Repair JBL speakers by determining the problem within the speaker assembly and then replacing or repairing the parts that are causing the loss of sound quality. While an overheated speaker driver should be replaced or repaired by a professional, foam surrounds, damaged cones and dented domes can often be repaired for a fraction of the cost of replacing the driver.
Many speaker assemblies and towers have multiple drivers; for example, a tweeter, a woofer and a subwoofer. It is uncommon for all of them to blow at once, and an inspection of the drivers while playing music at a reasonably high volume often reveals which of the drivers is causing the problem and needs to be replaced.
The foam surround, or the elevated circular part of the speaker's face that surrounds the cone, is fairly delicate on most drivers and can be replaced using a foam surround replacement kit, an X-Acto knife and some PVA glue. Use the X-Acto knife to cut a careful circle around the outside of the cone where it meets the foam surround, and then remove the foam. Glue on the replacement foam surround, being careful not to use too much glue.
For repairing dented domes and damaged cones, a suction device (some people use their mouths) or an adhesive tape can often pull out dents; if the cone is torn or has a hole, the recommended repair is PVA glue or a soft tape such as electrical tape. The objective in this repair is to use as little of the foreign material as possible, as it is likely to affect sound quality as more of it is used.