LENOX, Mass. — There are really two Tanglewoods here in the bucolic Berkshires. One is the popular summer home of the Boston Symphony Orchestra. The other is the less-known Tanglewood Music Center, the orchestra’s prestigious training institute for exceptional student performers and composers.

But during a few densely scheduled days every summer, the Tanglewood Music Center takes center stage to present the Festival of Contemporary Music. This year’s edition, directed for the second consecutive year by the composer and conductor Thomas Adès and spread over five days, was no exception. On a recent visit, I attended both festival events and Boston Symphony programs — a total of eight concerts in three days, an exhilarating immersion in the two Tanglewoods.

Before Saturday night’s Boston Symphony concert at the open-air Shed, the festival presented a program at the smaller Seiji Ozawa Hall performed by students along with members of the New Fromm Players, a contemporary music ensemble comprising recent alumni of the Tanglewood center. Though billed as a “prelude,” it was a substantive 90-minute program with challenging works by Ruth Crawford Seeger , Chaya Czernowin and Poul Ruders (whose latest opera, “The Thirteenth Child” recently premiered at Santa Fe Opera).

Mr. Ruders’s String Quartet No. 4 (2012) was especially striking in the incisive performance here. This 30-minute work exemplifies the composer’s postmodern style, juxtaposing gritty harmonies, fiendish outbursts, dancing episodes and radiant lyricism — contrasts so sudden they can seem like non sequiturs.