page 6
THX subwoofers
to the Left subwoofer and the Right cable to the Right subwoofer. See Figure 2 on page 5.
TESTING THE SUBWOOFER (THX MODE)
Once all of the interconnect cables are in place, you are just about ready to plug in the subwoofer.
Set the "LOW PASS FILTER" toggle switch to the "THX MODE" position. Set the "BASS LEVEL"
toggle switch to the "THX" position. Set the "BASS EQ" toggle switch to the "THX" position.
Set the "PHASE" switch to the "+" position. If your THX controller has a SUBWOOFER (OFF/ON)
switch on its front panel, rear panel, or remote control, set it to ON. (See the controller's manual).
Plug the subwoofer's AC cord in. The red LED on the back panel should illuminate.
Play some program material with good bass content through your system. Carefully advance the
system volume control. You should hear the subwoofer operate. If you think the subwoofer isn't
working, walk up to the speaker and listen to it from a distance of a foot or less.
If you confirm that it is not working, unplug the subwoofer and check all of your connections before
trying again. If you have a problem that you cannot solve, contact your dealer or the M&K factory.
When your system wiring is complete and the subwoofer is plugged into the wall, leave it plugged
in, even when the system is turned off. The normal mode of operation for the subwoofer is to remain
plugged in 24 hours a day. Among other things, this means that you don't have to walk over to the
subwoofer to turn it on every time you want to use the system.
DO NOT PLUG THE SUBWOOFER INTO A SWITCHED OUTLET ON ANOTHER COMPONENT. IT CAN DRAW UP
TO 600 WATTS FROM THE AC LINE. IT MUST BE PLUGGED INTO A SOLID AC LINE.
5. CALIBRATING THE SUBWOOFER (THX)
On the back panel of the subwoofer, four toggle switches allow you to select various modes of
operation. Three are described here. A description of the function of the fourth toggle switch can
be found in section 7, SATELLITE & SUBWOOFER PHASING TEST (page 12).
OPERATION OF THE "LOW PASS FILTER" SWITCH (THX)
When using the subwoofer with a THX controller, set this switch to the "THX MODE" position. When
using the subwoofer with a standard stereo system or a surround sound processor that is not THX-
certified, set this switch to either "80 Hz 24 dB/OCTAVE" or the "VARIABLE" (center) position.
The THX mode bypasses the internal crossover of the subwoofer.. The THX controller contains the
crossover and sets the rolloff point of the signal fed to the subwoofer to 80 Hz (with a Linkwitz-Riley
characteristic).
OPERATION OF THE "BASS LEVEL" SWITCH (THX)
When using the subwoofer with a THX controller, set this switch to the "THX" position. The
controller sets the output level of the subwoofer, so this switch disables the subwoofer's level control.
This position provides a sensitivity of 90 dB SPL for 100 mV input for one subwoofer in the system.
The "REFERENCE" level control mark is calibrated to the level set by the "THX" switch. If you set
the switch to "VARIABLE" and the level control to "REFERENCE," its output level is the same as when
you set the toggle switch to "THX." The +3 and +6 marks indicate the points where your subwoofer
is producing 3 dB and 6 dB more output, respectively, than the "REFERENCE" level.
OPERATION OF THE "BASS EQ" SWITCH (THX)
Set this switch to the "THX" position. The "THX" position gives you the flattest in-room frequency
response, with flat bass extension to frequencies well below 20 Hz. This position is the most accurate,
