Dynamic processing compressor detailed
A Compressor is an amplifier that reduces its gain as the input signal level increases. The fundamental change is the ratio of the input to the output signal. The compressor is one of the important characters in the processing of audio dynamics. Most of the time in the audio sound reinforcement system is to install the compressor between the mixer and the amplifier, and sometimes also for the processing of the live sound source, such as the bass drum of the live band. Drum sound processing will also be applied to audio program production and live sound reinforcement.
The compressor is explained in detail below by the compressor DSP in the Symetrix digital audio processor.
Figure 1
Figure II
In the second figure above, the red coordinate x-axis is the input signal level, the y-axis is the output signal level, the green line is the relationship between the input signal and the output signal, and the green dot is the set threshold. The compressor compresses the level above the threshold, while the level below the threshold remains the same, and the relationship between the input and output after compression depends on the setting of the compression ratio. In Figure 3 and Figure 4 below, we have a threshold of -36dB and compression ratios of 2 and 3. When we compare, we can see that different ratios have different input-output relationships.
Figure 3 (compression ratio is 2) Figure 4 (compression ratio is 3)
From Figure 3 and Figure 4, we can see that after the signal larger than -36dB enters the compressor, its output will be less than the input level. For example, if the -18dB signal enters the compressor with a compression ratio of 2, the output will be -27dB. It is the output of -30dB after entering the compressor with a compression ratio of 3. So when the compressor's ratio value is set larger, its output is closer to the threshold. Similarly, when the compression ratio is set to positive infinity, the compressor at this time is a real limiter.
Next, we will explain the debugging parameters of the Symetrix compressor DSP in detail.
Knee Turning Point:
The compression ratio during the transition from linear (below threshold) to compressor operation is determined. The Soft Soft Inflection point makes the signal processing when the audio processing is large and the threshold value becomes smoother when the output of the compressor becomes smaller, and the hard hard turning point causes a sudden change in its change. The turning point in Medium is between the soft inflection point and the hard turning point.
Threshold Threshold: A threshold whose value is set above what level will be compressed according to the ratio parameter. The representation of the image is that the input level above the threshold will reduce the gain according to the setting of the ratio.
Ratio ratio: Determines the degree to which the output reduces the gain when the input signal is above the threshold. Generally, a ratio lower than 10 is regarded as compression, and a ratio higher than 10 is regarded as a limit.
Attack start time: refers to the time when the input signal is greater than the threshold, the time will reach the corresponding output. If the start time is set to be shorter, the sound will show an angular change without a smooth change. The longer the boot time setting, the less effective the compressor will be.
Release release time: refers to the time required for the compressor to follow the set compression ratio to 1:1 output when the input signal is from large to small and less than the threshold.
Sde Chain In Sidechain Input: This is a function in the Symetrix compressor that uses a third-party audio signal as a reference to compress this signal. If you press this button, the compressor uses sidechain audio input to control compression. When not pressed, the input signal is used to control compression (standard operation). If there is no connection to the side chain input and the side channel input is pressed, no compression will occur.
GR. Valid: This level meter shows that when the compressor is in motion, the depth of action and reaction time can be displayed through the table.
Output fader: A fader that controls the output gain of the module. If the compressor significantly reduces the signal level, it may be necessary to increase the output gain to maintain a certain volume, which is often referred to as a false gain.
The working principle, debugging method and understanding of various parameters of various brands of compressors on the market are the same, except that the compressor in the Symetrix DSP has one side chain input control function. If the above description is inappropriate, please correct me.
Source: Yike International
Author: Wang Tiansi
Linear Comparators,Ic Linear Comparators,Ics Linear Comparators,Integrated Circuits Linear Comparators
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