Sony MEX-BT5100

Forget add-on modules and external hands-free calling speakerphones. The easiest and cleanest way to make calls in the car is routing them through a built-in Bluetooth phone system. If you're among the majority of drivers who doesn't have a factory-installed calling system, Sony's MEX-BT5100 is a useful all-in-one stereo and Bluetooth calling system for the aftermarket. Retaining most of the features of its predecessor--the Sony MEX-BT5000--the 5100 combines an intuitive user interface, a straightforward menu structure, and a stylish faceplate design.

Design
The MEX-BT5100 features an elegantly simple design with a usable multidirectional joystick controller, a minimal number of buttons, and some snazzy brushed aluminum trim. The X-shaped motif on the left-hand side of the system shows that it is part of Sony's X-Plod line of car stereos. This joystick controller provides the primary interface for navigating phone menus, skipping and searching for music, and adjusting sound and volume. In contrast to a number of other similarly designed interfaces, the controller on the MEX-5100 is firm enough to resist tipping over when trying to make a selection, and has a solid feel to it. We also like the accessibility of the other controls including the prominent Source buttons situated closest to the driver, and the backlit phone and menu buttons that call up the system's intuitive menus. We like the way that the Menu button calls up different options depending on whether the system is in phone or music mode. All information is shown on the stereo's monochrome LCD display, which features a number of movie and wallpaper screen patterns and which we found a little too busy for our liking. A soft-open mechanical fold-down faceplate completes the picture.

Features and Performance
The MEX-BT5100 doubles as a music player and a hands-free calling device. To make calls, users have to pair their Bluetooth phone with the stereo, which is a very straightforward process requiring them to search for a phone using the head unit itself. Once the phone is found and connected, drivers can then import up to 50 contacts from the phone into the stereo's phonebook memory. It may just be that we have too many friends, but we found this limit to be unduly restrictive as it meant that we could not simply dump our entire contact list onto the stereo. With contacts copied to the MEX-BT5100, the easiest way of calling out is by using the Phonebook option. Navigating the call menu structure is pleasantly straightforward, and we are impressed with the speed at which the menu options appear and disappear once selected. We were less thrilled by the process of browsing through contacts once we got to the phonebook, which entailed a somewhat laborious process of notching through the contact names one at a time without the option for scrolling through by holding down the joystick.

We like the MEX-BT5100's phonebook transfer feature.

Other dialing options include selecting from call history (which is also copied over from the phone and can be called up on the screen), by assigning and then selecting a speed dial number via one of the six preset buttons, or by manually entering a number one digit at a time using the joystick, which is probably the most time-consuming method. With a call under way, sound quality is clear and even: an option in the call menu lets drivers choose the speakers through which the incoming call audio is played. From the other end of the line, sound quality via the MEX-BT5100's mic is also reasonably clear, albeit a little tinny.

The monochrome LCD display shows ID3 tag information for MP3 discs.

One of the best features of the MEX-BT5100 is the way it manages to integrate phone and music functionality into the same device while keeping the controls so simple. For audio sources, the stereo supports AM/FM radio, regular Red Book CDs, MP3, WMA, and ATRAC-encoded discs, and external sources via a rear-mounted auxiliary input. Those wanting to branch out can also invest in add-on modules for iPods and HD and satellite radio. When playing MP3 discs, the monochrome display can be configured to display a whole host of information including folder and track information, and tags for song, track, and artist information. While we like the ability of the system to display ID3 tag information, we are less impressed with the navigability of digital audio files, as there is no way to browse folder/song/artist information other than skipping through files one at a time. In partial mitigation of this, a one-touch shuffle function lets drivers play back discs in random mode. Like its predecessor, the MEX-BT5100 also comes with the ability to play audio streamed by the A2DP Bluetooth protocol.

The MEX-BT5100 features a user-configurable equalizer .

All audio plays out through the system's built-in amp producing four channel's worth of 17 watts (RMS) output. Base sound quality is adequate (if a little flat), but it can be enhanced with a number of audio-tweaking functions. These include a three-band equalizer with six presets and a customizable EQ setting, a low-pass filter for customizing low-end crossover, and Sony's Dynamic Stage Organizer (DSO) function, which throws farther up into the car's cabin. The DSO function works particularly well for compressed audio formats, giving the audio a fuller, richer sound. For those who want to add their own external audio components, the MEX-BT5100 features a volume control for a separate subwoofer as well as three preouts for external amps.

In sum
With a price tag of around $330, the MEX-BT5100 is not cheap for a single-DIN car stereo. Its integrated Bluetooth hands-free calling interface, however, makes it more than a simple audio receiver, and for those looking for a good-looking, intuitive all-in-one entertainment and communications device, the MEX-BT5100 provides a compelling option.

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