Make-believe maestro

Poised at the ready, I stand in front of the loudspeakers in the den. Solti and the Chicago Symphony explode with the opening chords of Beethoven's ''Eroica'' Symphony, and with a stab of my yellow pencil I pick up their beat as it pulses off the record.

This is somewhat different from leading the Terrace of Paris 15-Piece Orchestra through ''You Were Meant For Me,'' circa 1929. For one thing, I go through the motions now, whereas before I only thought about it.

That was back when getting a passing grade in high school geometry was my biggest problem, almost, and my musical tastes were limited to the confections of Tin Pan Alley.

Often I would put myself to sleep by fantasizing. I and my orchestra were presenting a choice selection of this gingerbread to my schoolmates at assembly in our high school auditorium.

Usually our assembly programs at Maple Hill High were on the order of Victor Herbert favorites sung by the Senior Glee Club, or a scene from ''Rosmersholm'' which the Dramatic Society was presenting Friday night. Or maybe someone from the post office would speak to us about what happens to your letter after you put a 2-cent stamp on it. But the show I put on was, everyone agreed, a doozy.

To applause that threatened to crack the plaster statue of Hebe that stood at the entrance to the auditorium, my Terrace of Paris 15-Piece Orchestra played the popular music of the day as I had memorized it from the recordings and radio broadcasts of Vincent Lopez, Isham Jones, Rudy Vallee, and other bandleaders. Wielding my baton up there, tricked out in a tuxedo and my own mustache, I was the cat's pajamas if not the bee's knees.

I wouldn't signal my piano player to give us the ''take five'' riff until I was satisfied that a certain 11th-grader in the front row, the girl with the soft eyes and the quick smile, was one sorry baby for turning down all my invitations - to the football game, the Chemistry Club outing at Wolf Lake, the soda shop. She, and not geometry, was really my biggest problem. She wouldn't even let me walk down the hall with her to Latin class.

After the assembly, when my schoolmates practically mobbed me in their adulation, I'd smile pityingly at her, forgiving her. Yes, I told her, I'd drive her home in my new Stutz Bearcat. End of dream.

Other than this fantasy, the closest I ever came to leading my own orchestra was standing in front of a bandstand, gaping and gawking until the drummer or trombone player seemed ready to throw something at me. My musical knowledge ran no deeper than my ear, but it was enough for daydreaming in the night.

Wherever there's a dream there's usually an alarm clock nearby. I heard mine when I graduated from Maple Hill and took a job lugging crates in a fruit market. My daydreams of my orchestra vanished: I couldn't see them for sour apples. Kid stuff. Besides, the soft-eyed girl's family had sent her off to finishing school in Virginia. Even the Terrace of Paris 15-Piece Orchestra couldn't compete with all those fellows down there.

But a confirmed daydreamer is going to do his thing. There's room in music for us amateurs. I joined a community chorus - Handel's ''Messiah,'' Brahms's ''German Requiem,'' Bach cantatas, and such. Before long I discovered my juvenile daydream hadn't disappeared forever after all. It had taken off on wings of song to classical realms. I went back into the make-believe-maestro business.

So here I am, up front once more. You name it: If it's in my record collection I'll give it a whirl. Maple Hill auditorium with its bleak green walls is out. Now it's Avery Fisher Hall in Lincoln Center one night, the Concertgebouw in Amsterdam the next. And I don't have to go to bed to get there.

Considering I don't know B flat from a demisemiquaver, I do all right. A miscue now and then, certainly - I may try to bring in Mendelssohn's flutes when it's the clarinets' turn, or in Strauss I'll point to the percussion section for the ping! of a triangle and get the shimmering splash of a cymbal instead - but my orchestras know the score. They play everything the way it's written, no matter what I ask of them. I wonder if this ever happens to better-known conductors.

There's no demand today for the Terrace of Paris 15-Piece Orchestra. What's more, Maple Hill High has become a county government building, and the soft-eyed girl with the quick smile, the one I was going to make so sorry, is no longer in the front row when I conduct. While I whip through Mahler's First Symphony with Kubelik and the Vienna Philharmonic, she's in the next room trying to read. I wouldn't dream of asking her if there's anything she's sorry about. If you think I'm going to give her an opportunity like that, ever after all these years, you'd better think again.