Recently I decided to free the music trapped in my computer. MP3s, streaming WFMU, internet radio - all of it stuck where my computer is, in my office. Though I have a good set of digital speakers (Roland DM-2100, not pictured) hooked up to my Mac I wanted the option to hear its audio in other rooms. I thought first of running a long cable from the analog out on my computer to the kitchen, where my Teac radio/CD player (pictured right) has an auxiliary input. But that would be a RPITA (Royal Pain-In-The-Ass) and I doubt the signal would make it that far (25 - 30 feet) without serious degradation. I decided to try a wireless approach and bought an AirPort Express Base Station with Air Tunes. It's a wi-fi router that allows you to (among other things) "broadcast" anything playing in iTunes. There's an 1/8" stereo jack on it so you can patch it into your home stereo. But beware: you can't simultaneously send audio to your computer speakers. I patched it into the aforementioned Teac stereo and hated the results. Because my computer's CPU is situated under my all-steel desk I was experiencing lousy connectivity that caused many audio drop-outs. I even tried an expensive extender cable to move the computer's antenna from under the desk but it didn't help much. And the damn thing kept freezing up on me, needing constant re-booting. I decided to try a third approach that would take advantage of the dozen or so FM radios I have in my apartment: low-power FM transmission.
First I tried the small C. Crane FM transmitter I've used with my iPod and found it can throw a signal reliably in a ten-foot radius and that's it (you might get better results where you live but I'm in an area with lots of FM "competition"). I've used many of the commercially-available FM "sound feeders" from manufacturers like Belkin, Griffin, etc., and find them all to be fairly anemic and unsuitable for moving audio more than a few feet. What was needed for my purposes was something more robust. I began looking where all quests begin in the internet age: eBay. Searching on "FM Transmitter" brought up nearly 7,000 items, almost all of which are the aforementioned "sound feeder" type, good for use in the car or covering short distances in the home. A revised search on "FM Stereo Transmitter" came up with a much more reasonable 131 items, most of which are junk. But scrolling through three pages of results also reveals a few models by Ramsey, like the FM25B and the FM30. These are available directly from Ramsey Electronics as kits but if you're not good with a soldering iron you can buy an assembled version on eBay, usually for $15 - $30 more than the kit.
Checking the results further brought me to the transmitters from Landmark Audio Technologies, including the model I eventually purchased, the FM350 USB (left). As its name implies, it patches into a USB port on your Mac or PC and draws audio and operating voltage - no power adapter needed. The FM350 USB is easy to set-up (full instructions are included): choose your desired operating frequency (do us a favor and stay out of the non-commercial end of the spectrum, below 92 mHz), hook up the USB cable and "Part 15" legal antenna and tell your computer to recognize the FM350 USB as a pair of digital speakers. Before you know it your computer has become an FM station.
My first test was streaming Fool's Paradise via wfmu.org through iTunes. I hit on one of Rex's "bubbling" mic. breaks and it sounded so right coming through the green rubber Lexon in my shower (the first test because it may be the most important radio in my apartment). Next I switched on my second bathroom radio (yes, even in my tiny W.C. I've got two radios). Again I was amazed to hear WFMU loud and clear in my apartment. My building is located in a "reception trough" and I barely get WFMU over the air but here it was, coming through every radio in my house: the kitchen table Tivoli Model One, the Beach Boy I got from Miriam at Norton Records, the SABA 300 in my office and even my tiniest radio, the Precision PS-700 purchased at the Meadowlands Flea Market. All I needed to do now was get the audio back to my desktop speakers, the Roland DM-2100 speakers mentioned earlier. Roland thoughtfully provided two inputs, each adjusted by its own volume control, so I connected a Tivoli PAL to the second input (the first is patched to a TV's audio) and I now have the same strong low-power FM signal carrying WFMU to my desktop.
The FM350 USB is a very "musical" transmitter, smoothing out my computer's audio and giving it back it's "radio-ness". It's also available as the FM350-U (right), which has an AC power supply and uses RCA jacks so it can be hooked up to any kind of audio device (it comes with an RCA- to-1/8" adapter cable). I've got it connected to my satellite radio receiver and it moves that audio through my place on a different frequency from the FM350 USB (one caution: using these devices might create interference to nearby radio users, so be aware). All I have to do to switch between the output of my computer and my satellite radio is turn a tuning dial.
If you need to move sound around, definitely look into low-power FM as an audio distribution option. Why not take advantage of all the radios you now own?