Telephone Remotes the JK Way

Appeared in Radio World 8/20/97
by Alan R. Peterson

The JK Audio way to do remote telephone broadcasts includes two portable mixers that work over POTS lines: the RemoteMix C+ and RemoteMix 3. These are not high-tech rocket-boxes that digitize, quantize or ISDN-a-size. They are simple, straightforward, well made interfaces/mixers that send telephonic audio back to the studio from the ball park, county fair or scene of the fire.

Both are self-contained, two-channel mic mixers with built-in DTMF keypads, headphone amps and modular connectors that jack directly into typical RJ-11C phone sockets. All in heavy black steel cases less than 7 inches wide.

With fax/modem adapters (available at cellular phone dealers), the RemoteMixers will work with most cellular telephones. The RemoteMix 3 has a three-position slide switch to select analog, digital or multi-line phones to connect.

One more time

The original RemoteMix C+ was redesigned into the new RemoteMix 3, following customer feedback and a preliminary RW review early last year.

The engineers and designers put some good thought into both of these little mixers. They have RCA connectors to accommodate cassette decks; users can talk up a prerecorded interview, then play it right into the mixer. A balanced line-level XLR jack connects the RemoteMix to pro boards and high-quality recorders.

The steel chassis feels solid and does not flex under finger pressure when dialing a number on the built-in keypad. And where many remote mixers have feeble keypads, this on feels serious.

There is a battery test button on the front panel, and a wallwart supply is included with the mixer. A ringer can be switched on and off at will. A 10-turn pot adjusts hybrid null to balance send/receive levels. Mic inputs are for dynamic mics; there is no provision for phantom power.

Testing

Lacking high school sports during early summer, we tested both RemoteMix units under more controlled conditions. Another phone was called from the RemoteMix and both sides of the conversation were monitored and recorded.

DTMF tones were clean and stable, and at the proper level to be "heard" by the phone company. A Dial/Hangup rocker switch on the top of the unit controlled the telephone part of the mixer.

A Sennheiser 421 mic was tested on both mic channels. Sound was clean on both inputs, but preamp noise was present on the original C+ unit. Mic signals tended to get clippy on loud passages, but this happens to nearly any mixer driven hard.

The null circuit, while not a true mix-minus, worked effectively. We did not need to readjust the balance, but if it had become necessary, the 12-page manual explained how.

There are two dials for Tape: Send and Receive. The user could easily grab the wrong one when mixing, so JK Audio gave the knobs different colors.

Two 9V batteries will power the RemoteMixer for 36 hours. They will quickly go soft if headsets are paralleled or run at excessively high levels. Also, the power switch is easy to forget when the broadcast is over. The batteries will continue to chug along and will not be there the next time you need the mixer. Use battery power sparingly and run off the AC adapter when you can.

Ch-ch-changes

My impressions about the original RemoteMix C+ included an observation about construction. It was efficiently made while not being shabbily built. A smeared legend screening and a dimply basecoat on the earlier version caught my eye, but both have been resolved on the new units. I noted noise in the original unit's mic preamp and headphone channel. This has been made better in the newer unit.

The earlier mixer had one headphone jack, and JK recommended a Radio Shack splitter for a second set of phones. Since then, a second jack has been added.

The C+ had no way to visually monitor signal level. I suggested a green/red clip 0 LED because I thought there was no room for a meter. JK proved me wrong and found enough space to put in a VU meter.

In fact, JK found room for a lot of things. The top panel now includes a talk-back button, a speaker and a switch to turn the keypad on and off. The panel is rather busy but easy to maneuver around.

My favorite improvement had to be the bushing added to the screw on the battery compartment door to keep the screw from falling out. The earlier box lacked this feature, guaranteeing loss of this screw less than an hour after purchase.

Conclusions

Stations always need a portable, no hassle telephone mixer at times. Both RemoteMix devices fit the bill nicely. Both are small and durable, have the phone built right in and work well. With a tiny headset/mic combo, your field package might fit into a fanny pack.

Maybe you won't want a talkback button. Perhaps you wish to have the keypad left on at all times to send DTMF tones back to the station to activate a recorder. Possibly a meter is not necessary for your needs. Having a choice of two boxes means you can get only the features you know you will need.

A suggestion: the RemoteMix comes in a cardboard shipping box. Keep it to transport the mixer when doing your road show or invest in a carrying case (see related article, pg 58). Besides keeping crud out of the circuitry, it minimizes the risk of your striking the device against a corner and shearing off the shaft of a pot. Location broadcasts are not known for gentle treatment of gear.