JOHN C.....Several years ago I got a Yamaha subwoofer with the purchase of one of my KN's....probably the 5K...
It is a small black box that sits under my 7K now & plugs in to the back of the KB & comes on with the KB....
There is a volume control, & a high/low control. One big speaker & one very small one....Probably got it in Phoenix, AZ...
It does a great job! I just read your initial post here....sounds like you may have the same one.....
ELIZABETH.....