MK Sound MX-125 MK II - Manual (Page 10)

page 10 powered subwoofers
play. Set the "BASS LEVEL" control where the Subwoofer sounds in balance with the Satellite
speakers. If the system is not working properly, unplug the Subwoofer and check all of your
connections. Call your dealer or the factory if you cannot solve any problem.
The best way to set the level of the Subwoofer is to do it by ear, listening over several hours or
days to familiar recordings. Make adjustments to the level in small increments, depending on whether
the bass level sounds too high or too low. Of course, you can always deliberately set the level higher
or lower than flat if you need a higher bass level or if you don't want to disturb your neighbors.
5. SATELLITE/SUBWOOFER PHASING TEST
You are now almost finished with the basic set-up. But before you can sit down to enjoy your new
Subwoofer, you need to perform one simple Phasing Test. This test insures optimum sound in the
critical bass frequencies where your Subwoofer and Satellite speakers overlap.
Play a familiar CD, LP, or tape with steady, consistent bass. Listen carefully to the mid-bass
(75 - 125 Hz) region — the part of the spectrum where electric or string basses and drums are found.
Then, move the "PHASE" switch on the SUBWOOFER's back panel from either up (+) or down (—) to
the opposite position.
Now listen to the same musical passage, concentrating on the mid-bass region. If you hear less
bass, the original connections were correct. If you hear more bass, the new connections are correct.
If you have two Subwoofers, perform one test for each Subwoofer. When you perform each test, make
sure the other Subwoofer is not operating by either unplugging its input cable or its power cord.
SPECIAL INSTRUCTIONS FOR THE VX-7 Mk II:
The VX-7 Mk II does not have a back panel "PHASE" switch. Therefore, to check phase, follow
these instructions: Instead of moving the switch's position, you must reverse the Positive and Negative
speaker inputs on the back of BOTH Satellite speakers. Move the lead on the Positive (+) terminal to
the Negative (—) terminal, and vice versa. You can also do this at the subwoofer's "TO SPEAKERS"
terminals, but never switch the inputs at both the backs of the Satellite speakers and the Subwoofer.
Another method of setting phase uses a pink noise source and a spectrum analyzer. If you have
these, place the microphone at the main listening position and look at its display in the mid-bass region
of 70 - 125 Hz. The wiring/ switch position showing the most output in that region has the correct phase.
You need to perform this test because when Satellite speakers are located separate from a
Subwoofer, each speaker is at a different distance from your ear. In some cases, the difference will
be just enough so that the output from the Subwoofer arrives out of phase with the output of the
Satellites. When this happens, that critical mid-bass is actually cancelled. You should re-do this test
any time you move your speakers.
If you want to experiment further, you can move the Satellite speakers either towards or away from
your listening position, making changes in small increments. This will focus the system's sound to its
optimum. When you hear the best balance between stereo image localization and maximum impact
and output in the mid-bass, you have the ideal location.