SWR Sound POWER 750 owner manual Electrical and Grounding Considerations

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ELECTRICAL AND GROUNDING CONSIDERATIONS

In a rack system with a large power amplifier such as the Power 750, placement of effects units and preamplifiers with respect to the power amplifier may be important as hum induction may occur. Generally speaking, install a preamplifier so that it is far- thest away from the power amplifier with line level effects units, tuners, etc., in between. Whenever possible, leave an empty rack space between

the power amplifier and other accessories in the same rack.

All patch cords should be made as short as possible using high quality shielded cable and plugs. Placement of patch cables should not run next to AC power cords and should not be routed in between different components. In other words, do not run a patch cable from the front of a preamplifier over the top or under the bottom and then to the rear input of a power amplifier, as this can cause "hum" in the system. If you must run patch cables in this fashion, experiment with the routing so that ideal place- ment is achieved.

Another consideration in a rack system is a ground loop caused by the chassis' of several pieces of equipment electrically "tied" together by the metal rack rails. Some equipment is built with this situation in mind, such as the Grand Prix Preamp from SWR. It comes with an option of separating certain

electrical grounds from chassis earth grounds thus isolating the chassis from the inner workings. This method is far superior than that of using a three prong to two prong adapter on your AC cord. These adapters "lift" the earth ground from your chassis and could make for an unsafe condition.

If you are experiencing a system grounding problem (each piece of equipment works good by itself, but connecting them together causes undesirable hum), and using a ground adapter on one piece of

equipment solves the problem, consult the manufacturer of that piece of equipment to see if there is a way to isolate the sec- ondary grounds from the primary or chassis earth ground. Feel free to contact our service department if a product from SWR is in question. (In situations with intractable ground issues in a complicated, multi-component rig, we here at the factory have found the Hum Eliminator by Eb-Tech to be an invaluable and inexpensive accessory available at most Guitar Centers and other large M.I. retailers.)

We sincerely hope that the Power 750 exceeds your expectations in the area for which it was chosen.