MK Sound VX-1250 - Manual (Page 9)

Play a familiar CD, LP, or tape with steady, consistent bass. Set the “PHASE” control to the 0˚ position. Listen care-
fully to the mid-bass (70 - 100 Hz) region — the part of the spectrum where electric or string basses and drums are found.
Then, adjust the "PHASE" control to the 180˚ position.
Now listen to the same musical passage, concentrating on the mid-bass region. If you hear less bass, the previous
0˚ position, would be the correct. If you hear more bass, the new 180˚ position is 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
switching it to the “OFF” position or unplugging the power cord.
Once you have established which position gives the most bass, you can further fine-tune the control to produce the
best possible sound by adjusting it between 0˚ and 180˚. When you hear the best balance between stereo image local-
ization and maximum impact and output in the midbass, you have found the correct setting.
If you hear little or no difference when you adjust the “PHASE” control knob, set it to the default 0˚ position.
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 - 100 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 speak-
er 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 can-
celled. You should re-do this test any time you move your speakers
7. USE OF THE "LOW PASS FILTER" CONTROL
The back panel control "LOW PASS FILTER" sets the upper rolloff point of the subwoofer, eliminating mid-bass and
midrange that are being reproduced by your satellite speakers. The control is a means of fine-tuning the transition
between your subwoofer and satellite speakers, and it provides a rolloff of 12 dB/octave up to 200 Hz, where the filter
shifts to 36 dB/octave. In most systems, including M&K satellites, 85 Hz gives the best blend. If you don't want to
experiment, set the control at 85 Hz. If you are using the K-5 / K-7 Satellites, set the control to 100Hz. If you are using
Xenon satellites (LCR45, LCR35, or LCR25), or the MP4512, set the control between 125 and 200 Hz.
The goal is to get a balanced acoustic output in your room. This is not necessarily the same as flat electrical out-
put. Rooms typically reinforce bass frequencies around 100 Hz, so by leaving an electrical gap, you may actually get a
smooth acoustical response where it matters, in the room.
Think of this control as a mid-bass fine tuning adjustment that you set to achieve the best transition between the
satellite speakers and the subwoofer. When you hear a smooth sound overall, well balanced between the deep bass
and the rest of the audible spectrum, the control is set properly.
8. USE OF THE "BYPASS" SETTING
If you have a THX, Dolby Digital, or DTS component with a built-in Low-Pass filter as part of its subwoofer output,
or if you are using a separate Electronic Crossover, set the “LOW PASS FILTER” switch on the back of the subwoofer
to “BYPASS” position. This bypasses the internal low-pass filter so that there is no interaction between the subwoofer’s
filter and your component’s filter. If you have any questions regarding the filters, please contact your M&K dealer or the
M&K factory.
9. USING MULTIPLE SUBWOOFERS
Using two (or more) subwoofers in your system gives you the ultimate in bass performance. You'll hear improved
impact and definition, as well as greater output and dynamic range.
If multiple subwoofers are used, place them in the same location. Stacking is best, but you can also put them side
by side. Alternately, you can put multiple subwoofers in different locations. This is appropriate when you have limited
choices in locating the subwoofer and none of the available locations work well. Try to place multiple subwoofers at
equal distances from the listening position to avoid phase cancellation.
POWERED SUBWOOFER
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