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

December 1, 2010


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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An AM/FM pair in southwest Missouri rebuilds right

A single rack in the AM control room houses the STLs, some audio processing and other central operating equipment.

A single rack in the AM control room houses the STLs, some audio processing and other central operating equipment.


Quick turnaround

The four-month turnaround was an orchestrated effort. As wire was pulled and furniture placed, sound treatments and wood flooring were completed. Despite the fast pace, Lee Wheeler still took the time to label every wire. Rather than develop a labeling plan that uses a master guide or book, Wheeler chose to label the end of each wire in plain English. P-Touch labels were applied and covered with clear heat shrink. This makes it easy for Wheeler, Rowe or anyone else to diagnose problems or make changes when necessary.

After 30 years, there was plenty of old wiring in place as well: some audio, some voltage. Nothing was clearly marked. The rebuild was also a chance to remove all the old wire and start fresh. As old wire was removed, cables were cut one by one to ensure a station was not taken off the air. For the IP audio needs, CAT-6 cable was used throughout the facility.

The two under-counter racks are mounted on slides to facilitate equipment access.

The two under-counter racks are mounted on slides to facilitate equipment access.


While the previous studios placed the console against a wall, the new studios' consoles are in the middle of the room so guests can sit around the end island. The new design also places the two racks below the counter on the side against the wall. To facilitate equipment access, these racks are on rollers and can be pulled forward to access the back of the equipment.

Although an overall internal remodel was undertaken, there was one element left in place. The building has Carthage marble placed on the lower half of the walls all around the facility. Rather than cover this unique building material, which is common in the area, it was left exposed. The floor is also covered in marble, but carpet was installed in the hallway to help control noise as well as provide a non-slip floor. Hardwood flooring was installed in the studios.

Wire labels make it easy to identify the function of any cable.

Wire labels make it easy to identify the function of any cable.


The original pressed-tin ceiling is also still in place, but it is covered by the dropped ceiling for better acoustics. The mix of wood, carpet and acoustic tile provides a studio with a little ambience.

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An AM/FM pair in southwest Missouri rebuilds right

Cable access in the studio is hidden behind panels below the console.

Cable access in the studio is hidden behind panels below the console.


Future planning

Redundancy was a key factor in the rebuild plan. There was some level of redundancy in the old studios, but it was far from easy to use when needed. This redundancy starts in the Audiovault Express servers. Each room has a server, and each station's audio is copied to the other systems. The IP-audio system also allows every source to be available on any console surface, and any studio can feed either transmitter.

The three rooms are also nearly identical. The AM and production studios are the same layout, while the FM studio is a mirror. Each studio has three monitors that show the audio editor, Wheatstone status/meters and Audiovault.

While all the audio is stored and played from the Audiovault, there are three reel-to-reel machines still in place for occasional use. One local program is archived on reels, so they are mainly for transferring that archive into the Audiovault. There are rare occasions when audio is sent on reel as well. A cassette deck and CD player are also in each studio if needed, but see little use.

The store-front studios of KMXL and KDMO.

The store-front studios of KMXL and KDMO.


One eco-friendly upgrade is the studio lighting. Rather than use hot incandescent lights, the station opted for LED lighting. Each studio has two lighting tracks with six lamp modules. Each module uses 3W, for a total lighting draw of 18W. Despite the low draw, the rooms have plenty of lighting for regular use. For additional work light there are recessed incandescent light fixtures in the corners if needed, but they are rarely used.

The complete facility occupies three adjoining store fronts. Nearly one-third of the total space is dedicated to the studios. There is a fourth room that could be used for a studio later. Currently used by the station manager for his office, the walls are finished like the other studios and it faces the street.

While budgets everywhere are tight, it's refreshing to see a local owner reinvest in his efforts, and to do so in a way that shows a dedication to radio. The new studios of KMXL and KDMO are on par with studios in much larger markets, and they're built with the latest technology, which will let the stations keep a competitive pace for many years to come.


Equipment List
Yellowtec Mika
Wheatstone Evolution 4, ip88ad, ip88e, WheatNet-IP Navigator
Vorsis VP-8, M1
Telos 1A2 Interface, One
Syntrillium Cool Edit Pro 1.2
Samson Servo 1200
Sage Endec
RF Specialties equipment dealer
Radio Systems DA-4X4B
Omnimout speaker mounts
O.C. White mic booms
Moseley SL9003Q
Marti STL10
Henry Engineering Multiphones Minipod
Heil PR40
Gepco D61801EZGF
Designcraft studio furniture
Broadcast Tools ACS8.2+
Broadcast Electronics AV Express
Behringer B2031P
Audiovault Express
AirTools 6100


More photos, including shots of the studios before the remodel are on page 4.



An AM/FM pair in southwest Missouri rebuilds right

Looking up the tower

Looking up the KMXL tower


transmitter site

The transmitter site for KMXL.


The KDMO studio before

The KDMO studio before


The KMXL studio before

The KMXL studio before


Production room before

Production room before


Production room before

Production room before



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