''The house of blues has many mansions.''

When Marshall Stearns wrote those words 35 years ago, introducing the Library of Congress album, Negro Blues and Hollers, ''house of blues'' was just a metaphor. Today, there are many real Houses of Blues, a chain of huge, fashionably funky nightspots in cities such as New Orleans, Chicago, Hollywood and Cambridge, Mass.

These upscale juke joints are the brainchild of nightclub genius Isaac Tigrett, the West Tennessee native who developed the Hard Rock Cafe.

There's also a House of Blues record label, a recording studio in Memphis and House of Blues-sponsored tours of hip-hop (''Smokin' Grooves'') and blues.

Saturday, Procter & Gamble Hall in the Aronoff Center becomes a House of Blues for a night, as Dr. John, Robert Jr. Lockwood, Charlie Musselwhite and Alvin ''Youngblood'' Hart come to town.

It's a tour that brings to life the metaphorical ''house of blues,'' with artists representing various regional approaches to the music.

The deepest blues come from the Mississippi Delta, the fertile crescent bounded by the Mississippi and Yazoo Rivers, with Memphis to the north. That's where Mr. Lockwood, 82, learned to play the blues, many of his early guitar lessons coming from his stepfather, the legendary Robert Johnson. Mr. Lockwood, who has lived in Cleveland since 1960, was also a pioneer of electric blues, performing with Sonny Boy Williamson II on Helena, Ark.'s King Biscuit Time radio show. Traveling to Chicago, Mr. Lockwood gained fame in the 1950s as a session player at Chess Records, able to play both raw blues licks and sophisticated jazz chords.

Mr. Musselwhite, though a white man, had a very similar background. He was born in Kosciusko, Miss., but his family moved to Memphis a few years later in search of better economic opportunities. Young Charlie grew up listening to the local street bluesmen, learning harmonica from such masters as Walter Horton and Will Shade of the Memphis Jug Band.

As a teen-ager he took off for better-paying day labor in Chicago. He soon discovered the blues scene on the South Side (or ''North Mississippi'' as it was known), and despite his race, frequently shared a stage with such fellow Delta emigres as Muddy Waters and Howlin' Wolf. With the rising popularity of the blues, he moved to the San Francisco Bay area in the mid-'60s and became one of the leaders of the blues revival. He remains a master musician who sings and plays harmonica and guitar with a laid-back virtuosity that has earned him numerous W.C. Handy Blues Awards, the Grammys of the blues industry.

At 33, singer-guitarist Alvin ''Youngblood'' Hart is the youngest member of the tour, but he plays the oldest blues styles. Hoisting a five-string banjo, he's even been known to dip into the pre-blues repertoire of African-American minstrel performers. His versatility and showmanship has landed him such prime showcases as the 1996 ''Furthur'' tour.

Mac ''Dr. John'' Rebennack is the most widely known performer on the tour, having hit the Top 10 in 1973 with ''Right Place, Wrong Time.'' Through the years, the singer/pianist/guitarist's rich gumbo of New Orleans R&B, rock and down-home blues has made him a regular on the rock circuit.

A New Orleans session player since his teens, Dr. John says one of his first music jobs was copying the blues sound of another famous river city -- Cincinnati.

He was working for Ace Records owner Johnny Vincent, he recalls, speaking on the telephone. ''His big competition in his head was (King Records owner) Syd Nathan. He used to give me like these (King) records, a lot of songs that (staff producer/songwriters) Sonny Thompson and Henry Glover wrote and say, 'Try to rip this off. Write an answer to it.'

''That's how I met Henry Glover way back in the game. I said, 'Man, my job is to rip your (material) off and I never can get nothing better than what you already did the first time.' But we got to be friends from me tellin' him that. He thought that was hilarious.''

Dr. John never met Mr. Nathan or visited King, but he remains a fan of the label, particularly its producer/songwriters.

''He (Mr. Glover) was real innovative. The sound they got on the drums on Willie John's ''Fever'' with brushes was so far ahead of the time,'' Dr. John explains. ''The same with Sonny (Thompson). Some of the stuff he did early on with Freddie King and some of the stuff even before that with Lula Reed. If he hadn't cut Henry Glover's song 'Drown in My Own Tears' with Lula Reed, Ray (Charles) wouldn't have had no basis to put his own 'Drown in My Own Tears.' Those records were real trendsetters.''

With his fond memories of King and long history playing in the city, Dr. John is looking forward to performing here. He has been enjoying the House of Blues tour, which, along with individual sets by each headliner, allows for the kind of impromptu jams that are a longstanding tradition in all the blues' many houses and mansions.

Some might think that the plush arts centers the tour has been playing don't mix well with ''fonky'' (as he calls it in his N'awlins patois) blues, but Dr. John has found otherwise.