The Dominant Compliance of Loudspeaker Drivers 910651

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. Paper,cloth, and foam are the three most commonly used materials and each will be examined as they are interchanged on a particular driver. Also, it is known that both the surround and spider become more compliant as the driver becomes broken in and this change will be documented for the different materials. The driver under consideration will be the 5 1/2 x 7 1/2 inch.