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One of the questions we often field as Car Tech reviewers is, "How do I get music and calls from my smartphone to play through my car's stereo without installing an aftermarket receiver?" That's a tricky one to answer, as every car's stereo is different. However, there's one thing that nearly every car audio system includes: an FM radio. This makes FM transmission the most universal way to connect a smartphone to a car stereo.
We're not the biggest fans of FM transmission technology--there are inherent limitations to its range, quality, and consistency. However, for many people, this low-tech solution is the only acceptable way.
The Gogroove FlexSmart X2 takes the FM transmitter and pairs it with Bluetooth connectivity for calls and audio streaming, giving the low-tech approach a high-tech makeover.
Controls and connections
Users interact with the X2 through a control knob and five buttons on the unit's face. The knob can be rotated to select an FM frequency and adjust volume. The control knob is pressed like a button to switch between the two modes. Surrounding the knob is a trio of buttons for toggling playback and pause of audio, skipping forward, and skipping backward. To the right of these controls is a monochromatic LED display that displays either the current FM transmission frequency or the selected volume level. To the right of the display is a pair of buttons for accepting and ending incoming calls. Farther to the right are two pinhole openings for the microphones used during calls. The X2's documentation makes no mention of noise cancellation technology being used by its microphones.
Rotate the X2 to reveal a single powered 5-volt USB port on the unit's edge that outputs 600mA of current. That's enough juice to charge most smartphones, including the iPhone and larger-screened Android phones. It probably won't fully juice your handset on your trip to the grocer's, but having access to a powered USB port does help combat the big Bluetooth battery drain. The X2 unit even ships with a pair of short USB cables (one Mini- and one Micro-) that you can keep in your car.
Over on the opposite edge of the X2 unit is a pair of 3.5mm analog audio connections. One is a line-level output that enables you to send audio from the X2 to a vehicle's auxiliary input. The other is a line input for physically connecting a device to the X2. Gogroove includes one audio patch cable for use with either port.
The X2 sits atop an 8-inch flexible stalk--putting the "flex" in the FlexSmart moniker--that can be easily bent and holds most positions. At the base of the stalk is a 12-volt connection with a built-in fuse for surge protection and a small power button. The power button itself had us a bit concerned when, on our second day of testing, it got stuck in the on position. With a bit of wiggling, we were able to fix its operation, but for the rest of the testing we elected to simply unplug the unit when we were not using it.
X2 wireless technology
The Gogroove FlexSmart X2 marries two wireless technologies: the high-tech Bluetooth and the pretty low-tech FM transmission.
Via Bluetooth, you can wirelessly pair the X2 with supported feature phones, smartphones, or portable media players with a four-digit PIN. (Yes, it's 0000.) When we attempted to pair the X2 with our HTC ThunderBolt 4G by Verizon, the handset was able to automatically complete the pairing process without the formality of the inputted PIN. Supported Bluetooth profiles include the Hands-Free Profile (HFP) for voice calls, the Advanced Audio Distribution Profile (A2DP) for streaming of audio and music, and Audio/Video Remote Control Profile (AVRCP) for basic audio playback controls.
The second piece of the X2's puzzle is an FM transmitter that outputs audio on the FM radio band, which can then be received by any FM radio that is within a short range and tuned to the proper station. Unlike most FM transmitters and radios that we've seen, the X2 can be set to transmit on both even- and odd-numbered stations, which potentially gives access to more open frequencies. These frequencies can be manually selected by rotating the control knob or an autotune feature can be used to automatically search for the cleanest open channel for audio transmission.
The combination of an FM transmitter, Bluetooth connection, and analog audio connections gives you three ways to use the X2 as a bridge between your handset and car stereo: Bluetooth-to-FM transmission, auxiliary-input-to-FM transmission, and Bluetooth-to-auxiliary output. We suppose that one could use the auxiliary input with the auxiliary output, but that just seems unnecessary.
Although we tested the Gogroove FlexSmart X2 in all three of its connection modes, the bulk of our testing was performed using it the way we think most consumers will: as a Bluetooth-to-FM bridge.
Pairing mode is initiated by pressing and holding the call button for 2 seconds. As mentioned above, our test Android phone was able to pair with the X2 automatically, skipping the four-digit PIN entry process. Once it was paired, we tuned the X2 to an FM frequency known to be empty, tuned our car's stereo to the same frequency, and hit play on our handset's MP3 application. As expected, music then played on our car's stereo. Of course, audio quality is limited to the lowest level in the chain, so in this configuration that meant the relatively low quality of the FM radio broadcast. Audiophiles will be severely disappointed, but for many people (including heavy podcast listeners) the ease of installation may be well worth the minor degradation in audio fidelity.
That said, the audio quality of the X2 we observed during bench testing was on par with some of the best FM transmitters we've tested. Your mileage may vary depending on how crowded the airwaves are in your area. In vehicle testing around hilly San Francisco, we found that a frequency that worked in one area of town was completely unlistenable in another, leading to a good deal of frequency changing as we ran our daily errands. This is an inherent weakness in all FM transmission technology and not a flaw in the FlexSmart X2's design.
To increase audio quality, we used the Bluetooth connection to output audio through the line output into our car stereo's auxiliary input. However, if your vehicle already has an aux-in, a $5 audio patch cable would yield even better quality than this $50 transmitter. If you're not looking to use the FM connection, this isn't the car audio option for you.
If you're no audiophile and you're simply looking for the easiest way to hear calls and music from your high-tech phone through the low-tech FM radio in your car, perhaps the Gogroove FlexSmart X2 is the stereo adapter for you. Its use of both Bluetooth and FM transmission wireless technology means that in most cases you can simply hop in your car, hit play, and go, without fumbling with wires or cradles. However, it includes connections and cables for the times that you do want to, for example, plug in and charge your phone.
There are a few weaknesses in the X2's design. The basic display gives no caller ID information, meaning that the phone's screen will need to be visible to discern incoming callers. Likewise, the lack of voice dialing means that you'll still need to use the handset when initiating a call other than a basic redial.
For a few bucks more, we'd recommend that prospective FlexSmart X2 purchasers also take a look at the Motorola Roadster, a visor-mounted device that offers the same capability of bridging FM and Bluetooth calls and audio, but also includes an internal loudspeaker and rechargeable battery for use outside the car, a superior noise-cancelling microphone with basic voice command, and integration with the Motorola MotoSpeak app for Android and BlackBerry.