Amplifiers and speakers: I will not explain what is a power amplifier and what a speaker is here. Here are a few issues that need to be paid attention to when using power amplifiers and speakers and the places where these devices are prone to failure:
1. Power matching: Generally speaking, the power of the power amplifier is greater than the power of the speaker. Under normal circumstances, the power of the power amplifier is more than 30% larger than the power of the speaker. If a low-power power amplifier is used to push a high-power speaker, the power amplifier is prone to overload. A current harmful to the speaker is generated, and the speaker unit is easily damaged at this time.
2. Impedance matching: At present, the power amplifiers used in professional audio systems are generally fixed impedance. Generally, the power amplifiers work at 4Ω--8Ω most. Some sound engineers like to push more than 2 speakers with one power amplifier. Pay attention to the impedance of the speakers. When multiple speakers are connected in parallel, the impedance will decrease. If it is lower than 2Ω then the power amplifier will be easily damaged at this time. This kind of approximate short-circuit working mode is better not to use.
3. The line connection between the power amplifier and the speaker: the signal line of the power amplifier should be balanced as much as possible. If there are multiple power amplifiers in the system, it is better to use a signal amplifier splitter to separate enough signal lines without attenuation to supply each signal line. A power amplifier is used alone, which can reduce system noise, reduce hidden dangers, and improve signal-to-noise ratio. At the same time, you also need to pay attention to the quality and connection of the speaker cable. Try to use a thicker and short speaker cable. When connecting, pay attention to distinguish the positive and negative poles and avoid short circuits, especially the professional four-core or four-core speaker plugs. The terminal is very small, so be careful when wiring.
4. Sometimes there are many change-over switches behind the power amplifier, such as: mono working mode, stereo working mode, bridge working mode; some have level adjustment switches, signal frequency switching switches, etc., we must pay attention when using them See these switches clearly and adjust the power amplifier to the correct or desired working state, otherwise it may cause unexpected failures.
Examples of power amplifier and speaker failures:
1. In 2005, when we were engaged in the audio equipment of the Shanghai DJ Competition, our engineer said that the bass was not enough. We were looking for the cause of the preamp. I saw that the 130Hz low cut switch in all the subwoofer amplifiers was turned on, which was equivalent to turning on the bass below 130Hz. All have been cut off, and in this case, it is naturally impossible to have satisfactory bass.
2. One of my apprentices was doing an outdoor performance. There are four power amplifiers in the system, 2 QSC and 2 old British recording masters. The signal line is switched and distributed through the input and output ports behind the power amplifier. , He connected the power cord and signal line of the entire system according to the normal and formal method. As a result, there was no sound from the system after turning it on.
I used to check that the mixer was normal, and other front-end equipment was okay. Later, I input the audio signal into the QSC amplifier and the speakers have sound, and when I separately input the audio signal into the old British recording master amplifier, the speakers also have sound. When the power amplifiers are connected together through the signal line, the speakers driven by the two power amplifiers are all silent. I took a closer look and found that in the XLR XLR connector of the old British recording master power amplifier, 3 is the hot end and 2 is the cold end. In the XLR XLR interface on the back of QSC and most professional power amplifiers, 2 is the hot end, 3 is the cold end, and 1 is the ground. Due to the different signal port formats and standards, when the signal of the two power amplifiers is different, When connected together, it is actually equivalent to a short circuit, and naturally no sound will come out in the audio system.
Later, I gave the two main output signals of the mixer to the QSC amplifier, and the two grouped signals of the mixer to the old British recording master amplifier. At this time, the system was normal. Of course, I later discovered that the signal port of the new recording master function was also adjusted to: 2 is the hot end, 3 is the cold end, and 1 is grounded. In short, the power amplifier and speakers are the last two devices in the system. All the peripheral devices in the front serve for them. In a project, if the power amplifier and speakers can be correctly and reasonably connected and configured, the project will be half the success.