Comparison Panasonic SC-DM504EG vs Panasonic SC-DM502

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 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 corresponding connectors. It can be used to transmit different types of data, but in this case it is meant to connect an audio signal from a preamplifier in analog format, one audio channel per connector. RCA is widely used in modern audio equipment, but its resistance to interference is very modest.

— Mini-Jack(3.5 mm). Standard connector for most modern portable audio equipment. In audio systems, it is mainly used to connect such equipment — primarily pocket media players. It uses analog signal transmission, but its resistance to interference, like that of RCA, is low, and the quality may be even lower due to the fact that both stereo sound channels are transmitted via one cable.

— Coaxial S/P-DIF. An electrical variation of the S/P-DIF standard that uses a coaxial cable with a tulip connector to transmit the signal. This interface should not be confused with the analog RCA described above — despite the identity of the connectors, these standards are fundamentally different: “coaxial” operates in digital format and allows for the transmission of even multi-channel sound over a single cable. Compared to optical S/P-DIF, this interface is less resistant to interference, but more reliable, since the electrical cables are not as delicate.

— Optical. One of the varie...ties of the S/P-DIF standard — 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 for working with multi-channel sound. Among the disadvantages, it is worth noting the high price of connecting cables, as well as the need for careful handling of them.

— For microphone. Input for connecting a microphone to an audio system; can use different types of connectors (3.5 mm mini-Jack, 6.35 mm Jack, etc.). This function is mandatory for models with karaoke (see "Additional"), but can also be used for other purposes.

— Instrumental. Connectors used to connect musical instruments (acoustic or bass guitars, keyboards, etc.). Most often, they are made in the form of 6.35 mm Jack sockets. The audio signal from the pickups has its own specifics, so the instrument input is usually characterized by a higher input signal level and special impedance matching to ensure optimal sound quality.

The presence in the audio system of its own LCD display. Such displays may have different characteristics: in some models, these are the simplest indicators in which symbols are made up of separate luminous fragments (similar to how numbers are made up of separate “sticks” in the simplest electronic watch); in others — full-fledged matrices with an image formed from pixels. However, anyway, the display makes the control of the audio system more convenient and intuitive, because. can display various additional information — the selected signal source, track name, RDS data (see above), equalizer settings, error messages and much more.

The ability to use the audio system to charge devices connected to it – pocket audio players, mobile phones, etc. For this usually a USB port is used (microUSB or USB-C in modern models); some models are able to play music from an external gadget right in the process of charging.