Suspension Part Measurement (SPM)
The nonlinear stiffness K(x) and the reciprocal compliance C(x) of suspension parts (spider, surrounds, cones) and passive radiators (drones) are measured versus displacement x over the full range of the operation. A dynamic, nondestructive technique according to the IEC standard IEC62459 is developed which measures the parts under similar conditions as operated in the loudspeaker. This guarantees the highest precision of the results as well as a simple handling and a short measurement time. Suspension parts are fixed in the measurement bench by using a set of clamping parts (rings, cones, cups) fitting to any size of circular geometries up to 222 mm diameter. The working bench excites pneumatically the suspension to vibration at the resonance frequency related to the stiffness and the mass of the suspension and inner clamping parts. The measured parameter is required for specifying the large signal properties of the suspension parts and to detect asymmetrical and symmetrical variation which are the cause for instable vibration behavior and nonlinear distortion.
Specification of suspension parts
Analysis of cause of distortion
Defining mechanical limits
Quality control in manufacturing
Optimal driver design in R&D
Robust, easy to use
Demo Video (Introduction)
The figure above shows the user interface of the SPM software for measuring the nonlinear stiffness K(x) and compliance C(x) versus displacement x. The software automatically adjusts the voltage of the stimulus to generate the desired target value (in this example 15 mm peak). The mass of the suspension part with inner clamping part is the only input parameter provided by the user.
The figure above shows the variation of the nonlinear stiffness versus time using the SPM module in the long-term measurement mode. While the suspension part is permanently excited at the target displacement (15 mm peak), the nonlinear stiffness is measured in 15 minute intervals.