1. The speaker and power amplifier configuration is unreasonable
The output power of the power amplifier is too large, causing damage to the tweeter, which is not the case. In professional situations, the speaker can generally withstand a large signal impact of 3 times the rated power, and can withstand a peak impact of 5 times the rated power instantaneously without any problems. Therefore, it is very rare that the tweeter is burnt due to the high power of the power amplifier, not due to unexpected strong impact or long-term whistling of the microphone.
As we all know, there are multiple speakers in a speaker, and the power received by the speakers is distributed differently according to the different crossover points.
The rated power of the speaker, generally professional speakers indicate the maximum pink noise power, that is to say, the rated power of the speaker refers to the analog signal power that can withstand pink noise or broadband. For a two-way speaker with a crossover point of 1.6kHz and a rated power of 100W, at rated power, the woofer can be allocated 78W of output power, while the tweeter can only be allocated to 22W. Therefore, applying 100W pink noise power or ordinary program signal power to the speaker can withstand it; and when using a 100W single-frequency signal to test, both the treble and woofer may be damaged.
If a three-way speaker has a crossover point of 4kHz for the middle and high pitches, then the tweeter can withstand only 5% of the nominal power. If the power distribution is improper, it will easily cause damage to the tweeter.
Under normal circumstances, if the signal input to the speaker is doubled, the power of the tweeter will only increase by 5W; but if the power of the power amplifier is insufficient, resulting in a clipping of the signal overload, the high-order harmonic components will increase sharply. The original 1kHz sine signal, when the overload clipping is close to the square wave, a large number of odd harmonics will be generated outside the 1kHz sine wave, such as the sine wave energy of 3kHz, 5kHz, etc., so that the proportion of the high-pitched components in the signal Greatly increase, and cause the treble spectrum energy in the signal to far exceed the power that the tweeter can withstand. Even if the total signal power at this time has not reached the rated power of the speaker, the tweeter has been overloaded and damaged. This situation is more dangerous than the short-term overload of the signal, but no clipping occurs. When the signal is not distorted, the short-term overload of the 1kHz signal, the power energy falls on the woofer with larger power, which does not necessarily exceed the short-term maximum power of the speaker, and generally will not cause the deviation of the speaker power distribution and damage the speaker unit. Therefore, under normal use conditions, the rated output power of the power amplifier should be 2-3 times the rated power of the speaker to ensure that the power amplifier does not cause distortion at the maximum power of the speaker.
2. Improper use of frequency divider
Improper use of the input crossover point or the unreasonable working frequency range of the loudspeaker is also a cause of damage to the tweeter. When using a frequency divider, you should choose a reasonable crossover point in strict accordance with the working frequency range of the speaker provided by the manufacturer. If the crossover point of the tweeter is chosen to be too low and the power burden is too heavy, it is easy to burn the tweeter, as is the midrange horn.
3. Improper adjustment of the equalizer
The adjustment of the equalizer is also crucial. The frequency equalizer is set up to compensate for the various defects of the indoor sound field and the uneven frequency of the speakers. It should be debugged with an actual spectrum analyzer or other instruments. The transmission frequency characteristic after debugging should be relatively flat within a certain range. Many tuners who do not have sound knowledge are free to make adjustments. There are even quite a few people who raise the high frequency and low frequency parts of the equalizer too high, forming a "V" shape. If these frequencies are increased by more than 10dB compared with the midrange frequency (the equalizer is generally adjusted at 12dB), not only the phase distortion caused by the equalizer will seriously stain the music sound, but it will also easily cause the sound tweeter. Burning, this kind of situation is also the main reason for burning speakers. Of course, the design of the sound system should be based on the actual situation, such as the size of the venue, use, sound construction conditions, etc., to determine the maximum continuous sound pressure level according to the actual use conditions, and then determine the maximum SPL value of the speaker.
4. Volume adjustment
Many users set the attenuator of the power amplifier at -6dB, -10dB, that is, 70%-80% of the volume knob, or even at a general position, relying on increasing the input of the mixer to achieve the appropriate volume, thinking that the power If the amplifier has a margin, the speakers are safe. In fact, this is also wrong. The attenuation knob of the power amplifier attenuates the input signal. If the input of the power amplifier is attenuated by 6dB, it means that to maintain the same volume, the mixer or pre-stage must output 6dB more, the voltage should be doubled, and the input The upper headroom, commonly known as "head space", will be cut in half. At this time, if there is a sudden large signal, the output of the mixer will be overloaded 6dB earlier, and a clipping waveform will appear. Although the power amplifier is not overloaded, the input is a clipped waveform, and the treble component is too heavy, not only the treble is distorted, but the tweeter may also be burned out.
The above analysis can make us clearly understand: an important reason why the speaker burns the tweeter is that the power of the power amplifier is too small, not too large. The signal sent by the power amplifier is a clipped signal, which causes damage to the speaker. Therefore, when configuring the audio, you must establish a correct understanding, and use the "big horse-drawn trolley" solution to prevent the power amplifier from sending out a clipped signal and damaging the high and mid-range speaker units. When designing the sound system, the power amplifier and the sound design power must match the above principles. In actual operation, the equipment in each link must be used reasonably to protect the equipment and achieve the best effect of the sound system.