To Float or not to Float...

georgehifi
2,766 posts                                                                   09-14-2017 7:50pm

You clearly don’t know or understand.
It still has to get a total system reference earth via the interconnect shield, if you disconnected that shield at either end (and be left with a single wire connection) you get a massive noise.

Cheers George

George,

The safety equipment grounding conductor is for electrical safety. It is not needed for the normal operation of home audio equipment. IF the audio equipment is not Class ll power rated, and Listed, for use of a two wire cord and plug then a three wire cord and plug shall be used and the equipment grounding conductor shall be bonded, connected, directly to the metal chassis of the equipment... The equipment grounding conductor is there to carry any leakage and or ground fault current back the electrical service service entrance neutral conductor where all branch circuit equipment grounding conductors connect. (Note the electrical service entrance neutral conductor is bonded to the service equipment cabinet enclosure as well is connected to the earth.)

2014 NEC

Grounding Conductor, Equipment (EGC). The conductive path(s) that provide a ground-fault current path and connects normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

~ ~ ~

Georgehifi
It still has to get a total system reference earth via the interconnect shield,

No it does not need an earth reference.

I don’t think you understand the difference between an equipment grounding conductor and a signal ground conductor.

Yes the signal ground wire of an interconnect cable must be connected to the signal ground of the source and the signal ground of the receiving load.

As for a shield. Not all ICs are shielded. And when a shielded IC has a separate signal ground wire, the shield as a rule is connected at one end only. Granted the shield of a coax cable must be connected at both ends. It is the return signal ground conductor.


Full circle.....

georgehifi
2,766 posts                                                              09-13-2017 5:08am

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

Jim
.

No it's you that doesn't understand, as interconnect shields are kept at earth potential, some thorough a very low ohm resistor, if they weren't they'd be useless as a shield for rf.

Cheers George   

Also look at the fact that you can buy mains earth cheater adaptor plugs, which give you the option to float the earth of that piece of equipment they are attached to from most hi-end audio stores, for doing exactly what I said before, to have one only earth point in the system as not to create a loop with the mains they are plugged into. Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed  Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points.
http://www.parasound.com/product-images/jc1_rear.jpg

Cheers George

georgehifi
2,768 posts                                                                 09-14-2017 10:08pm


No it’s you that doesn’t understand, as interconnect shields are kept at earth potential, some thorough a very low ohm resistor, if they weren’t they’d be useless as a shield for rf.

Cheers George

George,

If what you say is true how possibly does the two pieces of Marantz audio equipment (see Links below) work as designed. Neither piece of equipment uses an earth equipment ground connection. In the world of the two pieces of audio equipment the only ground that exists is the B- power supply that connects to the metal chassis of the two pieces of equipment. I am pretty sure the signal ground of each piece of equipment is also connected to B- and chassis. The metal enclosure rejects RFI just fine without being connected to an earthed ground. How can that be?

I could use an isolation transformer and float the secondary winding above ground and feed the Marantz SA/CD player and Marantz integrated amp and they would operate and sound as designed. They wouldn’t even know an earth ground exists outside their boxes.

Here is a picture of the back of a Marantz PM8005 Integrated amp. Note the inlet connector is a 2 wire non grounding type.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/PM8005/XL_pm8...

Here is a picture of the back of a Marantz SA8005 player. Note the inlet connector is a 2 wire non grounding type.
http://www.us.marantz.com/us/Products/Pages/ZoomImage.aspx?img=/Assets/images/products/SA8005/XL_sa8...


NO earth ground connection is used. How do they possibly play together with one another? The job of the ICs is to transfer the signal from the SA/CD player to the integrated amp. That is their purpose.

Jim

I’ve tried.

No use discussing it any longer, as your set in your ways. 

Cheers George