Impact of AC Distortion & Noise on Audio Equipment

[b4nt]

all of which are used throughout the day. Now I’m pretty sure that is well outside normal domestic loading and there’s no doubt that these items all cause the power to fluctuate wildly (I have an extension cable which has a light that I can watch flickering like a candle even with nothing connected to it!).

You may perhaps need to ask an electrician to check your devices and installation before your building catches fire.

 

[Grooved]

Granted. But I review research papers all the time, and it's important to me that conclusions (expressed or implied) are supported by the data at hand. That includes drawing contextual boundaries around what was tested and why, as Amir later did, up to a point.

What I did see was the assumption that "distortion factories" should be more (or less) apt to show the effects of dirty power than clean devices, and that statement is an opinion not supported by the facts in evidence. A distortion factory can have a perfectly good power supply capable of filtering crap effectively, and still be a distortion factory. That's why some of ASR's leading lights suggested including some different kinds of devices with different kinds of power requirements.

Rick "who sees power-line hum in his main system, coming from somewhere" Denney

I understand, it's about not just answer to a manufacturer claim by only doing the opposite, so showing one example of where it should have an effect would make it a fully honest POV, and let clearly people know when (rarely) they need one, and when (most of the time) don't need one.

 

[b4nt]

I understand, it's about not just answer to a manufacturer claim by only doing the opposite, so showing one example of where it should have an effect would make it a fully honest POV, and let clearly people know when (rarely) they need one, and when (most of the time) don't need one.

I wrote similar some pages ago, suggesting Amir should perform more tests, in common and diff mode, and so, for real live noises, and not only for mains/sine "distortion". Showing also a case where a device would fail. Some of the rare situations mainly being cablings issues (or maybe any hardware box to fix).

Changing for balanced not being an option, many use unbalanced and won't change their hardware.

 

[pma]

The nature of possible audible mains interference into audio chain is transient, impulse (switching of breakers, ripple control, motors switching etc.). Not the steady state. So it cannot be measured with steady state distorted wave as an input. Such measurement is close to pointless. It is necessary to catch and analyse interference impulse voltages at the output of audio components.

Multiple measurements of amplifier output (persistence mode). Please see random occurrence of wideband transient spikes.
This kind of interferences can be fixed by good line filtering.

 

[b4nt]

@pma The problems will come from the setup. Assuming all boxes are new or decent, all will be individually EMC compliant, correct, but the setup won't necessarily be immune. Things going worther with any bad cablings or box.

 

[Headchef]

You may perhaps need to ask an electrician to check your devices and installation before your building catches fire.

been there, done that, all within acceptable tolerance apparently! Hence no issues with the PCB tripping out.

 

[b4nt]

been there, done that, all within acceptable tolerance apparently! Hence no issues with the PCB tripping out.

Cause at some point, it really is up to a safety and hazards issue.

 

[DSJR]

These just start to do something above the audible range and only for the mains frequencies. There is NO audio passing through these filters.
Just short current pulses.

Ferrites are intended to do something in the MHz range.

Post edited to hopefully make it a little clearer

 

[solderdude]

This signal does have transients (from 0V to 35 degrees voltage) which is visible in the spray of harmonics.

This signal is equivalent to connecting an audio device to a classic dimmer which is a really bad thing to do (and no one does either).
Of course PMA is correct that the pulses on mains (from switching motors etc) are MUCH higher in amplitude and can reach kV.
Yes... folks kV this is not a typo. Except these pulses are really short and often common mode and not differential mode.
The voltage across mains is differential for those wondering.
These high frequency short duration peaks are filtered by MOV's, GDT's and capacitors as well as inductors in those filters.

When you are plagued by 'ticks' from all kinds of devices in your home chances are there is a (combination of) stereo equipment doing this.
Filtering could help.
When only 1 device does this (for instance a fridge or washing machine) then it is best to address that device.

 

[solderdude]

Post edited to hopefully make it a little clearer

The filter is a decent mains filter which merely is encased in a handy enclosure. It is a 'normal' filter that is intended to filter HF crap on mains between 100kHz and several MHz. It does not filter any of the mains harmonics but it does lower HF spikes coming from various electrical appliances connected to mains.
It also works the other way around. When you have a device that emits a lot of HF crap (more than it should when complying to rules) it can keep the mains a bit cleaner.

It is a lot cheaper than the tested device and probably works just as well.

 

[Headchef]

Cause at some point, it really is up to a safety and hazards issue.

yep, I was concerned, hence I had both a local electrician and the national grid out to determine what was going on. All perfectly normal given the property, supply & usage. Their suggestion? Get hold of something to isolate and protect any sensitive equipment. And here we are!

 

[b4nt]

View attachment 145583

This signal does have transients (from 0V to 35 degrees voltage) which is visible in the spray of harmonics.

This signal is equivalent to connecting an audio device to a classic dimmer which is a really bad thing to do (and no one does either).
Of course PMA is correct that the pulses on mains (from switching motors etc) are MUCH higher in amplitude and can reach kV.
Yes... folks kV this is not a typo. Except these pulses are really short and often common mode and not differential mode.
The voltage across mains is differential for those wondering.
These high frequency short duration peaks are filtered by MOV's, GDT's and capacitors as well as inductors in those filters.

When you are plagued by 'ticks' from all kinds of devices in your home chances are there is a (combination of) stereo equipment doing this.
Filtering could help.
When only 1 device does this (for instance a fridge or washing machine) then it is best to address that device.

The noises added by the dimmer or the washing machine won't be as clean as that BK precision output is. They will add more transients, depending of their buid or state, up to in both common/diff mode.

And I would fix that at the audio install side, I won't start to diagnose what all in my house could add noises on mains.

 

[GXAlan]

Shunyata has a medical division which is used for cardiac electrophysiology. This is where cardiologists figure out where to ablate (burn) portions of heart tissue to correct irregular rhythms.

https://clearimagescientific.com/case-studies/

Cardiologists are making life changing decisions based upon improvements made by power cables.

It seems most of the signals they deal with are in the
0.050 - 0.250mV
Range

 

[b4nt]

@solderdude @pma @amirm I do not have a password/account to read that doc:

A digital oscilloscope was used to measure transients on the single-phase 120 V RMS mains in a residential environment. Naturally occurring transient voltages between the hot conductor and ground and between the neutral conductor and ground were recorded simultaneously. Each record contains 1024 samples taken at the rate of 10 samples/ mu s. Waveforms are shown for transient overvoltages on the mains caused by three nearby lightning strikes and one unknown source. Statistical summaries are presented for all naturally occurring transients. It is shown that the common-mode voltage is often larger than the differential-mode voltage. https://ieeexplore.ieee.org/document/18785

 

[GWolfman]

Ah, you noticed that. They are all producing similar voltages. For some reason though, my measurements show half the output for PS audio P300. I tried to troubleshoot the reason but ran out of time. From my quick testing, it may be that it is producing balanced power as I think I measured 60 volts referencing PE ground.

So neutral is carrying 60VAC 180° phase shifted (from hot/live)?

Thanks.

 

[pma]

@solderdude @pma @amirm I do not have a password/account to read that doc:

You may try to request from the author through researchgate

https://www.researchgate.net/public...nts_on_the_mains_in_a_residential_environment

 

[b4nt]

You may try to request from the author through researchgate

https://www.researchgate.net/public...nts_on_the_mains_in_a_residential_environment

Cost is $33 for non member. Not sure the author will answer, it is dated of June 1989

But such a material might be a good starter to define an alternate and probably a more close to reality test protocol.

 

[solderdude]

There already are test protocols and test equipment for this.
Every EMC lab is filled with them.
One can measure and test to various norms.
This equipment is screamingly expensive.
Have tested a few (non audio but analog & digital signal devices for railway application) devices I designed in such EMC labs.

There are no secrets here. The whole issue is you can test what equipment can handle (some tests are destructive) and if they comply.
One can also measure and test on site. Those are the difficult ones because reality differs substantially from lab conditions.

 

[b4nt]

Those are the difficult ones because reality differs substantially from lab conditions.

Tittle here being: "Impact of AC Distortion & Noise |on Audio Equipment]". Noise from mains not being only sine distortion.

I my reality/home, pretty common, I get other sorts of noises via mains lines. I have no dimmer and had noise popping in audio.

 

[Pdxwayne]

A general question:

If 1khz measurements show no difference, would it automatically mean no difference for all frequencies?