i'm currently using a TV rack I bought from Mandaue Foam, Las Pinas. I'm sure they have the same rack available at their other branches.
I dunno how to embed a picture link here. PM me your email/Viber # for I can send you the actual picture of my unit =))
it's a standard 4ft width and around 13" depth. it is a 3-tier rack/shelve. As I know, its shelves has around 13" distance, so better double check if it'll fit your center speaker on the middle shelf.