Those of us rock'n'roll fans who grew up in the '60s, when there seemed to be a new superstar every week, tend to lament the '70s - especially the late '70s, when superstardom seems based on factors having nothing to do with talent, with much of the music sounding like mush.

So it's a bit startling when a respected concert promoter tells you to keep your ears peeled for The Knack. Or when your mailbox fills with flyers claiming that Gruppo Sportivo is the best thing to happen to Holland since Heineken's. Or - most startling of all - radio announcers tell you that the song you just heard was performed by Bram Tchaikovsky. Who are these bands, anyway?

They're new acts with debut albums that are making more headway than most new acts have been able to make in the past few years. Not that new acts aren't constantly being discovered. But, other than the disco field where a new No. 1 surfaces hourly, in the past few years rock'n'roll has not been easy on its newcomers.

Part of the reason is economic: It costs a record company a lot of inflated dollars to record and promote these acts, so lately the've been less inclined to take a gamble. For every Ricki Lee Jones and Van Halen, there are two dozen or more potential stars that go back to the salt mines of real life.

Another part of the problem for rock'n'roll rookies is the nationwide consolidation of radio playlists. Stations that once would give interesting unknowns a shot are now programmed by huge consulting firms or networks that believe that if you have the choice between a hit and an unknown, go with the hit. Fleetwood Mac, but no Knack. So the Established bands get more established and the unestablished ones get lucky, give up or go back to playing local bars.

All that may be changing, though, as the pop music audience cries out for new sounds. One new sound is The Knack, four guys from Hollywood who are veterans of Southern California's bar circuit. Unlike most bar bands, though, their sound is light and filled with singable choruses. The album "Get the Knack" sometimes sounds like Cheap Trick and has some of the innocence of the early Beatles. The Knack is not yet in either's league, But there is no question that they want to be.

Capitol Records, which marketed the Beatles here for nearly all of the Fab Four's career, has enclosed Knack fan club information on the record sleeve. This may seem a bit presumptuous as the jacket's rear photo. That shows The Knack in practically the same pose as the Beatles on their "Something New" album. At a fast glance, "Get the Knack" looks a lot like a Beatle album. It's not. But it doesn't sound bad for beginners, either.

Gruppo Sportivo's lyric sophistication is in sharp contrast to The Knack's naivete. This probably will doom the group commercially, since they must really be heard to be appreciated. Their first American release, "Mistakes," is a compilation of songs from two previous European releases that made them cult stars overseas.

Though the name "Gruppo Sportivo" comes from an Italian poster, the whole band is Dutch. That kind of bizarre humor pervades "Mistakes." Many of the songs deal with sex and violence, but in such an offbeat, nonchalant way that the impact doesn't register until after the song is over.

"Mission a Paris" starts off like a basic love ballad, but ends up with a man being pushed off the Eiffel Tower. And "Henri" tells a cute little tale that includes the lines "I loved him so / For when I smashed his head in, the only thing he did was bleed . . ."

On the other hand, it's hard not to like a band that can put two titles like "Blah Blah Magazines" and "Beep Beep Love" back to back. (Not to mention "I shot My Manager" ['cause he would not pay my royalties].)

"Blah Blah Magazines," in fact, is probably the most astute observation on the album. Just as you're thinking that this band sounds a bit like ABBA - probably due to the presence of female vocalists Meike Touw and Josee Van Iersel - they sing about how stupid magazines compare them to ABBA. They also go on to say: "Yes it's true we steal every 'tra la la' we hear / Yes you're right, we're like the Monkees, we've got no ideas of our own." They're kidding. Just listen to the album.

As for Bram Tchaikovsky, the initial question was whether it was a who or a they. The answer is both. Bram Tchaikovsky plays guitar and bass and sings vocals for a trio of the same name. Their debut, "Strange Man, Changed Man," sounds like bits of the original British Invasion. Their melodies are simple, but full and chord-oriented.

The vocals are unrefined, but not nearly as raw as the early Stones - Bram Tchaikovsky has been smoothed over just enough to meet today's standards. Not that that detracts from a generally pleasant, if not overly brilliant, first effort.

"Girl of My Dream" uses a nostalgic formula and "Lady From the U.S.A." reveals some lyric depth. There's also a cover of Neil Diamond's "I'm a Believer" (also a hit for The Monkees) that attempts to transform the pop tune into a heavy rocker. The attempt is noble.

And besides, how long has it been since we've had any new material from Tchaikovsky? CAPTION: Picture, GRUPPO SPORTIVO: A DUTCH GROUP WITH AN ITALIAN NAME INVADES THE AMERICAN MARKET.