Introduction to the use of stage sound equipment

Introduction to the use of stage sound equipment

Audio equipment includes: monitor mixer; power amplifier mixer; portable mixer; power amplifier; dynamic microphone; condenser microphone; wireless microphone; speaker; monitor speaker; power amplifier speaker; ultra-low speaker; equalizer; reverberator; Effector; Delay; Compressor; Limiter; Crossover; Noise Gate; CD Player; Recording Deck; DVD Player; Projector; Tuner; Song Player; Headphones and many other equipment. The tuner is the professional who is responsible for all the audio equipment on the performance stage. First, you need to concentrate all the audio sources on the mixer, and then divide them into sub-channels, groupings, and adjustments. Then, the output audio from the main channel is sent to the power amplifier and speakers to emit sound through the total audio balance to make it compatible with the venue. Acoustic characteristics are compatible.

The tuner needs to know the musical characteristics of each link, the frequency that is easy to feedback, and the resonance point of the venue, in order to control the volume of each song and balance them. In addition, he will use effects to improve unused vocals and musical instruments, and be familiar with the functions and limitations of each piece of equipment, so as not to cause distortion and other undesirable effects. The quality and reliability of the selected equipment must be ensured, and possible failures must be prepared in advance, and effective remedial measures must be taken in time. Sometimes it is necessary to complete the preparation work a few hours before the performance. Although the time is very tight, for the sake of insurance, each signal line must be personally connected to it.

1. Power amplifier (ROWER AMPLIFIER)

Amplifiers need to work continuously for a long time in large-scale activities, and they must be able to withstand the vibration and impact during handling. Therefore, compared with general audio amplifiers, professional amplifiers pay more attention to the durability of long-term use and the reliability of construction. Amplifiers have an important impact on the sound quality of sound reinforcement, accounting for about 30% of the full set of audio equipment. Therefore, in order to give full play to the performance and role of audio equipment, we must pay attention to the quality of the amplifier. Otherwise, a high-quality sound reinforcement system will not work.

There are three types of power amplifiers:

1. Monolithic power amplifier;

2. Mixer + power amplifier integration;

3. Integrated speaker + power amplifier.

Monolithic amplifier: This kind of power amplifier is an independent component, you can combine the sound system according to your own plan. Generally, a power amplifier consists of two channels.

Mixer + power amplifier integration: this kind of power amplifier is simple to connect and easy to operate. Small and medium-sized sound reinforcement systems are often used.

Amplifier + speaker integration: Because of the consideration of the matching of power amplifier and speakers, it is simple and convenient to use, mostly used for monitor speakers and keyboard instrument speakers. When connecting the amplifier and the amplifier and the amplifier and the amplifier, the impedance matching between them (impedance is in ohms) should be considered. Impedance matching means that the rated output impedance of the power amplifier should be equal to the rated impedance of the speaker. At this time, the speaker The absorbed power is large. If the rated impedance of the speaker is much smaller than the rated output impedance of the power amplifier, it will cause the working current to increase sharply, which will damage the speaker and amplifier.

When one channel of the power amplifier drives two speakers, the total impedance of the speakers will become smaller, and then the load impedance value of the power amplifier will become smaller, and the power amplifier will be overdriven in the case of a near short circuit. Therefore, when the power amplifier is connected to the speaker, it must be noted that the input impedance of the speaker is within the load impedance range of the power amplifier. Power matching: In principle, the rated output power of the power amplifier should be equal to the rated power of the speaker, but since the power amplifier tube will have serious nonlinear distortion after overload, the rated output power of the amplifier is usually increased deliberately to make it greater than the rated power of the speaker . The correct connection should be: the output power of the amplifier is 30% greater than the nominal power of the speaker. If the power of the speaker is too much smaller than the power of the amplifier, you should be extra careful when using the amplifier. The volume should be gradually adjusted from small to large, and not too loud, otherwise the speaker will be damaged. In actual work, the output power of the power amplifier is relatively large, which is beneficial to improve the sound quality. In addition, the dynamic range of the sound source is very large, so pay attention to the damage of the speaker caused by the momentary overload of the power amplifier.

The average output power refers to the power of continuous work for a long time. Peak power refers to the large power that can be withstood in a short period of time, which is much larger than the rated power. The output of the amplified sound is determined by the power amplifier. For a concert of a certain scale, there must be a certain amount of power, and the standard is one watt per person. Depending on the type of concert, the size of the venue, the reverberation and the number of speakers, the power will vary.

Total power/output power of a power amplifier = number of power amplifiers required

Bridge output: Bridge output is a way to use stereo amplifier as mono amplifying. It is a circuit form used to obtain a large power output, also known as the BTL method.

The principle of the bridge connection method: Use the A channel to amplify the positive half cycle signal, and use the B channel to amplify the negative half cycle signal to double the power of the output.

Bridge connection method and specific steps: When a set of power amplifiers work separately, the rated output power of each channel is 400W4? This is the ordinary stereo connection. When a larger rated power output is required (below 400W), the bridge connection method can be used:

1. Put the mode switch on the "BRIDGE" position;

2. The signal is input from channel A;

3. The power is output from the "+" terminals of the two channels, the A channel is the output "+", and the B channel is the output "-".

Power amplifier output level display: The display is a ladder group of color light-emitting diodes, which is used to display the level of the power amplifier in real time. The normal level is in green; when the power amplifier requires the transmission of a high-pitched continuous signal, the level signal is in yellow; at the peak of the audio signal of the music or drums, the red LED flashes (and sometimes flashes). The above are normal phenomena.

If the red LED is always on, it means that the amplifier may be overloaded. This situation often occurs when one power amplifier drives multiple speakers. At this time, the system should be reconfigured to eliminate this overload phenomenon.

Power amplifier peak display (PEAK): When the PEAK peak diode flashes, the gain control should be lowered.

Power amplifier protection display (PROTECTION): In the event of some misoperation, the built-in protection circuit of the power amplifier will be automatically disconnected, and the protection display will flash. After the misoperation is eliminated, the protection indicator light will go out.