Yamaha IS Series Installation Subwoofer

The IS cabinets are the low-frequency half of Yamaha's Installation Series, built to be flown or stacked in a permanent room and left there. Enclosures are Finnish birch ply, 11-ply throughout with a 13-ply baffle on the larger boxes, finished in textured black or white and drilled with twelve M10 points for shoulder eyebolts.

IS1112 is the small one, a 12-inch driver on a 4-inch voice coil with a 35 mm pole socket and a Speakon through output so a top box can be fed from it. IS1118 moves to an 18-inch woofer reaching 33 Hz. The dual cabinets, IS1215 and IS1218, run in parallel mode at 4 ohms by default or can be rewired discrete as two 8-ohm drivers, which is what you want when a system processor is driving each cone separately. All four wire through a Neutrik NL4 and a barrier strip in parallel.