Eight Reasons Why Horns Burn Out

- Mar 11, 2020-

1. The speaker and power amplifier are not configured properly

Many professional players will think that the output power of the power amplifier is too large, which is the cause of damage to the tweeter. Actually not. In a professional situation, a speaker can generally withstand a large signal impact of 2 times the rated power, and it can withstand a peak impact of 4 times the rated power instantly without problems. Therefore, it is rare that the tweeter is burned by the power of the power amplifier due to the unexpected strong impact or the microphone howling for a long time. However, if the power output of the amplifier is too large, both the tweeter and the woofer may be damaged. If the power of the power amplifier is insufficient, resulting in clipping of the signal overload, the harmonic components will increase sharply.

Signals that were originally sine waves generate a large number of odd harmonics when the overload clipping approaches a square wave, which greatly increases the proportion of treble frequency components in the signal, causing the treble frequency energy in the signal to far exceed the tweeter's capacity. Withstand power. Even though the total signal power at this time has not reached the rated power of the speaker, the tweeter has been overloaded and caused damage. This situation is more dangerous than a short-term overload of the signal, but without clipping. When the signal is not distorted, the short-term overload signal, the power energy falls on the woofer with higher power, which does not necessarily exceed the short-term * power of the speaker, and generally does not cause the speaker power distribution deviation to damage the speaker unit. Therefore, under normal use conditions, the rated output power of the power amplifier should be 1-2 times the rated power of the speaker, so as to ensure that the power amplifier does not cause distortion when the speaker's * power.

2. Improper debugging of the equalizer

The adjustment of the equalizer is also crucial. The frequency equalizer is set to compensate for various defects in the indoor sound field and uneven frequencies of the speakers. It should be debugged with an actual spectrum analyzer or other instruments. After debugging, the transmission frequency characteristics should be relatively flat within a certain range. Many tuners who do not have sound knowledge can adjust it at will, and even a considerable number of people have raised the high and low frequency parts of the equalizer too high to form a "V" shape. If these frequencies are increased by more than 10dB compared to the mid-frequency (the equalizer's adjustment amount is generally 12dB), not only the phase distortion caused by the equalizer will seriously stain the music sound, but it will also easily cause the audio tweeter. Burning, this kind of situation is also the main reason for burning speakers.

3. Improper use of crossover

In the case of external crossover, improper use of the input crossover point or the unreasonable operating frequency range of the speaker is also a cause of damage to the tweeter. When using a frequency divider, the frequency division point should be reasonably selected in strict accordance with the speaker operating frequency range provided by the audio manufacturer. If the crossover point of the tweeter is selected too low and the power load is too heavy, it is easy to burn the tweeter.

4. Volume adjustment

Many users set the attenuator of the post-stage power amplifier at -6dB, -10dB, that is, 70% -80% of the volume knob, or even in a general position, increase the front-stage input to achieve a suitable volume, and reserve it for the power amplifier. With a margin, the speaker is safe, but it is actually 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 front stage must output 6dB more, the voltage must be 1 times higher, and the input headroom Will be cut in half. At this time, if there is a sudden large signal, the output will be overloaded 6dB earlier and a clipped 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 burn out.

5. Improper low-cut selection causes damage to the woofer

Many tuners do n’t pay much attention to the low-cut problem. In fact, this low-cut is a hidden danger of woofer damage. Many woofers ca n’t reproduce some ultra-low frequencies, such as frequencies below 40 Hz, but they ca n’t. The frequency component reduced to acoustic energy still exists, and it is converted into thermal energy, and our horn is glued by many parts with glue. When inputting ultra-low frequency component signals that cannot be converted to the horn for a long time with high power, due to The volume of the cabinet is limited, the heat is not released in a timely manner, and a large amount of heat is gathered. Once the glue cannot bear, it will melt, causing the elastic waves to fall off, the voice coils scattered, and the speakers damaged. The use of low cut can greatly reduce the damage to the woofer from ultra-low frequencies.

6. Difference in input sensitivity when different amplifiers are used at the same time

In engineering, there is often a situation where different brands and models of power amplifiers are mixed. There is a problem that is easy to be ignored, which is the problem of power amplifier input sensitivity. This problem is often ignored, which is the same power, different models. There may be a problem of inconsistent sensitivity and voltage between two power amplifiers. For example, the output power of two power amplifiers is 300 watts, the input sensitivity of A power amplifier is 0.775V, and the input sensitivity of B power amplifier is 1.0V. When the signal voltage reaches 0.775V, the output of A power amplifier reaches 300W, but the output of B power amplifier only reaches 150W. Continue to increase the signal level. When the signal strength reaches 1.0V, A power amplifier is overloaded, and B power amplifier has just reached the rated 300W Output Power. In this case, the speaker unit connected to the overload signal will be damaged. When power amplifiers with the same power and different sensitivity voltages are mixed, the input level of the power amplifier with high sensitivity must be attenuated. It can be unified by adjusting the output level of the front-end equipment or reducing the input amplifier of the high-sensitivity power amplifier. For example, the two amplifiers mentioned above are 300W output power amplifiers. The sensitivity voltage is 1.0V and the other is 0.775V. At this time, the level of the input to the 0.775V amplifier is reduced by 3dB or the power discharge flat knob is put. At the -3dB position, when the two amplifiers input the same signal, the output power is the same.

7. The large signal is disconnected for a while, causing the woofer to freeze.

In KTV, many times the box guests or DJs have a very bad habit, which is to cut songs or mute in the state of loud pressure. Especially when playing Diqu, it is easy to cause the voice coil of the woofer to get stuck or burned. The audio signal is input to the horn through the current method. The horn drives the paper cone back and forth through electromagnetic force to make the air vibrate into sound. When doing a large-scale exercise, the signal input is suddenly cut off, which can easily cause the exercise to lose its recovery ability after a certain degree. The unit is damaged.

8.Preamp, power amplifier components self-excitation

The circuit of the pre-stage output part is broken down, resulting in a pure tone frequency output of sine waves, similar to howling at some frequencies, and the output power is large, which can directly cause the bass unit to burn out because of power overload. Due to the current breakdown, the power amplifier becomes a DC output, which damages the speaker woofer and woofer. The eight points summarized above are both for KTV venues, and for bars and on-site situations.