Composers have long dreamed of bigger orchestras.

In Mozart's day, when orchestras were small by modern standards, he boasted in a letter of hearing one "with 40 violins" play a symphony of his. Berlioz fantasized about an ensemble with 467 players. And even if it is a bit hyperbolic, there is a reason Mahler's epic Symphony No. 8 became known as his "Symphony of a Thousand."

But as some American orchestras struggle in the post-downturn economy, they are taking a page from the corporate world and thinking smaller: They are downsizing, shedding some full-time positions while making up the difference with less costly part-time musicians.

The Atlanta Symphony Orchestra ended a contentious labor dispute and a two-month lockout this month by agreeing to a new contract that will effectively keep it smaller for the next few years.

The symphony's contract called for 95 players a few years ago but was lowered to 88 in 2012. The new contract will keep it this year at 77, where it has fallen after retirements, deaths and departures, and give it four years to grow back to 88.

The cuts place Atlanta's symphony in the company of major ensembles in Philadelphia, Detroit, Indianapolis, Minnesota and elsewhere that have temporarily or permanently trimmed their number of full-time musicians in recent seasons to save money. Some are now slowly rebuilding.

Such reductions do not mean that they must become chamber orchestras, or even play their fortissimos with less issimo. But they do require a greater reliance on freelance musicians to play large-scale works by, say, a Bruckner or a Mahler or a Richard Strauss.

Freelance fix-it?

Some of the orchestras say they can maintain quality by hiring talented musicians to sit in and note that even major, healthy ensembles use substitutes in the case of vacancies or absences.

But musicians warn that an overreliance on freelancers endangers the things that make orchestras great: the cohesion that comes from playing together over many years, the performing traditions that are developed and passed down, even the ability to divine in a flash what a familiar conductor is seeking with a cocked eyebrow or a flick of the wrist.

Michael Kurth, a bassist in the Atlanta Symphony, stirred debate in the music world with a blog post he wrote during the lockout lamenting that his section had dwindled in recent seasons to five players from eight, forcing a greater reliance on freelancers. He wrote that it was like a championship baseball team trying to turn a triple play with a star shortstop who had just arrived from elsewhere.

"He may be a phenomenal player, but we've been turning that triple play together for years," he wrote.

Some freelancers took exception. But Kurth, who stressed in an interview that he respected their talent, said he had experienced the phenomenon from the other side when, while locked out of his regular job in Atlanta, he was hired as a substitute player with the National Symphony Orchestra in Washington.

"I was that player on the outside, struggling to fit in, and not always sure how to anticipate the conductor," Kurth said.

Bruce Ridge, chairman of the International Conference of Symphony and Opera Musicians, a players' conference of the American Federation of Musicians, said such cuts were shortsighted.

"Our belief is that no arts organization can cut itself to success, and that no business ever solved a financial problem by offering an inferior product," he said.