If I were a gambling man I would bet on somebody using either
an Ethernet over powerline or some other kind of multiplexer that use the AC
wiring to distribute a signal or make a connection that is inconvenient to
do via actual installed cable.
Does the signal come and go at different times of the day? Is it a steady
signal or does it modulate?
All the best,
On Tue, Aug 30, 2011 at 2:07 PM, Martin Fisher <[log in to unmask]>wrote:
> Hi gang,
> FYI, the following is cross posted to two list serves.
> A mysterious squeal appeared in the transfer chain here in the audio lab
> about two months ago. It's a tone centered around 10,330 hz and seems to be
> coming in on the AC power lines for a good portion of the building. This
> has been determined by taking a piece of equipment (in this case a
> Soundesign 8 track deck with integrated amplifier and a pair of headphones)
> and plugging into several outlets in the building. The tech power outlets
> for the recording studios are clean as well as some outlets on the 2nd floor
> but many of the 1st floor outlets have the offending tone present.
> I've tried isolation transformers and low cost IsoBar type line
> conditioners with absolutely no luck. The tone appeared at approximately
> the same time of a revamping of the air conditioning system for the building
> and stringing of lines for some sort of digital cable. One of the campus
> electricians did some switching around of breakers and various things but
> nothing has helped. Before I go out and get a high end line conditioner to
> try out I thought I'd tap the collective wisdom of two of the best informed
> list serves. Any ideas?? I'm sure I've not provided the best description
> in the world so I'll try to answer any questions that arise.
> Thanks. :-)