jbl s3900JBL S3900 A true high end speaker! The JBL S3900 is a 3 way floorstanding speaker with two powerful 10 bass drivers, combined with two specially made high end compression drivers with pure titanium diaphragms, mounted on bi radial horns made of SonoGlass. The compression drivers are among the fastest drivers in the world, and they play with headroom and dynamics all the way up to 40kHz that far exceed what any conventional speakers are capable of.