The OB subs are very quick and will play up to 250Hz, they match planers, electrostatics etc in speed and dispersion. They also don't pressurize the room like a boxed cone. The room lets go of the note quicker and your ears don't get fatigued as easily. Kick drum sounds as real as it gets.
![Thumbs up :thumb:](https://www.audiocircle.com/Smileys/audiocircle/smiley_thumb.gif)
Down sides are minimal, no good place to mount the amp, they have to be 3' min from the back wall. They don't quite have the grip at 20Hz that a box based servo sub has. Danny usually augments his OB subs at the show with one 12" servo in a sealed box close to the listening seats. Wiring also needs to be done carefully as it can be slightly tricky if it's your first build.