Should I add a subwoofer?
Subwoofers are the large speakers that handle the lowest bass frequencies. They are not integrated with full range enclosures both due to their size and the potential damage that can be caused to other components by their strong vibrations.
Adding a subwoofer will of course make your PA less portable overall. Unless you opt for a powered subwoofer, you will also need a power amp capable of supplying the wattage required by power-hungry subs. Bands that play heavy rock, metal, reggae, hip-hop, and other styles that depend on powerful bass and drum sounds are most likely to want to include a subwoofer.
As with other PA speaker cabinets, you’ll find a large assortment of subwoofers available at Listen-Acoustic which can make both active and passive versions.