It took me 2 years to find an exact replacement low frequency driver for my JBL 4690A speakers. The original LF driver was the JBL E140-8, which is no longer being produced and is no longer available on the market. Beyma, a Spanish loudspeaker manufacturer, makes a LF driver with the exact TS parameters as the JBL. Well, the Beyma 15P80Fe's finally arrived today and they are gorgeous, massive LF drivers with huge strontium-ferrite magnet structures. Each driver weights almost 30 lbs. These are definitely professional grade LF drivers. Can't wait to get them installed and hear what Star Wars sounds like through the upgraded speakers. The Force be with you all!