Evaluating Equipment-induced EMI noise in one’s audio system

Audiophiles have long recognized power line noise as the bane towards enjoying one’s audio system since at least the 1970’s (if not earlier). Folks appreciate their rigs often when the power grid has lower traffic during off-peak hours, such as late into the evening. More recently, perhaps beginning in the mid-1980’s or so (please don’t hold me to dates here, as I’ll stipulate I might be off on time), audiophiles have employed numerous devices such as power conditioners, power line filters, power regenerative devices, even battery-driven gear as a way to reduce power line noise getting into one’s system. And many of these devices actually work as claimed. But in this thread. I want to explore the extent to which the audio equipment, itself, whether a power line noise treatment device or an essential or auxiliary piece of audio electronics component introduces EMI or RFI noise into one’s system. I’ll describe a simple, inexpensive tool and method to evaluate any component’s inherent line noise. And whether one should use that as a guide to accept or reject a given audio component in one’s system. I will present my findings for two well known components familiar to most folks here in the forum. One will be a power conditioner that regenerates a corrected AC power signal. The second component will be a Class D amplifier and external power supply. Buckle up and let’s have some fun! 


And then there’s the path from power to signal path, and sources power supply vs environmental RFI, vs AC power supply. And individual parts EMI generation. Rather complex issues and measurement problems to be identified prioritised and solved.


Will you reveal power conditioner brand Y?

Brand X can remain anonymous,  thus touting a brand yoy like and not giving any specific brand a thumbs down.


Watch M. Fremmer's You Tube journey to clean power. There are people and firms that specialize. If you have problems at the outlet, then all you can hope for is to alleviate or mitigate the actual issue, like plugging in the "right" "fix" between the outlet and your equipment. Maybe you will find a component that will satisfy, and then you won't have to address the real issues in your power distribution. Good luck. Bring in a Master Electrician and an Engineer for consultant and remedial steps, someone who specializes in "clean" power, hospitals, computers and Hi-Fi share this need. If you can swing it, a complete separate service from grid to meter to panel to ground (you are at the mercy of the grid...). Or a one to one isolation Xfrmer into an isolated distribution panel. A Motor/Generator might also be an answer, but not perfect, a DC system to AC, like solar and batteries might be the most elegant solution. Be sure of your equipment's electrical grounds. Balance the neutral leg (make sure each circuit has its own neutral (never "borrow" a neutral which leads to stray voltage, a difference of potential, on the neutral wire and always utilize a dedicated ground wire back to the single common ground in the panel). Have the Earth ground system tested (no clamping to a water pipe- that's a chance for difference of potential too; and there's a lot more non conductive plastic water pipe out there, a single earth ground in your distribution system is very important). It's likely most home distribution shows a voltage on the neutral, get that fixed. Eliminate any aluminum conductors in the system if you can (some older homes use Al wire, which has specific termination requirements, and for $$$ considerations from grid to meter is often Aluminum...). Isolate motors (vacuum cleaners appliances, hair dryers, etc.) to outside your protected distribution system. If a motor is necessary, vacuum/air pump, cooling fan, motion control...etc, DC ONLY, dedicated, and brushless. If your problem is RF, like a ham radio nearby or commercial transmitter, or big AC motors close to you, (water tower or other lift pumps, treatment plants for example), a Faraday Cage might be helpful with RF interference, Make sure each piece of your system is properly grounded. Some equipment will ground through the shield on an RCA, or the center wire in a balanced plug (two grounds to a unit is not ideal, go with the "best" grounding technique, or preferably the manufacturer's requirements). Learn the difference between capacitance noise and 60 cycle hum. Ideally one load per properly sized circuit breaker.  Quality solid wire is better than stranded, and don't over size the conductors, make sure they are sized correctly for their load (physics has had a recent revolution in electron motion theory, a big change from what I was taught). Surge and lightning protection at the input side of the panel (if you have eliminated motor noise and in rush, other wise circuit by circuit). Consider the effects of fluorescent, neon, and LED lighting, if possible do not share with your "clean" outlets (incandescent is a resistive load and should not usually cause problems). Use top quality components (brand name is a good place to start, then hospital grade and up..., outlets, junction boxes, wire, conduit, etc. These are things we have used to isolate delicate and sensitive computers, test equipment and sensors in a commercial manufacturing building situated in a heavily industrialized area, and also steps I have taken at home. The supply of clean, uniform power can turn into a money disposal unit. I suggest a professional work with you to IDENTIFY the issue(s) and then address them in a systematic way with quantifiable results.  But that's only my suggestion.

I treated my entire home using Rochelle Salt with  stunning  results  and little cost.

Those of you interested can do a Google search.