Been doing it this way for 15 years, no suppliers in the UK I know of sell rough in rings. Unfortunately most plasterboarders like to bring the cable out right next to the joists or don't bring it out all together.
On December 9, 2015 at 12:27, Trunk-Slammer -Supreme said...
Use a piece of stiff wire (coat hanger) with a 90 degree bend to ensure the wires are coming out of a hole in the middle.
Stiff wire needs to be about an inch longer than the speaker cut out. Shove it up through the existing center hole and spin to ensure you are indeed, in the center.
Use the supplied cardboard template, pencil mark the drywall and RotoZip freehand.
Doesn't have to be perfect, the speakers DO have a flange.
Should take you longer to move the ladder than to cut the holes.
Might be a two hour job for the average slacker. :-)
