MK Sound MX-125 MK II - Manual (Page 15)

page 15 powered subwoofers
Make sure that the input cables are in phase. Reverse the (+) and the ( — )
connections for ONE CHANNEL ONLY at the "FROM AMPLIFIER" terminals. If the
problem remains, put the cables back as they were. Then perform the test in Step 4.
4. If the midbass range (the area of transition between Subwoofer and Satellite
speakers) sounds weak:
Refer to Section 5, Phasing Test, on page 10. Reverse the (+) and ( — ) connections
at the back of BOTH Satellite speakers, OR switch the "PHASE" switch from (+) to ( — ) or vice
versa. The wiring configuration that gives the most bass is correct.
5. If you are using the "FROM PREAMP" input terminals, and you hear
a thump through the Subwoofer every time you turn the system on:
Either the preamp, receiver, or surround sound processor is generating the thump,
and the Subwoofer is reproducing it. To eliminate this problem, switch to the speaker
wire "FROM AMPLIFIER" input terminals.
6. If you hear a persistent hum or buzz through the Subwoofer:
Because the Subwoofer reproduces the 60 Hz hum frequency, it is often blamed for
causing hum that originates elsewhere in the system. Always avoid running all
speaker wires and RCA interconnect cables near to AC cords and component power
supplies. Wires and cables running close to AC lines are a common source of hum.
If necessary, reroute your cables.
To identify the source of hum, remove all input cables to the Subwoofer, but leave it
plugged into the AC outlet. Carefully turn the "BASS LEVEL" control up towards the
"MAX" position. If you hear hum coming from the Subwoofer's speaker driver, the
Subwoofer is the source of the hum. If you hear no hum or less hum, the problem is
probably coming from another component.
Hum can also be caused by AC ground loops. If the Subwoofer is plugged into a
separate AC outlet, try plugging it into the same outlet used for your amplifier or
receiver, or reverse the polarity of its AC plug. If these suggestions do not solve
your problems, contact your dealer or M&K.
7. If there is an unusual sound coming from the Subwoofer with no music playing:
Try removing the input cables as described in Step 5 above. If the noise disappears, it is coming
from another component. If it does not go away, contact your M&K dealer or the factory.