One Systems PM4-M V4 - Manual (Page 11)

Figure 7 represents a down tilt angle of 20 degrees from vertical and is shown
with the chain section, three quick links and the turnbuckle.
Angles of less then 35 degrees may require that sections of the chain be
dropped. This is shown in Figure 8. Note that one of the Links has been dropped
to allow for an angle of less than the 35 degrees. The required number of links to
be dropped is based on the enclosure and the desired down tilt angle.
In any position, the turnbuckle must be adjusted to allow the proper amount of
tension on the Link.
The link should never pull the loudspeaker up towards
vertical but should always have very slight tension.
Figure 8
Warning: If the turnbuckle assembly is turned and the loudspeaker enclosure
angle begins to change (if the down tilt angle begins to move toward 0 degrees
vertical) then the turnbuckle has been OVER TIGHTENED. Turn the turnbuckle
until there is VERY slight tension on the Link assembly and the down tilt of the
enclosure is set by the tilt bolts on the PM4-M.
Secondary safety cables are STRONGLY recommended and should be secured
to a structural point NOT associated with the PM4-M bracket. The Link assembly
is NOT a secondary safety! Secondary safety cables are NOT supplied by One
Systems.