Because of the presence of mains current in mains-powered audio equipment as well as ubiquitous AC electromagnetic fields from nearby appliances and wiring, 50/60 Hz electrical noise can get into audio systems, and is heard as mains hum from their speakers.
In addition to mains frequency humming, the mains power can also contain higher frequency noise that is often referred as EMI (Electromagnetic Interference) noise. Problems range from straightforward ‘hums’ (which normally include various levels of the mains harmonics, such as 50Hz, 100Hz, 150Hz, and so on in the UK, or 60Hz and higher multiples in the US), to a wide range of scratches, ticking, buzzing and other digital gremlins.
Don’t let buzz, hum, or hiss ruin your AV experience. Check that your wiring is is right and after that if problem persists turn to look mains power quality. It’s only worth ‘cleaning up the power signal’ if it’s dirty, and a huge number of background noise problems are caused not by mucky mains, but by audio wiring that results in ground loops. This is the source of lots of unwanted nasties that sneak into your audio signals.
There are many products advertised to help power noise issues. Advertised tools include mains filters, isolation transformers. UPS devices and even special power regeneration devices. Slightly cheaper than an online UPS, but absolutely effective against all kinds of line noise is an isolation transformer.
To get idea of mains power noise take a look at Electrical noise on your power line video
One EMI meter that is commonly used to measure mains power noise is Greenwave Broadband EMI Dirty Electricity Meter sold at Amazon. Greenwave Broadband EMI Dirty Electricity Meter measures the dirty electricity (a.k.a. electrical noise, line noise, power line EMI) present on the wiring in buildings. It is designed to easily compare EMI levels before and after installing dirty electricity filters. Simply plug the meter into electrical outlets to get measurements. This instument says that it measures a broad range of dirty electricity frequencies at approximately 3 kHz — 10 MHz frequency range. The meter includes a speaker that lets you listen to the dirty electricity on a circuit and hear noise to decrease as filters are installed.
Listen To Dirty Electricity with Greenwave EMI Meter. Hear the Difference Greenwave Filters Make!
There are also other mains EMI meter brands. Ebay sells also OLED Digital AC Noise Meter EMI Tester Wideband AC Power Ripple Analyzer and similar.
There are many companies that sell mains filters that promise to make wonders in the mains power filtering. Not all of them seem to live up to their promises, and it seems you need to be careful what you buy. And you should test the product before buying.
PS Audio is selling incredibly small and advertised to be effective noise harvesting instrument converts damaging line noise into harmless light. Their video What’s a Noise Harvester? tells about the product and promises a lot:
The question is if PS Audio’s product is incredibly small and effective noise harvesting is as effective as promised. How does it work and how effective is it? It seems that based the on several tests it is not very effective.
PS Audio Noise Harvester Review (AC Filter)
In the video above Amir dropping the Hammer on the Snake Oil. According to this video this looks like to be true snake oil…that real living snakes.. wouldn’t want to go near..but some audiophiles… really like snake oil.
Does PS Audio Noise Harvester Really Work For Cleaner Electricity video shows a quick test to show whether or not it really does what the manufacturer says it does.
Video comments: Ps audio, ” it does something “. Yes it flashes a blue light. AudioScienceReview has measured this device. Thank you for this review!
Audio Science Review on PS Audio Noise Harvester AC Cleaner Review has lots of measurement results that do not seem to be promising on this filter performance. Audio Science Review proved with measurements that this product does absolutely nothing useful. In some of the tests made the noise actually went up when you plugged in the snake oil.
Collinsaudio took some measurements and wrote a report that has also some technical details what is inside the device. If anything this devise adds switching noise, because inside there is a transistor, triac, inductor (choke) and a few caps.
“If I were to speculate on the operating principles of this device, I wouldimagine that the power line is AC coupled then applied to the primary of the toriodialtransformer. The secondary is then connected to some type ofhigh-pass filt er an d fin ally t o a mo n o-stablethat flash es the LED.While it’s somewhat hard to imagine the benefits of this type of line filter, I was unable see any objective improvement with the Noise Harvester™.”
This seems be be pretty muuch purely a psychological device. This seems to be audiophoolery specifically “designed” to rip off gullible people. Brand should be more like BS Audio.
A real effective mains noise filters has power flowing through it and has several LC filter stages. Something like this:
95 Comments
Tomi Engdahl says:
AudioQuest PowerQuest 3 Review (AC Filter/Surge Protector)
https://www.youtube.com/watch?v=XolFn8QTEHE
This is a technical review of the AudioQuest PowerQuest 3 AC Mains Surge Protector and filter intended for audio and video applications. Detailed measurements are provided as well as description of the device and alternatives.
Tomi Engdahl says:
Power Plant Musical Expectations
https://www.youtube.com/watch?v=hNHkfhBa42g
What should you expect from your high end audio system when you use a Power Plant Regenerator? This quick documentary explains what to expect, how the Power Plant differes from conventional conditioners and how it’s built inside.
Tomi Engdahl says:
Maybe some of those “Chinese Power Savers” would work as better filter as that BS audio plug?
https://www.youtube.com/results?search_query=big+clive+power+saver
Tomi Engdahl says:
https://www.eevblog.com/forum/beginners/diy-mains-emi-filter-(advice-needed)/
Tomi Engdahl says:
https://emcfastpass.com/wp-content/uploads/2017/04/Electromagnetic-Interference-EMI-in-Power-Supplies.pdf
Tomi Engdahl says:
OLED Display Mains Noise Tester EMI Measuring Instrument Broadband AC Power Supply Ripple Analyzer line EMI meter
https://www.aliexpress.com/i/4000044983211.html
Tomi Engdahl says:
Identifying & Solving Mains Supply Problems
https://www.soundonsound.com/techniques/identifying-solving-mains-supply-problems
Most of us never have trouble with the electricity in our studios — but as with everything we take for granted, fixing problems can be difficult when they do arise. We look at some of the main problems and solutions.
Tomi Engdahl says:
Tons of gear that is designed like shit selling for big money.
Tomi Engdahl says:
I had years ago some amplifiers that have been sensitive to mains noise like hearing spike when someone switches light on/off next room. Tried to help the situation with few filtering tests. Helped somewhat reduce the problem, but did not completely solve it so finally changed to other amplifier. Yes the problem came through mains power, not the line input or speaker wires.
I once have also lived in a building with quite powerful radio transmitters in it (HAM club), and remember having to have filtering arrangements on audio interconnections, speaker wires and mains wires on some equopment to keep the noise out (not hearing them transmitting).
There are legitimate uses for mains filters and there is lots of bullshit marketing related to them.
Tomi Engdahl says:
Do you need AC noise filtering for audio devices?
https://www.youtube.com/watch?v=QQ22BxjA-T4
Audiophiles often think they need external noise and surge filtering in the power feeding their audio devices. They don’t realize that similar circuits exist in their audio gear already!
Amazon Basics 80 Watt Amplifier Teardown
https://www.audiosciencereview.com/forum/index.php?threads%2Famazon-basics-80-watt-amplifier-teardown.20945%2F
Inside of an Audio/Video Receiver (AVR)
https://www.audiosciencereview.com/forum/index.php?threads%2Finside-of-an-audio-video-receiver-avr.7%2F
Tomi Engdahl says:
Monster Cable EnTech EMI Noise Analyzer Review
https://www.youtube.com/watch?v=5FU_MV3GWSQ
Here’s a review of this weird Monster Cable noise analyzer that they wanted you to use to try to sell their power conditioning products but it’s actually pretty handy to identify noise sources in your power from anywhere or to identify faulty power conditioners . .
Tomi Engdahl says:
Entech Versus Alpha Labs Noise Detectors
https://www.youtube.com/watch?v=ot6x0I3QKX0
Which is most useful and most accurate to detect noise on the powerline?
Tomi Engdahl says:
DENALI Series – Noise Reduction Demonstration
https://www.youtube.com/watch?v=Z6f1kwyZbM8
Tomi Engdahl says:
Listen To Dirty Electricity with Greenwave EMI Meter. Hear the Difference Greenwave Filters Make!
https://www.youtube.com/watch?v=oUqSDfsbs7E
This Greenwave meter is easy to use. Simply plug it into outlets to see and hear the level of dirty electricity (a.k.a. electrical noise, line noise, power line EMI) on nearby wiring. The meter provides digital readings in millivolts (mV) and also lets you listen to the dirty electricity on your wiring. Hear this electrical pollution (“noise”) decrease as Greenwave filters are installed.
Tomi Engdahl says:
Testing Dirty Electricity – Line EMI Meter & Graham Stetzer Meter | EMF Minimalist
https://www.youtube.com/watch?v=BHeyJMyGrlM
Here I compare the effects of filtering dirty electricity and measuring the levels using two different DE meters.
Video comments:
One is measuring MilliVolts (Alpa Lab) but the Graham Stetzer Meter is measuring transients and harmonics, not mV .
Both meters are measuring the same thing: dirty electricity. You can measure the same thing using different units. GS happens to use a propriety unit. The Line EMI meter has a legend in the manual…
1000 = Extreme Concern
Tomi Engdahl says:
Dirty Electricity: detect, measure and eliminate it.
https://www.youtube.com/watch?v=LotupK7lQBs
Eric uses Stetzer Meters to measure dirty electricity (DE) and when appropriate uses Stetzer filters to reduce the DE level.
Tomi Engdahl says:
Greenwave Spectrum EMI Meter – A Revolutionary New Dirty Electricity Meter – COMING SOON!
https://www.youtube.com/watch?v=XlUtjIT8MMo
Greenwave is developing a second meter for measuring the dirty electricity (a.k.a electrical noise, line noise, power line EMI, voltage transients) present on wiring in homes and other buildings. This advanced EMI meter shows dirty electricity levels and characteristics from several different perspectives, helping users visualize this energy like never before. The meter can show the intensity of dirty electricity and how it varies at different points along the electromagnetic frequency spectrum. It can also provide dirty electricity readings in millivolts (mV) and show the erratic waveforms of this type of electrical pollution. Convenient touch screen technology lets users move easily from one type of dirty electricity reading to the next.
The Greenwave Spectrum EMI meter is a great tool for measuring and analyzing the dirty electricity in buildings and for seeing the difference Greenwave dirty electricity filters make in reducing this unhealthy pollution. The meter is currently in the final stages of development.
Tomi Engdahl says:
Perils and Problems with Dirty Electricity Filters: What to be Aware of!
https://www.youtube.com/watch?v=-M4j-YdyrVo
Some people actually feel worse when they use Stetzer and GreenWave filters, here is why. By Michael Neuert, an EMF test engineer with 23 years experience.
Tomi Engdahl says:
“Dirty electricity”: what, where, and should we care?
https://www.nature.com/articles/jes20108
Environmental exposure to high-frequency voltage transients (HFVT), also termed dirty electricity, has been advocated among electro(hyper)sensitive interest groups as an important biological active component of standard electromagnetic pollution. A literature search was conducted in PubMed, in which only seven articles were identified. Exposure to HFVT was associated with increased cancer risks, while preferential removal of 4–100 kHz HFVT from 50–60 Hz ELF circuits was linked to a variety of improvements in health (plasma glucose levels in diabetic patients, symptoms of multiple sclerosis, asthma and other respiratory illnesses, and insomnia), well-being (tiredness, frustration, general health, irritation, sense of satisfaction, mood), and student behavior. However, all these published studies were subject to significant methodological flaws in the design of the studies, the assessment of exposure, and the statistical analysis, which prevented valid assessment of a causal link between this exposure metric and adverse effects. Environmental exposure to HFVT is an interesting EMF exposure metric, which might explain the spurious results from epidemiological studies using ‘standard’ ELF and RF exposure metrics. However, at present, methodological problems in published studies prohibit the valid assessment of its biological activity.
Dr. Mercola and Dr. Milham on Dirty Electricity (Full Interview)
https://www.youtube.com/watch?v=utalU9uIlTQ
Tomi Engdahl says:
Stetzerizer vs Greenwave (or other knock offs)
https://www.youtube.com/watch?v=CcSS0MJ6oMo
Some companies (e.g. Greenwave) marketing knock offs of the Stetzerizer Filter are making performance claims that cannot be substantiated.
This is NOT a comparison of functionality between Stetzerizer filters and knock off filters. Stetzerizer filters do exactly what we say they do – reduce/eliminate high frequency energy, between 2 kHz and 150 kHz, on the electrical wiring in buildings. Knock off filter vendors make outrageous and misleading claims, and this video is intended to educate people on the facts.
Tomi Engdahl says:
Stetzer Electric Dangerous Products
https://www.youtube.com/watch?v=8TlJuQte3jQ
CONSUMER ALERT
About Stetzer Electric Inc.’s dangerous EMF filter products. The company produces Stetzerizer Filters which allegedly help you to eliminate electrical pollution. Their filtered powerstrips – surge suppressors – are supposed to protect your equipment and home from electrical surges. Instead, these surge suppressors, also known as “protectors” have a tendency to catch fire and fill your home with smoke and toxic fumes. They are also supposed to help you save money on your electric bills. There is no evidence that such a claim is true. A Canadian health report even calls Stetzer products dangerous, saying they add to the electrical load in a home.
Video comments:
When I saw this video I started my own research.
A Canadian health report from as far back as 2006 reviewed the Stetzer products and found them useless when it comes to stopping dirty electricity and said they can even be dangerous. Here is the exact quote: “Since Stetzer filter currents add vectorily to the other load currents in the home, their distortion products (harmonics) are carried on the electricity supply and add to the level of “dirty electricity” in the house.”
Tomi Engdahl says:
Filtering the Highest Dirty Electricity Producing Product in my Home
https://www.youtube.com/watch?v=1Hx1aCMl0l0
Tomi Engdahl says:
One simple DIY filter idea, not very effective but might help on some cases or not…
Making a Capacitive Filter Plug for Dirty Electricity
https://www.youtube.com/watch?v=Hc8gC0DhqbQ
Parts: 10,000pF disc capacitor, 1Mohm (1,000,000 ohm) resistor, metal 120 volt AC plug. All parts must be rated for a continuous AC voltage of at least 120V RMS in the USA. Capacitor and resistor connect in parallel. One side of the circuit connects to the neutral connection, the other connects to the live. If the circuit buzzes in operation it means that you have dirty electricity that you should have an electrician investigate. You should only build this circuit if you are competent to do so, as electricity can shock, burn, and kill you.
Tomi Engdahl says:
Smart Meter creates pulsed dirty electricity (2-50 kHz) on the electric field in a home
https://www.youtube.com/watch?v=yHrLBb3igr4
Using a Fluke 215C Scopemeter we look at biologically active frequencies (2-50 kHz) created by a Smart meter.
Tomi Engdahl says:
Do you need AC noise filtering for audio devices?
https://www.youtube.com/watch?v=QQ22BxjA-T4
Audiophiles often think they need external noise and surge filtering in the power feeding their audio devices. They don’t realize that similar circuits exist in their audio gear already!
Video comments:
Unless one is an experienced electronics engineer, it’s difficult for most audiophiles to put these things into perspective. Some of these AC noise filtering, isolation transformers or regeneration products can cost an arm an a leg. You can spend way more money on some of these on a SOTA amplifier like a Benchmark AHB2. This video is a much needed warning.
Power quality varies widely and expecting any device to protect itself from this is pretty much a crap shoot. The consumer is fed all manner of marketing hype and lies about this. A real review about what is coming in to your house would at least give the audience some perspective. You will give it an honest perception as few others will!
Most domestic AC lines are not horrible. They are not wonderful but they are not disasters either, so in general some kind of line filtering isn’t going to have a positive audible impact. But- there are probably some scenarios where a line filter would be useful. Running off a small portable generator maybe, or sharing a power line with a welding shop. But for most domestic audio gear I’ve ever bought, if the manufacturer didn’t put enough into the design of the power supply to keep line noise out of the audio, I would return the thing and ask for my money back.
Tomi Engdahl says:
EMF filter test: Stetzerizer Vs. Satec
https://www.youtube.com/watch?v=HG3EyKNB9iQ
Stetzerizer and Satic EMF filters tested. Stetzerizer actually increases the amount or electromagnetic radiation.
Stetzerizer vs Satic filter
https://www.youtube.com/watch?v=WfOUzz0t2fs
Tomi Engdahl says:
Oscilloscope measures router that uses the homes wiring to transmit data.
https://www.youtube.com/watch?v=_R728Kxbrkc
Tomi Engdahl says:
DIY Dirty electricity filter
https://www.youtube.com/watch?v=SGSpuC0CQU8
Tomi Engdahl says:
https://diyaudioheaven.wordpress.com/tutorials/power-supplies/mains-filters/
Tomi Engdahl says:
https://www.testandmeasurementtips.com/measure-powerline-quality-oscilloscope/
Tomi Engdahl says:
https://interferencetechnology.com/mains-input-filters-what-is-inside-the-box-and-why/
Tomi Engdahl says:
Details of the ETI Mains Conditioner produced here with the kind permission of ‘Everyday Practical Electronics’ magazine who took over ETI.
http://www.decdun.me.uk/mainsconditioner.html
The filter section begins with six VDRs, which are Intended to remove the damaging effects of high energy tran-sients on the mains. To some extent they will reduce Impulsive Interference effects loo but will not eliminate them.
The filter section will remove RF Interference from the power lines.
The pick off coll from the first toroid detects any imbalance caused by interference currents flowing to ground via via (he Y-capacitors. The signal is amplified by IC1a and passed to the detector circuit consisting of Q1 and 2 and associated components.
This detector responds to the peak value and to the duration of the signal, so a short, high voltage pulse wfll give the same reading as a sustained, low amplitude burst.
Tomi Engdahl says:
https://www.powerelectronictips.com/early-warning-emc-problems/
Tomi Engdahl says:
https://www.com-power.com/blog/emi-and-emc-differences
Tomi Engdahl says:
Monster Cable EnTech EMI Noise Analyzer Review
https://www.youtube.com/watch?v=5FU_MV3GWSQ
EMI Sniffer Mains Noise Analyzer Unboxing
https://www.youtube.com/watch?v=Ey2lthaCql8
Tomi Engdahl says:
Entech Versus Alpha Labs Noise Detectors
https://www.youtube.com/watch?v=ot6x0I3QKX0
Tomi Engdahl says:
https://6moons.com/audioreviews/bluehorizon/2.html
Tomi Engdahl says:
https://www.soundonsound.com/techniques/identifying-solving-mains-supply-problems
Tomi Engdahl says:
Do Power Conditioners Really Work? Snake Oil?
https://www.youtube.com/watch?v=3qFh1e7razo
This video demonstrates whether or not a power conditioner actually cleans and filters the electricity going to your devices. If you are looking to purchase a power conditioner for your music studio, then you definitely need to watch this before you buy a power conditioner. I used a broadband EMI Meter to show proof of the power conditioner’s performance. Are they worth it? Depends on why you need one.
Tomi Engdahl says:
The Magnetic Fields of a Capacitive Filter
https://www.youtube.com/watch?v=0X1X4PSUfj4
Capacitive filters have become popular for offsetting the effects of biologically harmful dirty electricity. However, on some circuits, they may generate high magnetic fields in the room which may lead to unusual mental behaviors and illness. We demonstrate the effect. We recommend the use of a Trifield 100XE magnetic field meter when installing these filters.
Fixing a Switched Socket Wiring Error
https://www.youtube.com/watch?v=RmQt566B_B0&t=0s
Fixing a Two Way Switched Socket Wiring Error. These were the magnetic fields of the room with the wiring error
Tomi Engdahl says:
A No-Nonsense Line Conditioner
http://www.enjoythemusic.com/magazine/sound_practices/4/line_conditioner.htm
Tomi Engdahl says:
https://alpha-audio.net/background/the-reader-question-power-filter-or-seperate-power-group/
Tomi Engdahl says:
http://www.10audio.com/diy_power_conditioner.htm
Tomi Engdahl says:
How do Power Cables work? – Demo Shunyata Research – Hifi Studio Wilbert Utrecht
https://www.youtube.com/watch?v=if2yKdd4WYI
How does power work? And how do Power Cables Influence the performance of a system? We filmed the presentation of Shunyata Research at Hifi Studio Wilbert in Utrecht – The Netherlands
Shunyata Research Venom 14 Digital power cord demonstration
https://www.youtube.com/watch?v=g2SAj7aKXGo
A demo showing the impact of the Shunyata Research Venom 14 Digital power cord and its noise suppression capabiility.
Tomi Engdahl says:
EMI noise Fixed and Cheap!
https://www.youtube.com/watch?v=vGfGIB22-ig
This is how we fixed our excessive electrical line noise without breaking the bank. After the electrician installed this box look at the results. Now back to the home theater build.
Tomi Engdahl says:
PS Audio Noise Harvester™
http://www.collinsaudio.com/Prosound_Workshop/Noise_Harvester.pdf
If I were to speculate on the operating principles of this device, I wouldimagine that the power line is AC coupled then applied to the primary of the toriodialtransformer. The secondary is then connected to some type ofhigh-pass filt er an d fin ally t o a mo n o-stablethat flash es the LED.While it’s somewhat hard to imagine the benefits of this type of line filter, I was unable see any objective improvement with the Noise Harvester™. If anyt hing , t he noise at some areas act ually increased when it was used
Tomi Engdahl says:
Stop RF “Radio Frequency” Interference! [Ways To Solve Noise Issues]
https://www.youtube.com/watch?v=tS7SvoT8Ivw
Stop RF “Radio Frequency,” and EMI “Electromagnetic Interference.” See how noisy your household and office devices are! Here are some ways to help you locate, and make your space quieter. Click the SHOW MORE tab below for links.
Tomi Engdahl says:
iFi AC iPurifier review — PROOF that it works!
https://www.youtube.com/watch?v=X5V1JOSjbRA
If you’re skeptical about whether the iFi AC iPurifier — or any power conditioner — actually works, here’s some proof that it does. In this video, you’ll see me introduce AC noise into my system by plugging in a “powerline internet” device, and then totally eliminate that noise by plugging in an iFi AC iPurifier.
By the way, I bought this with my own money, and was fully ready to call BS on this if it didn’t work!
Tomi Engdahl says:
Measure iFi AC iPurifier Part1
https://www.youtube.com/watch?v=KEO5VBo6R4w
Measure iFi AC iPurifier Part2
https://www.youtube.com/watch?v=H6OMx0Z6zKQ
Tomi Engdahl says:
AC Power Considerations for Your Home Theater System
https://www.youtube.com/watch?v=HmAPfl2txns
AC Wall Power Considerations for Your Home Theater System
https://www.audioholics.com/audio-amplifier/ac-power-home-theater-system
We often get asked how much AC wall power is needed to run a typical home theater system. There are lots of factors that determine this such as the number of AV components you have plugged into the same outlet and their associated power consumption, and whether or not that outlet is shared with other appliances or lighting on the same circuit. This article and related YouTube video discussion provides guidance on helping you decide whether you need dedicate outlets for your home theater to deliver 1.21 Gigawatts!
Most domestic homes have standard 120V/15A outlets but if you’re building a new home, you can request dedicated 120V/20A lines for increased power capability.
Standard 120V/15A outlet provides up to 120V * 15A = 1800 watts
Standard 120V/20A outlet provides up to 120V * 20A = 2400 watts
The typical 20A line uses thicker 12AWG cabling while a typical 15A line uses 14AWG. Keep that in mind when pre-wiring a new home or retrofitting an existing home. A dedicated 20A line is NOT just about a large fuse at the panel. You also need a proper gauge wiring from the panel to your wall outlet.
If you are trying to determine if you need a 15A or 20A circuit, as a rule of thumb sum the maximum rated power of all your audio/subwoofer amplifiers and other devices connected to that outlet and divide by a factor of four (4).
IE. Typical Scenario
HDTV: 200 watts
AV Receiver: 800 watts
Subwoofer: 1000 watts
Source devices: 100 watts
Total: 2,100 watts / 4 = 525 watts, which is < 1,800 watts. In this scenario, the standard 120V/15A outlets are fine.