To Float or not to Float...
This is extremely dangerous - interconnects are not intended to carry safety grounds.No it’s not as many sources have two pin mains plugs and rely on the ground from the next stage via the interconnect same goes for some preamps. If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well. Cheers George |
georgehifi If you were to have a grounded mains plug at the source and the poweramp you have created an earth loop with the ground wire between the power points as the interconnect carry the earth as well.It is clear that you are confused about this issue. The matter of ground loops is only an issue when the grounds are of different potential. Having multiple safety grounds in an audio system is not itself an inherent problem. As for interconnects carrying safety grounds again, you are confused, particularly with respect to balanced connections. |
georgehifi What if all the AC powered audio equipment uses two pin mains plugs? (There in the equipment uses internal double insulated AC power wiring.) The safety equipment ground is for electrical safety. It is not needed for the operation of the equipment electronics or SQ, (sound quality), of the equipment. In fact sometimes an equipment ground can harm the SQ of audio equipment. It can introduce noise and of course, as cleeds said in his last post, it can cause a ground loop when a difference of potential, voltage, exists between equipment grounds. |
weebeesdad OP Cleeds triggered the solution when he (or she) wrote "a properly grounded power cord", which reminded me that I was having intermittent problems with the connecting plug of the preamp’s power cord. Swapped out the power cord and problem solved. It may have stopped the buzzing but it, just my opinion, is only a band aid that stops the buzzing. Just a guess on my part you may have a cold solder connection internally with the return signal ground output jacks on the preamp. When you close the ground lift switch the signal ground connection is being completed through the power cord equipment ground wires. There in the signal ground of the equipment is connected to the chassis of the equipment. The safety equipment ground is connected to the chassis. (If designed properly the signal ground does not connect directly to the chassis. May be through a resistor). When you close the ground lift switch on the preamp you completed the signal ground circuit from the preamp to the power amp through the power cords equipment ground wires. Preamp power cord >> to the wall receptacle "U" shape equipment ground contact >> to the power cord of the power amp. Jim |
Cleeds wrote:This is absolutely correct, and it amazes me that audiophiles will accept a potentially lethal component in their house. Interconnects are not designed to carry a safety ground. There are several techniques for eliminating ground loops while at the same time having every component's SIGNAL ground connected to the SAFETY ground (i.e. the chassis and ground lug of the mains outlet) . Look at section 15.10 of the document downloadable on this page for one sample solution: http://www.valvewizard.co.uk/Grounding.html It would be easy to retrofit the above suggested circuit (4 parts) into a vacuum tube component (especially one that's hard-wired). Cheers, Thom @ Galibier Design |
