PHILADELPHIA -- Roger Waters knows what's in a name -- and that a Floyd by any other name won't sell as sweet.

As the conceptual visionary, principal songwriter, singer and bassist for Pink Floyd for 16 years, Waters was used to stadium sellouts, instant platinum record sales and the attention of Floydophiles around the world, a still-expanding universe that has bought more than 60 million Pink Floyd albums and has kept one of them, 1973's "Dark Side of the Moon," on the pop charts for an astounding 692 consecutive weeks (and counting).

But after years of escalating intraband tensions, Waters left Pink Floyd in 1983. Which should have been the end of one story and the beginning of another.

Waters' subsequent solo effort, however ("The Pros and Cons of Hitchhiking," a muddled concept album about sexual politics), sold only 600,000 copies, and a world tour (with an expansive production designed by Mark Fisher and Jonathan Park, who also did Pink Floyd's "Animals" and "The Wall" tours) was ill attended. His most recent album, "Radio K.A.O.S.," is only in the 60s on the Billboard chart and the new world tour, complete with a stunning multimedia stage show by Fisher and Park, has not been selling out at arenas like Philadelphia's Spectrum or the Capital Centre, where Waters and his new Bleeding Hearts Band play tonight.

Meanwhile, the Waters-less Pink Floyd -- guitarist David Gilmour, drummer Nick Mason and keyboardist Rick Wright -- are well on their way to selling out a four-night stand at Cap Centre in late October and sold all 180,000 seats for three September shows in Toronto. A new Waters-less Pink Floyd album, "A Momentary Lapse of Reason," hits the stores next week and will probably shoot to the top of the charts.

Pink Floyd kept a low media profile over the years -- interviewed about as often as Howard Hughes, more frequently a critical target than subject -- and Waters concedes that may have been a drawback. "There's a price to pay for everything, but I think the pros have outweighed the cons." Still, it makes you wonder if people were paying attention to just who was doing just what in Pink Floyd.

So it's not surprising that Roger Waters, 43 and still intensely protective of his private life, is a little perplexed by his diminishing returns, though he insists it concerns him "only up to a point.

"It would be nice if a million people rushed out and bought the record," he says, "but I learned a big and somewhat painful lesson with 'Pros and Cons.' Not that it was the kind of record that was ever going to be an enormous commercial success, but I was surprised by the complete lack of interest. It came as an enormous shock to me that the public at large, and the record-buying public in particular, didn't associate me with any Pink Floyd stuff ..."

"But I have a quite steep learning curve, and it doesn't take me very long to catch on to what's going on. I think {Pink Floyd} were very surprised when they put tickets on sale in Toronto in May for a show at the end of September, which they obviously did to test the waters, and they found out it was hot, hot, hot. It's two or three succeeding generations going 'Wow, Pink Floyd! They're a legend! I'll go to that!' "

As it happens, Waters is suing his former bandmates over the rights to the Pink Floyd name and assets, including the many elaborate stage effects used on past tours. But the ex-legend says he's not doing it for the money.

"My beef is a moral beef, but the law is only interested in property," he says. "My beef is as follows: Pink Floyd was a name used to describe a number of individuals joined together in making a certain number of records over a certain number of years, and in my opinion, that band is now over. None of the people in that band want to work together, and I mean none of them. Nobody wants to work with anyone else, but a couple of them -- Gilmour and Mason -- have decided to make a few quid and try and go on the road. Through a loophole in the recording contract I can't actually stop them making a record -- and they've made a record.

"It's not very good, which is beside the point, except maybe it's not beside the point, because whether it's good, bad or indifferent, in point of fact, it is not a Pink Floyd record and it should not be called that. But 'shouldn't' isn't a word that lawyers understand; they go, 'C'mon, do you own the name or don't you? Who owns the name? Let's look at the papers.' "

Such moral distinctions, Waters concedes, seem lost on many fans. "The public generally seems to be only interested in the number of tickets sold or the grosses or the number of weeks 'Dark Side of the Moon' has been on the charts. What I'm interested in is what the songs were about, not the charts. So I'm faced with this dilemma. What I do in the end I don't know, but my feeling is that the name is not for sale.

"None of us are Pink Floyd."

Big Pink Once, of course, they were.

Waters was not Pink Floyd's original visionary. That role was filled by Syd Barrett, the group's lead singer, guitarist and songwriter from the time the band came together in mid-'60s London until 1968. Waters and Barrett, born in the university environs of Cambridgeshire, had first met as toddlers in a Saturday morning art class. Years later they wound up in London -- Barrett as an art student, Waters, like Wright and Mason, an architecture student -- and formed a band, taking their name from two obscure American bluesmen, Pink Anderson and Floyd Council (an earlier, fortunately abandoned name: the Meggadeaths). Like many bands at that time, Pink Floyd was interested in all kinds of music -- from blues to rock to classical to jazz -- and, fueled by Barrett's eclectic and eccentric spirit, quickly became favorites of London's arts underground.

Pink Floyd's first single, "Arnold Layne," was a slice of innocent psychedelia about a transvestite who stole women's clothing off laundry lines. They cut their first album, "The Piper at the Gates of Dawn," on Abbey Road in the studio next to the Beatles, then working on "Sgt. Pepper." Barrett's aspirations to "painted sound" were reflected visually in increasingly elaborate light shows (the first in England), and aurally in the most elaborate and advanced sound system in rock, including the first quadraphonic sound system, in 1969. The band also experimented with a wide range of effects, from feedback and distortion to subliminals like submerged speech and incidental sound, or noises that careened between speakers or headphones.

By 1968, Barrett was gone, replaced by David Gilmour. Barrett's musical innovations and surrealist songs couldn't obscure his mind's degeneration or his increasingly erratic and self-destructive behavior. He had simply lost control of his life, and eventually disappeared from view, except as a tragic cult figure at least partly revitalized by Waters as the lead character in "The Wall."

After Barrett's departure, Pink Floyd moved to the forefront of the British acid-rock movement with albums like "A Saucerful of Secrets," "Ummagumma" and "Atom Heart Mother," and sound tracks for "More" and "La Vallee (Obscured By Clouds)." They got a reputation as a mind-bending, psychedelic "space band," though Waters is annoyed by this description.

"That space thing was a joke, I never understood that," he says.

He does admit to a certain cosmic lyric sensibility. "At the time my songwriting was about looking through books of poetry of the late T'ang period, which I used to rip off. It's difficult to listen to some of those songs now, like 'Doctor, Doctor,' on the first album ... Very tough listening," he chuckles.

With 1968's "Saucerful of Secrets," Waters began to emerge as Pink Floyd's new creative voice, though the next few albums were very much band projects. By 1972's "Obscured By Clouds," his lyrics were decidely less cosmic and more personal. In a '70s concert program Waters defined his favorite food as "reality sandwiches" -- and his reality, it turned out, was unflinchingly melancholy and depressed.

"I paint what I see and I guess I always will," he says.

Waters' tangled visions and obsessions -- sanity, emotional isolation, impending apocalypse and survival, crushing social structures, nature versus industry, his father's death in World War II the same year he was born -- were hardly the stuff of mass appeal music. But the first album that brought many of these concerns into focus, "Dark Side of the Moon," was also Pink Floyd's biggest seller (it's still selling after 14 years; the previous record holder, Carole King's "Tapestry," had a chart run half that long).

"I'm proud of it," says Waters. "It was a proper collaboration, though it was my idea and I wrote the words and I was in charge of everything. Nevertheless there was a lot of input from Dave and Rick. There must have been, it was a very good record."

"Dark Side," which has sold some 20 million copies (Capitol refuses to release the exact figures and has never even had the album certified platinum) is a tract on sanity ("Brain Damage"), death ("Time" and "Eclipse"), avarice ("Money") and alienation ("Us and Them"). "Money" was Pink Floyd's first American hit; it quickly elevated the group to superstar status and, Waters has said, settled its fate. The next albums -- "Wish You Were Here" in 1975 and the Orwellian "Animals" in 1977 also sold astonishingly well, with an ironic twist: As Pink Floyd drew an increasingly larger, younger audience, the group responded with increasingly spectacular theatrics, moving from arenas to stadiums -- a commercialization bitterly examined in the song "Welcome to the Machine."

Little wonder that Johnny Lydon (rechristened Rotten) was invited to join the then-forming Sex Pistols after being spotted wearing a Pink Floyd T-shirt with "I Hate" scrawled above the name. The band had become the kind of quintessential rock dinosaur that inspired punk rock's rebellion. But even Waters was beginning to agree with Rotten's shirt.

Hence "The Wall" in 1979.

Just Another Crack in the Floyd By then, the band was already in serious trouble, with Waters and Gilmour in particular having grown apart philosophically, politically, musically, "in every possible way." Making records, Waters says, "was almost impossible. It was amazing that we made any. It could have very easily stopped after 'Dark Side.' I think it should have stopped. If we'd been brave, we would have."

On the other hand, there were financial considerations (much of the money made from "Dark Side" had been lost in ill-advised investments) and the security of being a brand-name band. "I'm not surprised that we carried on as long as we did," Waters says. "It's a hell of a thing to give up, as we're witnessing now."

"The Wall" was a double album tracing the convoluted emotional despair of a rock star (named, oddly enough, Pink Floyd) and his gradual disintegration and distancing from self and audience behind a brick wall of insanity. It also examined rock's mob mentality, the potential for pop fascism, the stress of a corrupted career and the smothering tactics of a whole line of Oppressors.

All in all, a bleak, cathartic concept. Then again, no one has ever called Waters "Jolly Roger." If he is perceived as a melancholy Brit, Waters concedes, "That's largely my own fault because I haven't really spoken, or didn't speak, to people for years and years and years, so all they had to go on was the songs."

Not everybody gets the message of those songs. Over the years, Waters admits, fans' enthusiasm for the medium has often led them to miss content. In concert, it can be disconcerting to hear near-Pavlovian reactions to certain lines stripped of their ironic or caustic intentions.

"In a rock and roll show you do have to accept that part of the medium is 'Let's boogie,' " he says, "and obviously I pointed at that very directly in 'The Wall,' saying 'Look how deranged some of this stuff is.' But of course that's not a position that a lot of the people who come to the shows come from." He cites the reaction to "Another Brick in the Wall": " 'We don't need no education' -- They accept that as a piece of literal rebellious information, and of course it has nothing to do with rebellion at all, in fact ...

"It used to irritate me a lot more than it does. If I'm going to perform in arenas like this, I have to accept that that's what it will be like."

"The Wall" sat for 15 weeks at the top of the charts, producing a No. 1 single in "Another Brick." Pink Floyd prepared a limited tour -- limited because mounting it, complete with a 30-foot high brick wall constructed as the show progressed and then smashed down, proved so prohibitively expensive they could only play arenas in Los Angeles, New York and London. When Waters went against the other band members' desires and turned down an offer of $1 million a night to bring "The Wall" to Philadelphia's JFK Stadium, it was just another crack in the Floyd.

"That was the whole point of the thing, that's what it was all about," Waters sputters. "The narrative was from autobiography but all that stuff with the crossed hammers, the idolatry, the demagogy and all that was how I thought rock and roll was sinking into a kind of Nuremberg mentality, which it has sunk even further into. So I really couldn't believe it when these guys wanted to go play 'The Wall' in stadiums."

They didn't; in fact, they would never tour again. The final Pink Floyd record confirmed the disintegration. "The Final Cut: A Requiem for the Post-War Dream by Roger Waters" was more of a solo album than a Pink Floyd effort -- a meditation on many things, but in particular the death of Eric Fletcher Waters.

"I remember an early song, 'Corporal Clegg' -- simple, straightforward, my first antiwar song. 'Corporal Clegg/ Had a wooden leg/ He won it in the war/ In 1944 ... ' It was the first stirring of my own bitterness and sense of loss of my father's death in the Second World War, which finally came out in 'The Tigers Break Free,' which was in 'The Wall' movie but not on the record."

Kind old King George sent mother a note when he heard that Father was gone

It was I recall in the form of a scroll with gold leaf about

And I found it one day in a drawer of old photographs hidden away

And my eyes still grow damp to remember His Majesty signed with his own rubber stamp ...

"I remember being really staggered finding this thing with the rubber stamp signature," Waters recalls, adding that "For me, it was impossible not to explore my father's death. It was central, it was my one big loss. Maybe I was lucky that I ended up in a situation where my work could be therapeutic. A lot of people have to live with those kinds of losses with no recourse to dealing with it in any way at all."

Radio Daze Waters' latest album, "Radio K.A.O.S.," is yet another concept album, both a satirical look at commercial radio and a high-minded treatise on the misuse of telecommunications. A Welsh boy named Billy -- a "vegetable" who can mysteriously access radio waves -- engages in conversations with Jim Ladd, a real-life L.A. deejay "fighting a rear-guard action against format radio." Naturally, there are many twists, turns and subtexts -- including Billy's simulating a worldwide nuclear war before deactivating all the military computers. Some of the story is synopsized in the album notes and some is expanded on in the stage show (which also features songs from all the Pink Floyd albums from "Dark Side" on).

This being a Waters show, the production is stunning ("I always lose money on my tours, though I try to lose as little as possible"), and the Bleeding Hearts Band is excellent. The set is partly a recreation of a radio station, with Jim Ladd playing himself and even taking live call-ins from the audience. The design by Fisher and Park includes a huge circular screen on which are projected a few classic animation sequences and some computer-generated graphics as well as a powerful collection of newly filmed and markedly political visuals by the acclaimed British documentary maker David Monroe. "He shot it all personally in Kampuchea and Nicaragua and El Salvador," Waters says.

At some point, Waters may take his show off the road and onto the screen. "I would like it to be a comedy," he says. "It would have to be a comedy."

Sort of a musical "WarGames?"

"In a rock show, you can be as bald as this, as direct, as uncompromising, but I think if you're sitting in a cinema ... Maybe I'm wrong, but I feel there's a lot of humor in this piece which we haven't delved into."

He is wary of the medium, however, after his experience with "The Wall," which he scripted but didn't control. Alan Parker's film, he thinks, was irritatingly literal, "unremitting in its cinematic assault upon the senses.

"I could not work in that way again, it was absolute misery," he says. "Alan Parker and I got along like a house that was never going to catch fire." He still thinks the record works, "if you don't have the images rammed down your throat at the same time. The record seemed much more three-dimensional."

Oddly enough, it was Bob Geldof -- the then-little-known Irish rocker who played Pink in Parker's film -- whose Live-Aid project gave Waters hope a few years later. In fact, his new album's closing number, "The Tide Is Turning (After Live-Aid)," is the most positive, optimistic song in a long career defined by pessimism and cynicism.

Television, of all things, has cheered him up. "It's a serious conviction of mine," Waters says, "that because of television specifically -- even though the show is about radio -- and because of telecommunications satellites, and because of the increasing access that the individual is gaining to information, it becomes harder and harder for the powers that be to pull the wool over our eyes.

"Fifty years ago, you had to be able to read articles in certain papers {to get at what was really going on} but now telecommunications have become an inadvertent tool of truth. There's so much volume of information coming that you get to see more and more what it actually is. And so we all make our small inputs, which is why telecommunications is so important: It does away with isolation."

From there, Waters says, we move to the idea of community and cooperation. Far from being "overly optimistic or overly idealistic," he says, "it's the only way. We are inevitably faced with two choices: to compete and die or to cooperate and live. I may be right or I may be wrong, but that's the battle, that's what's going on now and it's being fought on television and in the papers and, hopefully, on rock records as well."

New outlook or no, however, Roger Waters is still a rock star, not a prophet. "Don't think I don't understand the reason I do this," he says. "Like anybody else in a rock band, I'm going, 'Look at me! Look at me!' and I probably will to the day I die. Nevertheless, within that context, there is more to it than just 'Look at me!' "