Comparison Kenwood KDC-BT640U vs Kenwood KMM-BT356

Tape recorders with a shortened body.

In this case, shortened means a case that has a shallower depth than classic radio tape recorders equipped with CD drives. Due to this, such models are quite compact, which, in particular, simplifies installation and facilitates wiring. Of course, CD / DVD discs are not supported in principle by such radio tape recorders, but this is not a serious drawback — nowadays there are quite enough alternatives to such media. Also note that the shortened layout does not affect the mounting size (see above) — it can be 1 DIN or 2 DIN, and standard solutions are even larger.

Media types supported by the car radio.

— CDs. Support for optical discs usually assumes at least compatibility with CD, the ability to work with DVD is somewhat less common . For more information about these types, see "Disk Types". Here we note that nowadays, disks are gradually being replaced by more compact and functional media — in particular, memory cards and USB devices; so many modern radio tape recorders, including high-end ones, do not have optical drives at all.

— Memory cards. Ability to work with removable memory cards, usually SD or microSD; the module for reading them is called a card reader. This feature is convenient primarily because such cards are supported by many other devices — in particular, laptops and photo / video cameras. The card reader facilitates the exchange of data between these devices: for example, a selection of music from a laptop can be written to a memory card. Note that the specific type of supported cards needs to be specified separately — the (micro)SD format includes several varieties that are not quite compatible with each other.

— USB drive (front). The ability of the radio to work with external USB-drives — " flash drives ", hard drives, MP3 players, etc. — to pla...y content directly from them. In this case, it means connecting such media to the USB connector located on the front panel of the radio — it is convenient because the connector is in close proximity, right at hand.

— USB drive (rear). Connecting USB drives (see above) through the rear panel. However, the external device is connected not directly to the rear panel, but to an external USB connector, which, in turn, is connected to the rear panel with a cable. Such a connector does not take up space on the front panel, but you can place it on a shelf under the dashboard — and the connected drive will not stick out of the radio, but lie neatly on the shelf. But in standard radios (see above), the “rear” connection can be carried out a little differently — there the cable from the rear panel can be connected to the standard USB socket on the instrument panel using a special connector.

— Connecting an iPod/iPhone. The ability to connect portable devices from Apple to the radio — primarily iPods and iPhone smartphones — through a special docking connector. Even the simplest options for such a connection, in addition to playing music, provide a number of additional features — in particular, control of the player's functions (for example, switching a track) from the control panel or remote control of the radio itself. And the most advanced models have a proprietary CarPlay system; for more information about it, see "Control functions".

— Android connection. The ability to connect smartphones and other devices based on the Android operating system to the radio. Connection methods may vary: for example, some radio models support only a wired connection, others can use Bluetooth (see "Multimedia"). The same applies to the set of functions available in each case, this point should be clarified according to the manufacturer's official data. Specific features include direct playback of music from the phone (with control through the radio), working with the contents of its drive, watching videos, using the radio as a car kit for receiving calls, etc. And in high-end models, there is support for Android Auto smartphone integration technology; for more information about it, see "Control functions".

— Remote control. The radio has a remote control. This function will be convenient primarily for passengers behind the driver — from the rear seats you can’t reach the radio itself. In addition, remotes often have more keys than the stock control panel, which allows you to access various additional functions on the go without digging through the settings.

— Remote control on the steering wheel. Remote control (see above) with the ability to mount on the steering wheel. Such a remote control allows the driver to control the functions of the radio without removing his hands from the steering wheel and thus not being distracted from driving the machine.

— Control from regular steering wheel buttons. The ability to control the radio from standard buttons, originally provided on the steering wheel for this very purpose. This function is similar to the steering wheel remote control described above, with the adjustment that the "remote" in this case is built directly into the steering wheel. Before buying such a radio, you must definitely check its compatibility with a particular model of car.

— Smartphone control. The presence of software (application) that allows you to control the radio using a smartphone, tablet, etc. This is not just about switching songs on the phone, but a full adjustment of all device functions.
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— Voice control. The ability to control the radio using voice commands. The implementation of such control can be different: in some models, to activate it, you need to press a button, others constantly “listen” to the environment and immediately respond to code words. Anyway, this function allows the driver to control the radio without taking his eyes off the road, which has a positive effect on traffic safety. Note that in its pure form, voice control in modern radio tape recorders is becoming less and less common, being replaced by advanced technologies like CarPlay and Android Auto (see “Control Functions”), which also include voice functions.

— Apple CarPlay system. Support for car radio technology CarPlay. This technology is designed to connect portable devices from Apple to the radio, primarily the iPhone, although it is technically possible to work with any “apple” gadget that has iOS 7.1 or later firmware, as well as a proprietary 8-pin Lightning connector. Thanks to this technology, many smartphone functions (including the Siri voice assistant, navigation, call and message management, as well as music) are integrated into the radio; using them through on-board electronics can be much more convenient than holding the iPhone in your hands. At the same time, CarPlay puts special emphasis on safety: it is designed with the maximum use of voice control, so that the driver has to be distracted by the radio screen as little as possible. For example, the mentioned messages can be dictated by voice and listened to "performed" by Siri. The connection itself is carried out by wire, through the mentioned Lightning connector.

— Android Auto system. Car radio support for Android Auto technology. Similar to the CarPlay described above, this technology is designed to combine portable devices with on-board electronics of a car — only, as you might guess from the name, in this case we are talking about gadgets running the Android OS. When you connect such a gadget, the radio actually plays the role of an external display for a mobile device, with its optimized interface and related capabilities. Features available through Android Auto include navigation (including mobile device access to external GPS antennas and modules), music control, receiving and making calls, listening to and composing SMS, and searching the Internet. Android Auto is only available for Android 5.0 Lollipop and later; in addition, if the mobile device uses proprietary firmware, its compatibility with the radio needs to be specified separately.

The number of line outputs (see above) provided in the design of the radio. It should be noted that usually these outputs use RCA connectors (“tulip”), and the analog format allows only one audio channel to be transmitted through one such. Therefore, to work with a stereo signal, two RCA connectors are required, and just a pair of such jacks is considered to be one line output - a set designed for one set of stereo speakers. The main difference between this interface and the same RCA used to connect speakers (see above) is that the line output receives a signal from a preamplifier that is unsuitable for feeding to passive acoustics. Such a signal must be sent to active speakers or an external amplifier (whereas the speaker is connected to the output of a power amplifier designed for passive speakers).