San Francisco’s KNBR (680 AM) – Origins and the Music Radio Era

KNBR, broadcasting on 680 AM from San Francisco, is one of the Bay Area’s oldest and most storied radio stations, with roots stretching back over a century. While it’s now synonymous with sports talk as “The Sports Leader” (a format it fully embraced in 1997), its earlier decades were defined by music programming, evolving from big band and classical to middle-of-the-road and adult contemporary hits. KNBR never fully embraced the high-energy Top 40 rock ‘n’ roll format that defined rivals like KFRC (610 AM) or KEWB (910 AM) in the 1960s. Instead, it catered to a more mature, standards-based audience with pop standards, crooners, and later contemporary adult hits—earning it a reputation as a “full-service” station blending music, NBC network features, and local news.

KNBR began life on April 17, 1922, as KPO (an acronym for “Kaleidoscope of Programs”), owned by the Hale Brothers department store at 901 Market Street in San Francisco. It was one of the West Coast’s earliest stations, starting with a modest 100-watt signal and experimental broadcasts of live music, weather reports, and store promotions. By 1925, its towers were perched on the Hale Bros. rooftop, beaming programming across the Bay Area. Early content was eclectic: classical concerts, vaudeville acts, and serialized dramas, reflecting the nascent radio era.

West Coast Flagship Station for NBC Radio

In 1932, General Electric acquired KPO and leased it to its subsidiary, the National Broadcasting Company. It became the flagship of NBC’s “Orange Network,” feeding Pacific Coast affiliates with network shows like Amos ‘n’ Andy, Fibber McGee and Molly, and big band remotes from the NBC Symphony Orchestra under Arturo Toscanini. Studios moved to the Merchants Exchange Building in the Financial District, and power increased to 5,000 watts (later 50,000 watts for clear-channel reach across the West). Music dominated, in swing, jazz, and MOR standards, with local talent like bandleader Tom Gentry and singer Virginia George. During World War II, KPO aired patriotic broadcasts and blackout alerts, solidifying its role as a community staple.

By the late 1940s, KPO was NBC’s West Coast hub, producing shows for national syndication and hosting celebrities like Bing Crosby for live performances.

On November 18, 1947, the station adopted the KNBC calls (shared with NBC’s Los Angeles TV station) to align with the network’s branding. Music remained central, shifting toward MOR as TV siphoned away drama and comedy. Playlists featured Frank Sinatra, Nat King Cole, and Perry Como alongside instrumentals and light classics—formats that appealed to adults over 25, contrasting the emerging youth-oriented Top 40 wave led by KEWB and KYA.

November 11, 1962 KNBC call letters moved from San Francisco radio to Los Angeles tv

NBC requested a return to the original KPO calls but withdrew it due to FCC conflicts, settling on KNBR (inspired by “NBC Radio”) on November 11, 1962. Studios relocated to Fox Plaza in Civic Center, and the station leaned into MOR with a “beautiful music” twist, including soft instrumentals and pop standards. In 1965, KNBR briefly flirted with a rock-based format amid the British Invasion and San Francisco’s psychedelic scene, adding more contemporary hits like those from The Beatles and The Rolling Stones. However, this “rock experiment” was short-lived; ratings couldn’t compete with KFRC’s bossy Top 40 energy or KSAN’s freeform FM rock. By 1966, KNBR reverted to MOR, emphasizing “the music you love” with jingles mimicking “I Left My Heart in San Francisco” and themes like “For the Good Times.”

1950s
MOR/Standards
NBC network shows; crooners like Sinatra
Decline of live drama; rise of Top 40 rivals (KEWB, KYA)

1960s
MOR with brief rock lean
Psychedelic boom; Beatles-era hits
1965 rock test fails; back to adult pop by 1966

January 20, 1977 – Mike Cleary (30:03) posted by Mike Schweizer on the web @ archive.org
The 1970s and 1980s were KNBR’s music heyday, as it evolved into adult contemporary —a softer, more current MOR variant with nearly 50% new music per hour, sprinkled with standards. It positioned itself as a “full-service” station: music, news, and talk, appealing to commuters and families rather than teens chasing Top 40.

Under NBC ownership, KNBR featured hits from artists like The Carpenters, James Taylor, and Barry Manilow, alongside recurrents like “Raindrops Keep Fallin’ on My Head.” Jingles promoted “The Music You Love,” and production balanced up to 15 minutes of commercials per hour with NBC newscasts (5 minutes hourly) and local features. The station avoided the edgier Top 40 disco or punk trends, focusing on melodic pop. It added sports play-by-play, like Oakland Raiders games, foreshadowing its future.

The air talent was polished and personality-driven:
Frank Dill (mornings, 1960s–1970s): The “Morning Mayor,” known for witty banter and hit-driven shows; his program later became the duo “Frank and Mike” with Mike Cleary in the 1980s.
Carter B. Smith: Afternoon host with a smooth delivery on AC favorites.
Doug Pledger: Evening staple, blending music with NBC spots.
Others: Al Hart (news), Don Bleu (overnight), and guests like Merv Griffin.

Ratings were solid but secondary to news giants like KCBS (740 AM). KNBR’s MOR/AC hybrid won fans for its reliability, often topping adults 25–54 demos.
1980s Transition: As FM AC rose, KNBR held onto AM with more talk integration. In 1986, NBC/GE began divesting radio assets amid deregulation. Studios moved to 1700 Montgomery Street, and music persisted until the sale. By 1989, Susquehanna Broadcasting acquired KNBR for $17.5 million (bundled with KFOG-FM), ushering in the talk/sports pivot.

Under Susquehanna (later Cumulus Media), KNBR flipped to full-time sports talk, becoming the Bay Area’s dominant sports outlet. It secured rights to the San Francisco Giants (1997) and 49ers (2005), with hosts like Ronn Owens and Ralph Barbieri. Music was phased out, though KNBR-FM (104.5, formerly KFOG) simulcasts sports today.
In 2025, Cumulus relocated studios from San Francisco’s SoMa (Hawthorne Street since 1991) to Daly City after 103 years in the city, sharing space with Bonneville. The 50,000-watt signal still blankets the West, but it’s all sports now—home to Greg Papa, Tom Tolbert, and ESPN affiliates.