Design Of Multifunction Loudspeaker Power Test System

For the low measurement accuracy,small number of test channels,a single measurement of performance parameter and small test power range and other issues that exist in the loudspeaker power test system in China at present,a set of loudspeaker power test system with multiple testing functions is designed and developed in this article.The system can achieve speaker high,medium and low power test,at the same time the system also can realize the real time online monitoring function of multi-parameters such as electrical parameters,power parameters,voice coil temperature and TS parameters,which provides data support for deep analysis of the cause of loudspeaker nominal power failure standard and damage.The design of the hardware circuit of the system mainly includes MCU master control module,power supply module,test signal allocation and conditioning module,test signal collection and conditioning module,reference signal source module,loudspeaker voice coil temperature measurement module,USB communication module,state display module and relay protection module.STM32 microprocessor based on the Cortex-M3 kernel is adopted in MCU master control module,there are ample development resources and rich peripheral interfaces in MCU,at the same time,the USB2.0 controller is integrated inside,so that it can communicate with the host computer through the USB interface.There are multiple high performance components such as channel selectors,attenuator and operational amplifier in the test signal allocation and collection and conditioning module,so that the variety of test signals are increased and the stable signal is collected to supply host computer to analysis and processing.There is a reference signal source module is integrated within the system,it can produce a stable reference signal to use for calibration of sound card input channels on host computer.In the voice coil temperature measurement module,through the relationship of real time impedance and voice coil temperature,the curve of temperature and time is generated in the host computer,so that users can observe the change of voice coil temperature in real time.The standard library function provided by the official STM32 are adopted in the mainly design of system software,system hardware circuit module drivers and the interface functions which can be called by the host computer are designed with Keil MDK.Through system hardware and software debugging and multiple loudspeaker power test,the stability,reliability and the accuracy of the measurement are verified in this system and the system meets the design requirements.