teac X-3 and the Akai GX-625D.

It was only about five years ago that this type of open-reel deck was just about counted out as a viable product for the home market, since many believed that the cassette made the most sense for the average consumer. Cassettes did provide fine audio response for the kind of taping the average home system owner might indulge in; they were compact and fairly easy to master, even by persons who had hitherto avoided tape as too complicated; and they were small, light, portable and easy to store.

As the open-reel deck lost most of its appeal as a "mass consumer" product, it evolved to the status of an advanced, sophisticated type of equipment catering to the new "semi-pro" or "audio activist" market. It became bigger, even more complex than before -- and costlier.

But performance has always been the essential consideration. And there is a growing realization now that the best any cassette deck can do -- in terms strictly of audio performance -- is come close to what a good open-reel deck can do. And when the latter start coming along at prices lower than some cassette decks, a significant shake-up of the home tape market may be imminent.

The first of this new breed of compact open-reelers was the Pioneer RT-707 which we tested some time ago. It has two speeds (7 1/2 and 3 1/4 ips) with response to beyond 20 kHz and 17 kHz for the two speeds respectively. S/N ratio is better than 60 dB. Wow and flutter are well down at 0.045 and 0.06 percent respectively for the two speeds. Distortion at the 7 1/2 ips speed is a mere 0.6 percent. This deck now costs $965 and offers automatic reverse. A non-reversing model, the RT-701, costs $100 less.

The Teac X-3 also runs at either 7 1/2 or 3 3/4 ips. Response at the faster speed goes well beyond 20 kHz; what is surprising here is that it also goes beyond 20 kHz at the slower speed. Wow-and-flutter are 0.06 percent at either speed. Distortion is less than 0.2 percent at 7 1/2 ips; less than 0.3 percent at 3 3/4 ips. S/N at either speed is a little better than 60 dB. This deck costs $550.