Kansas City, Mo ? There would be separate halls for opera and orchestral productions under a revision of plans for a new performing arts center in Kansas City, but the orchestra hall has been scaled back from 1,800 seats to 1,200.

It was the second change of plans in four months for the $304 million Metropolitan Kansas City Performing Arts Center. In June the board decided it would be too expensive to maintain two big halls, proposing instead a single facility that could be converted to serve the Kansas City Symphony, the Kansas City Ballet and the Lyric Opera of Kansas City. Those plans included a smaller 500-seat hall for community theater and other smaller organizations.

But the plan announced Monday calls for a 2,200 seat facility for opera and ballet and the 1,200-seat hall for symphony performance. A third, 500-seat theater intended for a later construction phase remains in the plan.

“We feel confident that this is clearly the direction this project should take,” the chairwoman of the center’s board, Julia Irene Kauffman, said in a letter to the three artistic organizations.

“We at the symphony are thrilled that the board has found a way to remain true to the original concept of the center,” symphony executive director Frank Byrne said of the new smaller hall. “Once it had been studied and the numbers had been calculated it was determined that this was actually doable.”

Performing arts center project manager Ken Dworak said the board considered operating costs, the needs of the organizations, capital costs and the Kansas City market.

“I think for the Kansas City market that 1,200 better suits the orchestra,” Dworak said. “We would rather see a sold-out orchestra hall. We thought — and hopefully they agree — that they can sell out this thing on a regular basis, and that they can keep the hall lit throughout the year.”

He also said the smaller orchestra hall would be easier to adapt to the uses of other organizations.

But some arts leaders questioned whether the smaller hall would be large enough for other purposes, like concerts of visiting orchestras.

Harriman Arts Program executive director Clark Morris said his visiting orchestra series, currently presented in the 2,400-seat Music Hall downtown, tends to draw at least 1,400.

Morris said Kansas City has no major hall that size. The Folly Theater in downtown Kansas City seats 1,100, and Carlsen Center’s Yardley Hall in suburban Johnson County, Kan., seats 1,250.

“The best halls that I’ve heard tend to be between 1,600 and 1,800 seats,” said Carlsen Center director Charles Rogers. “It just seems that volume of room works really well for the orchestra’s acoustics.”

Construction on the center near 16th and Broadway streets is start next year, and performances could begin in 2007.