Mechanisms Of Subharmonic Distortion In A Woofer At Low Frequencies

Even China is one of the biggest loudspeaker manufacturing country, most companies remain in the OEM (original equipment manufacturer) stage, only a few have entered the ODM (original design manufacturer) stage. Nonlinear distortion is an important factor which will affect the quality of a loudspeaker, so it is significant to figure out the mechanisms of the nonlinear distortion. The nonlinear distortion factors are different due to the frequency range. The nonlinear of the loudspeaker shell is considering as the most important distortion factors for a loudspeaker at medium-high frequency. Analyzing on this factor provides theoretical basis for designing a new shape of a shell. The stiffness (Kms) of the suspension, the force factor Bl(x), and the reluctance force are the most important distortion factors for a loudspeaker at low frequency. Analyzing on these factors provide theoretical basis for developing new material and designing magnetic circuit and electrical circuit. Main studies on my master’s period is listed as follows:1. Confirming the nonlinear factors of the studied loudspeaker by using the Klippel analyzer system. The nonlinear vibration equation is given by the simplified mode depending on the value of this system.2. The using instructions of the nonlinear analysis software AUTO07is given, as well as the meaning of the important constants of this software.3. Using the nonlinear analysis software AUTO07to analyze the bifurcation of the nonlinear vibration equations of woofer at low frequency and getting the voltage response curves. By analyzing the curves we can figure out the reluctance force is the most important nonlinearity generating the sub-harmonic distortion.Using the4th Runge-Kutta method to get the time process solutions under certain parameters.4. Experiment by using laser scanning vibrometer and sound spectrograph carry analyzer, have observed the sub-harmonic phenomena, and verify the theoretic analysis.