2. misc-audio
  3. 145462-1445

AC mains noise Borrowed noise sniffer and tested my AC lines...

I borrowed this AC line noise sniffing device (Blue Horizon Mains Noise Analyser) today. (Do not ask from where, I do not feel at ease saying.)
This device sniffs out noise and has a range of "000" to "999" and over that it just is "MAX".
So first test was kitchen light with wall plug. "784"
Kitchen outlet tied to refrigerator (frig ON) "MAX"
Bedroom wall nothing around in use "220" wow good number.

Furutech Duplex at amplifier "013*" WHAT!!!! yes "013". That is on a direct 44 ft extension cord from 20 amp wall outlet (also Furutech) * with the C7 to the noise sniffer one way, it is 13, other way it is 20. ALL the measurements change with reversing the noise sniffer AC plug, about the same amount each time)
That extension does have an additional Furutech duplex on the cord, six feet back of amp Furutech plugs end, and that duplex has two PS Audio Noise Harvesters. The wiring is a quad twist. and each side or pair is connected to one out side. so each Noise Harvester is on one half of the quad.
So I can say the PS Audio Noise Harvesters really DO a fantastic job!!!

The other similar line (from he same 20 amp outlet) does not have any Noise Harvesters on it. And with the stereo running, it has "297" noise level. However IF I do stick one PS Audio Noise harvester in an out 3 feet back ot the one the sniffer is in. The noise drops to "143". (I cannot leave the Noise Harvester or a pair in there due to it being in use, normally, plus adding them in where the noise sniffer is, seems to make the sound go too thin.)

Another major discovery is just HOW NOISY Digital equipment really is!!! I have my two CD changers plugged into a separate power conditioner. A PS Audio P-600.
Testing the PS Audio P-600 I own (tested at 60Hz) With nothing turned on plugged into the P-600 the baseline noise is "040" With one five disc CD changer turned on the noise level jumps up to "740" With the other one only on the nose is also "740" with both on the noise jumps over "MAX" This is with a PS Audio Noise Harvester plugged into the same duplex (on the back of the P-600) as the CD changer!
On the other hand.. The Marantz SA-10 is pugged into the Furman (also with a PS Audio Noise Harvester in same duplex and that area is "032". So SOME equipment is not spewing, and some is.

This is all I have learned in a half hour of fooling around.
elizabeth

Showing 9 responses by erik_squires

erik_squires
5,268 posts
 
BTW, I just read this article from 6moons (worlds ugliest audio web site) :

https://6moons.com/audioreviews/bluehorizon/4.html

And I found the results very interesting. It's kind of what I expected. Based on this, I repeat, you don't want perfect AC cords.  You want perfect power conditioners, and band limited, shielded, power cords.
erik_squires
5,268 posts
 
Hey Elizabeth,
I remember you are a big fan of Furman, like I am.
I'm curious if you have measured how much the Furman cleans up the noise? Like what is the noise at the Furman vs. the wall in the same location?

Also, what model Furman are you using?
Best,
E
erik_squires
5,268 posts
 
This is pretty awesome. Too expensive for me to play with, but I have wanted something short of an AC noise analyzer that was easy to use for a long time.

I have used oscilloscopes to examine problems from wall warts, and digital power supplies before, and I know from experience the Furman unit I have really makes my stereo sound better.

One really interesting thing from this article is the quality of noise coming out of the Hypex units. I totally believe it. When I build I add ferrite cores to the AC lines, but I have no idea if they really help.

Would be really interesting if the problems with Class D amps was not the amp, but the noise they inject.

Then the problem is not about what gear they match, but how good the power supplies in the other gear is.
erik_squires
5,268 posts
 
But system on. Second measurement twenty minutes later was "003" (I am thunderstruck.) Music was playing.        


I am sorry, but what does this mean?  What changed?

erik_squires
5,268 posts
 
What’s different I think is the Alpha labs is specifically about EMI. It is limited to 10kHz to 10 MHz. This is also the range at which most cheap noise suppressors work. Kind of useless for audio gear IMHO. So, I am not at all surprised it has little bearing on sound quality.

We need to see everything between 60Hz to 20kHz. That is very little overlap with the Alpha Labs product. Sad because it’s much cheaper!

This is why the Furman gear is something I really like. Their noise suppression’s -6 dB point is at 3 kHz. A much more useful starting point.
erik_squires
5,268 posts
 
I was just thinking, this also kind of leads us to simplify.

I mean, between routers, switches, streamers, amps, televisions, preamps, and DACs, managing all this power and noise issues becomes very expensive (as evidenced by Elizabeth's own set up).
The idea of having a 1 or 2 piece system seems to have exponential benefits in terms of cost and simplicity.
erik_squires
5,268 posts
 
The one thing I had not realized is how some audio equipment removes grunge from the line. And others. particularly the CD changers just SPEW tons of junk. I should measure the DVD players... ?? maybe.. And the plasma, just to know, while I have the tester in hand.

Yep!!

This is why multiple filter banks (some Furman units have them) or keeping your digital (especially network) stuff outside your analog power conditioners can help lots.

I like to think of it as a kind of demilitarized zone (DMZ).

The inexpensive Furman with LiFT and SMP like this one:

https://amzn.to/2Gpffj3


for my wall warty stuff, and then something else for preamp and amps, like this:

https://amzn.to/2TqBJU9

This keeps my wall warts 2 entire filter sections away from my audio reproduction.


Unless you use an active device like a PS Audio regenerator, this type of isolation seems mandatory to me.

If you can't afford 2 units, at least keep your wall warts outside your conditioners.
erik_squires
5,268 posts
 
@spatialking:

Actually, when monitoring noise, one cannot include 60 Hz since that voltage will swamp everything 


Yes, and it's clear from the description of the Blue Horizon Mains Noise Analyzer that this is exactly what they do. I've never said otherwise. To quote myself:
We need to see everything between 60Hz to 20kHz. That is very little overlap with the Alpha Labs product. Sad because it’s much cheaper! 

Should I have said "between, but not including..." before you could read the meaning of my post correctly?

The main noise concerns start around 1 to 5 KHz or so and goes up from there to about 30 MHz. So, a 10KHz to 30MHz analyzer is probably about optimum.   

<< cough >> OK, spatialking, you go on selling that.


Best,

E
erik_squires
5,268 posts
 
@spatialking

Really too tired for this.  Have a nice time.
More to discover