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spampup
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Last seen: 8 months 6 days ago
Joined: Nov 25 2005 - 8:59am
Power Cord Upgrade: Grounding & Shielding?

Hi, All,

I have an interesting question about a possible future power cord upgrade.

All of the aftermarket upgrade power cords I have seen are three-wire grounding types. Many are shielded as well, to prevent noise pickup, and also to prevent interference generated in the connected component from being radiated from the cord.

Using a shielded power cord on a digital component makes at least some sense to me.

The conundrum:

I recently ordered (but haven't yet recieved) a new Marantz SA-11S1 SACD player. This component has an IEC type socket that will accept most aftermarket cords, but the connector has only two pins, for hot and neutral.

No big deal, right? The cord shield is probably connected at the "wall socket" end anyway.

BUT... I plug my components into an MIT "Z-Center" power line conditioner.

One of the outlets in the Z-Center, the one I usually use for my CD player, is isolated, using two large isolation transformers. The isolated outlet is floating ground; the ground pin of this outlet is not connected! In this connection scheme the power cord's ground wire and shield would be completely unconnected.

Given this scenario, Is there a way to utilize the power cord shield?

I could probably use one of those "cheater plug" adaptors and connect the ground wire somewhere else in the system, but where would be the best location?

Could it be dangerous to connect the ground wire in an isolated outlet?

Has anyone either used a similar system, or had similar experience?

Thanks!!

Ken

Jim Tavegia
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Joined: Sep 1 2005 - 4:27pm
Re: Power Cord Upgrade: Grounding & Shielding?

Often times the ground causes more problems than it solves. Often times hums from ground loops can only be eliminated from removing the ground pin. This is why many of the new accessory chords are coming with removable, screw-out ground pins.

Once we in the electrical industry bonded the neutral to ground for safety reasons we created others like making lightning protection more difficult. Now when a lightning strike hits ground it can back feel into the ac line since it is now bonded to the neutral leg.

All should be well with what you have. It sounds like Marantz is just heading off any ground loop problems. You should enjoy your new player.

spampup
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Re: Power Cord Upgrade: Grounding & Shielding?

Thanks for the reply, Jim, but I am not really concerned with the power line ground connection or hum/ground loop problems. I could be perfectly happy with a two-wire cord, since the Marantz player does not have a power line ground connection anyway.

I am just curious about connecting the SHIELD of the power cord. Since the ground wire would not be connected at either end in my setup, what would be the best way to connect the shield in order to minimize both noise pickup and noise radiation?

For instance, should the shield be connected to the power line ground, or to the Marantz chassis ground, or to the preamp ground?

Any ideas?

Thanks!

Ken

Jim Tavegia
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Re: Power Cord Upgrade: Grounding & Shielding?

I would leave it unattached. If you have no problems my rule is not to try and make any. Do not connect the shield to the power line ground.

I always keep a supply of those little gray ground lift adaptors around ever since I started using tube audio gear. Since you have "clean power" box you should have an excellent source of cleaner power.

I am surprised at some issues on AudioAsylum from owners of certain gear that pick up some stray RF once is a while. There was a recent test of a very good amp that had stray RF showing up in the scope output...considered rather strange in well designed gear these day. I would sit back and just enjoy your very nice system.

Jim Tavegia
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Last seen: Never ago
Joined: Sep 1 2005 - 4:27pm
Re: Power Cord Upgrade: Grounding & Shielding?

Music Direct.com has some adaptor plugs for using IEC type cords on gear like your Marantz. Check out their web site:
www.musicdirect.com

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