They connect to an amplifier like a normal subwoofer. The subwoofer phase control found on many subwoofer amplifiers is actually a polarity inversion switch. Hz upwards, without needing a separate subwoofer. After the bass management system there is a subwoofer signal. David Hall founded Velodyne in 1983 as an audio company specializing in subwoofer technology. "front left and right", "surround left and right", and "center + subwoofer". Each subwoofer is driven by eight 18-inch subwoofer drivers with voice coils. In the largest stadium venues, there may be a very large number of subwoofer enclosures. This increases SPL for the subwoofer, at the cost of increased distortion. Mere use of the term "subwoofer" is no guarantee of good or extended bass performance. Integrated into the car body, it turns the entire interior space into a large subwoofer. Equalization can be used to adjust the in-room response of a subwoofer system. Since large drivers require undesirably large cabinets, most subwoofer drivers have large excursions. In the 1980s, Origin Acoustics developed the first residential in-wall subwoofer named Composer. Careful positioning of the subwoofer within the room can also help flatten the frequency response.