We will see all kinds of boxes, large and small, with holes, with slits, some with open backs, and various uncommon names. How do they look and what are their characteristics?
1. The most classic closed box,
It evolved from the concept of infinite panel, and changed the disadvantage of energy waste behind the speaker cone caused by the infinite panel, so that the speaker can work in a relatively small volume, but it is still inefficient. The advantages of this box are small size, minimal sound stain, low frequency roll-off slow, and low distortion! Usually this type of box is equipped with a soft cone cone horn (basically equal to high Q). The main point of making the box is to pay attention to the tightness of the box!
2. Bass reflex type (commonly known as domestic inverted type)
This is the most commonly seen box, with the advantages of moderate volume, medium efficiency, and good sound quality in a wide frequency band. The disadvantage is that the low frequency is turbid and rolls off too fast! (Not applicable to low-frequency hifi playback) The second-level inversion is a form of enhanced bass reflection effect, which enhances the low-frequency enhancement effect, but it also causes a deep valley in front of the low-frequency peak and distorts the low-frequency turbidity. Also increased! Difficult to make and adjust.
3. Open back or open baffle (abbreviated as OB)
Electric guitars mostly use this box. It requires a harder cone speaker. The benefit type is simple and easy to make, and the disadvantage is that the low-frequency money owes money. Make sure that the side panel is not too deep when doing this box, otherwise there will be resonance.
4. Transmission Line and AcousTIc Labyrinth
This kind of box often has a huge volume, and the sound wave behind the horn is put back into a pipe that is several meters long and fed back. The pipes are often folded, and a lot of sound-absorbing materials are used inside to absorb all sounds except low frequencies and reduce distortion. The low frequency is coming out of the pipe opening and is in phase with the sound of the front of the horn. The characteristic is that while the low frequency is strengthened, the quality is quite good.
5. Rear Loaded Folded Horn
4. Transmission Line and AcousTIc Labyrinth
This kind of box often has a huge volume, and the sound wave behind the horn is put back into a pipe that is several meters long and fed back. The pipes are often folded, and a lot of sound-absorbing materials are used inside to absorb all sounds except low frequencies and reduce distortion. The low frequency is coming out of the pipe opening and is in phase with the sound of the front of the horn. The characteristic is that while the low frequency is strengthened, the quality is quite good.
5. Rear Loaded Folded Horn
In the horn box, the sound passes through a cavity that continuously enlarges the cross-sectional area, the energy is amplified, and the direction is strengthened. The difficulty of making a horn is at the junction of the unit and the horn. It is necessary to prevent the distortion of the resonant resonance. Sound dyeing is also a problem. The low-frequency horn has a huge volume, and the advantage of the right-angle folded horn is that it is compact enough. The disadvantage is that high frequencies are suppressed and cause distortion. The box still uses the front sound of the speaker to output directly. Although the efficiency is higher than the inverter box, it is still the lowest efficiency low-frequency horn box!
6. Front Loaded Straight Horn
This kind of box has extremely high efficiency and directionality! Common in large occasions such as stadiums. But it is not suitable for lower frequencies, because of the huge volume and length. In addition to the previous two points, it has the advantages of small sound stain, good sound transient and high resolution. On hifi, it is often used in mid-to-high frequency and requires a compression driver.
7. Front Loaded Folded Horn
The classic W-Bin horn box is this type, the advantage is that it is efficient and compact! The disadvantage is that the bandwidth is narrow and the sound is large. Although efficient, some people think that the bass quality is not as good as the inverter box.
8. Band Pass
Box designs that have only become popular in recent years generally have 4th and 6th order designs. The sound quality of this kind of box is very bad, and it is generally not used for hifi purposes! But because it can improve the low frequency and has a low-pass filtering effect, it is very suitable for AV subwoofer design.
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