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Replay low voice

Replaying low sounds is a very tricky task, which adds a lot of trouble to speaker designers and audio enthusiasts. But this is also a challenge, and the potential reward fully proves that it is worth trying to improve the low voice replay as much as possible.

The center of the problem lies in the fact that speakers do not operate in isolated environments, but many speaker designers and HI-FI sound enthusiasts often overlook this. Designers always rely on sound-absorbing rooms isolated from the practical environment to develop their products. Practice has proven that there is a close mutual influence between the sound quality of speakers and the practical listening room, especially in the low frequency range. As we all know, the frequency range of human ear sounds is approximately from 20Hz to 20000Hz, with a span of about 10 octaves. The center C of the piano is located at the center of the fourth octave from the sound. Therefore, the low pitched area itself is simply confined to the scale of the octave (20Hz-40Hz) and the second octave above it (40-80Hz). Although simple low pitched sounds are not heard much in practical life, they play an important role in creating the realism and intensity of music.

If we do not use ultra-low sound speakers and rely solely on ordinary speakers to create low sound, then this type of speaker is not only huge in size, but also very bulky. The ultra-low sound box has many advantages, such as small size, inconspicuous placement indoors, and equipped with its own amplifier and filter, so there are no additional requirements for the system. In the system, there is a specialized ultra-low sound box for reproducing low sounds, and smaller speakers can be used in other channels. The equipment and application of the entire system are more flexible and convenient. Generally speaking, building a low sound requires the use of larger speakers, but placing a pair of small speakers on the wall is enough to make the replayed sound dive to a medium to low sound level. Part of the reason is that placing it next to the wall helps to increase the low sound of 50Hz~100Hz, while another part is that the "standing wave resonance" caused by the shape and scale of the room provides the "room gain effect". The common problem with most commercially available ultra-low sound boxes is that the low-end roll down frequency cannot dive below 50Hz, and its frequency response cannot achieve an ideal match with other channels of general speakers. Moreover, their partial frequency response often forms harmful overlapping phenomena.

The influence of standing waves

Every room, whether it is a concert hall or a living room in a typical household, experiences standing wave phenomena, which are the primary cause of low sound reproduction problems. The frequency of standing waves is closely related to the scale of the room. In music halls with large indoor spaces, the standing wave frequency occurs in the most depressed low and infrasound areas, lower than the frequency of low pitched instruments, so it does not have a negative impact on low pitched playback. But in the small living room of a typical family, due to the small size and space of the room, the standing wave frequency will be higher and enter the low sound area of the music, overlapping with the latter, resulting in poor sound quality. Standing waves, in addition to providing room gain, also make the frequency response in the low sound area very uneven, that is, they will increase the response of certain frequencies in between and cancel out the response of other frequencies. In addition, different rooms have different standing wave modes, which are related to many factors such as wall materials, furniture decoration, listening position, and speaker placement in the room, making it difficult to accurately predict them.

Building a low voice indoors

As we all know, in order to make a sound from a speaker, it is necessary to use the vibration of the sound bowl to move air molecules and excite sound waves in the air with the same frequency as the vibration of the sound bowl. Due to the low frequency of low sounds and the slow vibration speed of the speaker cone, in order to produce strong low sounds indoors, it is necessary to make the cone move a lot of air molecules per unit time. To achieve this goal, ultra-low sound speakers usually use large diaphragm, small stroke sound pots or small diaphragm, large stroke sound pots. The latter has a small aperture in the sound basin, which is conducive to reducing the volume of the entire low sound box, and has the advantages of high power and high loudness, making it the mainstream of modern ultra-low sound boxes.

However, installing a subwoofer in a huge speaker can reproduce some of the intimidating explosions and earth shattering sounds in movies, but replaying a lot of high-intensity bass while listening to music can be very unpleasant. In addition, both research and practical results have proven that making the loudness of ultra-low sound boxes greater than other speakers in the system does not have much practical significance. These are precisely the reasons why modern ultra-low sound boxes are made smaller in size.

Article source: LED Bluetooth audio system http://www.www.zaozhijixie.net.cn/