User Manual

Comparing the Woofer’s Excursion in the

Three Boxes

 The sealed box requires the same excursion at all useful

frequencies

 The vented box reduces excursion at the frequency

where the box is tuned (Fb). Adding a subsonic filter

(included in most JBL amplifiers) minimizes excursion

below Fb

 Once the subsonic filter has been set, excursion in the

vented box is LOWER than in the sealed box with the

same amount of power. This means it’s OK to apply more

power!

 The bandpass is similar to the sealed box at low

frequencies

 The bandpass box minimizes excursion at higher

frequencies, but it isn’t very useful.