Northern Community Radio Expands: An Engineer's Perspective

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The main studio for Northern Community Radio's KBXE-FM in Bemidji, Minn.

When Northern Community Radio set out to build a new community radio station in rural northern Minnesota 38 years ago, naysayers said that it would be broadcasting “only to a bunch of gophers.” That station, KAXE, is still going strong and in 2012 put another rural northern Minnesota station on the air, KBXE, with full studios, transmission plant and antennas on a new 500-foot tower. Operating at 50 kW, KBXE was needed to give permanence to a signal previously served by a translator in the commercial band. Designed to operate as a network of two with transmitters 87 miles apart, both KAXE and KBXE contribute programming to the common air signal delivered across a large swath of northern Minnesota. Programming for the small network will originate live in either the KAXE studio in Grand Rapids, Minn. or at KBXE located in Bemidji, Minn. and switch locations several times throughout the day. With the studio-to-studio link, some programming is originated with hosts at both locations simultaneously.

Studio Construction

It has been said that an engineer should return to the first studio he or she has built and apologize for the mistakes made. Having been a new engineer when the KAXE studios were first being built, there are some issues I let slip by that I am now less than pleased with. The studios had been architecturally designed and are beautiful, but there are acoustic problems that I was determined not to repeat. Operating with a finite budget for KBXE that did not allow for hiring acousticians and state-of-the-art noise isolation construction, I was able to use simple noise isolation techniques and work with a receptive general contractor. Studio walls were double-frame stud walls; studs offset, plates resting on closed cell foam, and filled with fiberglass insulation. Internet research showed that people had been obtaining good isolation results with two layers of 5/8-inch sheetrock on the inside walls treated between the sheets with a product called Green Glue []. One half gallon of Green Glue was used between each 4’ x 8’ sheet layer, extruded out from quart sized caulk tubes with conventional sheet rock screws binding the layers together. Once cured, I was very pleased with the noise isolation of the studio and production room walls. Homemade absorptive sound panels using 2’ x 4’ Owens Corning 703 fiberglass drop ceiling panels mounted in a simple pine frame and covered with cotton cloth painted by a local artist finished the rooms and dampened acoustic reflections. Sound-isolating windows into the studio and a visual communication window between air studio and the production room were made by sandwiching two double-pane argon filled thermal windows together with a large air space between, for a total of four panes of glass in each window. Mounted in butyl to restrict vibration, these inexpensive windows work well.

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