Eliminating hum

Ground Loops and hum have been the source of many discussion hear on Audiogon. I would suggest that you do a search of ground loops and hum and read a few.

That said, ground loops can be caused by several things.

1. Poorly designed and constructed equipment with insufficient grounding schemes. This is the hardest to fix because the item itself is badly designed.

2. noise generated by home items such as lights, refrigerators, motors, etc.

3. poor interconnects, where the return and shield are connected.

4. Poor electrical connections where neutrals are shared by other lines. This happens a lot.

5. Poor electrical connections of the audio components.

As was mentioned previously, you must first find the source of the problem in your system.

The best way is to unplug and disconnect all the components except the amplifiers and speakers and then turn the amps and speakers on. Noise? no? Then move on to the next section. Noise? yes? Then it is the amps.

Connect the active crossover (if you have one), if not connect the pre-amp to the amp(s). Make sure all other components are unplugged and disconnected (interconnect cables) and only the crossover or pre-amp, amp and speakers are connected. Noise? yes, then it is the crossover (if you have one), interconnect cables, or pre-amp. No noise? Then move on.

connect a source component to the pre-amp and plug it into. pre-amp, amp and speakers are still connected. Noise? yes, then it is the source component or interconnect cables. No? then it is another source component that plugs into the pre-amp and test those.

Also, and very important to lower the noise floor extremely and to help eliminate ground loops are dedicated lines and proper connection of low level components.

I always advocate at least three dedicated lines. More depending on what you have. Two dedicated lines. One for each amp and one additional dedicated line for all of my low level source components. My low level source components (pre-amp, active crossover, tuner, cd transport, DAC, turntable) are all plugged into a power conditioner ( I really like the Transparent Audio Power Isolator 8 unit) which is in turn plugged into its own dedicated line. This helps eliminate ground loops.

The problem arises when your system is sharing a line with other stuff in your house before the electrical panel, such as the lights, and refrigerated.

Also, a dedicated line is as follows: A hot, neutral and ground wire "dedicated" solely for the one pair of outlets, which all three together go to the electrical panel and the neutral is not shared.

12 gauge or 10 gauge "romex" with hot, neutral and ground per line to the panel.

I had a ground loop the other day only to discover that I had accidentally plugged one component's power cord into the same outlet as my low level components connection. When I corrected this by plugging it into its own dedicated line (as it was supposed to be), the ground loop disappeared.

You don't need cheater plugs to find the source of a ground loop. Just follow the instructions above. People use cheater plugs to "fix" the ground loop and that is not the proper way to go. It is totally unsafe and being in the power/electrical field, is really......stupid. Once you discover the cause of the ground loop. Fix the problem.

enjoy

Using cheater plugs is completely safe and often effective.

No disrespect Bojack but that statement is completely untrue, irresponsible and ignores why the ground was there in the first place.

Again, find and fix the problem. Using a cheater plug may mask a ground loop problem, but causes greater concerns by lifting an important safety element in the home's protection and placing your home, equipment, family, etc. at risk.

01-02-15: Bojack
Using cheater plugs is completely safe and often effective.

Don't let the underwriter of your homeowner's policy see that post :-)

Assuming the equipment is in good physical condition, so that there is little risk of an internal short developing between a "hot" AC wire and chassis, the risk that is entailed by the use of a cheater plug is extremely small. However, it cannot be said that the risk is zero. And if that very small risk were to ever materialize, perhaps because the component was marginally designed with respect to how the internal AC wiring is routed relative to nearby sources of heat within the component, or perhaps because the component was wired on a Friday afternoon by someone who was in a hurry to leave, or for whatever reason, the result could very conceivably be either a fire or electrocution.

Yes, use of a cheater plug is "often effective." However the third prong is provided on AC plugs and outlets for a reason. A claim that use of a cheater plug is "completely safe" is, frankly, misleading, potentially harmful, and nonsense.

Good comments by the others. Regards,
-- Al

Not to harp on this, but electricity will try to find the shortest/easiest path to ground. By removing that short, certain path by lifting the ground, and a fault occurs, "You", your family touching something else, your pet, or other equipment may become the shortest/easiest path to ground instead.

Be safe, be smart, don't take things for granted.