How quickly a crossover or filter attenuates signals (decreases their power) outside its passband (those frequencies intended to pass through without attenuation); expressed in decibels per octave. lopes are designed as first order, second order, third order, and fourth order. First order slopes attenuate signals fairly slowly, cutting their output by only 6 dB each octave. Second order slopes operate at 12 dB per octave. Third order slopes decrease signals by 18 dB per octave, and fourth order slopes decrease signals by 24 dB per octave. The steeper the slope (more decibels attenuated per octave), the less interaction there is between components operating in the same frequency range. rossovers do not act as absolute cut-offs but instead cut-off signals gradually. Most subwoofers use steep 24 dB per octave slopes to cut high frequency information out of the sub and cut low frequency information out of the of the other speakers quickly and precisely. Other speakers may use a combination of different slopes, although the steeper slopes tend to be used most frequently (third and fourth order).