We have a few suggestions you could be interested in;
OmniMount's 20.0 Stainless Steel speaker mount is a unique, top-of-the-line speaker wall mounting solution for speakers weighing up to 20 lbs (9 kg). The polymer ball fits snugly within the wall-mounted bracket, and a small threaded shaft connects the ball to the speaker. The ball can then be rotated within the bracket so the connected speaker can be moved to the desired position to maximize the audio distribution.
Polymer-injected ball controls resonance frequencies for better soundStainless steel hardware for strength and durabilitySuitable for all-weather useBall and clamp design for greater mounting flexibilityIncludes clamp and jawIncludes complete hardware kit
Fits most: Bookshelf speakersSupports up to: 20 lbs (9.1 kg)Thread size: 3/8"-16Tilt: +/-30ºPan: 180ºBase Rotation: 360ºColor: Black or White