When to use/how to choose a power conditioner

[RayDunzl]

anybody ever measured noise on their AC mains to see if they need one?

Mains are always noisy.

Your own gear puts in spikes as the rectifiers turn on and off, and the power draw flattens the peaks creating harmonics, along with everyone else's draw on your utility's local transformer.

Measure your outputs to see if it actually creates a problem.

 

[MRC01]

anybody ever measured noise on their AC mains to see if they need one?

There's always going to be some AC line noise. A good piece of audio gear having a well filtered power supply will squash a certain amount of noise. So just because there's some AC line noise doesn't mean you have a problem. How much noise is too much? It seems like you'd have to measure not only your AC mains to quantify how much noise is there (which will vary day to day and time of day), but also measure the output of your equipment to see whether any of that noise is getting through.

 

[NTK]

anybody ever measured noise on their AC mains to see if they need one?

Here is an article I remember reading a few years back. The motor drivers for the newer appliances that use energy efficient BLDC motors (air-conditioner compressors, fans, washing machines, etc.) can back-feed a lot of noise into the AC mains.
https://www.edn.com/why-is-everything-junk-heat-pump-edition/

 

[Wes]

There's always going to be some AC line noise. A good piece of audio gear having a well filtered power supply will squash a certain amount of noise. So just because there's some AC line noise doesn't mean you have a problem. How much noise is too much? It seems like you'd have to measure not only your AC mains to quantify how much noise is there (which will vary day to day and time of day), but also measure the output of your equipment to see whether any of that noise is getting through.

Seems like you should be able to characterize a noise level that will not significantly affect HiFi gear, then see if it is above that level or not.

Or is HiFi gear that variable?

 

[MRC01]

Audio gear of different types from different manufacturers is highly variable in the quality and filtration of the power supplies. Some are over-built like military equipment, some are so cheesy you wonder how it works at all, others after seeing how they're built you might never plug in again due to risk of fire or explosion

What makes this even more complex is that even if the audio gear isn't performing to spec, it doesn't necessarily mean the AC line noise is the cause. It seems to me one would have to measure both AC line noise and equipment output (record the signal and compute an FFT) together at the same time, on different days at different times. A power conditioner makes sense as a solution only if the gear is out of spec and it happens at the same times the power shows high levels of noise. Otherwise, a power conditioner is just an expensive solution looking for a problem.

 

[trl]

anybody ever measured noise on their AC mains to see if they need one?

Mains AC - 230V measured with an 230-115V converter (a coil/inductor placed in series)

Same as above, but with a low-quality (probably defective) SMPS in the same outlet (notice the THD increase due to the DC added on top)

Noise measured between Null and Earth when vacuum runs (it is pretty close to zero without vacuum cleaner)

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Most of the time I prefer to use an isolation transformer (a cheap one) to my audio stuff (not to my speakers amp) because there's some filtering that is done by the transformer, also the removal of the DC coming from the bad switching supplies (if exists nearby). Also, if a poor SMPS gets inserted into the outlet from the outputs of the transformer, then there's going to be a strange noise coming from transformer's coils, so it's easy to troubleshoot which SMPS is not OK and which one is not.

However, YMMV.

 

[RayDunzl]

Noise measured between Null and Earth when vacuum runs (it is pretty close to zero without vacuum cleaner)

I used to worry about the ugly waves on Neutral to Earth.

Now I have a nice 60VAC sine on my neutral, in opposite polarity to the 60VAC sine on the Hot line.

If that doesn't cause a problem, well...

 

[trl]

I used to worry about the ugly waves on Neutral to Earth.

You might want to measure the DC voltage too, because if it's because 50V, then a Type-A or Type-F RCBO/RCCD might be needed, instead of the cheap usual one Type-AC that can't protect over the DC pulsating currents that could get injected by a bad SMPS. Although, not sure the 115V can actually do any injury to a grown up adult.