Comparison Denon AVR-X250BT vs Onkyo TX-NR474

A digital-to-analogue converter (DAC) is an indispensable element of any system designed to reproduce digital sound. The DAC is an electronic module that translates sound information into pulses that are sent to the speakers. The technical features of such a conversion are such that the higher the sampling frequency, the better the signal at the output of the DAC, the less it is distorted during conversion. The most popular option in receivers today is 192 kHz — it corresponds to a very high sound quality (DVD-Audio) and at the same time avoids unnecessary increase in the cost of devices.

Another indicator that determines the overall quality of the digital-to-analogue audio converter. For details on the converter, see "Audio DAC Sampling Rate"; here we note that the bit depth is standardly expressed in bits, and the higher it is, the more accurately the signal at the output of the DAC corresponds to the original signal and the less distortion is introduced into it. Today, it is believed that a 16-bit indicator provides quite acceptable signal quality, and 24-bit DACs are suitable even for premium-level equipment.

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.

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 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.