How important is EMI and RFI rejection?


In designing a cable....and what cable manufactuer(s) excell...

Power cords
IC's
Speaker cables
wavetrader
I don't want my to amplify any signals other than the pure music. I wonder if the expensive MIT speaker cables allow RFI & EMI to contaminate the signal from the amplifier to the speakers?
1. Even decent equipment filters the AC line
2. Non-power line induced noise isn’t of a concern in the home environment (no large co-factors like multi-phase motors, baluns, etc).
3. I keep LV and HV cabling separated.
4. I run a fully balanced setup (outside of power at the wall)
5. All my equipment is chassis ground (as it should definitely be)

Simple steps using sound, best engineering, practices.
@jinjuku, I would beg to respectfully disagree with you on points 1 and 2.

1) "Even decent equipment filters the AC line"

Not true if you’re talking about hifi gear. If you mean power conditioners and the like, then they may indeed filter somewhat, but their usual track record is a mixed bag at best at doing so without introducing some sort of sonic negative in the process.

2) "Non-power line induced noise isn’t of a concern in the home environment (no large co-factors like multi-phase motors, baluns, etc)."

Technically true, but the assumption that those noise sources are all one would ever have to worry about with hifi in the home environment is IME wholly false. Audiophiles in general should have at least a passing understanding of what, for example, EMI is and how it’s generated.

Whenever voltage is present in a wire or a circuit, there is along its length an ’electromagnetic radiated field’ that extends outward from the voltage in 3D space and it weakens the farther out from the source. The field strength is in flux with varying voltage and its shape will dynamically morph and twist in 3D space wherever it’s influenced by the nearby presence of anything metal (or most anything conductive), other voltages, equipment, metal conduit, in-wall metal pipes or wiring, appliances, etc. As far as noise sources go, it isn’t really the motors or baluns that we most often have to worry about, it’s all the rest of it. In fact, it’s everything that’s plugged into the wall - every computer, every charger, router, wifi, light bulb, HVAC, microwave, etc...not to mention all of your AV gear (each piece actually can’t help but pollute both itself and the other nearby pieces). A portion of all the noise sources in total in the home can be radiated through walls and through the air into your gear, but on top of that every item in the home is also a source of electrical noise that travels along any wiring (in both directions, upstream or down) and, while that noise dissipates over distance, too much of it will make it back to the circuit breaker box where it is redistributed all over the home...back into your gear.

3) "I keep LV and HV cabling separated."

In general an excellent idea when you consider their respective EMF fields and how they might influence each other. But, this alone will not be sufficient because the fact is, on a somewhat larger scale, this same concept is being played out all over the home. Your home is in it’s own EMF/RFI swamp. To have the best impact on the problem, you must find a way to effectively drain the swamp (my apologies to any Trumpsters). There are very few ways to do this, one of which I have tried and absolutely swear by (a whole-home approach advanced by Alan Maher Designs, a company that many audiophiles do not yet have direct experience with yet, but that I can highly recommend). BTW, in case anyone is wondering, I’d say that attempting to turn your whole home into a Faraday cage, is IMO a fool’s errand.

It’s because of my direct experiences with the AMD company that I can tell you that 1) most audiophiles simply do not have the Slightest clue yet of just how truly destructive EMF/RFI and electrical noise (at the quantum level, like shot noise) is to AV performance and that 2) it is possible to do something about it. Most everybody has heard, at one time or another, someone say that’s way important. But, what audiophiles lack most is the opportunity to have it inexpensively and unquestionably demonstrated in their own system or someone else’s system, or at shows or dealers. AMD offered some products that were cheap enough and effective enough to first open my ears and then open my eyes as to just how profoundly true all that actually is.

4) "I run a fully balanced setup (outside of power at the wall)."

Nothing wrong with that, but as with #3, noise reduction wise it’s only a drop in the bucket of what stands to be gained overall, really.

5) "All my equipment is chassis grounded (as it definitely should be)."

It probably always should be, although I understand there might be issues if the equipment uses a floating ground.

In general there are 4 things you can do with EMR - you can block it, absorb it, reflect it and you can redirect it back into the circuit. When you can manage to do the last one, you in a very real (measurable) sense actually lower resistance in the circuit...you also are lowering impedance. That right there is a new development in the hifi world (as of less than about 5 yrs ago now) and most audiophiles haven’t begun to wake up to it yet. AFAIK, AMD is the only company that makes products that, when applied at a few certain strategic points around the home, can actually do that.

There are many noise-related myths out there now that are finally beginning to be busted.

Regards,
John