Is there an easy way to measure speaker angles and distances for surround sound?
SOS Forum Post
Technical Editor Hugh Robjohns replies: You will need some masking tape, a piece of string, a protractor and a helper (and maybe some Hobnobs). The first step, which I imagine you have already taken, is to decide on the listening position. Mark it with a cross on the floor using the tape, then decide on the centre axis and how far away the centre speaker should be. Mark their positions on the floor with tape as well.
Next, stretch the string between the listening position and the centre speaker location and mark the string with a tape 'flag' so that the distance from the listening position to the centre speaker is known. Next, using the protractor, find the appropriate angles for the other speaker positions — typically 30 and 110 degrees around from the centre line in each direction, although some people working with surround sound prefer a more square arrangement, using angles of 45 and 135 degrees.
With one end anchored at the listening position, rotate the string and, at the appropriate angles from the centre speaker axis, mark the floor at the distance from the listening position marked on the string. That ensures that all the speakers lie on the circumference of a circle, with the listening position at its centre.
Finally, place the speakers on the marks, aim them directly at the listening position, connect everything up, and align the system for levels. Good luck!