The only voices heard on Jack-FM are Crystal Z and Dr.Cranfill with "Jacktivities" (events and whatever announcements deemed worthy by "Jack") and Howard Cogan supplying prerecorded quips and ironic remarks between songs.

In the mid-1960s, KNX-FM, along with other CBS-owned FM radio stations, began airing an easy listening format branded as "The Young Sound".

It played mostly instrumental cover versions of popular songs, but it was a bit more uptempo than competing beautiful music stations.

The original KKHR disc jockey staff consisted of Lou Simon, Dave Donovan (whose real name is Joe Cipriano), Chris Lance, Todd Parker (replaced by Jack Armstrong several months later), and Mark Hanson.

Rich Fields, who would later become the announcer on The Price Is Right for over six seasons, also joined KKHR in the station's last year with the "Hit Radio" format.

[10] On March 2, 1989, at 12 pm, following a day-long stunt with a ticking clock during songs and an announcement from vice president and general manager Charlie Seraphin, an oldies music format was introduced and the heritage KNX-FM call sign was dropped yet again.

(The KNX-FM call letters returned to the Los Angeles airwaves on December 21, 2021, when they were picked up by co-owned 97.1, formerly KNOU).

[11][12] KODJ competed with crosstown oldies rival KRTH, which later came under common CBS Radio ownership when limits were relaxed by the FCC.

DJs on KODJ were The Real Don Steele, Charlie Tuna, Rich Fields, Machine Gun Kelly and Jeff Serr.

In addition, KRTH brought in Bill Drake as consultant while featuring all new jingles by the Johnny Mann Singers, which helped it reach higher ratings.

[16] KCBS-FM struggled with low ratings, while KRTH continued to hold the majority share of the oldies market.

The new format focused on the late 1960s and the entire 1970s decade with an emphasis on only classic rock oldies, not including adult contemporary hits, Motown, bubblegum, disco or doo-wop.

CBS also introduced the Jack FM format in New York City, Las Vegas, Chicago, Dallas, Minneapolis, Seattle and Baltimore.

Though the station has no DJs, KCBS-FM will occasionally respond to current events, such as playing all Michael Jackson songs following his death, or spinning a celebratory tune or two following a local sports victory (especially with the Rams).

In addition to the main Jack FM format on HD1, KCBS-FM-HD2 simulcasts KFRG, its co-owned country music station in San Bernardino.