Any one measured the EMI/RFI attenuation performance of audiophile power conditioners?


I was looking for a very good/robust power conditioner which will clean up reliably very noisy/dirty power supply that I have in my aprtment. While looking for one I went through catlogs of AudioQuest, Shunyata Research, Synergestic Research etc. but no one published charts showing attenuation performance over frequency range like you get for EMI filters from Schurter or Schaffner etc. which are in the industry for EMI/EMC compliance.

Since audio is very subjective, but contrary to audio reproduction Power and EMI/RFI reduction is completely objective and can be clearly demonstrated via attenuation charts.

Hence I am asking if anyone has measured the actual performance of these audiophile power conditioners. I am not denying someone saying they hear improvement after using XYZ product, but since I am talking about power conditioning or EMI reduction it's as objective as it can be.

I am not at all surprised to see all the manufacturers not publishing the performance data, else it would be used in other industries and research fields where it's far more critical and have far more stringent requirements on the performance of conditioner/EMI filters. But I am shocked to see even products ranging above 5-10K are following the same practice of not publishing the results.

Please note I am not a measurement fanatic, but I know where I can chase the measurements and where I can rely on my hearing to gauge the difference.




EMI testing requires a Faraday cage.  The video with the FFT analyzer testing the effectiveness of a PC on an amp is fun to watch but keep in mind that this is a comparative test.  Like when we listen to a stereo component, we compare it to something else we have heard- be it live music or another component.  That is a subjective evaluation.  What this guy in the video is doing is also a subjective evaluation but with an analyzer.  Just because he has a computer outputting numbers does not make his comparison less subjective than someone doing a listening test.  Many people with highly developed listening skills can match or outperform measurement equipment.  Especially because we don’t always know what to measure or how to measure it.  The guy in the video could do the same tests again on a different day and get different results depending on the state of his power grid and local interference in his area.

An objective test must start with a baseline that is calibrated and repeatable.  That is why EMI testing requires a Faraday cage.  That is the EMI equivalent of an anechoic chamber.  That way even his test equipment is isolated from outside influence.  

I’m not knocking comparative testing.  We often have no choice and comparative listening is how we make purchasing decisions.  Item A sounds better to us than Item B and so we are satisfied with our purchasing decision until we hear something better.

I heard a difference in different PC’s and I hear a difference with and without one.  That is how I made my purchasing decision.  If I can’t trust my ears who can I trust?

@vonhelmholtz I had written to Shunyata as per your suggestion asking them for the measurements & below is the response related to measurements.

"We've published our own measurements on our up-market Everest and Denali power distributors that show a -68dB down at 1mHz noise measurement, which is top in the field.

We do not publish noise specs on each product we make, but the more affordable Gemini and PS10 power distributors drop noise in the -26 to -28dB down at 1mHz range. 
Please keep in mind that published noise figures are not the most important performance- feature of power distributors when used for audio systems."
Now I am at loss of words on how to react to this statement. If a device whose primary function is to reduce EMI/RFI and there is no measurement (objective) regarding how effectively it does that & manufacturer feels its not important to meaure that parameter or publish it for prospective buyer then I can't understand what is important.

Besides as a fun fact check out the datasheet for the Schaffner's two stage single phase EMI Fliter from the series FN2090. For 20A rated filter it's noise attenuation at 1Mhz is close to 80dB for CM & close to 90db for DM which far exceeds the performance of Everest/Denali as claimed by Shunyata & while Shunyata's products cost north of $6K whereas the Schaffner's filter costs mere $60.

Now I have developed a feeling that these companies do not publish the measurements because they actually don't measure well especially compared to their asking price. Otherwise if they publish the data then people can easily point out the issues with their asking price and actual performance. If their performance was world class they would be harping on it by publishing the hard facts/measurements which clearly is not the case with all these companies.


The problem is that too many variables exist to definitively say this PC will make this system sound better in this way or another system will sound about the same with or without the PC.  These manufacturers are making a product that reduces line noise.  If it makes the audio system sound better, that's almost a side effect.  

Published measurement data of these PCs might be one way to show that they are working but how they affect the sound of an audio system is almost incidental.  For example, plugging an amp into one could make the amp sound worse because it limits current.  Measurements can only go so far.

Supposing you bought two different cakes from two different bakeries.  You take those cakes to a chemist and have him analyze them.  He gives you a list of ingredients and relative weight of each ingredient.  That analysis might give you some idea of the flavor of those cakes but until you take a bite, you will not know how they taste.  Furthermore, the chemist cannot tell you how each cake was mixed and baked- the process.  And the mixing/baking process could have a significant impact on the flavor.  

@tonywinga completely agree with you on the part that one cannot say what and howuch improvement one can hear from adding a power conditioner in your system as there are a lot of variables included. Since the only job of this piece is to decrease the EMI/RFI from the power line, it’s a completely objective parameter to measure and report which these audiophile companies are giving a complete miss, hence my original post.


My first thought is manufacturers of PC’s prefer to keep their performance data proprietary as much as they can.  Why give their competitors easy access to performance data or also, it becomes a specification contest with no connection to sonic performance.  

I worked in Automotive where our products had to meet EMI/RFI emissions per the SAE and DIN specs.  I do not recall specifications or standards for devices that attenuate EMI/RFI.  Maybe I am wrong but that leaves noise conditioner designers to find their best design paths to meet performance or audio goals.  But without measurement or industry performance standards the claims and measurements of Power Conditioners with respect to we consumers could become very confusing.   It is already confusing for us because results vary between applications, local EMI noise conditions and how our unique audio systems respond to PCs.