I comprehend your reaction fully, 
...
Part of the journey, as I see it, is to deliberately overcook a bad influence, exaggerate it so much that one's hearing picks up what going on, because it is now so obvious - thus you develop a sensibility to the effect; then you can steadily tone it down while still being aware, consciously, of it happening. One's unconscious mind is most likely aware of something not quite right, the trick is to be able to shift it to the conscious mind's focus - you "learn" to hear it ...
...Part of the journey, as I see it, is to deliberately overcook a bad influence, exaggerate it so much that one's hearing picks up what going on, because it is now so obvious - thus you develop a sensibility to the effect; then you can steadily tone it down while still being aware, consciously, of it happening. One's unconscious mind is most likely aware of something not quite right, the trick is to be able to shift it to the conscious mind's focus - you "learn" to hear it ...
The interference may be very complex in nature, highly chaotic, RF material - impossible to capture unless an ultra high end scope is used. Yet this may be the very worst offender - just because something is not easy to trap doesn't mean it should be left to last to consider - first stimulate the 'bad behaviour' in the DUT, by whatever means, then narrow down to an injection source which is completely controllable, if you want total repeatability ...
EMC engineering, CE mark FCC compliance...Henry Ott
Other fields of electronics engineer solutions, though a PC is the worse rig I can think of for playing music as are cheep PC speakers.
You're partially right, I'm somewhat surprised that the onboard DAC does as well as it does - but I have to carefully choose the environment in which the PC is running to get a decent outcome; eg. switch off the monitor, completely disconnect Ethernet.
The speakers are a known item - apart from issues in their bottom octave bass they are quite revealing.
The setup certainly benefits from having a low electrical noise environment, the more I do to minimise such the better the sound.
Solutions can certainly be engineered, but first the fact that there is a noticeable impact has to be acknowledged.
The speakers are a known item - apart from issues in their bottom octave bass they are quite revealing.
The setup certainly benefits from having a low electrical noise environment, the more I do to minimise such the better the sound.
Solutions can certainly be engineered, but first the fact that there is a noticeable impact has to be acknowledged.
I've had issues both with short line sets (a meter or two), and long line sets (125 feet). Most of the issues I had dealt with unbalanced lines, on occasion a balanced line gives me problems (pin 1). But you're right, this miles and miles scenario is a strawman argument.
First, he would rant incessantly about the use of unbalanced audio cables feeding boxes with power gains in the 10e6 to 10e7 range, then he'd have set the stage for EMC theory. But he'd have understood it.
Don't worry about far field intrusion. Worry about local magfield coupling, as you mention with the transformer example.
And yes, the interconnects are indeed the coupling mechanism. Unfortunately, they are the victim, the power cord is the aggressor.
jn
We use a screened room if need be, labs in general are wired by the same electricians. Yes different phase of 220 on neighboring benches, so bring in your old timey hot chassis radios and forget that half your gear is plugged into your neighbors bench including an old scope on a 3-2 cheater.
Explain all that to Jim Brown, past AES committee chair on EMI/RFI and is also a Ham radio operator.
Lets start with the first few pages of this paper. Ignore the title, it started as a audio paper then the Ham chapters were added.
"A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing"
Revision 5a 5 Jun 2010
by Jim Brown K9YC
Audio Systems Group, Inc.
Audio Systems Group, Inc. Home Page
http://www.audiosystemsgroup.com/RFI-Ham.pdf
*************************************
Many other Jim Brown papers and PowerPoints at:
Don't let the other titles fool you either.
Audio Systems Group, Inc. Publications
true
and AC mains are pure...
for any competently designed power supply and subsequent components, pure enough for audio purposes.
- Status
- Not open for further replies.