Comparison Onkyo TX-SR494 vs Onkyo TX-NR575

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.

Receiver support for HDR technology; this clause may also specify the specific supported HDR format.

HDR stands for High Dynamic Range. This technology allows you to expand the range of brightness reproduced simultaneously on the screen; to put it simply, the viewer will see brighter whites and darker blacks. In practice, this means a significant improvement in color quality: colors are more vibrant and at the same time more faithful than without HDR. However, to use this function, in addition to the receiver, a TV/projector that supports the appropriate HDR format and content recorded in this format is required.

In terms of specific formats, the most popular options these days are basic HDR10, advanced HDR10+, and high-end Dolby Vision. Here are their features:

- HDR10. Historically the first of the consumer HDR formats, less advanced than the options described below but extremely widespread. In particular, HDR10 is supported by almost all streaming services that provide HDR content at all, and it is also common for Blu-ray discs. Allows you to work with a color depth of 10 bits (hence the name). At the same time, devices of this format are also compatible with content in HDR10 +, although its quality will be limited by the capabilities of the original HDR10.

- HDR10+. Improved version of HDR10. With the same color depth (10 bits), it uses the so-called dynamic metadata,...which allows transmitting information about the color depth not only for groups of several frames, but also for individual frames. This results in an additional improvement in color reproduction.

Dolby Vision. An advanced standard used particularly in professional cinematography. Allows you to achieve a color depth of 12 bits, uses the dynamic metadata described above, and also makes it possible to transmit two image options at once in one video stream - HDR and normal (SDR). At the same time, Dolby Vision is based on the same technology as HDR10, so in modern video technology this format is usually combined with HDR10 or HDR10+.

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 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 range of sound frequencies that the receiver is capable of outputting (this parameter can also be specified for models without their own amplifier, see “Number of channels” for more details). The completeness of the transmitted sound depends on this parameter; of course, the sound quality in general is highly dependent on a number of other factors (for example, frequency response), but the wider the frequency range, the less risk that the amplifier will completely “cut off” some part of the sound. On the other hand, it should be taken into account here that the normal hearing range of the human ear is approximately 16 – 20,000 Hz, and deviations from these limits are rather small. And although many modern receivers provide a much wider frequency range, however, this is more of a marketing ploy than a really significant indicator (or some kind of "side defect" in the design of a high-quality amplifier).

It is also worth considering that in order to reproduce the full frequency of the amplifier, you will need speakers with the appropriate characteristics.

— AM/FM radio. The presence of a built-in tuner that allows you to receive AM and FM radio broadcasts without additional devices (except perhaps an antenna is required, and then not always). In FM, it is possible to realize the transmission of high-quality stereo sound, however, the waves propagate only within the line of sight (10-20 km); therefore, most of the stations in this range are classified as "urban music". In AM, the transmission range is already measured in hundreds of kilometers, but the sound quality is noticeably lower; therefore, such stations usually specialize in talk programs (particularly news).

— USB stick. The ability to connect a USB drive to the receiver — for example, a "flash drive" or an external hard drive — and play content from it directly. This requires a USB connector. Most often, in models with this function, it is located on the front panel (see below) — this provides ease of connection; at the same time, there are exceptions. Also note that the very presence of USB does not necessarily imply the possibility of playing from external media — this interface can be used for service purposes, for example, to update the firmware or play from a PC (see "Advanced (inputs) — USB Type B").

— Network audio streaming. The ability to play streaming audio over a local network or the Internet (including from services like Grooveshark o...r Last.Fm). The name "streaming" is due to the fact that each song is played directly from the network, without being written to the receiver's own permanent storage. This function, by definition, requires connection to computer networks; most often, a Wi-Fi module is used for this purpose (see "Interfaces") or a LAN connector.

— Internet radio. The ability to use the receiver to receive and play Internet radio broadcasts. This feature is similar in many ways to the network audio described above — in particular, it requires a network connection to work, and the data is streamed; however, in the case of network audio, the user himself chooses what and when to listen, here the broadcast is similar to conventional radio transmissions and is controlled from the radio station. Actually, many major stations broadcast their programs not only on the traditional air, but also via the Internet; There are also specialized projects broadcasting only on the Web. In general, the choice of programs is much more extensive than for conventional radio broadcasting — after all, Internet radio has no range restrictions. And the receivers themselves may provide additional tools for managing such broadcasting — for example, catalogs, search by genres, languages, etc.

Audio and video file formats that the receiver is capable of playing on its own. Models with player features generally support most popular media file types (particularly AVI, MPEG and MKV for video, MP3, WAV and WMA for audio), but the file set may have its own peculiarities. This item allows you to find out.