People who first touched the horn speakers are generally interested in the speaker unit used in the speaker horn. Yes, the effect of the unit on the sound of the speaker is indeed great, but it is not the whole factor that determines the sound of the horn loudspeaker. . The box that is usually regarded as the speaker's face value is actually not as simple as the "shell of a unit placed in your imagination". It is a second consideration for the cabinet. Factors, the realization of acoustic optimization is its main responsibility. Today we will talk about the impact of the cabinet design on the sound of the speakers.
Many beginners are estimated to have experience with Amway wooden cabinets. The so-called wooden speakers are not the pure solid wood cabinets you imagined, because in terms of solid wood, they can naturally meet the requirements of manufacturing cabinets. Wood with characteristics such as density uniformity is extremely rare, and the price is very expensive, so a small amount of solid wood as a cabinet decoration can be used, and the whole solid wood is rarely used now.
The high-end entertainment speaker box materials on the market are basically birch plywood, which has high hardness and light weight. The density of the multi-layer sheet is not uniform and the resonance frequency is reduced. It is suitable for the material of the box, but it is generally used in professional. On the speaker.
Birch plywood has good acoustic properties. We know that a wooden box-like instrument like an acoustic guitar requires that the box must be able to enhance the vibration of the string to create a greater resonance. The speaker cabinet is just the opposite, requiring the cabinet to not follow the unit. Vibrate and vibrate to avoid distortion of the cavity resonance. Birch plywood is the material of choice for speaker cabinets because it meets the acoustic needs of speaker production. Moreover, the surface of the birch plywood is flat and easy to apply on various veneers, so we can see that the wood grain on the speaker is basically attached, one is good-looking, and the other is to enhance the moisture resistance of the birch plywood.
There is another detail on the speaker cabinet that we may not have noticed is the inverted phase hole (the fully enclosed cabinet has no inverted phase). This hole can sometimes be a round hole, and sometimes it can be a long seam, but the effect is the same. When the speaker works, it will drive the air to send two sets of sound waves. The two sets of sound waves have the opposite phase. At this time, a sound tube is installed inside the speaker, which can reverse the phase of the sound emitted by the speaker, and then the speaker The sound waves emitted before are superimposed on each other to achieve a greater sound pressure.
The lowest frequency sound of the speaker is radiated to the listening position through the inverted aperture opening, and all other frequencies are radiated by the speaker unit. When the frequency is very low and the sound pressure level is high, a large amount of airflow will repeatedly enter and exit through the conduit opening on the casing. Therefore, the key to the design of the inverted phase hole is to enable the air to efficiently enter and exit unimpeded when the volume is large and the speed is high, and the turbulent noise is not generated in the inverted tube and the nozzle. If the air flow in the inverted well is blocked, then audible low frequency distortion and low frequency loss are immediately produced.
We see that some inverted holes are set to the back of the speaker, some on the front of the speaker, some on the bottom, and some are special shapes, but the position of the inverted hole in the speaker is not important, because it is relative to The wavelength of the very low frequency sound waves radiated by the inverted phase holes, the size of the speaker is negligible. For example, the wavelength of 50 Hz has been as long as 6.8 meters, and the thickness of the general box may not exceed 60 cm, so the low-frequency sound waves can be completely diffracted, and the phase difference caused by the size of the cabinet is small enough to be inaudible to the human ear. Although the position of the inverted hole is not important, the speaker has to talk about the aesthetics of the design in addition to the sound. It is not just a hole in the box. The clever design can often add a product.
Note: This article is transferred from the audio network. The article is an independent view of the author and does not represent the position of the home theater network.
