What Is a USB Subwoofer?

The subwoofer is a common name or abbreviation for everyone, strictly speaking it should be: subwoofer. Heavy bass is actually a name for bass music in electronic music. This term was first developed by innovation, and the term subwoofer, a vernacular character, was pioneered by Mai Lan (now Maibo).

bass

Internal power amplifier circuit, divides the sound into several frequency bands through a frequency divider, and the middle and high frequency bands are output to satellite speakers.

Subwoofers can be broadly divided into active subwoofers and

Low-grade plastic speakers can't be overcome because of their thin cabinet

The speaker is divided into bookshelf type and floor type according to the structural form. The former is small in size, clear in layers, accurate in positioning, but limited in power, and insufficient in low-frequency band extension and volume sense. It is suitable for enjoying high-fidelity music. Is also our multimedia

In terms of the subwoofer circuit structure, it is generally composed of preamplifier, low-pass filtering, phase adjustment, power amplification, protection, and power supply. In terms of its role, preamplification is to further the subwoofer signal output by the AV amplifier. Amplify enough to drive the full power output of the power amplifier. Because the voltage of the subwoofer signal provided by the AV amplifiers of different brands is different, generally ranging from 0.3-1 volts, so the pre-amplification is still necessary. An important role is to play the role of isolation and buffering, because there are differences in the subwoofer signals output by various brands of power amplifiers. Some manufacturers have stolen materials in their designs, causing their output internal resistance to be very high. It is possible that the effect is very bad; low-pass filtering is a more important unit in the circuit part of the subwoofer. Its role is to further filter out signals above the low frequency mixed in the subwoofer signal output by the amplifier. -180Hz (Many high-end products design the filter's low-end cut-off frequency to be continuously adjustable), if it is a fixed frequency Rate filter, generally the value is about 110-150Hz, too low speakers are easy to produce mixed sound, too high, easy to mix into human ears identifiable music signal; the subwoofer signal used by the AV power amplifier of each brand is There is no uniform regulation of reverse phase or normal phase. Therefore, phase adjustment is to use the subwoofer in normal phase or reverse phase according to the needs of the system connection when placing the subwoofer. Depending on the effect, it is generally necessary; the power amplifier unit is Do nt worry, it is the core of the active subwoofer. Similarly, in order to protect the subwoofer to work safely and to protect the equipment from being damaged by valuable parts or to expand the fault, the protection circuit is generally necessary; the power supply is each circuit The driving force of the unit work is the basic component. What needs to be added is that some subwoofers also have an automatic power control function, so that the subwoofer automatically turns off the main power of the subwoofer when there is no signal.

Extension

It refers to whether the speaker supports multi-channel simultaneous input, whether it has an output interface for passive surround speakers, and whether it has a USB input function. The number of external speakers that a subwoofer can connect to is also one of the criteria for measuring extended performance. The interfaces of ordinary multimedia speakers are mainly analog interfaces and USB interfaces. Others, such as optical fiber interfaces and innovative digital interfaces, are not very common, so they are not introduced here.

Sound effects

Hardware 3D sound effects technologies include SRS, APX, Spatializer 3D, Q-SOUND, Virtaul Dolby, and Ymersion. Although they each implement different methods, they can make people feel the obvious 3D sound field effect. The former three are more common. They all use the Extended Stereo theory. This is to add additional processing to the sound signal through the circuit, so that the listener feels that the sound image orientation has been extended to the outside of the two speakers. Sense and three-dimensional sense, to produce a wider stereo effect. In addition, there are two sound enhancement technologies: active electromechanical servo technology (which essentially uses the principle of Helmholtz resonance), BBE high-definition plateau sound playback system technology, and "phase fax" technology, which also have certain effects on improving sound quality. For multimedia speakers, SRS and BBE technologies are relatively easy to implement and have a good effect, which can effectively improve the performance of the speakers.

tone

Refers to a signal with a specific and usually stable pitch, which is, to put it simply, the degree to which the sound sounds toned. It mainly depends on the frequency and also depends on the sound intensity. The human ear responds to high-frequency sounds with a high pitch, while the low ears respond to low-frequency sounds. The change of pitch with frequency (Hz) is basically logarithmic. Different instruments play notes of the same frequency. Although the timbre is different, their tones are the same, that is, the fundamental frequency of the playing sound is the same.

Tone

The perception of the sound quality of a sound is also a characteristic quality that distinguishes one sound from another. Different instruments can sound very different when they sound the same tone. This is because although their fundamental frequencies are the same, the harmonic components are quite different. Therefore, the tone is not only determined by the fundamental frequency, but also closely related to the harmonics of the integral multiple of the fundamental frequency, which makes each instrument and each person have a different tone.

dynamic

The ratio of the strongest to the weakest sound, expressed in dB. For example, the dynamic range of a band is 90dB, which means that the weakest part has 90dB lower power than the loudest part. Dynamic range is the ratio of power, independent of the absolute level of sound. As mentioned earlier, the dynamic range of the human ear is from 0 to 130dB. The dynamic range of various sounds in nature also varies greatly. The general speech signal is only about 20 ~ 45dB, and the dynamic range of some symphonies can reach 30 ~ 130dB or higher. However, due to some factors, the dynamic range of the sound system rarely reaches the dynamic range of the band. The inherent noise of the recording device determines the weakest sound that can be recorded, and the maximum signal capacity (distortion level) of the system limits the strongest sound. Generally, the dynamic range of the sound signal is set to 100dB, so the dynamic range of the audio equipment can achieve 100dB, which is very good.

Total harmonic

When the audio signal source passes through the power amplifier, the output signal due to non-linear components has more harmonic components than the input signal. Harmonic distortion is caused by the system is not completely linear. We use the percentage of the rms of the newly added total harmonic component to the effective value of the original signal. For example, an amplifier with an output of 1000 Hz at 10 V and 2000 Hz at Lv would have 10% second harmonic distortion. The sum of all additional harmonic levels is called total harmonic distortion. Generally speaking, the total harmonic distortion at the frequency of 1000Hz is the smallest, so many products use the distortion of this frequency as its index. However, total harmonic distortion is related to frequency. Therefore, the US Federal Trade Commission stipulated in 1974 that total harmonic distortion must be measured in the full audio range of 20 to 20,000 Hz, and the maximum power of the amplifier must be at a load of 8 ohms. Harmonic distortion is measured under 1%. The minimum requirement for total harmonic distortion specified by the International Electrotechnical Commission is: 0.5% for the preamp and 0.7% or less for the combined amplifier, but it can actually be less than 0.1%: the FM stereo tuner is less than or equal to 1.5%. Can achieve less than 0.5%; laser record player can achieve less than 0.01%.