MK Sound VX-7 MK II, V-75 MK II, V-125 If you hear a persistent hum or buzz through the Subwoofer

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powered subwoofers

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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.

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Contents MX-SERIES Table of Contents Powered subwooferspage Safety InstructionsWhere to Locate Your Subwoofer IntroductionSubwoofer HOOK-UP Important Note for Dolby Surround Sound Systems Standard AMPLIFIER/SPEAKER Wire ConnectionsSPEAKER-LEVEL HIGH-PASS Filter Satellite Speaker Wiring OptionAlso Shows USE of the SPEAKER-LEVEL HIGH-PASS Filter Using the RCA Jack Inputs Wiring with the RCA Jack InputsPlugging in the Subwoofer Using the HP-80 or VF-80 Electronic HIGH-PASS FiltersSpecial Instructions for the VX-7 Mk SATELLITE/SUBWOOFER Phasing TestUsing Multiple Subwoofers FINE-TUNING Subwoofer PlacementUSE of the LOW Pass Filter Control Home Theatre Usage Special Installation Notes MX-300, MX-200, MX-125 Mk II, MX-105MX-200, MX-145, MX-125 Mk II, MX-105, MX-70B Troubleshooting MX-70BIf your Subwoofer has no output If you hear a persistent hum or buzz through the Subwoofer If YOU Need to Replace the External Fuse If YOU Need Service