Grounding boxes?

[Mr. C]

Some very reasoned points there chaps excellent debate.

Below are a couple more images of my findings this time at a customers house, I took base line readings of the audio system equipment all off this was taken at the customers vampire poo box. System had been off from the previous evening. Span of the spectrum analyser is from 10Khz to 750Mhz and resolution bandwidth is pretty tight @ 3Khz it also matches the VBW as well. Mixer level @ -10dbm, ref levels @-65dbm

The second screenshot is with all three system components now switched on but not actually playing. you can clearly see the disturbances start around 84Mhz and extend up to around the 230Mhz region so far and away beyond the audio band of 20Khz

Measurements were taken with a 6.5Ghz Real time spectrum analyser using an optional OXCO reference clock 0.5ppm stability and a 500Mhz rf passive probe (BW useable up to 800Mhz) used for conducted emissions emc testing. Both pieces of test equipment are fully calibrated to UKAS standards. Test leads are T-flex 405 18Ghz ultra low loss lab cables

The probe was placed around one of the grounding leads approx 60mm before entering the device.

Bear in mind these figures are -dBm so in reality the larger peaks are around +5dBm from the base line reading.

What does it all mean................over to you guys

[Wakefield Turntables]

What about the concept of level of cost compared against level of enjoyment. The concept is simple in that do I feel my cash outlay is worth the increased enjoyment/pleasure I experience every time I listen to my system. If the answer is no then it's a complete waste of money, irrespective of cost, if the answer is yes then the investment is a long term worthwhile investment. I've never heard a grounding box in my system so I can't quantify this concept. I love reading the science and at least some people are making an attempt to explain how these things work. Me, personally, I'll keep my money in the bank until I can hear one in my system. It's irrelevant listening to these things in other peoples systems, they simply don't replicate what you own in your own listening room.

[Barry]

Tony, it's not clear to me what the yellow and blue traces represent in both of the screen shots?

[Mr. C]

Hi Barry

The brown trace is live trace the blue is max hold (peak) each image is taken after 100 average sweeps each taking 1 ms I can tighten down the rbw to around 100hz at this bandwidth but the sweep time would very long.
Have other large data files which are which demonstrate very similar results in over 30 systems all different configurations.
Not trying to convince anyone that this a magic bullet I am curious as to why this demonstrates sonic differences so I decide to look into what could possibly be having an effect. I have had a good journey so far in exploring this area of vampire poo

At the weekend I will narrow the dweep bw down to a peak spread and perform a full RTA this gives access to spectral density which would an easier way to interpret the results

[Pharos]

We need to clearly identify a change, or what we think is a change, and then DB test for it.

The smaller the change, the more susceptible to both error and the psychological failure mechanisms; pre-conception and expectation bias. Worst of all, placebophilia.

Ignoring high clock rates and oscillators, which should be screened off, I cannot accept that the deliberate introduction of RF signals into audio equipment is ccts going to be positive in any way.

[Macca]

We need to clearly identify a change, or what we think is a change, and then DB test for it.

The smaller the change, the more susceptible to both error and the psychological failure mechanisms; pre-conception and expectation bias. Worst of all, placebophilia.

Ignoring high clock rates and oscillators, which should be screened off, I cannot accept that the deliberate introduction of RF signals into audio equipment is ccts going to be positive in any way.

It's been suggested that it acts like dither in a digital system, I.e it reduces distortion at the expense of adding some noise.

[Mr. C]

Ignoring high clock rates and oscillators, which should be screened off, I cannot accept that the deliberate introduction of RF signals into audio equipment is ccts going to be positive in any way.

I am in complete agreement with you, so many dac/streamer design has poor rfi management, although you will never really remove it all just not possible, however you can improve matters no end with care design considerations.

Also these devices DO NOT inject any form of RF at all, what is shown is the measurement actually going into the box itself, not the other way round. This is with the box actually connected to the audio system.

The first image I put up in the first pair of screenshots is showing the the RF measured at the balanced analogue output xlr socket.

Can offer some further information from customer feedback from a loan device they tried, gent has an all streaming system in his front from by a bay window where is router is located, he uses a short 1m RJ45 to his streamer. He placed one of these devices quite close to the router (8 inches) as he has limited space on his rack.

I received a long phone call from the chap who was tearing his hair out as to why his streamer was now not working and the internet could not see the control device no matter what he tried. We ran through the obvious and not so obvious reasons. Both stumped??

So thinking Sherlockian if you have eliminated the logical only the illogical remains, also usually try the last thing you did also helps!

He took out the the device and hey presto internet returned, they upshot was this, his i-pad could not connect via wifi (and the other wifi devices in house had the same issue) although the streamer could see the IP as it was hard wired. So something was killing both the 2.4 and 5Ghz bandwidths stone dead.

That weekend I went to see him to investigate after much time involved the result was moving the VP device onto the floor resting on a wooden block, all wifi back to normal plus a happy chappie. This has happened one other time with a dealer friend of mine. Maybe a clue maybe a red herring but the effect was real.

[Pharos]

It is beyond me that dither can reduce distortion in these circumstances.

Preventing entrance of external undesired RF seems to me to be a rational approach, as well as mag fields; good screening and mu metal practices. The prevalence of RF is a real problem, and likely to grow.

[Macca]

It is beyond me that dither can reduce distortion in these circumstances.

.

I agree, I think it is straw-clutching. But the theory is out there nonetheless.

[AJSki2fly]

It is beyond me that dither can reduce distortion in these circumstances.

Preventing entrance of external undesired RF seems to me to be a rational approach, as well as mag fields; good screening and mu metal practices. The prevalence of RF is a real problem, and likely to grow.

Time to build and live inside a Farady cage.