The sound box is affected by various aspects such as structural form, box material selection, processing precision, etc., in the process of using the sound box, it itself is a mixed sound source of direct sound and diffracted sound. Early labyrinth speakers relied on the long bass duct in the speaker box to enhance the low-frequency energy. Although the bass release hole is set directly in front of the speaker panel, the low frequency part released by it is enhanced by the multiple reflections of the longer bass channel. Therefore, this part of the low frequency has the characteristics of strong diffraction sound-this is its unique positioning ambiguity. The frequency response of the labyrinth speaker is also prone to slight disconnection at the low frequency end.
The labyrinth speaker is a product of the era of hard-folded ring woofers. In the woofer of the loudspeaker decades ago, the folding ring on the edge was mostly a hard folding ring, which was made of cloth material with glue. The folding ring of most civilian products is basically the extension part of the paper diaphragm. Due to the high hardness of this type of folding ring and the small travel range of the diaphragm, it is called a hard folding ring unit. The low frequency f L of this type of woofer itself is relatively high, generally in the range of tens of Hz to 100 Hz, and it works in a vibration-type sounding state. Due to its low frequency f L is not low enough and the vibrating sounding state, it is appropriate to use a labyrinth box structure to enhance the bass.
With the advancement of speaker unit production technology, soft folding ring woofers with rubber edges and foam edges have come out. This type of woofer has a long stroke, and its own f L is low, generally tens of Hz, and the lowest can reach a few Hz. The woofer of the soft folding ring works in a piston-type sounding state in the low frequency range, so there is no need for a labyrinth-type cabinet to enhance the low frequency. Some manufacturers and enthusiasts who do not have a deep understanding of the sounding principle of speakers have added a long labyrinth bass channel to the woofer of the soft folding ring, which has caused the adverse consequences of poor transient characteristics of the speakers and serious bass disconnection. This is also the theoretical basis of why manufacturers with strong modern technology have eliminated labyrinth speakers.
The working state of the inverted speaker is also in a mixed working state of direct sound, diffracted and reflected sound. Since the length of the inverter tube of the phase-inverted speaker is shorter and the distance from the bass unit is relatively short, the ratio of diffraction and reflection of the phase-inverted speaker is relatively small when it is working, and the replay tone and phase are more accurate. This is also the main technical basis for the popularity of inverted speakers at this stage.
There is also a type of speaker, this is a closed speaker, this type of speaker does not have a labyrinth of sound release holes and inverted holes. Theoretically speaking, closed speakers can easily achieve better frequency response and complete direct sound, but the actual working state is not like this. Due to the strength of the box material itself, the box body of the closed sound box is vibrated by the higher air in the box, and the box body will produce strong vibration (diffraction sound) under working conditions. Labyrinth and phase-inverted speakers have relatively small vibrations due to the semi-open state of the cabinet. The test curve of a closed speaker is relatively straight, because the test is in a low-power working state where only 1W of power is input, and the input power is much greater than 1W during normal use. Due to the restriction of the volume of the cabinet and the influence of the damping material in the cabinet, the frequency response of the low frequency end of the closed speaker will be significantly degraded when working at high power, and the transient characteristics of the speaker are not as good as the inverted speaker.
After knowing the working characteristics of speakers, it is easy to understand that speakers of different structures with the same frequency response, power, and sensitivity will have very different timbre and sound performance during replay.