Search Results

A new system for determining the maximum and minimum radii of nearly circular two dimensional objects has been developed. The measurement uses a video camera and digitzer board to import a snapshot of the object. First, the pixels defining the contour of the object are traced. Then, a coordinate system transformation is performed and an iterative and adaptive least squares curve fitting algorithm is employed to extract the information of interest. Both the largest and smallest radii can be estimated with an accuracy of better than 0.1%. Completion of the measurement requires less than 4 seconds using a fast personal computer. Details of both the algorithm and the physical system are investigated with an emphasis on developing a measurement that is optimal in terms of both speed and accuracy. Results from simulations of the algorithm as well as actual measurements from a real life application will be presented.

A new system for measuring spider compliance has been developed. The result of the measurement is a plot that maps the compliance versus displacement. The technique quickly and nondestructively generates the data and is almost completely automated. The method is reviewed and results documenting performance and improvement over an EIA standard test are presented. Several examples of actual measurements that illustrate the usefulness of the measurement are shown as well.

Of all the loudspeaker driver parameters needed to predict important performance aspects such as the resonant frequency and the Q, none remain as elusive to the design engineer as the mechanical compliance of the driver. The other parameters are either easily measured (e.g. moving mass or voice coil resistance) or easily calculated (e.g. effective diaphragm area or free air loads), but this is not the case with the compliance. The reason for this stems from the fact that the total driver compliance is actually two separate compliances in parallel (from the spider and surround) and each of these employ complex geometries and are made from an array of materials which can be treated in a number of different ways. In this paper a method for separating the total driver compliance into it's individual components is documented. The method is then used to evaluate the relationship of the spider compliance to the surround compliance as the surround material changes.