Three new twists in audio products have been announced that seem really innovative.

Analyzer-Equalizer: Graphic equalizers have been around for years; they permit specific frequency-segment adjustments to improve room acoustics and system response. Realtime analyzers are somewhat newer but have been priced for the most part well beyond consumer reach. Their operation too has been fairly complex.

What a real-time analyzer does, essentially, is the work of several meters all at once. Instead of a step-by-step measurement process, it shows total response as it happens, i.e., in "realtime." It is generally conceded to be the most accurate way of judging just how much equalization is needed for a given room or system.

The equalizer and the analyzer have been brought together in a new kind of combination component and at prices that are not out of reach for many enthusiasts. There's the model C-101, $549, from Audio Control. A model SEA-80, at about $600, will be released in August by JVC. From Soundcraftsmen, there is word of a forthcoming model that the feeds "pink noise" into a sound system, picks up the response on a microphone, and allows octaveband adjustments by matching LED indicators. Its price is not yet set, but it seems apparent that a new design trend may be under way.

Half-Speed Cassette Recorder: Nakamichi's model 680 cassette deck operates at half the standard cassette speed, or 15/16 inches-per-second. Its published specifications are almost as good as those of many top-quality models at the 1 7/8-ips speed. The trick here is the use of the new metal-particle tape, and the technology it involves (new head designs and modified electronics). Also usable at the regular 1 7/8-ips speed for even better performance, the model 680 has three separate heads, logic control, and random access capability.

Since the slower speed means double the program time (in recording or playback) for given length of tape, it obviously offsets the higher cost of metal tape, assuming tht the new recorder performs as claimed. Its price is $1,350 - high, but not higher than present top-ranking single-speed models.

Hybrid Headphones: The Austrian firm of AKG, represented in the United States by Philips, has just released the model K-340 HEADSET. IT USES BOTH DYNAMIC AND ELECTROSTATIC TRANSDUCERS TO REALIZE THE BEST PERFORMANCE ASPECTS OF EACH TYPE. THE LATTER ELEMENT, WHICH HANDLES TONES ABOVE 5,000 HZ, IS A SMALL ELECTRIC FOIL THAT NEEDS NO EXTERNAL VOLTAGE SUPPLY, AND THE HEADSET ITSEFL MAY BE PLUGGED INTO THE SAME HEADPHONE JACK AS CONVENTIONAL ALL-DYNAMIC MODELS. WEIGHT IS 1 POUND, AND WEARING COMFORT IS VERY GOOD.

PERFORMANCE IS SUPERB. THE CLEAN, FULL BASE OF AKG's former top model, the K-240, has been retained; the upper-mid range and extreme highs sound smoother an clearer. There is excellent definition, but none of the "over-etched" quality sometimes felt with electrostatic headphones. And this is apparent on music ranging from string quartets to loud, complex passages as in a Mahler symphony. Price is about $150.