【 Weak current College 】 what is compression limiter?

Compression limiter is a compressor and limiter. It is an audio signal processing devices, you can connect the audio signal of dynamic compression or restrictions. Compressor for variable gain amplifier, its magnification (gain) can be input signal intensity and automatically change is inversely. When the input signal reaches a certain level (threshold or threshold), the output signal with the input signal increases, a condition known as compression (Compressor); no longer increase is called limit (Limiter). Past press adopts hard abduction (Hard-knee) technology, the input signal is a threshold value. Gain on the reduction, which immediately appears on the signal in the corner (gain change turning points) dynamic mutations in the human ear clearly feel a sudden strong signal is compressed. In order to address this deficiency, the modern novel from the compression device incorporates a soft corner (soft-knee) technology, the compressor in the compresses better than before and after the threshold is a balance, a gradient, change the compression, the sound quality is difficult to detect.
The compression used in the recording process to make musical instruments and singing to maintain a certain balance volume; ensure a balanced variety of signal strength. Sometimes also used to eliminate the singers ' articulate sounds, or by changing the compression and release time, produce sound by the small size of the "reverse sound" special effects.
In the broadcasting system is used to compress a large dynamic range of signal modulation in the prevention of distortion and prevent transmitter overload, increase average emission level.
In sound reinforcement system and dance hall, the compressor is the signal through the compressed while maintaining the original program appearance, reduce the dynamics of the music, to satisfy the amplification system and artistic activities.
Although compressor for a variety of purposes, the modern compressor ordinary adopts new technologies such as soft corner, can further reduce the compressor for the side effects of compressor, but does not mean that the compressor is the destructive effect of the sound quality is lost. Therefore, in sound reinforcement systems, not to abuse the compression, even if you want to use and should be used sparingly to reduce compressor for signal processing. This is not only protect the power amplifier, speakers, but also to improve the sound quality.
Compressor is also able to use the following process work:
(1), in the auditoria, as well as radio broadcasting, television broadcasting and recording etched, which limit the dynamic range of the signal, to adapt to the specific technical requirements. Limiter is sometimes also played the role of security protection, avoid transmitter and sound reinforcement system (especially the treble speakers) overload and even damage.
(2), when a player or singer suddenly change their distance between the microphone and makes the volume of the major changes occurred, use the compressor allows the volume changes smoothly.
(3), use the compressor can make the electric guitar, electric bass and other instruments volume stable. Often electric guitar bass chord volume than treble strings, compressor enables different range of volume level is balanced.
(4), manufacture of special sound effects, such as on a plucked instruments, carefully adjust the start time, recovery time, compression, threshold and compression ratio, in particular the recovery time is much shorter transfer, you can get a similar to the sound of the accordion.
(5), the limiter before joining area pass filter (can also use the equalizer) into the limiter of signals for the human voice in overweight wanna be tone and musical instruments of high frequency noise, which trigger the limiter can only due to the microphone or improperly tuned balance resulting from excessive hissing restrictive effect.






What is a DSP
DSP is a fast and powerful microprocessors, unique in that it can process data, it is immediately the instant capacity makes it the most suitable support DSP cannot tolerate any delay of the application. For example, you ever used a does not allow the handset to talk by both? you must wait until the other finish, you can then say; if you have two people talking at the same time, the signal will be cut off so that you do not hear each other's voices. Today's digital mobile phone allows you to talk to the normal way, because it uses a DSP.
Mobile phones within the DSP to ultra high speed processing of voice, so you can instantly hear each other, completely do not feel any delay. Then in the same application, for example, early mobile phones often appears echo, but digital mobile phone was able to answer and call a halt to completely eliminate the phenomenon. DSP will sound like the real-world signals, through mathematical operations to change its characteristics, in order to get better sound quality; DSP can compress data (your voice), elimination of background noise, make your voice more high-speed transmission, which in turn provides a clear and strong call quality, no annoying echo.
This is the most simple DSP applications. To improve the signal, you need a digital signal, and then process it, the result might be more clear sound and sharper picture or more quickly; and this signal capacity also brings breakthrough new applications such as Internet music and home broadband are therefore to be achieved.



What is an active speaker
Typically, the active sound box is equipped with a speaker internal amplifier mixes a class speakers. The power amplifier is designed to promote the sound of the Horn, as a specialized matching design, these amplifiers can be better used to promote the sound of the Horn, so that users do not need to take into account the amplifier's power is the impedance mismatch. In addition, because the speaker also equipped with the front of the amplifier will be frequency electronic dividers and each amplifier is only responsible for zoom a frequency audio signals amplifier efficiency often could be higher, distortion or relative can be as small as possible.
At present, except for home theater front main speakers, but also has specialized as a subwoofer, and surround speakers in the active speaker. As far as it used to VCD home theater with the active loudspeaker, recently saw some on the market, such as those who become the high-fidelity 3D active speaker is in theseSpeakers also with 3D surround sound decoder (processor). You only need to configure two such active speakers that can use dual Mono signal phase, delay and associated processing, only the original performance or stereo two channel signal into not just left, right, and can also have front and back of the other three dimensional sound. VCD's greatest advantage is the hardware and software is cheap, but to VCD for program source of "home cinema" device always is a popular type of cheap-home theater. With the previous reset, reset, and surround speakers, and so is not cost-effective, isn't necessary. If one of these active speakers, will be "temporary" home theater is used for a while, but do see it two or three years. Of course, a few years later, to buy genuine home theater, and the complete set of non-equipped DVD home theatre speaker system is not used.