[Home Theater Network HDAV.com.cn] Talking about the subwoofer, it is the most common audio component in the home theater system! It is mainly used to replay the low-frequency effect channel inside the movie track to create a shocking low-frequency effect. At the same time, it is necessary to make up for the low frequency lower limit of the main speaker, so that the main speaker can achieve the purpose of full frequency playback. The subwoofer is represented by ".1" in the audio-visual system, namely 7.1, 5.1, 2.1. After many years of audition and comparison, we feel that the subwoofer is very important in the home theater system! A high-performance subwoofer not only delivers powerful, compact and fast low-frequency effects, but also needs to maintain high stability. It will easily break down! These are directly related to the design of the subwoofer. Today we will briefly introduce the basic types, construction and design of the subwoofer.
Type of subwoofer
The subwoofer is mainly divided into active and passive. Among them, the active subwoofer is one of the most common types at present, and it is the current mainstream design, and it is also the most important type of products to be evaluated in the next period. Its biggest feature is its own power amplifier, which solves the matching problem between the woofer and the power amplifier, making it more convenient to use. Passive subwoofers do not have their own amplifiers. Users need to configure their corresponding amplifiers according to their own environment and the performance characteristics of the speakers. These subwoofers are often used in professional audio fields, so they basically need professionals to operate! Partially embedded subwoofers are passively designed because of the volume limitation of the cabinet. However, the factory usually gives an option, and even directly specifies the corresponding amplifier brand and model, so that professionals can quickly find the right amplifier!
The way to distinguish active or passive is to look at the position of the terminal. Due to the active design of the built-in amplifier, all the terminals have power switch and signal input interface, volume control function, while passive only speaker line input interface.
Subwoofer design
For the design of the subwoofer, the cabinet structure, unit design, power amplifier and electronic correction system all affect the final replay performance of the subwoofer.
Box structure
The cabinet structure of the subwoofer is divided into two types: closed type and reflective type. The characteristic of the closed type is that the vibration of the unit diaphragm will cause repeated compression and expansion of the air inside the box. Although the sensitivity is low, the power amplifier is required to be high. However, in the low-frequency transient response, it tends to be more advantageous. The low-frequency sounds more compact and more textured. The reflective type uses the back-wave of the woofer to lead out through an opening in the box to obtain more low-frequency energy. And the reflective speakers are more sensitive and relatively easier to drive!
Unit design
In the design of the unit, in fact, basically adhere to a principle, that is, the diaphragm of the woofer is required to be lighter in weight and higher in strength, so that it is easy to drive and has low distortion. Therefore, everyone has worked hard on the material and structure of the diaphragm of the woofer to develop a light and hard diaphragm, which can be described as various methods! For example, paper, metal film, and other composite materials. So which kind of material is better? This is actually not a generalization, this involves the manufacturer's own mastery of the material application. Just as JBL is good at using paper cones, ELAC likes to use metal basins... At the same time, the stroke of the woofer (the amplitude of the front and rear vibrations) is generally longer, which can increase the driving amount of air and get more low-frequency feeling.
Amplifier
In addition to the structure and unit design of the cabinet, the amplifier is also an important element. At present, most of the subwoofer amplifiers are class D amplifiers, and only a few adhere to the class AB. Although the D-class amplifier is not good for HiFi enthusiasts, it has an absolute advantage as a subwoofer. First of all, the output power of the D-class amplifier is large, and there are hundreds of watts of output power, even on Kilowatt or several kilowatts of power output, high efficiency and high damping coefficient, and smaller size and lower heat output at the same output power, so that the amplifier can be installed into the subwoofer. Inside the box.
Electronic correction system
There are two main types of electronic correction systems used in the subwoofer. One is to correct the distortion produced by the woofer during operation; the second is an acoustic correction system to overcome the difference in sound effects caused by the use environment. For the former, its concept is equivalent to the negative feedback in the amplified line. By continuously detecting the working state of the woofer and feeding back the working status information to the DSP chip, and then issuing a correction signal to correct the working state of the woofer, thereby reducing distortion. For example, the famous Velodyne Digital Drive Plus series uses this correction technology to achieve very low distortion. As for the latter, many of the high-end subwoofers have this correction function. It needs to be processed with a professional microphone and a series of test audio signals. The microphone collects the test signals in the room and then analyzes it through the internal DSP. Compared with the internally set target frequency response curve, the correction curve is finally obtained, which plays the role of acoustic correction. For example, Paradigm's PBK, Velodyne's automatic EQ parametric adjustments are used for acoustic correction purposes.
The basic types, construction and design of the subwoofer have been briefly introduced, but in fact, different brands and different types of subwoofers have their own unique design methods, which requires specific analysis and specific design. Introduction. More fresh and fun home theater information, please pay attention to home theater network http:// (WeChat: cnhifi), the country's most influential home theater audio player interactive media website.
Note: This article is transferred from Solan. The article is an independent view of the author and does not represent the position of the home theater network.
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