Comparison Sony HT-CT390 vs LG LAS655K

The ability of the projector to output a video signal in 3D format — that is, a "volumetric" image that has three full dimensions (including depth). Since 3D uses the division of the “picture” of the image into two parts (for the left and right eyes), the format of such a signal differs from the usual two-dimensional one, and not every model is able to work with it. You also need to consider that in order to view 3D content, you need not only a projector, but also a TV (or other playback device) with the appropriate screen capabilities.

This feature requires the projector to have at least one HDMI output (see below). In this case, the video signal source can be either an external device or the projector itself, operating in the format of a media centre (for example, a model with direct playback from USB media).

The total power rating of the sound projector speakers (including subwoofer, if present).

This parameter is often used to estimate the overall sound volume of the device, but this is not entirely true. The fact is that the actual sound volume is determined mainly by the power of the main speakers of the sound projector, and the total power is the sum of this power and the power of the subwoofer. Therefore, models with the same power rating can vary markedly in actual volume: for example, a 150-watt soundbar with a 50-watt subwoofer will be louder than a 100-watt projector with a subwoofer of the same power, although in both cases the rated power will be equal to 200 watts.

Summing up, we can say that it is possible to evaluate the volume by rated power only if the sound projector is not equipped with a subwoofer — in such models, the rated power is equal to the power of the main speakers. In other cases, it is worth focus on the power of the soundbar and the power of the subwoofer directly stated in the characteristics (see below for both).

The nominal power of the speakers installed directly in the soundbar, excluding the subwoofer (in models with a built-in subwoofer, respectively, only the power of the main speakers is taken into account).

This indicator directly determines the overall volume of the sound projector; It is worth choosing according to this parameter taking into account the specifics of the room in which the projector is planned to be installed: the larger the room and the greater the distance to the viewer, the higher the power should be, otherwise the soundbar will not be able to effectively sound the scene. Detailed recommendations on the optimal power for different situations can be found in special sources.

Impedance is the projector's resistance to alternating current, or more precisely, to the analog audio signal input from an external power amplifier. Actually, this parameter is of practical importance precisely if the device is planned to be used with an external amplifier. Ideally, the projector's impedance should match the impedance for which the amplifier is designed - otherwise, the volume may either decrease (if the impedance is too high), or distortion, overload, and even damage to the acoustics (if the impedance is too low) may occur.

Higher impedance is also thought to reduce the likelihood of interference. However, modern speakers (including sound projectors) have standard impedance values of 4, 6 or 8 ohms - the difference is not so great that the differences in sound quality are noticeable.

The rated power of the subwoofer included in the design or delivery of the sound projector.

The higher the power, the louder the sub can sound, the richer the bass it can provide. On the other hand, an increase in power inevitably promises an increase in the size and cost of the speaker. Therefore, an overly powerful subwoofer is just as undesirable as one that is too weak. Detailed recommendations for selecting power for the size and acoustic characteristics of a particular room can be found in special sources.

Note that the external subwoofer in soundbars should be approximately twice as powerful as the soundbar in order to prevent sound sags at maximum volume. So, if the total output power of the speaker system is 300 watts, then 100 of them should come from the soundbar alone, and 200 should go directly to the subwoofer.

The diameter of the speaker in the subwoofer used by the sound projector.

It is believed that the larger the speaker, the louder the sub and the deeper and richer sound it can provide. Models up to 200 mm in size are entry level; This is exactly the size that built-in subwoofers usually have (see above). But free-standing bass speakers can use larger speakers, up to 254 mm (10").

— Airplay. Wireless technology for connecting an external signal source to the projector. Developed by Apple, it is mainly used to connect with its devices (for example, iPad tablets or MacBook laptops), although it is also used by other manufacturers. AirPlay allows you to transfer not only sound, but also text and graphic information, and even video, which can be useful when connecting the projector to a TV. This technology, by definition, means support for Wi-Fi (see below), because. it is based on this interface.

— Airplay 2. The second generation of the AirPlay technology described above, introduced in 2018. Among the main innovations of this version is support for the "multi-room" format, that is, the simultaneous transmission of several audio signals to different compatible devices installed in different places. In this way, you can, for example, turn on an online broadcast of a news programme in the living room, relaxing music in the bedroom, etc. In addition, AirPlay 2 received a number of other improvements — improved buffering, the ability to stream to stereo speakers, as well as support for voice control via Siri.

— Chromecast. The original name is Google Cast. A technology for broadcasting content to external devices developed by Google. Allows you to transmit an audio signal from a PC or mobile device to the soundbar, the broadcast is standar...dly carried out via Wi-Fi, while the receiver and signal source must be in the same Wi-Fi network (Chromecast media players are an exception). Note that in signal sources (smartphones, tablets, PCs, etc.), Chromecast is implemented at the level of individual applications. For example, at the time of its creation, this feature was available, among others, in the YouTube and Netflix apps for Android and iOS, as well as in the web versions of these apps for Chrome. Thanks to this format, this technology is extremely widespread nowadays, and the ability to connect a particular gadget to an audio system with a Chromecast is usually limited to the ability to install appropriate applications on this gadget.

— Wi-Fi. Wireless technology with multiple applications. One of them is connecting to a computer network; in sound projectors, it is primarily used for local resources (see DLNA below) or AirPlay technology (see above), as well as for controlling the projector over a network. Another option is to connect directly to other devices. The possibilities of such a connection in different models may also be different; one of the most popular options is remote control of the projector from a smartphone, tablet, etc.

— Bluetooth. Wireless technology designed to directly connect different electronic devices to each other. In sound projectors, it is primarily used to broadcast audio wirelessly from another Bluetooth device, such as a smartphone or laptop. However, there may be other options — for example, connecting wireless headphones to the projector itself or remote control from the same smartphone. It is worth noting here that the sound quality when transmitting via Bluetooth is somewhat lower than with a wired connection; on the other hand, this is offset by convenience, and some models of sound projectors may even have a "sound restoration" system.

— NFC. NFC is a wireless communication technology over short distances, up to 10 cm. In sound projectors, it is used mainly as an auxiliary, to facilitate connection via Wi-Fi or Bluetooth. It looks like this: instead of manually digging into the settings, just bring an NFC-compatible device to the projector chip and confirm the connection.

— FM radio. The projector has a built-in FM tuner. This function actually turns the device into a full-fledged radio receiver, allowing you to receive broadcasts on the FM band (which broadcasts most music radio stations). Note that some models with a tuner may support other bands, such as AM or digital DAB.

— LAN. A standard wired connection to a computer network, also known as Ethernet or RJ-45. Like Wi-Fi (see above), in sound projectors it is used primarily for working on a local network; however, LAN capabilities can include both playback of network content via DLNA (see below) and control of projector settings via a network from a computer. A wired connection is not as convenient as Wi-Fi due to the need to run a cable, but it is more reliable and can come in handy when the air is “loaded” (an abundance of Wi-Fi devices nearby).

— 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 claimed are able to effectively interact regardless of the manufacturer. And the network itself works on the basis of a conventional computer "local area", connection to it is carried out via LAN or Wi-Fi (see above). In sound projectors, DLNA can be used, for example, to play music from a computer hard drive.

— RS-232. A service interface used to connect the sound projector to a computer and control the sound settings from the PC through a special programme. On some models, it can also be used to update the firmware.

— Connecting an iPod. Special interface for connecting Apple iPod players. Most often it is based on a regular USB connector, to which the player is connected via an adapter cable; however, it may look like a dock — a stand with a proprietary connector, where the gadget is directly placed. Anyway, connecting in this way provides not only playing music from the player, but also other possibilities — for example, switching tracks from the projector's remote control, charging the battery, etc.

— Wireless connection to TV. Ability to connect the sound projector to the TV wirelessly. The advantage of this option is obvious: it eliminates the hassle of additional cables. On the other hand, a wireless connection is usually based on a certain proprietary technology (LG Sound Sync, TV SoundConnect, etc.) and requires a TV that supports the corresponding technology to work. This limits the use of this feature. In addition, such a connection is more susceptible to interference than a wired one, and “wireless” projectors are more expensive than wired ones. Therefore, it is worth specifically looking for a model with such a function if you have a TV with wireless technology support and at the same time the absence of extra wires is fundamental.

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.

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, D...TS 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. A separate variant of DTS X is the DTS Virtual:X decoder for providing surround sound without the use of additional upward speakers on the soundbar. You can rely on just two channels and a separate subwoofer to achieve the desired DTS Virtual:X effect. A separate variation of DTS X is the DTS Virtual:X decoder to provide surround sound without the need for additional upward-firing speakers on the soundbar. DTS Virtual:X can rely on just two channels and a separate subwoofer to achieve the desired effect.

— 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.).

— USB A. In this case, we mean a USB connector that allows you to connect external drives (flash drives, hard drives) to the projector and play content directly from them. At the same time, models with video outputs (see below) can often work as a media centre, outputting the video signal to a TV or other external display.

— mini-Jack (3.5 mm). By itself, the 3.5 mm plug can be used in different types of interfaces; in this case, it means a linear audio input with a mini-Jack socket. This input is mainly used to connect portable audio equipment (players, smartphones) to the sound projector.

— RCA. Technically, RCA (colloquially "tulip") is a type of connector that can be used in different interfaces. However, the term "RCA input" is used to refer only to line inputs for connecting an analogue signal in stereo format. Note that this input consists of two sockets for RCA cables, because. Only one channel of sound can be transmitted through one cable.

— Optical. Connector for digital audio signal connection via TOSLINK fibre optic cable. This interface allows for multi-channel audio transmission and is virtually immune to electrical interference; its disadvantage is the fragility of the cable.

— Coaxial S / P-DIF. A connector for connecting a digital audio signal via an elect...rical cable with an RCA connector (not to be confused with linear RCA, described above). Similar to the optical input described above, in particular, the ability to transmit multi-channel audio through a single connector. At the same time, a coaxial cable, on the one hand, is not so delicate, and on the other hand, it is sensitive to electrical interference (therefore, it is advisable to use a special shielded wire for such a connection).

— Composite. In this case, we do not mean a full-format composite interface of three connectors that allows you to transmit audio and video signals, but only one connector for working with video. And since sound projectors don't display images, the composite input is used to send video through the projector to another device, such as a TV. The composite video interface does not allow working with HD and is not of high quality; on the other hand, it is widespread and can even be used to work with frankly outdated video equipment. Typically this input uses a yellow RCA plug.

— Component. An input designed to receive an analogue video signal for further transmission to another device — a TV, video projector, etc. This connection typically uses three RCA connectors, each carrying a different video component (hence the name). Due to this, the component interface has good bandwidth and picture quality, it allows you to work with HD and is considered the most advanced modern analogue video standard.

— IR control input. Connector for connecting an external infrared remote control receiver. When properly placed, such a receiver will allow you to use the remote control even in places where the signal from the remote control cannot reach the main (built-in) sensor — for example, in another room. Note that the role of the receiver can be played not only by a specialized device, but also by another component of the audio system — for example, an amplifier with an IR control output.