To make things a little easier for you, JBL has brought to you a speaker mounting pole that does the adjusting for you!
It's the JBLPOLE-GA with lower end M20 threaded adapter. This speaker pole has an internal pnuematic shock that will raise the height of the pole for you. The internal shock can handle lifting up to 35 lbs with no problem and no effort on your part. The "Z" shaped knob allows for comfortable adjusting. You'll find that this speaker mounting pole is compatible with virtually all JBL subwoofers.