Knowledge of Speaker Dual Amplifier Drive

- Jul 18, 2018-

In the field of professional sound reinforcement, the traditional speaker drive mode is a built-in crossover mode of single-amplifier drive, which is only suitable for general applications. In modern sound reinforcement systems with high requirements and high power, bi-amplifiers (bass amplifiers and mid-high-pitched amplifiers) or three-amplifier drives (high, medium and low-powered three speakers are often used). Compared with single-amplifier drive, this matching method can eliminate the shortcomings of many single-amplifier drives and make the sound quality more pleasant.

1. Improve the damping coefficient of the speaker system.

The damping coefficient reflects the ratio of the impedance of the speaker to the total impedance of the circuit in front of the speaker. The higher the damping coefficient, the more obvious the response of the output signal of the amplifier to the speaker. That is, the higher the control power of the amplifier on the speaker. . The crossover components used in the built-in crossover are high-impedance originals, so the power divider will greatly increase the total impedance of the circuit, thus reducing the control power of the amplifier and affecting the improvement of sound quality.

After using the bi-amplifier or the three-amplifier drive, there is no built-in crossover circuit, so there is no adverse effect on the damping coefficient of the system.

2. Eliminate the insertion loss of the speaker.

The so-called insertion loss is the part of the power that is output to the amplifier but cannot be transmitted to the speaker and converted into sound. The built-in crossover is also called LC crossover. Its principle is to use the low-pass and high-pass characteristics of the inductor (L) and capacitor (C) to block the signal of a part of the frequency from passing through a certain circuit, thus completing the frequency division. However, the original components such as inductors and cement resistors used in the built-in crossover are themselves power components that consume a lot of energy. The energy lost on these components constitutes the so-called "insertion loss", and the more the frequency divider is Complex, the insertion loss will be greater.

After using the bi-amplifier or the three-amplifier drive, since there is no third device between the amplifier output and the speaker unit, it can perfectly eliminate the insertion loss, that is, it has a significantly higher utilization rate of the output energy of the power amplifier.

3. The phase characteristics are better.

The LC originals of the power dividers, in addition to the troubles caused by internal resistance, their phase effects as phase originals are also carefully considered when designing power dividers. For a speaker, the phase condition of the high and low volume unit and the frequency divider itself is very complicated at different frequencies. If the phase difference is not considered when designing the frequency divider, proper phase compensation is made, which is likely to cause although the crossover attenuation of the high and low sound speakers is perfect, the phase of the two is inconsistent, resulting in uneven curves. Even a speaker with a perfect curve but poor phase is often less than a phase problem. The ideal speaker is much harder to hear.

After using bi-amplifier or three-amplifier drive, the electronic crossover circuit design is easier to phase-control than the built-in crossover, and the phase characteristics are much better than the built-in crossover.

4. The drive power distribution is more accurate.

With bi-amplifier or three-amplifier drive, each speaker unit can obtain accurate driving power, giving full play to their respective advantages and features, and the sound quality is more pure and sweet.

5. The crossover point and frequency division characteristics are easier to control.

Bi-amplifier or three-amplifier-driven speakers, because they use integrated circuit active filters to divide the frequency, the sound signal is very weak before the amplifier, so it is easy to divide the sound completely, and can be easily adjusted by adjusting the input parameters. The frequency dividing characteristic compensates for the acoustic defects of the unit in a certain frequency band, and at the same time reduces the crossover cross area, the adjustability is good, and the electro-acoustic index is improved.

6. Reduce modulation interference.

The single-amplifier-driven speaker, the harmonic distortion and overload distortion of the woofer can be transmitted to the corresponding middle and high-frequency speaker unit through the crossover network, so that the system distortion is increased, and the high-frequency speaker unit is easily damaged. After adopting bi-amplifier or three-amplifier drive, the inputs of high-frequency, medium-frequency and low-frequency are independent, which avoids the modulation interference of low-frequency signals on high-frequency signals during the transmission of “long” speaker lines, thus improving the quality of high-pitched output. .

Therefore, the use of bi-amplifier or three-amplifier drive mode reduces sound distortion and power loss, ensuring a perfect interpretation of sound quality.



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