All the PS Audio power cords have a removable ground pin for this very reason. They seem to be well thought out plugs.
04-18-10: Mulveling
True,... but you will also notice they are not approved by UL or any other recognized testing agency.
On my system the solution is open the IEC Oyaide (equipment end) and lift the ground.
The reason to not do this at the wall is that would leave the ground as potential antenna into the equipment. This method leaves the wall plug ground pin in place which helps secure connection, especially for heavy AC cords.
04-17-10: Albertporter
Albert is not alone in his thinking about the lifting of the equipment grounding conductor at the source end of the PC acting as an antenna. There are a few EE on AA that say the same thing.
Remember the other end of the power cord's equipment grounding conductor is still connected to the case, chassis, of the equipment. One other point that comes into play is the small induced voltage from the hot conductor of the PC that crosses over into the lifted equipment grounding conductor. With the induced voltage EMI/RFI noise can travels up the PC equipment ground conductor to the chassis and on into the signal ground of the piece of equipment as well through ICs to other pieces of equipment.
In previous incarnations of my system, it worked well to have just the preamp with a 3-prong plug, and the other components (phono stage, power amp) on a 2-prong plug. Putting a 3-pong plug on my old power amp yielded a loud BUZZZ. However, my new monoblock amps (maybe due to their balanced input stage) and phono stage are both doing just fine with 3-prong plugs as well.
04-18-10: Mulveling
I read this a lot here on Agon and AA where the preamp is used as the connection for the safety equipment ground for all other three wire equipment connected together by their ICs.
Star grounding.....
I have yet to read any post where a ground fault condition , say from a power amp, successfully passed through the ICs to the preamp signal ground > to the chassis > on out the PC > through the equipment grounding conductor of the branch circuit to the electrical panel causing enough current flow to cause the branch circuit breaker to trip open....
I would appreciate any links to the contrary.....
Jea48,
Could you explain "JMHO if you are going to lift the ground do it on all the three wire cord and plug audio equipment."?
I didn't quite get it.
Thanks
04-18-10: Maril555
First I do not advocate lifting the safety ground. But if you must, JMHO, it would be safer to lift the ground on all equipment that uses the safety ground. To receive an electrical shock there has to be a difference of potential, voltage, that a person's body comes into contact with. I personally would not rely on the ICs from a preamp to a power amp for a suitable ground fault path from the amp to the preamp. Instantaneous ground fault current flow can be well over 100 amps. Will the #20 ga wire withstand that amount of current flow long enough for the 15 or 20 amp branch circuit breaker to trip open. Better yet how is the output of the preamp jacks signal ground connected to the chassis? Could the path pass a high ground fault current flow?
Basically what I am saying if you have to lift the safety ground do it on all the equipment. Remove any chance of a difference of potential to a grounded object within arms length or from any part of the body to any electrically grounded object.
Food for thought. A bird perches on a high voltage wire and does not receive an electrical shock.
A squirrel jumps onto a high voltage wire and runs down the wire without a care in the world. His fate is in his method of dismount.
