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User Report: BluePack Enables Cell Connections

JK Audio Solution Helps Reporters, Hosts and Engineers Connect With Studio

PITTSBURGH Airing weekly since 1978, “The Saturday Light Brigade” (SLB) is a radio program for children and adults carried on seven regional public radio stations in Pennsylvania and Ohio from 6 a.m. to noon on Saturdays. The program originates in Pittsburgh, home to hundreds of family-friendly cultural institutions and attractions. SLB often broadcasts from these places to keep our program lively and serve the community.

For program-length remotes, we typically use ISDN, POTS or IP-based codecs. While this approach works well, it has the drawbacks of (1) acquiring or taking over a communications line at the site, (2) advance testing, (3) fixed wiring and (4) having an extra engineer or technically-savvy host on duty at the remote site.

The author uses the JK Audio BluePack at a remote location to connect with the studio. In short, the solution frequently is overkill for simple delivery of voice interviews from the field and, were it the only option, would cause us to turn away brief appearances at events. The workload simply is not justified.


One past attempt to right-size this activity was to send a field reporter out with a cell phone for cut-in interviews. He would hand the phone to the interviewee, who would then be interviewed by the program host from the studio.

Without eye contact, interviews were often not as sharp as they could be. Moreover, the mics in even the best of cell phones are not designed for this purpose nor are their earpieces designed to monitor return audio. We set out to find an affordable interface that would essentially turn a cell phone into a field interview kit.

Key features for us were quality, ease of use, ruggedness and size. We found that the JK Audio BluePack Wireless Interview Tool exceeded our expectations.

After opening the box, I was impressed with the build quality. The metal case is rugged and fingerprint- and scratch-resistant. The jacks and controls have a solid feel.

> The potentiometers are countersunk nicely to protect them from accidental movement. They also have a solid resistance that provides the user with assurance that the selected level will not inadvertently be altered. Also, in this regard, the numbered indices on the pots let the user remember the preferred settings.

For some tests, I used a Sennheiser e835 microphone, AKG K240 Studio headphones and an AT&T 8525 cell phone (G3 service) calling into a Telos One-x-Six phone system. Out of curiosity, I also connected the BluePack unit’s stereo line output to a Zoom H2 Handy Recorder handheld digital recorder to archive the interview and test the device for use as an off-air phone call recorder.

Before heading into the field, I plugged the mic and headphones in and simply listened. I found a surprisingly quiet preamp yielding clear sound from the microphone, especially for an application where corner-cutting might be justified given the ultimate destination of the audio. The red clipping LED was accurate and helped me find the right microphone volume level.

Pairing was simple. I pressed the blue multifunction button on the BluePack unit and the phone immediately recognized the unit by make and serial number. Easy-to-decode flashing patterns on a blue LED display provided assurance that bonding had been achieved without having to look at the cell phone.

I then placed a call from the telephone to an incoming studio line. Our reporter strolled the 40,000 square-foot Children’s Museum and interviewed children and adults. Both the reporter and his subjects were clear and consistently modulated. Sitting in the studio, I did not need to ride gain to compensate for inconsistent feed volumes or noisy connections. As the reporter and I engaged in conversation, we could hear each other well. Cues sent to him through our mix-minus bus did not interfere with on-air audio.


I was curious about introduction of RF noise from the telephone and asked the reporter to move the phone near the BluePack unit, headphones, mic and cables. The only interference detected was when the phone was placed several inches from the microphone, an unlikely scenario.

While on the subject of Murphy’s Law, readers might be curious about whether the cell phone mic mutes when the BluePack unit has been bonded. We mused about this, too, and the answer is as one would expect from a well-designed product: Of course it does, as does the phone speaker.

On return to the studio the reporter noted how confident he felt with the unit.

Perhaps counterintuitive to those unfamiliar with Bluetooth, achieving a the cell phone-interface bond via Bluetooth is ultimately far simpler and more reliable than the headaches associated with selecting from a menagerie of 2.5 mm, 3.5 mm or proprietary USB-style connectors to achieve a hardwired connection that, regardless of cable quality, always seems to come loose or audibly wiggle.

Once the Bluetooth bond is made, our reporter comfortably walked through areas full of children and confidently did his interviews while the BluePack unit and cell phone handled the transmission flawlessly and the H2 recorder archived the results.

Which brings us to the BluePack unit’s extra stereo line out. This little extra actually is a powerful value-added feature.

Per the JK Audio design, the left channel of our recorder captured the microphone directly from the preamp while the right channel captured caller audio, both of which sounded great. Why is this powerful?

For one, this nifty feature allows the device to be used to record telephone interviews (without a mix-minus, hybrid or control board) and apply post-production to the individual channels to create a great final mono mix.

Moreover, when we send a field reporter out to interact with an in-studio host, recordings can be made on both ends of the conversation and subsequently edited to yield full bandwidth archives for rebroadcast or to deliver to a client sponsoring the remote.

While some may be concerned about options such as AC power, limiter circuitry, multiple mic inputs or the ability to use noncellular or corded telephones, I found this unit to have the right features to yield simple, high-quality results.

Moreover, it’s fun to use ā€” which means it will be used. That factor alone makes the device worth every penny.

For information, contact JK Audio at (815) 786-2929 or

Larry Burger is executive director for SLB Productions.

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