User`s manual
SECTION 5
B-CHAIN ALIGNMENT
5-1
5.1 Check Theater Equipment
Thoroughly check the loudspeakers and power amplifiers for sources of poor
performance:
• Check that the loudspeaker cables are in good condition and that they of a
suitable gauge for the impedance of the speakers and the length of the run.
• Rattles (a leak in the woofer cabinet may appear to be a rattle).
• Loose bolts or other hardware.
• Open drivers.
In systems with pairs of drivers — woofers or tweeters — one voice coil
of the pair may be open but the system will still function. Check the
speakers with an ohmmeter. If one channel requires markedly more
equalization than the other or if one speaker overloads at lower levels
than the other speakers, an open driver circuit could be the cause.
• Missing drivers or other components.
• The settings of the crossovers to match the type of drivers in use and the
acoustics of the theater.
The tweeter level control must be set for the best possible frequency
response before you attempt any equalization. This is also true if the
system uses active crossovers with bi-amp equipment.
• Phasing between the woofers and tweeters, and between the channels.
• Aiming of speakers.
Check that the speakers are correctly aimed into the auditorium, and
that they are not obstructed by the screen frame, struts or other
obstructions.
• Check that speakers are correctly connected; that the speaker on the left is
connected to the left power amplifier, etc.
Amplifiers
• Distortion.
• Gross gain differences among amplifiers.
If one amplifier differs in performance from the others, it should be
checked and repaired before proceeding further. Input gain controls
should all be at the same setting.
• Blown fuses.
Some types of power amplifiers operate at very low gain and distortion
even if fuses are blown.
• Good air movement through power amplifiers.
Air-conditioning
If air-conditioning noise is audible in the theater, arrange for lubrication of the
motor, fan bearings, adjustment of belts and drives and cleaning of filters to reduce
the ambient noise to a minimum.