Comparison LG CM-2760 vs LG CM-2640

Tuner support for Radio Data System technology. This technology is used mainly in the FM band; it allows, in addition to the sound signal, to transmit additional textual information by radio — for example, the names of broadcast compositions, announcements, advertising messages, etc. For RDS-enabled audio systems, this information is shown on the display.

Nominal sound power (see "System power") on each of the main channels of the audio system. This indicator is most often indicated in models with a subwoofer (see "Number of channels"); knowing it, you can estimate the power distribution between the main speakers and the subwoofer.

The term "impedance" refers to the resistance of a speaker system to alternating current. Note that in the case of audio systems, this parameter plays a secondary role: it is important for selecting acoustics for an amplifier, and here both of these components are in most cases optimally matched by the manufacturer to each other. Therefore, in fact, information about the impedance can be useful only when looking for speakers to replace the complete ones: it is highly desirable that the new acoustics have the same impedance as the standard ones.

The total frequency range reproduced by the acoustics of an audio system. Measured from the lower threshold of the lowest frequency speaker to the upper threshold of the highest frequency: for example, in a 2.1 system with main speakers at 100 – 22000 Hz and a subwoofer at 20 – 150 Hz, the total value will be 20 – 22000 Hz.

In general, the wider the frequency range, the fuller the reproduced sound will be, the less low and high frequencies will be lost due to insufficient acoustic capabilities. On the other hand, do not forget that the actual sound quality also depends on a number of other parameters — primarily the frequency response. In addition, human audible frequencies range from 16 Hz to 22 kHz; deviations from these values are very small, and the upper limit also decreases with age. Therefore, from a practical point of view, it does not make sense to provide too large a frequency range; and impressive performances like 10 – 50000 Hz, found in top-class models, are usually more of a kind of "side effect" of high-quality speakers (and at the same time — a marketing ploy) than a really significant moment.

The phase inverter is a tube installed in the column housing and having an outlet to the surrounding space. The length of the tube is chosen so that a signal comes out of the outlet, inverted in phase relative to the signal from the front of the diffuser. This enhances the sound pressure and improves the sound of the speakers, including at low frequencies. Note that such audio systems should be placed at a certain distance from walls, furniture, etc. — otherwise, a hum may occur due to the movement of air through the phase inverter tube.

A similar function in some models is performed by a passive radiator (see below).

— RCA. The RCA interface uses coaxial cables, with characteristic "tulip" plugs, and the corresponding connectors. It can be used to transfer different types of data, however, in this case, it means outputting an audio signal in analogue format, one channel of audio per connector. RCA is widely used in modern audio technology, but its resistance to interference is very limited.

— Mini-Jack (3.5 mm). One of the standard connectors in modern audio equipment, it is widely used in portable devices, as well as for connecting headphones. However, we note that in this case we mean the jack responsible for the line output — an interface for transmitting an audio signal in analogue format to an external device, such as an amplifier. The headphone jack is listed separately in our catalog, even if it belongs to the 3.5 mm mini-Jack standard; See below for details on headphone output.

— Coaxial S / P-DIF. An electrical version of the S / P-DIF standard, using a coaxial cable with a “tulip” connector for signal transmission. Do not confuse this interface with the analogue RCA described above — despite the identity of the connectors, these standards are fundamentally different: "coaxial" works in digital format and even multi-channel audio can be transmitted over a single cable. Compared to optical S/P-DIF, this interface is less resistant to interference, but more rel...iable because electrical cables are not as delicate.

— Optical. One of the varieties of the S / P-DIF standard is, along with the coaxial one described above. In this case, the signal is transmitted via a TOSLINK fiber optic cable. The main advantage of this interface is its complete insensitivity to electrical interference, while its capabilities are sufficient even to work with multi-channel audio. Among the shortcomings, it is worth noting the high price of connecting cables, as well as the need for careful handling of them.

— Subwoofer. A separate output for connecting an external subwoofer — a specialized low-frequency speaker. The use of such a speaker allows you to significantly improve the sound of low frequencies, make the bass powerful and rich, which general-purpose speakers are not capable of. Note that such an output can also be useful in systems with a built-in subwoofer — external "subwoofers" are in most cases more powerful and provide more options for adjusting the sound.

— Headphones. Separate headphone output. Most often, a standard 3.5 mm mini-Jack or 6.35 Jack is used for this purpose, but there may be other options — for example, a manufacturer's proprietary connector. Anyway, headphones can come in handy in situations where you need to keep quiet — for example, if you want to listen to music at a late time when others are already sleeping — or vice versa, in noisy environments when ambient sounds drown out the speakers of the audio system.

— Composite. The full-size composite interface includes three connectors — one for video transmission and two for left and right stereo channels. However, in this case, a composite output usually means only a video connector (the standard acoustics of the audio system are responsible for the sound, it usually makes no sense to broadcast it to a TV). Anyway, this output allows you to connect the audio system not only to the latest, but also to frankly outdated TVs. Its disadvantages are poor image quality and incompatibility with HD.

— Component. Output for transmitting video signal in analogue format. Outwardly similar to the composite interface described above, because also uses three RCA cables; however, in this case, these cables carry three components of the video signal (hence the name). The component interface is considered the most advanced among the popular analogue video standards, it provides the highest image quality among them and is even capable of working with HD resolutions. Among the shortcomings, it is worth noting the impossibility of transmitting sound — this will require a separate connection.

— S video. Analogue interface for video transmission. In some way similar to the component described above, since it also provides separate wires for transmitting video signal components; however, in this case there are only two of these wires. This, on the one hand, allowed us to limit ourselves to one connector instead of several, on the other hand, it slightly reduced the quality of the “picture” and limited the bandwidth, so HD is out of the question with such a connection.

— SCART. Universal audio/video interface using a characteristic large 21-pin connector (20 pins plus a rim around the connector). For a long time it was the standard for European video equipment, but today it is considered obsolete due to its low bandwidth and significant dimensions. Note that SCART can work with signals of different formats, which allows the use of adapters — in particular, for connecting external devices via composite and component interfaces.

— HDMI. Universal digital interface that allows you to transfer HD-video and multi-channel audio over a single cable. It is practically a standard for modern video equipment, in particular, it is present in most TVs. In audio systems, this type of output is used in the same way as the coaxial S / P-DIF described above — that is, to output the audio signal in digital form.