Newsgroups: rec.audio.tech
Subject: Re: 220 power sounds better
References: <[email protected]>   <[email protected]> <[email protected]> <[email protected]> <[email protected]> 
"mc"  writes:

> "Peter Larsen"  wrote in message 
> news:[email protected]...
> 
> > I found a subtle difference in terms of inter-transient silence, a
> > subjective listening test parameter, to be perceived after adding mains
> > filtering, quite probably because I live near to a mains grid
> > noisemaker, a hospital. But it is subtle, and it is not an effect that
> > is all that easy to to prove via DBT, I prefer to rate it as "just a
> > perception", the real world is like that. Addressing tbe issues that are
> > easily measured usually contributes way more to perceived sound quality.
> 
> Years ago I gave some thought to inventing an instrument for listening to 
> your mains grid noise (transients, etc.).  It shouldn't be too hard to do, 
> and it would enable people to determine whether their power was clean.

There are power quality analyzers used by electrical power people. 
Those can give you idea on the quality of electrical signal on the 
mains cable, measure voltage, harmonics and general noise. 

For making such measurements one way to do that is to use a 
suitable measurement transformer that takes in mains voltage 
and outputs voltage suitable for PC soundcard input 
(0.2-1V AC signal very OK). Then just record mains power 
waveform to computer, and do anyses that are needed... 
Like for example make fourier transform, filter out the 
mains 50/60Hz and then listen to the rest etc..


For simple listening system for mains noise the idea would 
be just use that measurement transformer, put a suitable 
band-stop filter after it (50 Hz or 60 Hz mains out) and 
listen to the results with headphones. 

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/