Having caught a midnight plane to Washington the night before a series of weekend concerts at Constitution Hall, Glady Knight is a little slow to greet Saturday morning. Every once in awhile, a phrase escapes in the soft growl that is evidence of Knight's extended pop career. Down the hotel hall, there's not a sound to be heard from the rooms of the sleeping Pips, brother Bubba and cousins William Guest and Ed Patten, who have been with Knight for almost 30 years since first singing together at one of Bubba's birthday parties. They are partners, family and friends, bound by much more than their collective name.

"We've had to grow together on both the personal and the business side," Knight emphasizes. "It's a special chemistry that's kept us together all this time. Hey, we did everything together -- ate together, slept together -- it was ridiculous."

At the start, it looked as if Knight might go it alone: She won a first prize on the Ted Mack TV "Amateur Hour" at age 7. A year later, following Bubba's birthday party, the group started working the gospel and secular soul circuits around Atlanta under two names, the Fountaineers and the Pips.

They began to tour, and the bond was strengthened. "In the '50s, with segregation, we had to go through a town and keep on moving after the show; we were victims of the times when we'd go to a restaurant and they'd say, 'You can't eat in here,' or 'Go around to the back door.' We experienced all of these things and we said, 'Let's make it more than just entertainment, let's make it something our people can be proud of; let's set some kind of example for other young people.' We had other things to accomplish and achieve outside of being well-known."

Knight officially became the group's front-person in 1961 when a Pips demo titled "Every Beat of My Heart" was released without their approval and became a hit. The group signed with another company, recut the song and released it as "Gladys Knight and the Pips." The two versions went to No. 1 and 2 on the charts at the same time. Since then, while crossing from gritty rhythm and blues to smooth pop and soul, the group has had a dozen gold or platinum singles and albums.

In the late '70s, they stopped making records for three years because of lawsuits involving several record companies. Fortunately, they had prepared for such a disaster by polishing their live act. "We knew that if we based ourselves on being a record act only, well, you're only as good as your last record," Knight says. "But if we based ourselves on entertainment, we had the opportunity to be around a much longer time."

Over the years, the costs of success have often been as great as the rewards. For all the sense of family the group provides its members, Knight has two failed marriages and three children, ages 7 to 19, whom she says she sees too little of.

in fact, only Guest has had an enduring marriage. Her oldest son is 19 and not at all interested in performing, the singer says.

Always a strong concert attraction, Knight has yet to develop a career outside her music. But a forthcoming guest role on "All My Children" may help the daytime soap-opera addict forget the bad reviews and low grosses for her only film role in "Pipe Dreams." And last year, with the legal problems resolved, the group started recording again for Columbia; their latest record is doing well.

"From the beginning, the most important asset that we've had in making it in the business is faith," Gladys Knight says quietly. "We've been blessed to be able to weather most of the storms out there." add e The Concert --------By Mike Joyce Washington Post Staff Writer

"It feels like a Sunday morning," said Gladys Knight. It wasn't. It was Saturday night at Constitution Hall and Knight and the Pips had just infected the capacity crowd with gospel fever.

The symptoms were everywhere. Joyful shouts filled the air during up-tempo numbers, cries of commiseration punctuated the emotional ballads, and hardly a song passed that wasn't immediately greeted with a resounding burst of recognition. Backed by a full orchestra and over 20 years of musical memories, Knight didn't really have to win the crowd's affection; that was hers from the moment she walked on stage. But she earned it nevertheless.

Unlike so many performers who telescope their hits into contrived medleys, Knight remains true to such songs as "Midnight Train to Georgia," "Got to Use My Imagination" and "Neither One of Us."

She obviously cherishes her numerous hits, and though her show is laced with the Pips' slick choreography and occasional humor, nothing compromises the songs. Her slightly weathered voice, marked by a dramatic catch in the way she phrases the lyrics, made the ballads particularly convincing.

The Manhattans opened the show by mixing satiny soul ballads and nostalgic do-wop harmonies with an occasional country twist. They also "went to church" whenever the spirit moved them, as it clearly did on the Beatles' "Let It Be" and their own "Shining Star."