The opening of a new St. Paul Chamber Orchestra season is always a cause for celebration. But this year, it was more bittersweet: 10 musicians, one-third of the ensemble, took advantage of the retirement option in the new contract that settled last season's lockout.

That represents almost 350 years of collective experience with SPCO, institutional memory that can never be reclaimed.

And their absence was heard. The ensemble was not as tight as it has been in times past. But the musicians, and artistic partner Edo de Waart, still delivered a satisfying evening on Friday.

Things got off to a rough start with Bach's Orchestral Suite No. 4. De Waart led a workmanlike reading, mechanical and lacking in passion. The strings played with a dry, vibratoless tone, as if imitating period instruments, and frequently sounded harsh.

The primary focus of the concert was on Beethoven's Fifth Symphony, one of the most popular compositions in the classical repertoire. This is the start of a four-week mini-festival of works from Beethoven's middle or "heroic" period.

De Waart's reading was more lyrical than heroic. With his leisurely tempos, his reading was muted and understated.

What was lacked in urgency was made up for in attention to detail, showing off the prowess of the ensemble. The final pages of the finale rang out with newfound intensity, bringing the performance to a strong conclusion.

In between was a truncated performance of the Mozart "Haffner" Serenade, the first four of the work's eight movements. This was loosely structured party music, written for festivities around a prominent Salzburg wedding. So the four movements made a satisfying whole.

Here, De Waart and the musicians seemed to be enjoying themselves and the performance radiated their joy. The playing was crisp and precise, but with a warm, appealing tone. The balance between the sections was still occasionally off.

In the last three movements, Mozart wrote what was essentially a three-movement violin concerto. This was the highlight of the evening.

Concertmaster Steven Copes demonstrated his usual degree of proficiency, while also playing with an enchanting, sweet sound. He made easy work of the fiery pyrotechnics, but he was at his best in the amazing cadenzas, managing to make them both virtuosic and plaintive.

William Randall Beard writes about music and theater.