How to select a receiver and speakers for surround sound

When giving the impression of space, sound has a very important function, because the image we observe is only two-dimensional. Achieving spatial imaging is difficult, and we know what happened to 3D TVs.

In contrast, surround reproduction from several suitably spaced speaker systems has been used for a long time, first in cinemas and then in home multimedia sets. One is able to recognize quite accurately the direction from which the individual sounds come, and according to the auditory perception, to get an idea of ​​the properties of the space in which the sound process takes place. The task of speaker systems is to radiate sound so that we get the most faithful impression of space. Either the space in which the sound was recorded using stereo microphones, or the space in which the sound masters try to evoke sound masters in a movie, game, or music by mixing sounds from different microphones, musical instruments, or other sources.

The accompanying sound of movies, whether on Blu-ray or from streaming services, is already primarily surround, so how well you can reproduce this sound at home depends only on your multimedia set. Let’s start with the speakers, because the selection of the receiver then depends on their number and distribution.

Systems 2.1, 4.1, 5.1, 7.1 …

In this common designation of the speaker system configuration, the number before the dot indicates the number of speakers that reproduce the pitches and mids, or the entire frequency spectrum. The number after the dot, most often 1, indicates that a subwoofer, ie a separate speaker system designed to reproduce the lowest frequencies, is also included in the speaker configuration. The subwoofer is common to all channels because the lowest spectrum of audio frequencies does not transmit space information because the human ear cannot determine the direction of the low frequency audio. For example, for perfect five-channel surround sound, you don’t need to place five large speakers in the room, each carrying the entire frequency band, but much smaller midrange and treble speakers that carry the surround component and one subwoofer, which is usually large and heavy, will suffice. , but can be located anywhere. Most subwoofers are active, so they have a separate power amplifier and power supply.

For example, 5.1 in practice means that a set of four speakers forming a square or rectangle around the listener is complemented by a center speaker designed to reproduce the dialogues so that the actor can be well understood. This speaker should be centered below or above the screen or screen. Therefore, it usually has a different shape or is placed flat. Since the screen is accented, the center speaker can also be placed behind it. Assembly 7.1 is created by adding 5.1 additional two loudspeakers to assembly 5.1.

Dolby Atmos technology, which significantly expands the possibilities of surround sound, adds two new audio channels above the listener, which allow you to determine the exact place where the sound will come from, and the sound source can move so that a flying helicopter, storm and the like can be reproduced in space. . The classic 7.1 speaker configuration is complemented by two ceiling speakers and another subwoofer, creating the 9.2. However, technology implementers also thought of users who could not drill into the ceiling, for example in a sublease. There are systems equipped with combined surround speakers with an upper output, which achieves the surround height effect by reflection from the ceiling.


Receiver connector

The height at which the speaker systems are located also affects the sound reproduced. The subwoofer or front speaker systems, which have subwoofers, are usually placed as low as possible, preferably directly on the floor, of course, via a suitable cushioning pad or dematerializing tips. The front panels of the front speakers should be parallel to the wall or plane of the TV or computer screen. The rear speakers are installed tilted at a slight angle to the listener, which protects their sound from reflections from the monitor or screen, which could affect the sound and create a feeling of less perceptible front-to-back movements. The subwoofer can theoretically be anywhere and as close to the floor or in the corner of the room. The typical location of the center speaker is under the TV, ie approximately 0.5 – 1 meter above the floor. Modern receivers also have a measuring microphone, which you can place where you will watch movies most often, and a guide to configuring the connected speakers will appear on the screen. The wizard shows you step by step where to place each speaker, and then sends out a wide range of measurement signals to adjust. The complete configuration with calibration to the room properties is thus performed completely automatically.

AV receiver

This unit is a key component of a surround sound system that integrates audio and video signals from a Blu-ray or DVD player, satellite receiver, game console and other devices at its inputs. Video output from the receiver is fed to the TV or projector and audio to the speaker systems. The receiver also includes surround decoders and a power amplifier with the appropriate number of channels. And just the number of audio channels is one of the most important parameters when choosing a receiver. Simply put, the more audio channels you have available, the better surround sound you can achieve. We emphasize the attributes of better spatial. This is because more channels do not necessarily mean better overall sound quality. The sound from a high-quality 5.1 set can be disproportionately better than the sound from a cheap 9.1 set. The difference in surround sound between 5.1 and 7.1 is not large, and if you have a limited budget, be sure to choose a better 5.1 set instead of the cheaper 7.1 set.

An important number when choosing a receiver is a sufficient number of audio and video inputs. Video sources, such as a Blu-ray player, are connected via HDMI inputs. Make an imaginary inventory of the devices you want to connect and select a receiver that has one, even better, two more HDMI inputs. You never know what will surprise us electronic device designers in the future. Music reproduction devices are connected via either optical (Toslink) or metallic (RCA) digital inputs, or via analog inputs with RCA connectors. If you plan to connect a turntable to the receiver, you need to have a phono input with a special preamplifier for magnetodynamic transmission. Some turntables have such a preamplifier built in, so you can connect them to a standard analog input. If you want to use older devices, you will appreciate if the receiver has at least one analog video input – either composite with a yellow RCA connector or component with a red, green and blue RCA connector.

Another important criterion is decoders for multi-channel audio formats. Dolby Digital and DTS decoders are mandatory. To take full advantage of the 7.1 set-up, you need Dolby Digital EX and DTS ES decoders. All modern surround sound equipment incorporates sophisticated technologies that use signal processors to produce multi-channel surround sound from stereo sound.

Sound power is given in watts per channel, most often 60 – 200 W / channel, of course, not for all channels at once. In other words, a receiver with a maximum configuration of 9.2, ie 9 speakers connected to the receiver plus two subwoofers with their own amplifiers, can have the electronic circuits of all nine power amplifiers rated at 200 W, but a look at the power label reveals that the receiver’s maximum consumption is 650 W The surround sound is mixed so that during normal listening, the most power goes to the left and right front speakers, and if loud sound is to be reproduced from the back, the front sounds will be lower. In addition, most power is radiated at lower frequencies, so it is important to have a suitably oversized subwoofer.

When assembled into a normal apartment, not to mention an apartment building where you have neighbors behind the wall, performance is more of a marketing matter and every quality receiver has enough power to sound normal living spaces. The impedance of the audio outputs, given in ohms, must correspond to the impedance of the speaker systems, or it may be lower, but then you will not take full advantage of the power of the output stages. Otherwise, if you connect 4-ohm speakers to the 8-ohm outputs, the output stages of the receiver may be damaged.

Modern receivers also have the ability to connect an audio source such as a smartphone, tablet or computer via Bluetooth and have integrated support for music streaming services such as Spotify or Tidal.

Pure stereo

The 5.1 or 7.1 surround sound speakers can be the same or have different sizes, shapes and features. For fans of high-quality stereo music reproduction, who also like to watch a movie or game, where they will appreciate surround sound, we recommend a configuration where the front speakers are of the highest quality, ie the one that a demanding listener would choose for stereo reproduction. Virtually all receivers for multi-channel surround sound have a pure stereo button, which allows stereo reproduction from only the two front speaker systems and the subwoofer. If you choose full-featured front speakers with sufficient volume and subwoofers, you’re sure to wonder if you need a subwoofer for that configuration. Basically, you don’t need to, because as we mentioned, in terms of surround sound, it doesn’t matter which speaker system or systems play the lowest tones. The question is whether they will play them. To illustrate, my three-way column speakers with an internal volume of 46 liters can play a frequency range of 35 Hz – 30 kHz in the 6 dB band. If I bought a subwoofer from the same manufacturer, it has a frequency range of 20 Hz – 140 Hz, so the lower limit of the frequency range would shift from 35 to 20 Hz, the lowest frequency that the human ear can still hear. So if you want your set to be able to play the lowest bass, you need a subwoofer. Interestingly, this subwoofer has practically the same internal volume as the mentioned speaker system. So how is it possible that he can play lower frequencies? In the subwoofer, the subwoofer has the entire internal volume available, while in the classic speaker system, part of the volume is taken up by a separate midrange speaker, the diaphragm of which would otherwise be deflected by the acoustic pressure caused by the subwoofer, which would lead to distortion. You must have noticed the difference in shape as well. The speaker system is usually cube-shaped and the cube-shaped subwoofer. This allows you to incorporate a larger diameter speaker into the subwoofer that better plays the lowest tones. In other words, the width of 50 cm required for a powerful subwoofer is too large for flat speakers that need to be placed in a strictly defined location, while a cube-shaped subwoofer with a 60 cm edge that you can place anywhere is acceptable.

Introductory photo: kjpargeter – www.freepik.com

Marantz NR1711

Receiver for configuring 7.2 speakers with a power of 70 W per channel. It has an FM tuner, supports Internet radio and Spotify, Tidal and also plays multimedia from home NAS servers. It has six HDMI inputs, analog, digital metallic and optical audio inputs, including a turntable input. It supports Dolby Atmos, Dolby TrueHD, DTS: X, DTS-HD Master Audio and DTS Virtual X. 4K support is a matter of course. In addition to the remote, you can also control the receiver with a mobile application.

Price: 848 EUR

JAMO S 809 HCS

A complete set of 5.0 speakers with two column, two rear and one center speaker from a renowned Danish company, which you can expand with a subwoofer. The total power of the set is 240 W, frequency range 37 Hz – 26 kHz, impedance 8 ohms and sensitivity 90 dB / mW. The front column speakers are equipped with 25 mm treble and three 127 mm woofer acoustic transducers. The rear speakers have 25 mm treble and 102 mm subwoofers. Dialog reproduction is provided by a central speaker and WaveGuide technology. Frames with accent fabric are fastened magnetically.

Price: 919 EUR

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Source: Nextech by www.nextech.sk.

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