DM Engineering Audio-Pod

January 1, 2009

Engineers are always looking for problem solvers. If you're responsible for engineering remote broadcasts, the Audio-Pod from DM Engineering is one such problem solver.

As our ability to deliver high quality remote broadcasts from just about anywhere has developed, morning shows, sports discussion shows, political talk shows and the like are moving out of the studio and into the field. And while these are technically remote broadcasts, show hosts and their guests need the same amenities they have in the studio. Engineers meanwhile are more pressed for time and looking for ways to provide those amenities while simplifying and speeding the remote setup. That's where the Audio-Pod system really shines.

The Audio-Pod system includes up to four Audio-Pod modules and a power supply capable of powering four modules. Power hookup to each module is via standard eight-pin PS2 style cables and 10' cables were supplied.

The Audio-Pod system combines several tools into a sturdy plastic case. The microphone section includes a low-noise preamplifier with a rear-panel variable gain control that can be adjusted to any level from microphone to line output. Connection to the microphone input and output is via standard XLR connectors. There is also on-board switch-selectable phantom power. Large LED-lighted on and off switches are included with cough-mute logic integrated into the microphone on button. A small red LED is mounted on the top of the unit to indicate when the microphone is turned on. There is also rear panel output logic to drive external indicators. The microphone's on/off functions can also be remotely controlled.

Performance at a glance
Mic preamp and headphone amp
Remote control of all functions
Phantom powered mic input
1/4" and 3.5 mm headphone jacks
VCA-controlled headphone amplifier

The integrated headphone amplifier contains some interesting and useful features. First, the headphone gain is controlled by a voltage-controlled amplifier (VCA) and includes a rear-panel trimpot to set the maximum allowable gain. A small pushbutton switch is included to select between low and high impedance headphones. Another switch inverts the phase of the headphone feed 180 degrees. This is useful where bone conduction phase cancellation is an issue.

The headphone output is via standard ¼” and 3.5mm jacks located on the front panel. On my model, the headphone feed input was connected via a Euro style terminal on the rear panel.

Use on remote

WLOH presents a weekly one-hour talk show from a different business location each week. We use a POTS codec for these broadcasts and while our audio quality is good, each location presents its challenges. I have been using four microphones fed directly into a mixer with a built-in compressor. I decided to integrate the Audio-Pod system into this setup.

I adjusted the Audio-Pod's microphone gain for a -6dB output to feed the mixer's line inputs. For an average voice, this gave me a 3/4 fader position with plenty of gain available for the soft talkers. The Audio-Pod instruction manual mentions that the FET switching can be overloaded if excessive gain is used. I had no problems at all even when I turned up the preamplifier output to 0dB. Overall the sound quality of the microphone preamplifier is very good.

I fed the show host and producer's headphone input with a mix of the audio return (mix minus/IFB) from the station and the local microphone mixer. I fed the other two headphone inputs with the local microphone mix. The results were very good: The show host likes being able to control her own mic and headphone volume, and guests aren't distracted by the IFB audio. The red LED tally lights allow the producer to know which microphones are on or off.

Other applications

While I found the Audio-Pod to be a natural fit for remote broadcast applications, engineers will find this system useful in permanent installations where microphones and headphones are needed but not a complete audio console, such as a news-announce booth or a voice-tracking station. This would also be a very handy way to add on/off and cough switching to existing studios.

DM Engineering

While preparing this review, I had the opportunity to discuss some ideas with Dave Mandelbaum of DM Engineering. First, I asked about the bleed-through issue mentioned in the manual. He responded that under normal conditions this is not a problem. They only mentioned it because there is always someone who wants to get +20dB out of an amplifier.

I also inquired about the possibility of producing a version of the Audio- Pod without a microphone preamplifier for users that employ external microphone processors with a built-in preamp. I was told that the microphone preamplifier would be optional.

Regarding the headphone input connection, I told Mandelbaum that I thought the Euro style block takes away from the quick setup appeal of the Audio-Pod. My units were pre-production units, and he informed me that production units would have a 3.5mm input jack for the headphone input along with the screwdriver connection.

Mandelbaum also mentioned that optional mounting brackets would be offered for tabletop mounting that would hold the Audio-Pod module at an angle. Also, the microphone on and off switches can optionally be located on the top case of the module.

If you are looking for a way to improve your remote broadcast setup and make your show hosts happy, the Audio-Pod is a handy and cost-effective problem solver. DM Engineering has combined many of the studio features we take for granted and made them available virtually anywhere.

Bohach is co-owner/general manager of the WLOH Radio company, Lancaster, OH.

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