Good live music is more fleeting than fame, and these days more remarkable. In an era when track-magic bands like Boston play over their own prerecorded dubs, the real empathy of roadwork groups rings even clearer. It's like that fractinal differance between stings tuned to the same note and strings in tune with each other; finer and somehow fuller, achieved by an intimacy that is almost telepathy.

Delbert McClinton's band has it; the Rolling Stones, the old Doobie Brothers. It's a matter of thousands of hours spent together: Springsteen said that only last fall the E Street Band finally crossed that fine line. Southside Johnny and the Asbury Jukes have it, and another ingreident in common with these other journeymen -- humor. Even the blues got taps on its shoes.

Southside Johnny's two-record live album, "Reach Up and Touch the Sky" (Mercury SMR-2-2608), is a textbook sampler of the varied delights of concertgoing. Recorded at six venues (including the Capital Centre) during the summer '80 tour, it reveals the shifting rhythms of each night, the spontaneity of vocals. This is true R&B gestalt, smooth and professional without being polished.

Southside Johnny Lyon's longtime friendship with Springsteen & Co. has elicted from the Boss and sometime Jukes producer Miami Steve van Zandt some of their best R&B writing. Among the Springsteen entries is "The Fever," which became the Jukes' first trademark, here in a long (almost seven minutes) version, less sultry than the original but still sharp with loss. Van Zand's dedication to the Jukes is best exemplified by "I Don't Want to Go Home," title cut of the first album, score of the live album's title and the best Stax-style sax wailer ever written by a white man. (Although this is primarily the Jukes proper E Streeters Garry Tallent and Max Weinberg make a pounding cameo apperance on "Stagger Lee," at 7 1/2 minutes the high stomppin' point of the evening.)

Side four is entirely taken up by a salute to Sam Cooke, including such classics as "You Send Me," "Bring It On Home To Me" and "Having a Party." While Lyon's back-barroom voice is no match for Cooke's smooth sensuality, he has all the soul and maybe a trifle more swing. In any case, Cooke could only have approved of a man who has dedicated his name and his life to such brassy eye-winking blues-rock.

You could do a nice thing for yoursef Friday, incidentially, by rolling out to Merriweather Post to see Southside Johnny live. Highly recommended for deep-summer sould survivors.

While the A's have as much sass as the Juke's and the occasional sax growl, this Philadelphia group hasn't fixed on an R&B identity. They haven't settled on any identity. This is the kind of group that used to play the frat parties in high school: something for everyone, the traveling Top 40.

In the group's debut album, "A Woman's Got the Power (Arista AL 9554), composers Rocco Notte and Richard Bush have tried on a half-dozen voices. (This could be the hit of your next party -- Recognize That Riff.)

Try "Little Mistakes," or "Life in the Fast Lane" by the Ramones: "Johnny was a boozer/Jackie was a user/It always would confuse her/Why they both had to be losers." There's a great deal of Parkerilla, especially in "Working Man" and "I Pretend She's You," occasional Costello ("Johnnie Silent") and a little? and the Mysterians ("Insomnia").

There are also a couple of potential radio hits: "Heart of America" has an enery that far surpasses Joe Vitale's "electric anthem," "Lady of the Rock." Its frantic frustration is vented with a sax shorus, then by a banjo break; and its lyrics neatly juxtapose the good, the bad and the ordinary: We got speace here in America But it's never really seen I can't wait to see America On my televison screen

"Electricity," a made-for-radio wonder, is a throwback to the Raspberries generation, all desire and desperation crowned by and Allman Brothers guitar. How can you top it? These guys are a whole industry, in their own write.