Comparison Onkyo TX-NR656 vs Onkyo TX-NR646

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.

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+.

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.

- AirPlay. Technology for transmitting multimedia data via a wireless connection ( Wi-Fi). Developed by Apple, it is intended mainly for broadcasting content from various Apple devices (primarily portable gadgets) to compatible external devices. Allows you to transfer audio files (in audio streaming mode, see “Tuner and playback” for more details), as well as images, text data and even video. The presence of AirPlay in the receiver will allow you to connect Apple equipment with support for this technology to it for direct playback, as well as display information about files on an external screen (for example, a TV) - song name, artist name, etc.

- AirPlay 2. The second version of the AirPlay technology described above, released in 2018. One of the main innovations introduced in this update was support for the multi-room format - the ability to simultaneously broadcast several separate audio signals to different compatible devices installed in different locations. Thus, you can, for example, turn on the next episode of your favorite series from your iPhone on the TV in the living room, and relaxing music from your iPod in the kitchen, etc. In addition, AirPlay 2 received a number of other improvements - improved buffering, the ability to stream to stereo acoustics, as well as support for voice control via Siri.

- Chromecast.... Original name: Google Cast. Technology for broadcasting content to external devices, developed by Google. Allows you to transmit video and audio from a PC or mobile device to the AV receiver; broadcasting is usually carried out via Wi-Fi, while the receiver and the signal source must be on the same Wi-Fi network (with the exception of Chromecast media players). Chromecast technology supports two modes - actual broadcasting through special applications (available for Windows, macOS, Android and iOS) and “mirroring” content opened in the Google Chrome browser on an external screen.

- Wi-Fi. A wireless interface used primarily for building computer networks. Accordingly, AV receivers may need its presence primarily to implement network functions - streaming audio, Internet radio (see “Tuner and playback”), AirPlay (see above), DLNA (see below). Connecting to computer networks can also be done through a wired LAN interface(see below), but Wi-Fi is more convenient due to the absence of wires and the ability to work through obstacles (including walls) at a distance of several tens of meters. In addition, in some models, this technology can also be used to communicate directly with other devices - for example, to use a smartphone or tablet as a remote control, or to broadcast live video using Miracast technology or another similar format.

— Bluetooth. Direct wireless communication technology between various electronic devices; operates at a range of about 10 m, although some specific operating formats provide a longer range. Technically, it can be used for different purposes, depending on the protocols supported by a particular device; In AV receivers, two protocols are most often found - A2DP for wireless broadcasting of audio signals and AVRCP for remote control. In the first case, we are usually talking about transmitting a signal from an external device (smartphone, laptop, etc.) to the receiver; theoretically, the opposite option is also possible - broadcasting sound to Bluetooth headphones or acoustics, however, for a number of reasons, this format of operation is almost never found in AV receivers. AVRCP, in turn, allows you to use an external gadget (for example, the same smartphone) as a remote control.

- LAN. A standard interface for wired connection of various equipment (including AV receivers) to computer networks, incl. to access the Internet. Due to the presence of a wire, it is less convenient to connect than the Wi-Fi described above. On the other hand, a LAN connection wins in terms of connection reliability and actual data transfer speed - especially if there are many wireless devices on the network and Wi-Fi channels are busy (which is often the case, since Wi-Fi modules are very popular in modern electronics ). Therefore, for working with large volumes of data - for example, watching high-definition video via DLNA (see below) - LAN is better suited.

— RS-232. A wired interface that originally appeared in computer technology. In AV receivers, it can be called a service connector: content is not transmitted through this connector, but through it you can connect the device to a computer and remotely change settings, as well as update the firmware.

— MHL. High-speed wired interface for transmitting multimedia data (video and audio) from mobile devices to external screens. The bandwidth allows you to work with high or even ultra-high resolution images, as well as multi-channel audio. Also, when connected, the gadget can be charged. In mobile devices, the MHL signal is output via a standard microUSB port; and the role of the input in AV receivers (and other stationary equipment) is played by the HDMI connector (see below) - however, not every connector, but only one that is initially compatible with MHL and has the appropriate marking. Adapters are available for connecting to regular HDMI, but additional functions (like charging) may not be available with this connection.

- DLNA. A technology used to connect various electronic devices into a single digital network with the ability to directly exchange content. Devices for which support for this standard is declared are able to communicate effectively regardless of the manufacturer. An AV receiver with DLNA can, for example, play a movie directly from the hard drive of a computer in the next room, or transfer photos from a smartphone to the TV. Connecting to the Network can be done either wired (LAN) or wirelessly (Wi-Fi, see above).

- Roon Tested. Roon Tested accreditation means the AV receiver is compatible with the popular audiophile music streaming platform Roon. Certified models have undergone a series of tests and meet the quality standards required to operate Roon flawlessly. This ensures convenient management and organization of content within the platform.

— Coordination of Remote control. A function that allows you to connect the AV receiver to another device (for example, a Blu-ray player or external amplifier) and control both devices with one remote control. When purchasing equipment with such a function, it is necessary to clarify compatibility - as a rule, only equipment from one manufacturer can work in such a “bundle”, and even in such cases, their own nuances are possible upon agreement.

— Voice assistant. Receiver support for voice assistant. The most popular assistants these days are:

• Google Assistant
• Apple Siri
  
• Amazon Alexa

However, other solutions may also emerge. In any case, it is worth noting that we are not talking about an assistant built into the receiver itself, but about compatibility with external devices that have this function (for example, a smartphone or tablet). But even such compatibility allows you to give commands to the receiver by voice - this is often more convenient than more traditional control methods. The specific set of supported commands and languages may vary depending on the voice assistant and its specific version.

A decoder can be broadly described as a standard in which digital audio (often multi-channel) is recorded. For normal playback of such sound, it is necessary that the corresponding decoder is supported by the device. The first signs of multi-channel decoding were Dolby Digital and DTS, gradually improving and introducing new features. The final stage for 2020 is Dolby Atmos and DTS X decoders. And the intermediate ones were Dolby TrueHD, Dolby Pro Logic II, DTS-HD, DTS ES, DTS Neural: X, DTS Neo (6, X).

Dolby Atmos. A decoder that does not use a rigid distribution of sound across channels, but the processing of audio objects, due to which it can be used with almost any number of channels on a reproducing system — the sound will be divided between channels so that each audio object is heard as close as possible to its proper place. When using Dolby Atmos, in-ceiling speakers (or speakers facing the ceiling) are highly desirable. However, in extreme cases, you can do without them.

— DTS X . An analogue of the Dolby Atmos described above, when the sound is distributed not through individual channels, but through audio objects. The...digital signal contains information about where (according to the director's intention) the object audible to the user should be and how it should move, and the processor of the reproducing device processes this information and determines exactly how the sound should be distributed over the available channels in order to achieve the required localization. Thanks to this, DTS X is not tied to a specific number of audio channels — there can be as many as you like, the system will automatically divide the sound into them, achieving the desired sound. Also note that this decoder allows you to separately adjust the volume of dialogues.

— IMAX Enhanced. The IMAX Enhanced Mark of Conformity is awarded to equipment that meets the audio certification requirements of IMAX Corporation. Combined with DTS audio technology to deliver signature IMAX theater-like sound in the home. The most accurate reproduction of such audio is possible in systems with a large number of channels (5.1 or more). Note that for a fully immersive experience, IMAX Enhanced certification must also apply to video equipment for playing content (TV, projector, etc.).

The number of analogue stereo RCA inputs provided in the design of the AV receiver. The more such inputs there are, the more transmitting devices can be simultaneously connected to the receiver. Thanks to this, when choosing between them, you do not have to reconnect cables — just set the signal source in the receiver settings.

By itself, the RCA connector (colloquially — "tulip") can be used in different interfaces. However, in this particular case, we are talking about a linear audio input responsible for an analogue audio signal. RCA is the most popular connector used in modern audio equipment for such inputs; it allows you to connect the receiver to an external audio source such as a CD player.

Note that connectors of this type are usually counted in pairs; in other words, one input consists of two RCA connectors. This is due to the fact that in this case only one channel of analogue audio can be transmitted over one wire; accordingly, two RCA jacks are required for stereo transmission.

HDMI interface version supported by the receiver. Usually, all HDMI connectors available in the device correspond to this version — both inputs (see above) and outputs (see below). Here are the current options:

— v 1.4. The oldest of the current versions, released in 2009. However, it supports 3D video capable of working with resolutions up to 4096x2160 at 24 fps, and in Full HD resolution, the frame rate can reach 120 fps. In addition to the original v.1.4, there are also improved modifications — v.1.4a and v.1.4b; they are similar in terms of basic features, in both cases the improvements affected mainly work with 3D content.

-v 2.0. Significant update to HDMI introduced in 2013. In this version, the maximum frame rate in 4K has increased to 60 fps, and the audio bandwidth has increased to 32 channels and 4 separate streams simultaneously. Also from the innovations, we can mention support for the ultra-wide format 21:9. In the v.2.0a update, HDR support was added to the interface capabilities, in v.2.0b this feature was improved and expanded.

— v 2.1. Despite the similarity in name to v.2.0, this version, released in 2017, was a very large-scale update. In particular, it added support for 8K and even 10K at speeds up to 120 fps, as well as further expanded the possibilities for working with HDR. Under this version, its own cable was released — HDMI Ultra High Speed, all v.2.1 features are available only when using cables of this standard,...although basic functions can be used with simpler cords.

The number of composite inputs provided in the design of the receiver.

Note that in this case, we do not mean a full-size composite interface that uses three sockets (video and two stereo sound channels), but only one connector — video. This is due to the fact that the sound can be output through standard RCA audio connectors. The video output also uses an RCA type connector, usually a characteristic yellow colour.

Due to the fact that all image data is transmitted over a single cable, the composite interface is somewhat inferior to the component (see above) in terms of video quality, and the bandwidth allows you to work only with a standard definition signal (not HD); and there is no talk of volumetric sound. On the other hand, this connection method has long been used in video technology and can be useful for connecting outdated devices (such as VHS VCRs).

As for the quantity, the presence of several inputs allows you to connect several signal sources to the receiver at once with the corresponding outputs and switch between them through software settings without fiddling with switching cables.

The presence of a linear audio input on the front panel of the AV receiver.

The line interface is the main interface for transferring an analogue audio signal between audio system components. It can use different types of connectors, but most often classic RCA is installed on the front panel of the receiver. Another option is a 3.5 mm mini-jack; such a socket is useful for connecting portable equipment such as smartphones or pocket players. There are models equipped with both types of connectors. Anyway, the placement of the line input on the front panel will be especially convenient for connecting temporary sound sources that are not planned to be permanently connected to the receiver. For example, during a party, you can quickly connect a DJ console or a player with a selection of music to the system, and just as quickly disconnect the device at the end of the event.