O.C. MUSIC REVIEW : Fireworks Are on the Ground : The Pacific Symphony concert at Irvine Meadows features well-played American tunes, but the show in the air is a letdown.

Everyone, it seems, turns up his or her nose at Fourth of July pops concerts--except for the people who flock to them in numbers that often dwarf the attendance figures for the rest of the season. It might not even matter what a lazy programmer throws together: Crowds such as these tend to be easy to please.

So when you get a hold of a good Fourth of July concert--like the one the Pacific Symphony played Thursday evening at its summer home, the Irvine Meadows Amphitheatre--hold it close, don’t let it get away.

The first half featured a well-played, Gershwin-dominated orgy of American music, ably led by Mark Gould, who normally makes his living as principal trumpet player of the Metropolitan Opera Orchestra.

He led off with a crisp, snappy rendition of an overture from the Gershwins’ “Girl Crazy”--not the original one but a cleverly stitched (and uncredited) potpourri by Robert McBride that had plenty of authentic Gershwin twists in the harmonies. From Jerome Kern came “Waltz in Swing Time,” a lurching fusion of styles that was written for a Fred Astaire film.

For about 20 minutes, everyone indulged in “Porgy and Bess’ ” greatest hits, with Gould sensitively accompanying singers. Soprano Geraldine McMillian struck exactly the right blend of operatic tone and slightly bluesy phrasing, and Peter Lightfoot sang Porgy’s music in a steady, theatrically informed baritone.

In Louis Armstrong’s signature tune, “When It’s Sleepy Time Down South,” Gould tried to filter Satchmo’s inimitable style through a conservatory prism, with limited success. A pair of George M. Cohan flag wavers in lock-step march tempo got the house stomping. Later, the orchestra served as a routine backdrop for the Manhattan Rhythm Kings, a retro-minded vocal trio that in its best rhythm tunes knocks off an ingratiating, hot-cha-cha impression of Paul Whiteman’s Rhythm Boys.

The sound system was outstanding, producing a vividly clear, floating, undistorted account of the orchestra and voices in the manner of a fine component stereo setup. Obviously these engineers know how to mike and project an orchestra electronically outdoors. And the audience was attentive: Unlike their brethren at the Hollywood Bowl, listeners didn’t hum along to the tunes or roll wine bottles in the aisles.

Oddly, the only real disappointment was the fireworks, a modest, conventional display that was not at all coordinated with the sounds of Sousa and Armed Forces anthems from the orchestra. Those in the cheaper seats had the best view--and it was amusing to watch the high rollers downstairs scrambling up the steps so that they could actually see something.

The head count: 10,300.