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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.

Post Subject: Experiment with the PP2000 groundPosted by drdna on: 2/21/2009

beachbum wrote:
Did so cause i was still using my BPT for everything but my amps. I had a hum and high pitch buzz from my speakers. Replacing the power cord feeding my amps was the cure.

There was some mild 60 cycle hum which was eliminated when I lifted the grounds to the amps. They are plugged into the PP2000. Everything is plugged into the PP2000.

Romy the Cat wrote:
drdna wrote:
There is only one path to ground at that point, the neutral path through the AC plug.
But if you lift the PP2000 output then the path is not there anymore!

Exactly. Thus, it suggests a ground loop internal to the PP2000, doesn't it?

Romy the Cat wrote:
drdna wrote:
No, when the PP2000 is totally unplugged from the wall (and hence the neutral path which is also grounded is removed), the hum disappears.
I still have no idea what the isolation transformer that you mention does in your system.

I am just talking about the transformer for the mains power supply, not an additional device.

Romy the Cat wrote:
What I would do next is to lift ground at the 2000PP input – and then ground the PP2000 to your own ground. Make sure that no other devises on your playback use the main’s ground. When you do so let me know how much AC voltage you have between neutral and ground.

I did this already; it did not eliminate the buzzing (I will call it buzzing to distinguish it from regular hum). Everything is plugged into the PP2000. There is about 500 mV between the neutral and ground.

Maybe I will need to have the house rewired. It's a pretty old house with only a few three-prong plugs that were put in during a remodel.

Adrian

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