Sunday, September 4, 2011

Thoughts about the Noise Sniffer

I've been testing the PS Audio Power Plant Premier in various technical ways, mainly with the AudioPrism noise sniffer.  Or should I say I've been testing the noise sniffer?

First let me suggest the Noise Sniffer does have some limitations:

1) You cannot simply leave the "volume control" at one position.  The "volume control" somehow tunes the sniffer to different spectra.  So the best use involves turning the volume control from minimum to maximum to back and noting the various levels, at least the maxima.  At maximum "volume" the volume doesn't necessarily increase much if any by itself on clean AC.

2) The Noise Sniffer does seem to be affected somewhat by RFI not in the power line.  Under some circumstances I could pick up lots of noise, including an AM radio station, or make it go away, by simply moving the Noise Sniffer around while it was plugged into wall.  Interestingly, the worst noise (and the AM radio station) was picked up most while sitting on the Simmons Hide-a-Bed convertible sofa, perhaps as a result of all the old metal inside the sofa, including springs.

3) The Noise Sniffer, as its name even suggests, does not seem to be particularly affected by harmonic distortion in the AC line.  The PowerPlant Premier goes to great lengths to reduce this distortion, and I believe the nice indicator when it says I have reduced THD from 1.8% to 0.2%.  But the Noise Sniffer doesn't notice this difference at all.  And of course it doesn't detect differences in AC voltage level, though it might detect abrupt changes.

4) I don't necessarily assume the Noise Sniffer detects the all the noise having audible effect on audio equipment (if there is any!) nor that it weighs the noise that it does detect on an audibility scale.  The noise sniffer is not an "A Weighted" instrument.  Actually it might be interesting to construct such an instrument; one could for example extract the noise and then apply "A weighting" to it.  But then there is additional assumption that equipment is affected in similar fashion.  It might well be that equipment is most effected by subsonic and supersonic noise which somehow affects audible performance of the equipment through intermodulation or similar processes.

In other words, it's crude, but it does give a quick sense of garbage on the line, that is difficult to the level of impossibility by other quick means, barring the availability of even more sophisticated equipment.  It's the best thing I have for a quick test, I just don't trust it completely.

No comments:

Post a Comment