Итак, немного о демпфировании:
Damping Equalizes Power Input to Speaker
From the illustrated numerical example, it can be readily seen that more electrical would be delivered to the voice coil of the speaker if the resonant impedance peak were subdued, and the extent of this increase in input power would be dependent upon the characteristic regulation of the amplifier and the actual degree to which the resonant impedance peak were to be lowered. However, whether this increase in power input would result in subsequent increase in acoustic output depends upon the manner in which the resonant peak is minimized and upon the baffling of the speaker. Thus, for instance, a speaker may be designed with a large value of mechanical resistance in the moving system, which will tend to restrict both the excursion and the impedance peak. However, much of the electrical power delivered to the speaker under these conditions of high mechanical resistance is wasted in overcoming this resistance. There is thus no essential gain in acoustic output. However, if the speaker is damped through the proper enclosure loading, in which useful acoustic output is obtained, as in a true horn baffle, the diaphragm moves very little at resonance, though it still delivers full power at high efficiency.
The reason why diaphragm moves only small distances under a horn load stems from the fact that the large horn mouth is actually the vibrating surface that communicates with the air, and it is quite large in comparison to the actual diaphragm. Hence, in a horn load, the mouth of the horn may be many times greater than the actual piston diameter. For instance, in a typical horn loaded enclosure, mouth may be at least 14 square feet in area. By horn transformer action it will be seen that this large “diaphragm of air” at the mouth of the horn is transformed into a high acoustic impedance at the throat of the horn by the “squeezing-in” action of the horn as one looks down the horn toward the throat area. The diaphragm sees this high impedance of the air load of the horn and is consequently restricted from moving over any great distances. It is, as we might say, highly damped by the acoustic load of the horn. But because this acoustic load is one that actually is effective in radiating acoustic power into the surrounding air, the subdued peak is then representative of useful loading upon the diaphragm; that is, the resonance of the diaphragm is subdued due to the load, and represents useful power consumption. Similarly, but to a lesser degree, in the case of bass-reflex enclosure and speaker, the final impedance characteristic peaks are considerably lower than the original free air impedance peak because of acoustic load imparted to the speaker by the baffle and the air which is driven by the baffle conditions. The impedance peaks are not only lowered but actually distributed and spread out over a larger area. This condition is again representative of, and due to, radiation load as seen by the system, and thus represents good acoustic efficiency, although not of the same order as that of the horn-loaded speaker.
In both these cases, then, the damping of the impedance peak is due to useful acoustic power been radiated without power been wasted in mechanical resistance. Thus it will be seen that the increased power put into the loudspeaker, due to resonance damping, is converted into useful acoustic power to the degree governed by the nature of the damping. Acoustic radiation damping will convert input power to acoustic output. Mechanical or acoustic loss methods of damping will only convert input power to heat.
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