The maximum number of channels that the receiver can output to external speakers. This parameter is specified for all types (see above): even AV processors that do not have an amplifier as such are often equipped with a very extensive set of audio processing tools (and this set is sometimes even wider than in models with amplifiers).
The most popular options by the number of channels today are as follows:
— 2.1. The simplest option found in modern AV receivers is the classic two-channel stereo sound, supplemented by a third channel for a subwoofer. It is worth noting here that the "volume" of such a sound is very limited: it allows you to simulate the shift of the sound source to the left or right, but does not cover the space on the sides and behind the listener. Receivers of this kind are usually entry-level devices.
— 3.1. Such a system is usually the 2.1 described above, supplemented by a third front speaker — in the centre. This provides a more authentic sound from the front. And for some 3.1 systems, design tricks are claimed that allow them to be used for surround sound, similar to
5.1. Rear channels in such systems are simulated by reflecting sound from the walls behind the user. Of course, the sound accuracy is noticeably lower than that of a full-fledged 5.1, but this option may be optimal in tight spaces where there is no space for a full set of six-channel acoustics.
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5.1. The most popular surround sound format that can provide the effect of "environment". 5 main channels include a centre, two front (left-right) and two rear (similarly), a unit indicates a separate low-frequency channel for a subwoofer.
— 5.2. Sound format similar to 5.1 above, except for two channels for subwoofers instead of one. This improves the quality of the bass sound, which can be useful for films with a lot of special effects, live performance recordings, etc.
— 6.1. A sound format with an expanded number of main channels relative to the classic 5.1. The sixth main channel in this format is usually the centre back — this increases the accuracy of the sound transmission in the back of the stage.
— 6.2. 6.1 version of the format described above, supplemented by a second subwoofer; this improves the quality of low frequency transmission and allows you to cover a larger area.
— 7.1. With this sound format, five main channels (similar to the 5.1 system described above) are supplemented with two more. There are a lot of options for installing speakers for these channels — for example, these can be additional speakers above two front or two rear speakers, two separate side speakers, an additional “centre” pair on the rear channel, etc. Anyway, an increase in the number of channels makes it possible to achieve a more accurate transmission of “surround” sound compared to 5.1, however, much less content has been released for such systems.
— 7.2. A variation on the 7.1 format (see above) that allows the use of two separate subwoofers; this increases the accuracy of the transmission of low frequencies and expands the possibilities for their adjustment.
— 8.4. A specific variant found in single models of AV receivers. It is not so much a generally accepted sound format as an illustration of advanced configuration options: up to 8 main speakers and up to 4 subwoofers can be connected to the device, which gives very extensive fine-tuning options (however, such options are not cheap).
— 9.1. One of the most advanced surround sound formats today: it includes 5 classic main channels (similar to a 5.1 system) and 4 additional ones, the location of which can be different — for example, two side speakers and two upper ones above the left and right front, or even 4 speakers, directed towards the ceiling. The 9.1 format allows you to achieve very high fidelity of multi-channel audio transmission, but it is expensive, difficult to set up, and very little content has been released for such systems.
— 9.2. Modification of the above 9.1 format, supplemented by a second subwoofer for more accurate and high-quality reproduction of low-frequency sound.
— 11.1. Further, after 9.1, expansion and improvement of the idea of multi-channel sound. Usually in 11.1 systems, the five "classic" main channels (see 5.1) are supplemented with six more in the following way: two speakers to the left and right of the centre (in addition to the left and right front), two height speakers above the main front and two more — above main rear. This significantly increases the accuracy of surround sound transmission and adds the ability to shift it not only horizontally, but also vertically. However, the price and complexity of setting up such systems is appropriate, so they are designed more for the professional sphere (for example, cinema halls of entertainment centers) than for home use.
— 11.2. Systems almost identical to those described above 11.1, but supplemented by a second subwoofer. The latter is useful not only for reliability, but also for covering a vast area.
— 12.4. A top-of-the-line AV receiver option that is designed to handle all existing surround sound formats (including "true" 3D sound) and offers extremely wide customization options (albeit at an appropriate price).
— 13.2. Another format typical for luxury AV receivers and similar to 12.4 described above (with the exception of differences in the number of channels, which are not critical in this case).
— 15.1. A very rare and expensive option, designed for the use of mainly advanced acoustic systems — in particular, the halls of small cinemas.
Note that this paragraph indicates the most advanced sound format that the receiver is capable of working with; the general set also includes simpler options. For example, 7.1 systems usually handle 5.1 without any problems, not to mention stereo.
the
maximum sound power that can be delivered by the power amplifier (if the receiver has one, see "Type") per speaker channel. It is worth noting here that in this case it is customary to indicate the so-called RMS (Rated Maximum Sinusoidal), or rated power. Rated is considered the highest power that the amplifier is guaranteed to be able to produce without interruption for an hour without any failures or breakdowns. Short-term jumps in the signal level can significantly exceed this value, but the main indicator is still the rated power.
The power of the amplifier largely determines the sound volume of the speaker system connected to the device. In fact, the loudness also depends on the characteristics of the speakers — sensitivity, impedance, etc.; however, other things being equal, the same acoustics on a more powerful amplifier will sound louder. In addition, this parameter also affects the compatibility of the speakers and the amplifier — it is believed that the difference in the nominal powers of these components should not exceed 10-15% (and ideally, the powers should generally match). And since different rooms require speakers of different power, this also affects the choice of amplifier for a particular environment; specific recommendations on the ratio of room characteristics and acoustic power can be found in special sources.
Also note that if the amplifier can operate with a load of different resistance (
...see "Permissible acoustic impedance"), then for different options the power per channel will be different — the lower the resistance, the higher the power. In the characteristics, in this case, the maximum value of this parameter is usually indicated — that is, the power at the minimum allowable resistance.The number of balanced XLR inputs provided in the design of the AV receiver.
The XLR connector itself has several varieties and can be used for different signal transmission formats. However, in this case, a three-pin plug of a characteristic round shape is used, and the audio signal is transmitted through it in an analogue format. The peculiarity of a balanced connection is that the role of the noise filter in this case is played by the cable itself. This allows you to get a clean signal with a minimum of distortion, even with long wire lengths. Thanks to all this, the XLR interface is considered professional, it is used even in advanced studio equipment. And in AV receivers, the presence of such a connection indicates a high class device, even by the standards of Hi-Fi and Hi-End equipment (although XLR is not used in all high-end models).
In modern electronics, a pair of balanced XLR connectors is usually provided. This is due to the fact that only one channel of sound can be transmitted through one connector; thus, 2 jacks are needed for a stereo signal. However, XLR connectors, unlike RCA (see below), are often counted in pieces rather than in pairs; this is due to the fact that this interface is often used in multichannel sound systems, and there is no particular need to bind the counting to two stereo channels. The same counting principle is used in our catalog.
