KMXL-FM/KDMO-AM: Small Town, Big Ideas


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An AM/FM pair in southwest Missouri rebuilds right

The KDMO-AM control room

The KDMO-AM control room


Life in a small town is different than in a big city. There's a strong sense of community, and that community can become almost an extended family through its radio stations. This is what I saw when I visited adult hits KMXL-FM and adult standards KDMO-AM in Carthage, MO. Co-owned since the FM signed on in 1972, the two stations have a strong presence in the Joplin market and compete against several dozen other stations.

KDMO signed on in the 1940s. Current owner Ron Petersen Sr. bought it from his mother a few years after she purchased it in 1962. In 1979, the stations moved to their current studio location in Carthage. In 1989, the station moved its transmitters to a site about three miles west of the studio.

After 31 years, the studios were ready for an update. Small upgrades were made over time, but the aging Autogram consoles and years of wiring updates had seen their better years. For the owner, a complete infrastructure rebuild made the most sense. The owner's son and station manager, Ron Petersen Jr., began working with station Chief Engineer (and AM morning man) Glen Rowe and contract engineer Lee Wheeler to lay the plans for a rebuild.

The KMXL-FM studio is the same as the production and AM studios, with the addition of a reel-to-reel.

The KMXL-FM studio is the same as the production and AM studios, with the addition of a reel-to-reel.


First steps

The first upgrade was made in 2009 when the stations replaced the Broadcast Electronics AV100 automation with Audiovault Express. In February 2010, the heavy work on refurbishing the studios began. The biggest change for the stations was to migrate to a networked audio infrastructure. To do this, the Wheatstone Evolution series E-4 consoles and WheatNet-IP blades were chosen as the backbone. In addition, new Vorsis M1 mic processors, Heil PR40 mics and Designcraft furniture were purchased.

Because this was an in-place upgrade, the old studios would be shuffled while new studios were built. It seems the old consoles knew their retirement was imminent because the number of equipment problems increased as the project unfolded. From February to June, the two stations stayed on the air without interruption. To start, the FM was put on the air from the production studio. The FM studio (in the middle of the three) was rebuilt. Once the FM was completed, the AM moved to the new FM studio so the AM studio could be rebuilt. Once the AM studio was finished, the AM moved home, the FM moved to its new home and then the production studio was rebuilt.

Except for an added mic, the production studio is identical to the AM studio.

Except for an added mic, the production studio is identical to the AM studio.


The old system of switching studios with Bud box-mounted switches was slowly replaced by mouse clicks. The WheatNet-IP Navigator software sets up the audio routing paths and now makes it very simple to switch studios and feeds when unique changes are required.

The original design layout from 1979 had each studio acting as a separate island. STL transmitters and other equipment were located in individual studios. While the two-station combo didn't require a dedicated master control, one rack was placed in the AM studio, which is slightly larger than the other two. This rack houses the STLs, some processing, modulation monitor and some switching equipment for the operation.

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