This article introduces a small part of the relevant speaker calculation knowledge, I hope to help everyone.
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Calculation of the inverted tube:
Take the cross-sectional area of ​​the inverted phase tube S=0.1~0.4 times the effective vibration area of ​​the woofer. The larger the area, the higher the low-frequency radiation efficiency, but the longer the tube length; the length of the inverted tube L=c×c×S/(4 × pi × x pi × f × f × V) - 0.82 root S (units are calculated in centimeters) where c = 34400cm / s (sound speed), f is the resonant frequency of the woofer, V is about the effective volume of the box Outer diameter 40mm
The larger the volume of the box, the deeper the low frequency dive, and the Q value will decrease; but after the low frequency, there will be gas weakness. At this time, the sandbag should be thrown into the speaker;
The smaller the volume of the cabinet, the better the low frequency strength, and the Q value will rise accordingly, but the resonant frequency of the opposite speaker will rise. At this time, more sponges can be added to expand the inner product;
The longer the inverted tube, the better the transient characteristics of the speaker, and the deeper the low frequency dive (but the volume will become smaller), but the sound will be tailed too long, causing the transient characteristics to worsen if the inverter is inverted. Too long to be too close to the surface of the cabinet, it will also produce airflow sound, this must not;
The shorter the inverter, the worse the transient characteristics and the higher the resonant frequency (but the amount of inductance will increase).
Related principles: Hemholtz (H. von. Haimuhuozi) is a great physicist and physiologist in Germany in the 19th century. The "energy conservation law" at the head of the three basic laws of conservation that we learn at university is his biggest. Scientific achievements. The Helmholtz resonance principle is one of Helmholtz's famous achievements in the field of acoustics.
First, a closed cavity composed of an ideal rigid body is created. This cavity is called a Helmholtz resonant cavity. A hole having a small surface area relative to the cavity surface is formed on the surface of the cavity, and a hole is inserted in the hole. The hollow hollow body pipe is composed of a structure called "Helmholtz Resonator".
For a Helmholtz resonator, when the internal air is forcedly compressed by external fluctuations (whether the force applied to the air in the cavity or the air in the pipe, the external force applied is from sound waves or cavity vibration) The air in the pipe vibrates, and the air in the cavity produces a restoring force (in other words, the air in the cavity is an "air spring"). In the case where the wavelength of the acoustic wave is much larger than the geometrical scale of the resonator, it can be considered that the kinetic energy of the air vibration in the resonator is concentrated on the movement of the air in the duct, and the potential energy is only related to the elastic deformation of the air in the cavity. Thus, the resonator is a one-dimensional vibration system composed of the effective mass of air in the duct and the air elasticity in the chamber, and thus has a resonance phenomenon with respect to the fluctuation of the applied action, and its natural frequency is: (see figure). In the formula, f0 is the lowest resonant frequency of the Helmholtz resonator, c is the speed of sound, S is the cross-sectional area of ​​the pipe, d is the diameter of the pipe, l is the length of the pipe, and V is the volume of the cavity. Under the action of a certain intensity of vibration, the vibration velocity of the air in the pipe reaches the maximum at this frequency.
This is the so-called "Helmholtz resonance principle".
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