Radio KCBS-FM (Jack FM)

KCBS-FM is a radio station in Los Angeles, California broadcasting to the Greater Los Angeles area on 93.1 FM. KCBS-FM airs an adult hits music format branded as "Jack-FM".

The station signed on in 1948 as KNX-FM. KNX-FM was a simulcast of sister station KNX until the mid 1960s. The radio station, along with other CBS-owned FM radio stations aired a beautiful music format branded as "The Young Sound".

In 1971, KNX-FM aired a mellow rock music format, featuring rock artists deemed too "soft" for album rock rivals KLOS and KMET.

In 1983, long after other CBS-owned radio stations moved on to other formats, KNX-FM adopted a Top 40 music format - again similar to the other CBS Radio stations branded as "93.1 KKHR". A change of the heritage KNX-FM call letters followed to KKHR. KKHR was not a traditional Top 40 music format of the time as the playlist was more stringent limited to 30 songs.

In 1986, the Top 40 format ran its course likely due to its lackluster ratings. The mellow rock music format and heritage KNX-FM call letters were returned under the new branding "Quality Rock".

In March 1989, an oldies music format was introduced and the heritage KNX-FM call letters were dropped yet again in favor of KODJ to complement the change in branding to "Oldies 93.1". KODJ competed with crosstown rival KRTH, which is ironically now a CBS Radio station. KODJ focused more on the 1950s and the early 1960s era of oldies music than rival KRTH. The DJ's featured were The Real Don Steele, Charlie Tuna and Machine Gun Kelly In response, KRTH gradually reduced the amount of newer songs from the playlist and received higher ratings. The Real Don Steele later joined KRTH in 1993 and Charlie Tuna in 2008.

On July 12, 1991 at 2:00pm KODJ changed to its present call letters, KCBS-FM. These call letters had previously been used by two CBS-affiliated stations (now KSOL and KLLC) in San Francisco. On September 1, 1993 KCBS-FM dumped the oldies music format in favor of classic hits music, focusing primarily on the 1970s; branded as "Arrow 93" using the slogan, "All Rock and Roll Oldies".

Infinity Broadcasting (as CBS Radio was known at the time) won the licensing rights to brand their adult hits music formatted radio stations as "Jack FM". Many Infinity/CBS Radio stations adopted the adult hits format and "Jack-FM" branding which led to yet another format change for KCBS-FM. On March 17, 2005, the classic hits music format was dropped in favor of its present music format of adult hits branded as "Jack-FM". The JACK-FM format was a break from the heavily niched formats that had developed beginning in the 1970s. JACK played 70s and 80s hits from pop, rock, and alternative genres, despite the fact that these were usually not played on the same station at the time they were originally hits. JACK was also unusual in that it eschewed DJs, and had a much larger playlist than the typical "oldies" or classic rock radio station.

The Los Angeles incarnation of JACK includes much more modern rock than most JACK outlets, reflecting the local influence of KROQ during its alternative heyday. The station debuted with a blend of pop and rock from the late 60s to late 80s, with a sprinkling of newer, sometimes almost current, tunes. Eventually the newer songs and pop songs were phased out in favor of mostly classic rock and classic alternative.

Though the station has no DJs and is automated, they will occasionally respond to current events, such as playing all Michael Jackson following his death, or spinning a celebratory tune or two following a local sports victory.

The "voice" of JACK-FM is indeed a real person named Howard Cogan. His quips that air between songs are created by a team of writers. As JACK became popular, Cogan moved to Los Angeles to record his comments more easily. He also does the "JACK voice" for other stations around the country.