Growing up is hard to do, especially if you're bis, a band that made its reputation promoting something called "Teen-C Power" and producing infectiously frisky pop songs with bitter lyrics about the inherent dishonesty of adults and the indignities of adolescence.

Nevertheless, the Glasgow trio's second album, "Social Dancing," is an impressive advance from their internationally admired debut, "New Transistor Heroes," which was released in 1997. Most of the songs on "Heroes" had been written while the band members were still in their late teens and are infused with the confidence of self-righteous youths who know they're on a creative roll. Unhindered by a lack of technique and sophisticated equipment, bis used rhythm boxes and toy keyboards to realize their musical ideas, most of which were borrowed from the louder/faster school of late '70s new wave.

The new album is just as assured as the debut, but moves further into dance territory, more specifically '80s disco and techno. The first single, in fact, is called "Eurodisco," and contains the bouncing bass lines and twittering synths that characterize that particular genre, while the lyrics play off the band's thoughts on the direction it's taking, alternating calls to "pump it up" with the self-questioning, "Is this a new beginning?"

The surprisingly low turnout at the band's June 1 concert at Shibuya Club Quattro might indicate that the new beginning is not what the fans want. The club was only about half full, and, judging by the number of guest passes applied to chests and thighs, I would say that half of the audience were industry or media folk, and you know how those people act at concerts.

Still, problems were evident right from the beginning, as the trio (John Disco and Sci-Fi Steven on guitars, and Manda Rin on keyboards) launched into "Action and Drama," a song about what bis demands from good pop music ("I like my idols human"). The song's complex chorus, where the three members sing separate lines that fall into place perfectly, became a jumble of indistinguishable syllables. The next song, "I'm a Slut," lost all its bitchy charm because Manda Rin's lead vocal was buried under the slightly discordant instrumental backing.

I wasn't the only one who felt there was something amiss. "Do us a favor," a young Japanese man shouted in English when the song finished. "Play louder!"

It was a nakedly desperate plea, and I knew how he felt, but I wondered if the volume level was really the problem.

After several more songs, the band had caught on to the audience's disappointment but mistakenly chalked it up to unfamiliarity. "All these new songs too confusing for you?" Manda asked with a touch of sympathy, as if they were confusing to her, too.

"Sale or Return," also from the new album, provided a clue as to the source of the problem. The arrangement is sparer and the resulting sound punchier than that of the previous songs. But despite clearly defined dynamic shifts and a beautifully set-up anthemic chorus, the audience remained unimpressed, probably because the song isn't super-fast.

By this time, the genuine fans had congealed into a tight knot right in front of the stage, pogoing with abandon when the music called for it and swaying and bopping when it didn't. John (who looks something like John Lurie with sideburns) and Steven kept urging the audience to make more noise, and they did, but it sounded as if they were doing it merely to please their heroes.

The fans vocally expressed their appreciation to the band for putting a song on the new album called "Theme from Tokyo," though I doubt if they understood its oblique message, which is mainly delivered via defiant epigrams: "Being on the outside is part of the attraction," "The way to creation is through destruction," and the repeated coda, "I don't want to spend my life pretending I'm you."

The band eventually let on that this was the first time they had played many of these songs in front of people, and dedicated "Detour" to their sound man, Jim. "He just got here," related John. "He had a body search at the airport and was traumatized." That could, of course, explain the unfortunate mix, but by this time we were halfway through the set, and no one on stage was acting as if anything was technically out of the ordinary.

Then they played "Dinosaur Germs" from the first album and everything changed -- the sound, the mix, and more importantly, the reaction. For me the new songs are richer, but the old stuff is blunt in its punky insistence on rocking all over the place. More significantly, the arrangements are skeletal, the pre-recorded component limited to beats.

John was impressed, or relieved. "Well, I guess we'll continue in that theme: old." They played "Starbright Boy" and then Manda came front and center to sing her personal empowerment song, "Monstarr," with its excellent chorus, "Funny how your life depends upon your waistline" (though it should be noted that she's lost weight since that song was first recorded, a development that tends to dominate the Japanese reviews of "Social Dancing"). She pogoed like crazy, Disco John freaked and Sci-Fi Steven erupted into a full-fledged Fred Schneider spaz-out.

They finished with "Making People Normal," my personal choice for the next single, but again the delicious interplay of the various melodies was buried in the mix. They salvaged the evening with three older songs during the encore, including their signature tune, "Kandy Pop," which even got the bizzers tapping their toes.

I hope the cooler reaction to the new material doesn't put bis off their current (dare I say, more adult) path. I don't think it was the songs that disappointed the fans but rather the fact that the songs didn't come through. What the new stuff lacked in concert was the one quality that makes live music so much more exciting than its recorded counterpart: presence.

Considering their doctrinaire allegiance to D.I.Y. principles I'm sure bis won't appreciate it, but my advice is: Hire a rhythm section.