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!