Product Roundup: FM transmitters

Judging by Apple’s silhouette advertisements, you’d think the iPod was tethered only to slim youths devoted to dance. Not so. The world’s most popular go-anywhere music player is increasingly going everywhere in people’s automobiles. After all, where better to kill time listening to your favorite music, audiobooks, and podcasts than in a ceaseless traffic jam?

Yet placing an iPod in the car requires more than the will to do so. Because it’s unsafe (and illegal in most places) to listen to your iPod with headphones while driving, you must find a way to plumb the device into your car stereo. A direct connection via the dock connector or headphone port to an auxiliary input on the car’s audio head unit provides the cleanest sound, but not all head units include such inputs, and replacing them or adding an input via an external box can be expensive.

Cassette adapters can provide decent sound, but they can also be finicky—working perfectly in one cassette player and not at all in another. Plus the number of new car stereos including a cassette player is dwindling fast.

That leaves FM transmitters, devices that act as short-range FM radio broadcasters. Plug your iPod into one, tune your FM radio to an open (unused) frequency, switch the transmitter to that same frequency, and unsullied sound streams seamlessly from iPod to stereo. At least, that’s how it’s supposed to work. All too often, many of these transmitters are overwhelmed by more powerful radio signals or, well, whelmed just enough to make listening an unpleasant, static-filled experience.

How to tell the good from the not-so? That’s what we set out to learn by testing 30 of today’s more popular FM transmitters, ranging in price from $20 to $100. These devices offer a variety of features: Bare-bones models include a single stereo cable running to a flimsy-looking, AAA battery-bearing box that broadcasts to only a few frequencies. Others sport power connectors, transmit to more stations than are found on most radios, and, in one case, project track title information to the head unit of compatible car stereos.

Testing

Testing FM transmitters can be difficult because there are so many variables: How choked are the FM airwaves with competing signals in your area? How sensitive is a particular car’s antenna to the transmitter’s signals (and to outside interference)? How does shifting the position of the transmitter in the car change its performance?

Because we can’t ride in every car, equipped with every possible combination of head unit and antenna, in every location on earth, I set up a fairly simple testing procedure. First, I chose a 1996 VW Bug with a stock head unit as our test vehicle. I chose the Bug specifically because, from past experience, I knew that its radio is not forgiving of FM transmitters—only the most robust transmitters provide a clean signal when used with this car’s stereo. Anything less results in hiss and interference. If a transmitter performed well here, it should (fingers crossed) perform well anywhere.

I then chose a series of test frequencies. For transmitters that broadcast to the entire range of the FM frequency, I tested on 90.1, an “open” FM frequency not used by a radio station in our test area, and 107.9, a frequency inhabited by a local station with a strong signal. For those transmitters that broadcast outside the normal U.S. FM band, I also tested on 87.9, a frequency offered on some car radio’s (including the VW’s).

Some transmitters broadcast to a more limited number of frequencies—typically 88.1 to 88.9 and 107.1 to 107.9. With these transmitters, I used 88.1 as our “populated” frequency (or 107.5 if the transmitter didn’t support 107.9) as well as the “open” 88.7.

I performed the tests with a 5G iPod and a 4GB iPod nano. For those transmitters that accommodate both kinds of iPods, I tested each to be sure that one iPod model didn’t produce different results than another. (For the most part, they didn’t.) In those cases where a particular transmitters was designed for a particular iPod, I obviously used the appropriate iPod model for the tests.

Where possible, I moved the iPod and transmitter around in the car to try to improve its performance. For some transmitters, that wasn’t possible, as they were necessarily chained to the car’s cigarette-lighter receptacle or jammed into a cup holder.

Finally, I conducted the initial round of tests in my driveway. I then tooled around with those that had performed the best to see how the better transmitters performed in different locations. The tool-around test helped reveal subtle differences between these transmitters.

Features

The transmitters I tested vary in their range of features. Some broadcast on a very limited number of frequencies while others can access more frequencies than your radio can play. Some connect to the iPod’s headphone jack, wherease others use the iPod’s higher-quality dock-connector port instead. Most allow you to store and recall presets for easier navigation, but a few don’t. And some let you switch between stereo and mono broadcasting—a feature that can help the transmitter drown out competing frequencies, and achieve longer range, at the expense of true stereo sound.

Although I appreciate some of these extra features, my main concern was sound quality: Does the transmitter offer a clear signal? If not, all the features in the world aren’t going to make it a good choice. Our ratings are based largely on how a transmitter performs in this regard—for this reason you’ll see many 3-Play ratings, as many of the transmitters were average performers. If they were also easy to use, that was worked into our scoring.

Of the possible “extra” features, those that offer the greatest benefit include:

  • The ability to tune outside the normal FM band—specifically 87.9. “Regular” radio stations can’t use this frequency, thus ensuring that you’ll always have an open frequency to work with.
  • The ability to output a stronger mono signal.
  • The ability to store presets. Unsafe though it may be, you’ll be tempted to change frequencies while driving as interference kicks in. Far better that you push a button to switch to a clear station than take your eyes off the road and try to scroll station-by-station through the frequencies.
  • A dock connector connection. The iPod’s dock connector port puts out a cleaner, line-level audio signal than does the headphone port.
  • Cigarette lighter power. (Yes, we understand that the politically correct name for this 12-volt port is the “auxiliary power receptacle,” but everyone on earth know what you’re talking about when you refer to this receptacle as the “cigarette lighter port.”) Being able to charge the transmitter and iPod from the cigarette lighter ensures that you needn’t charge your iPod before taking it on a trip and saves you routine trips to the store to purchase AA or AAA batteries for your transmitter.
  • FM Transmitters for iPod

    Vendor Product Type Price Rating
    ABT iJet for iPod nano Anywhere $70 3.5 Play
    Belkin TuneBase FM for iPod nano Auto only $80 3.5 Play
    Belkin TuneBase FM for iPod Auto only $80 3 Play
    Belkin TuneCast II Anywhere $40 2.5 Play
    C. Crane FM Transmitter Anywhere $70 3 Play
    Digiana Audia X iTube-201 Auto only $75 3 Play
    DLO Transpod Auto only $100 4.5 Play
    DLO nanoTune Anywhere $70 3 Play
    DLO TransDock micro Auto only $70 4.5 Play
    Griffin Technology iTrip (Dock Connector) Anywhere $50 4 Play
    Griffin Technology iTrip nano Anywhere $50 4 Play
    Griffin Technology iTrip Auto Auto only $70 3.5 Play
    Griffin Technology RoadTrip Auto only $90 3 Play
    CTA Digital 3 in 1 Car Kit Auto only $35 3 Play
    i-Rocks i-Pod/MP3 Car DJ Auto only $35 3 Play
    iRock Beamit (410FM) Anywhere $20 3 Play
    iRock Beamit (440FM) Auto only $30 3 Play
    iRock iRock 450FM Anywhere $40 3 Play
    Kensington FM Radio & Transmitter for iPod Anywhere $80 3 Play
    Kensington FM Transmitter/Auto Charger for iPod Auto only $60 3 Play
    Kensington Digital FM Transmitter Auto only $80 4 Play
    Kensington Pico FM Transmitter for iPod Anywhere $55 2.5 Play
    Kensington RDS FM Transmitter/Car Charger Auto only $90 3 Play
    MacAlly iceFM Auto only $30 2.5 Play
    MacAlly FM Cup Auto only $60 3.5 Play
    Radian Technologies iBlast FM for nano Auto only $50 4 Play
    Sonnet PodFreq Anywhere $100 3 Play
    Sonnet PodFreq nano Anywhere $100 3.5 Play
    Virtual Reality Sound Labs MP3 WMA FM Modulator Auto only $35 4 Play
    XtremeMac AirPlay 2 Anywhere $50 2.5 Play

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