What is a subwoofer? In fact, a passive subwoofer is a speaker that connects to a computer or speaker system. It is capable of reproducing low-frequency sounds (from five to two hundred Hz). There are passive and active subwoofers. This affects their ability to transmit sound.
For a good sound system, just one large speaker is enough, which for convenience can be placed under the table. Choosing the most suitable place to place the subwoofer, you can try to damp the standing low-frequency waves that appear in a closed small room. Most often, a passive subwoofer is used in home theater speakers to watch movies with special effects and listen to music. It transmits low frequencies well.
It happens that subwoofer systems do not interface well with the equipment connected to them due to the mismatch of their phase and amplitude-frequency characteristics. To overcome such sound defects, some subwoofers have the ability to adjust the phase and high frequency.
Types of Subwoofers
There are two types of subwoofers: active and passive. There are questions about how the active subwoofer differs from the passive one, what functions do they perform in speaker systems?
The active subwoofer has a built-in power amplifier. Thanks to what he is able to remove low-frequency load from the amplifier. In addition, the active subwoofer has an active crossover that allows you to filter high frequencies, helps to coordinate the operation of the subwoofer with an acoustic broadband system. Quite often, he has additional customization options in accordance with the conditions of use. It has a tone and volume control.
In contrast to the active passive subwoofer does not have an amplifier. It is subordinate to the device to which it is connected: to a computer, speaker system. Therefore, it is connected as an addition to the main stereo speakers. It can be connected to a separate power amplifier. The main disadvantage of the passive subwoofer is that it creates an additional load on the stereo channels, which reduces the volume and dynamics of the sound system. But, the higher the sensitivity of the subwoofer, the less it loads the amplifier.
Features of the design, which has a passive subwoofer, make it be demanding for placement in the room. It should be moved until a good bass sound is found. The frequency range available to the subwoofer can be divided into three types: deep (from twenty to forty Hz), medium (from forty to eighty Hz), and high (from eighty to one hundred and sixty Hz) bass. The sound transmitted by the subwoofer depends on the area of the diffuser. The power and organicness of the bass depends on this.
Subwoofer Designs
According to the device, passive subwoofers are distinguished: horn, bass reflex and strip. They have their own advantages and disadvantages. The woofer of the horn subwoofer is located on the wall of the sealed box. Closed types of subwoofers can have large, bulky sizes, despite the fact that they have the ability to reproduce a juicy, deep bass.
The phase inverters have a speaker, which is located in the housing. Most often there is a hole on one side of it. Subwoofers of such models transmit bass of a lower tone than closed speakers, because the diffuser travel increases. They are more suitable for large rooms, as they are distinguished by high volume.
The next view that a passive subwoofer can have is a bandpass. It is a band-pass filter that combines the properties of the two types described above. This is manifested in the fact that the subwoofer consists of two parts: a closed box and a bass reflex. Therefore, there is an increase in sound pressure, but the frequency range becomes smaller.
Closed-type or bass-reflex subwoofers are more suitable for home use. Choosing them, it is worth paying attention to the following. The subwoofer amplifier must exceed one and a half times the power that the speaker system has. Compliance with this condition will ensure sound quality.