Comparison Denon AVR-X2500H vs Denon AVR-X250BT

In this case, the function of automatic adjustment of each individual sound channel in terms of level and delay is implied so that all of them together provide surround sound that best matches the intention of the creators of the film or musical composition. The need for such a setting is due to the fact that practically no room (neither residential, nor even specialized) is acoustically perfect: the sound propagation is affected by the wall material, floor covering, furniture (sofas, wardrobes, etc.) and other factors. Therefore, the technically correct arrangement of the speakers alone does not guarantee a full-fledged surround sound.

Typically, automatic tuning uses a microphone placed at the intended listening position. During the calibration process, the device outputs test sound signals through the acoustics and “listens” to the features of the sound through the microphone, if necessary, independently changing the audio parameters.

Such a function can greatly simplify the preparation for work — after all, the device will carry out the main part of the setup on its own. However, keep in mind that even in the most advanced receiver models, automatic calibration algorithms are not perfect. As a result, it is highly likely that the automatically set parameters will not meet the tastes of demanding audiophiles. In addition, the reliability of the calibration is also highly dependent on the characteristics of the microphone used — and options with high...sound quality can be quite expensive.

This function automatically adjusts the volume level of the sound when it changes abruptly. Such a need is associated, for example, with the fact that one film can contain both dialogue and intense special effects; as a result, at low volume, conversations can sometimes be hard to hear, and at high volume, the sound can periodically “beat on the ears” and disturb others. In addition, while watching TV, many have probably come across commercials that sound noticeably louder than the main programme. Automatic level control boosts the volume at low audio levels and lowers it at high levels, thus helping to avoid the discomfort of too loud sound while maintaining normal hearing.

Possibility to simulate multi-channel (for example, 5.1) sound in traditional two-channel headphones. For this, a Dolby Headphone decoder is usually used, which processes the sound in such a way that the sound heard in the headphones is perceived as multi-channel — in particular, the intended position of its sources can be determined much more accurately. And considering that modern Hi-Fi class headphones are not inferior in sound quality to acoustics (and are significantly cheaper), this feature may well come in handy even for demanding audiophiles.

The ability to increase the resolution of the video signal processed by the receiver - if the original video resolution is lower. Depending on the capabilities of the receiver, in particular its HDMI ports, upscaling to Ultra HD 4K and upscaling to Ultra HD 8K may occur.

The principle of upscaling is that a relatively low-resolution video is supplemented with the required number of pixels using special algorithms. Due to this, when playing such a video, the quality of the “picture” is noticeably higher than without upscaling (although somewhat lower than that of content originally recorded in UltraHD). It makes sense to specifically look for a receiver with this function if you plan to use it with a 4K or 8K screen.

The possibility of using the receiver for simultaneous transmission of signals from different sources to screens and speakers located in different places (zones). For example, in a large house, you can simultaneously stream a movie from a Blu-ray player to a screen in a large room, a TV show to a TV in the kitchen, and a radio programme to speakers in a library. Another option for using Multi-Zone is entertainment centers with several rooms of different types (for example, a cinema hall, a roller skating rink and a cafe).

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.

— 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.

This indicator determines the amount of extraneous noise that accompanies the sound output by the receiver's amplifier. It is convenient because it takes into account almost all possible significant noise — both created by the device itself and due to external causes. The higher the signal-to-noise ratio, the lower the noise volume compared to the main signal, the cleaner the amplifier will sound. A reading of 70-80 dB is considered normal for most consumer electronics, but in AV receivers, which are usually premium devices, this can only be called satisfactory. In the most advanced models, this figure can significantly exceed 100 dB.

The lowest impedance of the loudspeakers of the speaker system, with which the amplifier is able to work normally. The nominal impedance of the speakers, also referred to as the term "impedance", is one of the key parameters in the selection of audio system components: for normal operation, it is necessary that the speaker impedance match the characteristics of the amplifier. If the speaker impedance is greater, the sound volume will decrease significantly, if it is less, distortion will appear in it, and in the worst case, even overloads and breakdowns are possible. Therefore, in the characteristics of receivers, it is usually the minimum resistance that is indicated — after all, connecting a load of too low impedance is fraught with more serious consequences than too high.