To Float or not to Float...

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

georgehifi
2,768 posts                                                                    09-14-2017 10:39pm


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

It may be called a ground cheater but that is/was not its’ intended design an Listed use.
The reason for the 3 wire to 2 wire adapter is to connect an appliance or piece of equipment to a grounded 120Vac power system where the 2 wire branch circuit, hot and neutral conductors, were installed in a metallic raceway, conduit, and metal box. The pigtail or ground strap tab on the adapter was to be connected to the center 6/32 trim screw, that supports the cover plate to the 2 wire duplex receptacle. (Note the female 6/32 threaded hub is mechanically, electrically, connected to the supporting back strap of the 2 wire duplex receptacle.) Ground conductivity/continuity from the duplex receptacle metal back strap to the metal box was as good as could be expected back in those days.

So bottom line they were not designed to lift the ground. Though in many cases that is what they ended up being used for.

georgehifi said:
"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

I would bet John Curl does not lift the safety equipment ground from the chassis of any piece of audio equipment he designs. I would bet the ground lift switch seen on the back of the amp lifts the signal ground from the chassis.

Jim

Whatever, you have your view, that has no other.

Cheers George

John Curl does not lift the AC mains safety equipment ground from the chassis on the JC 1 amp.

"TECHNICALLY SPEAKING",     page 14

3. Use the Ground switch on the JC 1 to eliminate most ground loops. This separates the JC 1’s signal input ground from its chassis ground to isolate unwanted voltage in the ground shield of the unbalanced (RCA) input cable. Be sure your system installation is finished before you try moving the Ground Lift switch from its “Normal” to its “Lift” position.

https://parasound.com/pdfs/JC1Manual.pdf

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