Hum and noise
In most cases, one of the following suggestions should help you solve a hum noise in your system. Please try these steps in the order shown, proceeding from one step to the next if the prior suggestion does not eliminate the problem.
Suggestion #1
To determine if a cable TV connection is responsible for the hum, first turn off all the components. Disconnect the cable TV feed to your system at the first place where it connects to your components. Alternatively, disconnect the cable TV wire where it is connected at the wall outlet. Turn your system back on, and listen if the hum has disappeared. If removing the cable TV feed has eliminated the hum, you will need to insert a Ground Loop Isolator (Knoll model GB634) before reconnecting the cable TV feed, or contact your cable TV operator to see if they can better isolate your cable feed.
Suggestion #2
Turn off all components in your system and then disconnect the input cables at the amplifier. Turn the amplifier back on to see if the hum is still present. If the hum disappears, the fault may be in the input cables used. Try replacing them with cables that have better shielding, and make certain that the input cables are not running on top of any AC power cords. Change the cables one at a time to determine if one or all cables are responsive. If the hum disappears when the input cables are disconnected but returns after the cables are changed and the system reconnected, your source device may be causing the problem.
Suggestion #3
Poor grounding of the electrical system in your home may also cause ground loop problems, particularly when there are multiple components with three prong, grounded, power cords. Unplug these components one at a time, and see if one or all of them is causing the problem. The ultimate solution to this type of problem is to rewire your house with an isolated, star
Warning: If you suspect that the grounding system in your home’s electrical wiring is causing the hum problem, it is important that you do not make any changes to the wiring. Only a licensed electrician should make any changes to household wiring and they must be made in full compliance with all local building, safety and electrical codes.
Installation
Installing the MA252 should be relatively easy. With a bit of planning, the MA252 will give
1.The most important consideration when installing the MA252 is cooling. The MA252 has a lot of power packed into a small chassis size. When installing it in an equipment stack, it should be the top component. It needs at least
2.When installing the MA252 in a rack, we suggest adding a
3.If MA252 channels frequently shutdown due to overheating, install a fan directed up from the MA252 bottom center.
4.Never operate the MA252 on its side, as the cooling potential drops significantly when operated on the side.
5.Connect the MA252 inputs to the source component outputs with good quality, short as possible RCA jack cables. Connect each channel individually.
6.Connect the MA252 speaker outputs to speakers using good quality speaker wire. Minimum 16 gauge copper wire is recommended with 14 gauge minimum for runs over 30' (10m).
Note: Ideally the MA252 likes
to 4 ohm loads won't hurt the MA252 but it may occasionally shutdown. Never connect a MA252 to less than 4 ohms.
Do not attempt to mono bridge the MA252.
7.Make sure the speakers in each room are connected in phase with the amplifier + going to the speaker + . Out of phase speakers give unstable imaging and poor bass response.
8.If connecting the MA252 to a whole house sound system or another amplifier make sure that the other amplifier is a common ground amplifier and that you use good quality speaker wire, minimum 16 gauge.
