Measuring EMF - the TriField TF2 meter

ack

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My new toy, to measure magnetic fields and interference around components. $168. There are other fancier meters but this one appears to be one of the best


You will not believe what's going on out there, and the reason I've been manic about component shielding over the last few years...
 

infinitely baffled

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Fascinating subject.
Is EMF airborne, or is it spread through the building's wiring?
Could you identify the dirtiest domestic appliances in the home?

As far as my own home is concerned, my money's on
1) wifi router / modem
2) satellite tv box
3) fridge freezer
4) heat pump

I don't have air conditioning or dimmer switches, nor do I count tv as that's never on when i listen to music. Or any chargers of any description.

I guess the real shock would be if significant emf is traced back to hifi components.
 

ack

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I guess the real shock would be if significant emf is traced back to hifi components.
Oh, but I have proven that it is affecting my equipment, hence the copper and mumetal shielding.

This device has shown me where the interference comes from, and your guesses are very much on target; you missed the microwave, which emits tremendous magnetic and electric fields, but not RF. The most important confirmation of RF - and perhaps a discovery for others - is placing the device next to power outlets, and the RF pickup is off the charts. This is why I am gaga over the Shunyata Denali 6000S/v2 that I've been using to beautiful results, which significantly attenuates very high frequency noise out of the power line (they claim some 60dB drop). So measuring RF out of the Denali has verified that it actually works really well - there is virtually nothing coming out.

Down low, the 60Hz magnetic fields are something to pay attention to as well. Not surprising to me, the Shunyata power cords and Denali emit virtually no magnetic fields, and this is especially important for me who runs a whole bunch of them close to each other, plus interconnects and speaker cables. Other cords may not fare so well. What was another welcome discovery is that even the connectors on either end of a cord do not emit either, which indicates great shielding all along the cord's length.

By contrast, and not really surprisingly, my DACs and amps are monsters of magnetic fields, and the DACs have been placed far away for years now. Unsurprisingly, the Pass external power supply for the XP-25 phono is also extremely well behaved, but that could be because of the mumetal shielding of the transformer I have done, plus the mumetal shielding all around the case.

It is also nice to run this device all around the turntable to see if there is hum interference; the surprising discovery was that the motor generates enough of a magnetic field to be affecting the cartridge even at rest on the other end, by a tiny bit - I will be shielding the motor soon. It would be fun to measure direct-drive tables in the future...

So at the moment, I have more mumetal on order to further shield the DACs, turntable motor, and possibly add to the MIT speaker cable boxes' existing shield. There is nothing I can do about the amps; lucky are those who can place them far far away from anything else.

-ack
 
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treitz3

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Thank you, ack. This is a subject that I was going to get into recently for my own rig. You beat me to it. The price of the item is not much in the whole scheme of things. Sometimes simplistic ideas yield the greatest results. I am interested in the end result.

Tom
 
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ack

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Indeed, the cost of the device is negligible. The real cost is in the solutions one may need.
 

ack

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The "typical issues" include excessive magnetic fields and RF, which in my experience affect the sound of our systems, quite significantly in fact. The audible effects will vary by each component's architecture and setup, with phono being the most sensitive, by definition. Therefore, how one's system is affected by hum and RF cannot be easily predicted, but can be investigated. Having dealt with these issues for over 5 years now and documented under my system thread, my impression is that is a neglected subject, and power conditioning is only a part of the solution.

The technique is rather simple: run it around your components, power outlets, and all nearby appliances. Observe how the magnetic fields' magnitude drop (or not) as you move away, from one component to the other. RF from the outlets will seep into your power supplies, whether we like it or not. WiFi is everywhere, and you notice it as chirping (quick pulses) on the device. My Mac laptop emits a lot of RF from its lower-left corner... etc...

In my system, and long before I bought this device, every time I shielded things the sound became clearer, more realistic and more dynamic - that's what I was hoping for. This device, and others like it, enable one to wave it around and determine where interference may be coming from and what the nature and amplitude is.

The real cost, again, is what do you do with that information: Do you change or move cables? Do you buy power conditioning? Do you move components farther away? Do you shield things, including tubes? etc...

Let me discuss a few of my solutions:

Digital Cables: I have found out that there are significant differences that go beyond cable reflections, and have to do with shielding of RF noise. A classic example of this was the latest generation of Transparent's SPDIF cable a few years ago, only to discover that its position in the air affected its performance and the Vivaldi 2.0 DAC would lose its lock to the transport. By contrast, replacing it with an MIT or Kimber fixed the problem.

Analog and speaker interconnects: I have gained sizable improvements by mumetal+copper-shielding the MIT boxes. More than that, I have seen interconnects discussed on this forum that go beyond the typical copper-mesh shielding and include a mumetal jacket, to shield both against RF and low-frequency hum. They are expensive, but I bet they ought to sound really clear.

Power cords: I'll just state the obvious, off the shelf "stock" power cords emit large magnetic fields; I bet they also act as antennas. Run a few of them close to each other, and the magnitude of the magnetic fields multiplies. Havoc. Chaos. By contrast, the power cords I buy are heavily shielded. The gains ought to be both in the construction of the cord conductors as well as the magnetic fields they do not emit.

Phono: with respect to my heavily shielded Pass XP-25 phono: night and day; ability to turn up gain to its native 76dB, ability to load at 47K, no hum or hiss at very high listening volumes; therefore, a much more dynamic and accurate sound... I am currently helping another fellow here with shielding his own XP-25 and he says he's thrilled with the results.

Cartridge: obvious interference pick up from nearby magnetic fields

Power Conditioning: if you can reduce power-line noise with no loss of current flow, I'd call that a winner. I am able to plug everything into the Denali, including my current-hungry amps. Staggering performance gains all around, analog and digital. I feel this is the new dawn of power conditioning products. The downside with such proper power conditioning can be that it may expose problems in one's system, otherwise masked by noise running through the components, a masking that's typically rendered as softness and lack of resolution which some folks like (they may even call it 'natural'), midrange glare that they think is in the recording, musical notes that are way off or exaggerated, etc. Such issues exposed by power conditioning are typically: a) ill-attributed to power conditioning; and b) may be resolved with more expensive and better-engineered products... that's not to say that there aren't bad power conditioning products that impose their own problems and are just not worthy.

Tubes: I don't do tubes (so not my solution per se), but I have a friend who's copper-shielded all his tubes (some two-dozen) and he claims his system has never sounded so clean before. He's gained the most out of shielding his phono tubes, he says. He just hates the fact there is no more tube glow to look at.

Bottom line: noise is everywhere; noise is a killjoy; noise has no business in a high-performance audio system, if you look at it from the instrumentation point of view (which I do). Noise management is not discussed or addressed to the degree it deserves.

-ack
 
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rando

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ack, have you pointed this in the obvious direction from your listening position? In the video a large number of the examples were measured at a respectable distance from speakers up to 1/4 mile away. Very interesting hearing how your system fared years on from starting to address these issues. Especially the cable testing.

Also, I never knew Mumetal flexible conduit shield existed. Filing that away for potential future use.
 

ack

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ack, have you pointed this in the obvious direction from your listening position?
Yes, and it doesn't say anything about anything. How magnetic fields or RF might look like at the listening position does not directly translate to what is going on at the rack.
Also, I never knew Mumetal flexible conduit shield existed. Filing that away for potential future use.
Yeah there are mumetal tubes in all kinds of sizes, like this one

1612400360050.png

available at https://www.amazon.com/MuMETAL-Shielding-Flexible-Conduit-Length/dp/B017O6PXJ0 as well as braided configurations.

Here's such a cable I just googled, from Allnic:


The Mu-7R Digital Intercable uses Mu-metal as a braided shield, which protects the signal from both kinds of noise. Other audio cable manufacturers tend to use copper or silver shields for signal cables. These are effective only for electric noise, not for magnetic interference.
  • Mu-metal braided shield for reducing electromagnetic noise up to max. 98%
  • 1000 °C hot melt welding of cable terminations and wire
  • Optimum thickness of wire
  • MRCT

Here's their phono cable http://allnicaudio.com/product/mu-7r-phono-cable/

Mu-7R Phono Cable​


The Mu-7R Phono cable uses Mu-metal as a braided shield, which protects the signal from both kinds of noise. Other audio cable manufacturers tend to use copper or silver shields for signal cables. These are effective only for electric noise, not for magnetic interference.
  • Mu-metal braided shield for reducing electromagnetic noise up to max. 98%
  • 1000 °C hot melt welding of cable terminations and wire
  • Optimum thickness of wire
  • MRCT

One well-known supplier is https://www.vermillioninc.com/products/vermalloy/vermalloy-622/ "A high permeability mumetal type alloy in standard stranded form. Used in critical shielding applications, especially in audio frequency ranges and high magnetic fields."

VERMALLOY®​

The Secure Voice Solution​

Vermalloy® shielding is recognized as the most effective secure voice shielding material available. Its installations speak for themselves. It is specified on numerous military programs. It is even used to solve interference problems on entertainment systems of corporate aircraft. When dealing with low frequency interferences or protection, Vermalloy® is your solution.
Vermillion’s Vermalloy® shielding is also the most effective solution to magnetic shield applications. The high permeability of this alloy increases the absorption loss and eliminates both magnetic and electrical interference. In order to maximize design effectiveness, Vermillion customizes your shielding and jacketing materials to provide the highest signal integrity for your application. Coupled with additional materials, Vermalloy® can provide substantial weight savings while enhancing the properties of the cables.
Since 1966, Vermillion has provided the military with secure voice and data cables utilizing our exclusive Vermalloy® shielding materials. Applications include secure data transfer on submarines, voice and data on Special Ops aircraft, as well as ground vehicles and launch systems.
 
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tima

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The "typical issues" include excessive magnetic fields and RF, which in my experience affect the sound of our systems, quite significantly in fact.

Thanks for the write-up and the time it took to do it. Do you find a generalized sonic improvemen of increased clarity and reduced grain, or are the improvements specific to the components and areas addressed?
 

ack

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Thanks for the write-up and the time it took to do it. Do you find a generalized sonic improvemen of increased clarity and reduced grain, or are the improvements specific to the components and areas addressed?
The improvements have been obvious in the areas addressed, and they are rendered as improved clarity, timbre and dynamics as I mentioned. At the top, and by far, are gains in the analog chain. The power conditioning results were universal, affecting all components. For example, plugging the amps directly to the wall results in an obvious drop in dynamics and a slight drop in clarity. etc... More mumetal arrives in 5 minutes... :)
 

ack

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So here's something else I discovered... I just double-shielded the turntable motor to measurable effect, but it looks like there is still residual effect measured at the top of the platter along the arm's tracking path, and temporarily placing mumetal under the device and on top of the platter reduces it quite well, below 3.0mG . So I may need to add mumetal to the platter as well, after careful auditioning now.
 

SuperDave

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May 12, 2017
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You mentioned power conditioning, what are your current thoughts on grounding? If I remember, you were skeptical of Tripoint and its effects but wonder if your thoughts on EMI/RFI & grounding have evolved. Grounding, IME brought clarity, realism, and dynamics, some of the same things you got from shielding. Curious if its all connected?
I'm not technical, just curious.

Dave
 

ack

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Dave, I have not spent any more time thinking about "grounding devices". Proper grounding is really important and I have discussed elsewhere the fact I am lifting the amps' grounds, etc. Proper grounding can be achieved via well-understood means, based on electrical principles. I simply do not see any science around these "grounding devices" to pursue them any further. But if they work for folks, so be it.
 

ack

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So I may need to add mumetal to the platter as well, after careful auditioning now.
The motor shield worked well from a sonic perspective (and mine is a beast of a motor), and I may opt for a third layer; there is clear reduction in some 60-Hz warmth, moving towards a more neutral and dryer bass, evident with drums on For Duke and upright bass string plucking.

I think I will further explore mumetal on the platter this weekend, when the next batch of sheets arrive.

And related to metals in general, the device is showing a clear *increase* in RF pick up when placed on top of metal surfaces like steel and even aluminum (e.g. faceplates, which is why copper shielding of the phono works so well), and that is why I hate metallic platters of just about any kind - especially large steel blocks - in addition to their ringing properties. Magnesium is distinctly different (e.g. as measured with my Canon camera body)
 

analogsa

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I wonder what would you do to one of those tonearms that employ a non metal, not screened arm tube. Would that not render all other analogue attempts at reducing emf pointless?
 

ack

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I wonder what would you do to one of those tonearms that employ a non metal, not screened arm tube. Would that not render all other analogue attempts at reducing emf pointless?
You can still wrap it with thin copper tape with a path to ground, and I have done that with my arm - as long as the added mass is tolerable, and it is in my case because of the very light cartridge. I am still looking for the magnetically-stabilized unipivot carbon-fiber or maghesium arm with a thin copper tube inside it.
 

ddk

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Power cords: I'll just state the obvious, off the shelf "stock" power cords emit large magnetic fields; I bet they also act as antennas. Run a few of them close to each other, and the magnitude of the magnetic fields multiplies. Havoc. Chaos. By contrast, the power cords I buy are heavily shielded. The gains ought to be both in the construction of the cord conductors as well as the magnetic fields they do not emit.
Havoc. Chaos? Definitely not sonically! Seems you make things up as you go along.
The downside with such proper power conditioning can be that it may expose problems in one's system, otherwise masked by noise running through the components, a masking that's typically rendered as softness and lack of resolution which some folks like (they may even call it 'natural'), midrange glare that they think is in the recording, musical notes that are way off or exaggerated, etc.
-ack
Your statement on what some folks may call lack of resolution as natural is basically your limited understanding of the subject and if there’s any ignorance here on natural sound it’s only on your part not understanding it. Perhaps you should stick to your wrapping instead of pretending of having a clue as to what some folks hear after all you wouldn’t have to mummy wrap and tweak everything if you got it right to begin with :)!

david
 
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analogsa

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Copper tape will dramatically change the sound of an armtube
You can still wrap it with thin copper tape with a path to ground, and I have done that with my arm - as long as the added mass is tolerable, and it is in my case because of the very light cartridge. I am still looking for the magnetically-stabilized unipivot carbon-fiber or maghesium arm with a thin copper tube inside it.
I shudder to think how dramatically the copper tape will change the sound signature of an ebony armtube, Besides, it will do virtually nothing for the magnetic component of the field.

Regarding the wholesale application of mu-metal for screening purposes i'd be very careful. IME it sometimes does more damage than good.

Interestingly, even a conservative manufacturer such as ARC acknowledges this when they offer a light, acoustically transparent top covers for their preamps in lieu of steel.
 
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