GoodSoundClub - Romy the Cat's Audio Site

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

Post Subject: The vampire effectPosted by Lx_ on: 1/6/2011

This evening I took myself to performing additional tests with the entire system completely disconnected from utility ground. Following Romy's considerations about different grounds, and Richard's absolute belief in the capacity of a properly working PP to isolate PP output from input, I had to make sure that ground did not get in the way.

I first lifted ground at the AC input of PP. I measured resistance (thanks Romy for the tip) between signal ground (at left amp) and utility ground. I was surprised to see only a few ohms. I quickly identified that utility ground was still connected through the PC network cable (BTW I cannot use a CDP, it's been a while since I had one and I now have only a PC transport). After unhooking some cables and lifting other grounds, I managed to have a completely floating audio system ground. Resistance between signal ground and utility ground was infinite and with the system on, the voltage between them was 110V (I run on 230V). Definitely not safe (I tested it) but a solid proof that I had what I needed.

It was now time to track external appliances turning on/off by listening.

For the next 30 minutes nothing much happened (no heater turning on). The sound was a bit more boring than usual. I discovered that I had left many appliances running: a second PC was not hibernating as usual, its LCD was on standby (I know it is noisy in that state), and the wifi, network switch and DSL box were all on. I turned them all off as usual. Sound immediately got better.

I will not bore you to death with the details. The result is that I can easily hear everything that goes on/off behind the system, even though the latter is completely off utility ground. How does it sound? Appliances suck the life of sound. The sound becomes totally flat. Dynamics are killed, noise floor is raised meaning I have no micro details. You know how you can hear the sound stage breathe when things are OK? Appliances choke the sound stage. This vampire effect seems to depend on the power consumed by appliances. I have a meter that shows me exactly how much power my apartment consumes. I have two large 1kW heaters in the audio room, there are smaller 500W heaters elsewhere. The water heater is 1.5kW. I can hear exactly what type of heater gets on/off. The refrigerator also has the vampire effect, but less than heaters. It consumes around 60W so you would think it would have almost no effect but it has. Also when it starts it consumes a bit more power (100W), probably to start the compressor. But it has the same effect as a large heater. So it is not only linked to consumed power. The vampire effect makes me believe that the PP is feeding the appliances instead of the audio system.

There you have it. Something is definitely wrong with my PP.

BTW, the totally off utility ground system did not sound better or worse, pretty much what I am used to. I would have to perform more extensive testing to confirm it, but if there is any difference it will be minor.

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