The JL Audio C1 speakers deliver real substance and great audio performance in a format designed for easy fit behind factory grilles. To facilitate fit, spacer/adaptor rings are included allowing the C1-690 woofers to be installed in bottom-mount applications. Surface and flush mounts are included with C1 tweeters for maximum installation versatility. C1 woofer drivers benefit from proprietary FEA modelling and JL Audio's expertise in low-frequency driver design. This knowledge is used to create speakers that can play loudly, while maintaining a smooth, dynamic, low distortion sound. At the core of the C1-690 is a proprietary, stamped, steel 6 x 9-inch (150 x 230 mm) oval frame and a DMA-optimized motor system. A mineral-filled, injection-moulded polypropylene cone is suspended with a.