When you walk into any talk-radio studio, the first thing you notice is the "On Air" sign, typically a red alert that commands the silence of a passerby and directs attention to the host at the microphone. The death last week of Philadelphia radio legend Frank Ford was a reminder that most of his brand of substantive local broadcasting has been off the air for many years.

Ford, a native Philadelphian out of the Logan section, was a late-night staple on WPEN-AM (950) during the late 1950s and '60s. His home base was at WPEN's building on Walnut Street near 22d Street. There he would host in-person guests in front of a live audience, which dined while watching the show in the first-floor William Penn Room.

The building was an aging testimonial to a pre-television time, when radio was the lone broadcasting medium, and the majestic, three-story structure with an Art Deco façade was a lure for the audience.

Ford, who followed in the footsteps of Red Benson and then Steve Allison in the 11:30 p.m.-to-2 a.m. time slot, was an educated, articulate host for many celebrities who passed through this city. At the time, Philadelphia was a tryout town for Broadway-bound shows.

Ford also may have been the first local talk-radio host to have direct, on-air dialogue with telephone callers.

But of even greater importance was his participation in the "total talk" format that began on WWDB-FM in 1975 and lasted until 2000. Ford was an integral component of an issues-oriented menu of programs characterized by both substance and balance.

Ford's left-leaning political bent was joined by hosts Jerry Williams and Bernie Herman. At its peak in 1980, WWDB also featured Bob Grant and Dominic Quinn on the political right. In the center, as a voice of moderation, was Irv Homer, later joined by Richard Hayes.

The shows were local in origin, with stimulating guests and provocative subject matter. The lineup had a balance of opinions and was a catalyst for thought - elements that are often missed in today's radio formats.

For five years during that time, I was a WWDB account executive, charged with the task of attracting advertisers to the programs. The fact that the business owners I was selling air time to were also listeners made my job easier. They listened to the stations' programs because they were engaged in civic issues, which affected their businesses and the world around them. Local democracy was in full bloom.

At the time, I recall lamenting the passing of the era embodied by the old WPEN, where I had also worked while in college. There was no longer a live audience, I thought, but there certainly was a lively one, inspired by the hosts.

Now my lament is for the passing of a balanced, local, substantive talk format. Just as this newspaper faces faraway threats to its local voice, Philadelphia talk-radio outlets lack robust local lineups. They tend to be dominated by one-sided views that emanate from other cities.

Philosopher John Stuart Mill expressed his appreciation for balance when he wrote: "If an opinion is suppressed, and it is true, then we lose the opportunity of exchanging truth for falsehood."

So we may be missing opportunities of our own. Yes, the "On Air" sign is still lit. But its message is hollow in a market longing for substance and balance.

E-mail Jeff Hurvitz at jrhurvitz@aol.com.