Opinions on A/C Noise Meter EMI Testers

A local dealer has a plug in device that gives a numeric readout of undefined scale or meaning, but is helpful in determining the rough scale of noise problems and how much each change has improved the conditions.  It has a speaker that also outputs a demodulated version of the noise (turning ultrasonic noise into something one can hear such that RFI can actually be heard as a radio broadcast).  Even after putting in a power conditioner, a customer had noise issues detectable with the meter which was helpful in finding the primary source of the noise--stuff was unplugged around the house until the noise source was found (a string of LED lights in a bedroom on a completely different circuit from the stereo).

I have found mine useful, it is a low cost RFI and EMI detector I bought on Amazon. I used it when building a custom streamer to test the shielding. I also use it to test components and power cables. They all emit something, but it is useful in finding items that are emitting more than their fair share. 

I think they measure something, but I've never seen of one fixing a problem a user could hear.

I've heard of users who could hear LED power supply problems, didn't need a meter though, it was pretty audible.

Even after putting in a power conditioner, a customer had noise issues detectable with the meter which was helpful in finding the primary source of the noise--stuff was unplugged around the house until the noise source was found (a string of LED lights in a bedroom on a completely different circuit from the stereo).

@larryi - It is exactly this sort of issue why I don’t put a lot of faith in dedicated circuits or heavy duty wiring for noise reduction. I use Furmans which have filtration down to around 3kHz. Not perfect but a lot better than pure EMI/RFI filters. I wouldn’t mind having a dedicated circuit for the sake of power stability but my regulator does a very good job.

Can anyone advise a EMI tester brand/price they bought and like?

Sounds like a worthwhile device.

Another thought-With all the information on how to bring good power

to your system it is bothersome to learn of Larry's LED on separate line issue.

What's a person to do???

Thanks to you all for the experience sharing!

I purchase a used AM transistor radio from the 1970's.

Turn it on, tune it in between stations and hold it close to whatever you are worried about as a potential source of problems.

The bigger the problem, the more static you hear.

Cost me $10, plus gas. I might have broke even of the purchase.

@tony1954 Genius. 

Yeah but those old radios are hard to find now!

@jeffseight See if you can find a "Monster Power, Dr. Power", on eBay. Well built and works well, plugs into the AC outlet, and/or hold the unit near potential noise sources to check.

The Monster device looks interesting, but I'm a bit wary about trusting a testing device that doesn't come with a shielded power cord (or simply runs on DC via battery).

I would suggest that if the noise is not audible, then it isn’t likely to have an affect on sound quality and especially enjoyment of the presentation. If this is the case, why would ‘knowing’ of any noise matter?…