Absolutely not. The issue is the amount of current the AC cable is rated for vs. interconnects. The AC ground is sized so that if a short to the chassis occurs it can safely blow the fuse/breaker in it or at the electrical panel. The interconnects, and all the little printed circuit board traces are designed for nearly zero current. A ground fault with only the ICs for grounding is likely to start a fire at the IC cable, or melt it and leave the high voltage at the chassis. |
I need to clarify a little. In many cases, the chasis and signal ground are connected, so if you used a continuity tester or Ohmmeter you would see little to no reistance from the chassis to the outer shield. Not always though, many either put a floating ground or a resistor to keep the two from being exactly the same. But generally speaking, yes, there is a current path from the chassis to signal ground. No, it is not a safe substitute for the AC cable ground. |
@chayro Lifting the AC ground is a thing that people do to eliminate ground loop buzz. Its an indication that the grounding scheme of one or more components in the system isn't well thought out. You can test for this sort of thing using a Digital Voltmeter set to the Ohms scale. The test applies to equipment having a metal chassis. You connect one probe to the RCA ground connection and the other to the chassis. If the reading is the same as when you connect the two probes to each other then the equipment you are testing has a grounding problem. Older equipment like the Dynaco ST70 didn't have a 3-prong AC cord. So on account of being vintage it gets a Murphy. But for newer equipment with a 3-prong AC connection there really isn't any excuse. |
@atmasphere can you elaborate on your last statement bout two pronged older equipment? I have an amp when you turn it on you get a ground loop hum hd it goes away when the preamp fully turns on. |
