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5th MO: Mains Line EMI Meter / AC Noise Analyser (MO is closed)

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MO is closed


Electrical power comes from a variety of sources through an extensive and far-reaching power grid. When it arrives at the switch room, it will most likely be connected in parallel throughout the neighborhood. Since these power lines are interconnected, and all electrical devices on the line present mild to difficult loads, harmonic distortion or noise is created that can interfere with sensitive audio and video equipment. This phenomenon is known as "electrical noise". 


Electrical noise? Yucks! No sane-minded audiophile likes them. Electrical noise is like pesky mosquitoes that keep buzzing around us but we simply can't do much to get rid of them... Bo pian... However, every year audiophiles invest thousands of dollars on power conditioners and noise filters hoping to eliminate, or at least minimise, electrical noise from their mains. But how do we know if a conditioner/filter is really doing what it is supposed to do? Technically-proficient audiophiles will gladly suggest using an oscilloscope to detect or "see" noise. Now here is the problem, are we going to carry an oscilloscope to every shop to test and measure their power conditioners before we buy? Imagine what Bobby of Audioline (Sine) or James of Sound Affairs (Plixir) would think? Is this guy siao or what?


If you already own a power conditioner/filter that is serving you well for years, good for you! You probably know power conditioners/filters are passive devices, they don't breakdown easily, but do you know the internal components can age and lose its efficiency (imagine us getting old)? Or let's say you are about to hoot a super-duper, sibei tokong Sine SAF-30A power conditioner selling used from another owner at a fantastic price. How do you know you are not buying a lemon? Okay, okay... I know what you are about to say next... Use an oscilloscope duh! Well, unless you already own one, or you intend to steal one from your workplace, the cheapest digital oscilloscope on the market will cost you at least SGD 300. Then how?  If you ask...


Here is how... In a joint-collaboration with LHY Audio of Guangzhou, China, "we" (meaning yours truly and LHY Audio) have developed an unique device called Line EMI Meter. Its main circuitry is based on the famous Monster Entech Wideband Powerline Noise Analyzer (retails for USD 170). We improved on its design by including a built-in small loudspeaker (buzzer), just like the AudioPrism Noise Sniffer (retails for USD 180). This meter can measure and detect electrical noise travelling on the power line. It incorporates an internal circuit that converts noise to audible signal thus enable the user to "listen" to the electrical noise that is almost always present on power lines. Simply plug the Line EMI Meter into an electrical outlet and you will be able to see and hear if your mains or a specific outlet has noise problem.


The Line EMI Meter is compact, portable and requires no battery. Measuring 92mm X 69mm X 28mm (size roughly equivalent to a packet of Marlboro cigarette) and weighs 100 grams, it sure beats carrying a digital oscilloscope to the shop or to meet your seller. The Line EMI Meter measures electromagnetic interference in a single-phase AC power line. Simply plug into the wall outlet (mains socket) or conditioner/filter and bam!... You get instant noise reading in millivolts (range 1999 mV, resolution 1 mV) in the frequency range 10 KHz to 300 MHz (the frequency limits at which sensitivity is ½ of the maximum sensitivity). A speaker plays the sound of the EMI, amplitude demodulated, in order to identify the EMI source (such as an AM or shortwave radio station vs. a motor vs. an electric arc). The higher the electrical noise, the louder the sound.... Simple right? You don't need a Ph.D in electrical engineering to use this meter.


Here is a general guideline on what is considered "quiet" power line:


<50mV : sibei tokong power!!! HUAT AH!


<100mV : tokong power!


<800mV : ok lah, won't die...


<1,000mV : walao eh!!


>1,500mV : wah piang!!!


*** IMPROVED & UPGRADED *** -  Considering switch-mode power supply (SMPS) has become a common piece of equipment in our everyday lives - for example: smartphone chargers, DAC power supplies and WiFi router AC adapters, etc, I have requested the manufacturer to improve on the existing function of the original EMI meter to measure up to 300Mhz (previously 10MHz). With the upgraded measuring capability, audiophiles can detect noise pollution emits from SMPS that shares the same power line with their hifi and AV systems, thus ensuring an even more thorough AC mains noise detection.








I hereby conduct the 5th mass order for the Line EMI Meter. This meter is assembled by LHY Audio in China. Price is SGD 100 per unit (price includes SingPost SmartPac with tracking).


MO closes on Sunday, 17th May 2020 at 6pm (Last order at 5pm). All payments are to be paid in full.


I accept payment prior to ordering via PayNow, POSB/DBS/UOB/OCBC ATM transfer, Internet Banking transfer or DBS PayLah!/OCBC Pay Anyone. International buyers may use PayPal (add 3.9% + SGD0.50 to the final total). Interested buyers please SMS/WhatsApp to me at 98805223. (Please provide your name. Do not call or SMS after 10pm and before 7am)


All items listed are strictly sold through mass order ONLY. I do not keep stock.


DUE TO THE COVID-19 CIRCUIT BREAKER MEASURES, item will be sent by SingPost SmartPac with tracking ONLY! Delivery to letterbox within mainland Singapore. Sorry, NO SELF-COLLECTION for now.


Delivery of goods takes approximately 4 to 6 weeks.





  • OLED screen displays noise and mains AC measurements.
  • Built-in speaker/buzzer emits audible sound that is directly proportional to noise output, allow better judgement of the severity of noise problem.
  • Mains noise amplitudes are demodulated to identify the exactly source of emission (such as AM or shortwave radios, motors and arcs).
  • Plugs directly into wall outlet or power conditioner/filter for measurement, no battery required.
  • Portable and lightweight.







  • Input voltage:  85VAC - 250VAC  ~50/60Hz (+/- 1VAC)
  • Frequency range:  10KHz - 300MHz
  • Noise range:  1mVAC - 1999mVAC
  • Accuracy:  +/- 5% @ 1MHz; +5% to -50% @ 10KHz TO 300MHz
  • Display:  4 digits yellow and blue two-colour OLED digital dot matrix display
  • Physical dimensions:  132mm X 91mm X 41mm
  • Weight:  100g (without cable)
  • Included accessory:  Test lead Type-A (US NEMA 1-15) 2-prong AC power cord, 0.8m length


Operation manual is available for download HERE.






Use an adapter (not included) for UK receptacle



Measurement direct from the wall receptacle



Measurement after passing through a noise filter







Also known as Larry, this true-blue Singaporean is going through a midlife crisis; he is grouchy and sarcastic. Previously taught in a public school, now a full-time tutor and an "ad-hoc" multimedia producer, Larry wants to divert his attention from his teaching job and focus on something he truly loves - hifi audio. A self-proclaimed audiophile of 40-odd years, Larry first exposed to "high-fidelity" at a tender age of 6 when his dad hauled back a set of Sansui-Luxman-Coral combo from "a friend's place" (so that Larry's mom believed it was a given set). He fell in love with the sound instantly, and the rest is history.


Throughout the years, Larry owned many "nice" equipment and accessories... until the year 2009 when he discovered Chi-Fi or Chinese Hifi. An euraka moment, it was the sound he had been looking for all these years despite spending thousands and thousands of dollars on branded, highly-reviewed equipment. He sold everything (except a few good cables) and downgraded to pretty much bare minimal. Larry wants to share his Chi-Fi journey and offer its great value to fellow audiophiles.



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  • 8 months later...



"Tested my DIY balanced power conditioner with meter." - Timothy Hong


Direct from mains



From DIY balanced power conditioner





"Noise level good for Divini Power Conditioner." - Scott






"You are right! Damn happy... Got to put it to the sound system to hear the result... [Following SMS] System gives inner-details of instruments especially violin and cello. Vocal is more vibrant. Good bass too. Better than using Sine." - Mark Loo





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  • 1 year later...



Strictly no discussions, comments and preposterous remarks on this thread. I want to keep it as clean as possible. Appreciate your cooperation.

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