This is very likely caused through incorrect frequencies reaching the driver on the subwoofer. This is sometimes the case with cheaper subwoofer options because the crossover inside the sub allows higher frequencies than normal to pass through when playing some types of music. To solve you need to preamp the sound from your mixer (using a seperate output source to restrict the high and mid frequencies) or on passive subs using a crossover. By removing mid-high frequencies only Bass frequencies reach the sub, allowing you to go louder without distortion. Some sub options have adjustment on the rear to produce either low "sub" type frequencies or more "punchy" frequencies to suit different music.