The Allman Brothers Band made their first Washington-area appearance in almost four years at the Merriweather Post Pavilion last night. And when Dickey Betts' quicksilver guitar set up Gregg Allman's world-weary vocals on "Whipping Post," all the drug trials, the People magazine ego trips, the recriminations and the breakup of the past four years no longer mattered. They were once again the best rock "n" roll blues band in America.

Betts opened the show by announcing they were taping for a live album and a videotape movie. Allman added: "Long time no see." A few years of playing in clubs and out of buses seemed to have restored the band's hunger.

The new songs sounded stronger than they did on the recent album, "Enlightened Rogues," because the new members were better integrated. Guitarist Dan Toler kept pace on the double-time duets with Betts on "Crazy Love." Singer Bonnie Bramlett wailed at will over Allman's vocals on "Blind Love." David Goldflies on bass and Jimm Essery on harmonica added the blues shadows to "Just Ain't Easy."

But the old songs were the show's highlights. Best of all was "In Memory of Elizabeth Reed," which began with slow variations on the familar theme before opening the throttles. A richly varied drum duet set up the kind of total climax that few other bands can provide.