Impact of AC Distortion & Noise on Audio Equipment

[dorirod]

I have measured a number of those including the Audioquest Niagara 1200 a couple of days ago: https://www.audiosciencereview.com/...view-power-conditioner-surge-protector.25443/

As you see, they essentially have no ability to filter the AC harmonics that matter (up to 90 kHz). To get cleaner power you have to use these regenerators which unfortunately are hugely inefficient and act like heater for your home!

@amirm I'm guessing (and I also am curious about this) is if you tried putting the BK Precision 9801 with its especially distorted waveforms in front of the Audioquest Niagara to see if it did anything when the AC power was really dirty (not with the relatively clean wall AC). Not sure it would have an impact, but probably a more interesting test.

 

[dorirod]

Awesome analysis.

And the firehose panther as a bonus! Looking forward to "PinkPantherStatuetteScienceReview.com" where baubles are microscopically analyzed and rated by a photograph adjacent to certain pieces of audio equipment.

I wonder, does the firehose mean it's about to throw some cold water on the heated arguments, or is it spraying harmonic distortions?

 

[Chrise36]

Can do. I only have true sine UPS's though. They have come down in price so much that I don't see any reason to get the non-sine ones.

Ok nice. Interesting to see how the device react with under/overvoltage with and without ups.Non sine ones are better for motors and heavy loads i read.

 

[Raindog123]

I wonder, does the firehose mean it's about to throw some cold water on the heated arguments, or is it spraying harmonic distortions?

What if it's not a firehose, but rather a mains power cable? Of "garden hose" variety?

 

[Francis Vaughan]

What you're basically arguing here is that the tube DACs' power supplies are simultaneously (a) too noisy to be improved by power cleaning devices, but also at the same time (b) robust enough in their AC filtering that their measured performance is not worsened by the application of dirtier AC power.

Nope. I'm not arguing that at all. I'm arguing that the tube based devices have so much intrinsic distortion (due to the use of tubes we assume) that they totally mask anything their power supplies may or may not do to the sound. They are dreadful no matter what AC power they are fed with. Thus they don't tell us much more.

 

[IVX]

My regenerator 2005 year, 2000VA. Input AC THD+N 2.5%, output 1800W PF = .79 (huge Pro power amp as a load).

 

[pma]

Demand-side management impulses are the source of non-harmonic frequencies in mains distribution network.

This is the "normal" spectrum of 230Vac mains at my home

only 50Hz + multiples

Now the DSM 183Hz control spread through mains line

This was captured and analyzed.

After application of 183Hz band pass filter we get this time record

It shows injection of the DSM 183Hz impulse control. And these are the moments when we measure change in amplifier output noise.

 

[levimax]

Panamax and Furman make some nice conditioners under $1K. Or is something like an AC Infinity (or any other brand) power strip with onboard surge protection for under $100 the sweet spot?

Since these "conditioners / surge protectors" are most likely to do nothing with a chance of degrading power amp performance I would say the sweet spot is to not use them at all. Home owners insurance will cover lightening damage and I have a hard time believing any other type of dirty AC power will damage anything.

 

[Raindog123]

It shows injection of the DSM 183Hz impulse control. And these are the moments when we measure change in amplifier output noise

Can you trace those past the power supplies of audio components? Eg, in the output of your PA?

Are you saying it time-correlates with this?

 

[pma]

Can you trace those past the power supplies of audio components? Eg, in the output of your PA?

Are you saying it time-correlates with this?

Yes. The correlation is in one of my previous posts
https://www.audiosciencereview.com/...on-noise-on-audio-equipment.25501/post-868518

I had measured this repeatedly during years, with different amplifiers.

 

[Raindog123]

Yes. The correlation is in one of my previous posts

Thanks. I am curious, do you have some statistical timing analysis of these 183Hz distortion occurances? An estimate of how frequent they are [at your place]?

 

[PeteL]

Yes. The correlation is in one of my previous posts
https://www.audiosciencereview.com/...on-noise-on-audio-equipment.25501/post-868518

I had measured this repeatedly during years, with different amplifiers.

Again, can you tell us what these graph are, they have no titles, we don't know what changed at the input between those to have these results at the output.

 

[rdenney]

Cool, just reiterates. Anyway, people who really buy these won't believe in measurements and they only trust their ears apparently

I wish they would trust their ears. If they did, they would let their ears do the evaluating, without input from their eyes and beliefs. Those who won't trust controlled testing (when they seek to challenge factual measurements) are specifically not "trusting their ears". When they reject controlled testing, they are saying their ears aren't good enough (or, they are saying my ears aren't good enough, in which case I also don't need their product).

Rick "noisy power can sometimes enter equipment through the air by spraying RF, for devices sensitive to RF" Denney

 

[Jim Shaw]

A long time ago, I wrote this in reply to one of Paul McGowan's infomercials on PSAudio's power regenerator: "If an audio device's power supply was properly designed, it can make good DC and filter out line noise that could impact its audio function. If you think you need a power conditioner, you probably just need a better audio electronic device."

The power supply in any/every audio device is a major cost subsystem. Compromise that item to save money and you risk the delivered audio quality. (And don't just weigh the size of the transformer or its shape to assess 'quality.')

Anecdotal: I have an inexpensive sound bar on a bedroom TV that occasionally emits a burst of racket in response to my HVAC unit starting up. It rather demonstrates the rule, above. Its power supply is the problem, not the power line. No other audio device in the house makes an audible noise in response to the HVAC disturbance.

 

[aasearles]

Great analysis of the impact of AC quality - and THANKS for the long awaited review of the Loxjie P20!

 

[rdenney]

I respect and agree with your desire for rigor and further testing - but while your comment here is clearly made in good faith, the effect of your comment is identical to FUD (spreading fear, uncertainty, and doubt). You have mentioned the poor-performing tube DACs but have completely ignored the fact that @amirm tested them after and in addition to the Topping DAC, which has excellent performance - low noise and low distortion.

So you can't have it both ways: if the tube DACs are too noisy and distorted for power "purifiers" to clean up, then the Topping should have been positively impacted by this test. If the Topping, by contrast, is too clean and robust to be affected by dirty AC power, then the tube DACs should have been.

What you're basically arguing here is that the tube DACs' power supplies are simultaneously (a) too noisy to be improved by power cleaning devices, but also at the same time (b) robust enough in their AC filtering that their measured performance is not worsened by the application of dirtier AC power.

With respect, that's completely illogical. Also, remember that SINAD for the tube DACs was around 81dB for one and around 66dB for the other, while the "torture test" dirty AC had SINAD of about 18dB with massive distortion. The claim that these DACs' power supplies and associated circuitry are too noisy to be iomproved by additional AC filtering, but somehow will not show a single iota of measurable degradation when subjected to an AC feed with 48 to 63dB higher noise and distortion, is not a persuasive claim (to say the least).

There's a logical fallacy here--that what makes quality is the distortion of the audio amplifier. We don't know if those poor devices had good or bad power supplies, but we are pretty sure they had good power supplies, with respect to their ability to address dirty power, because dirty power didn't affect them.

So, the question isn't "do these devices help?", the question is "are there devices that depend on good power supplies to work well and don't have them?" That question was not explored by Amir's choices.

I agree with Amir as far as busting the myth that all devices benefit from cleaner power (as if they have no ability to do their own cleaning), and that is indeed the myth that is behind the sale of many such devices. But I also agree with John that the test does not support the categorical conclusion that external power conditioners are always a waste of money, because they certainly do solve specific problems in specific cases for reasons that can most definitely be described and measured.

Rick "who has actually looked at the waveform of a Music Hall Cruise Control on a scope, and found it to be quite smooth--a visibly better waveform than Amir's wall power--but who uses it only to provide adjustable turntable speed control" Denney

 

[Grooved]

...
I agree with Amir as far as busting the myth that all devices benefit from clean power (as if they have no ability to do their own cleaning), and that is indeed the myth that is behind the sale of many such devices. But I also agree with John that the test does not support the categorical conclusion that external power conditioners are always a waste of money, because they certainly do solve specific problems in specific cases for reasons that can most definitely be described and measured...

I agree that Amir could add some other devices to the test, but what amazes me is that in this kind of product, if you want to be sure that it does an effect, you surely have to test and measure, so if done, how is that possible that the manufacturer prefers to provide some comic ads with bad acting than the measures themselves ? To avoid having to clarify that it would have an effect in some very rare cases only, and sell more than they should ?

 

[rdenney]

I agree that Amir could add some other devices to the test, but what amazes me is that in this kind of product, if you want to be sure that it does an effect, you surely have to test and measure, so if done, how is that possible that the manufacturer prefers to provide some comic ads with bad acting than the measures themselves ? To avoid having to clarify that it would have an effect in some very rare cases only, and sell more than they should ?

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

 

[JJB70]

For most people most of the time power conditioning and filtering is unnecessary but there are scenarios where it helps or is necessary. However you don't need to spend lots of money on crazy products. It's something I have only ever seen in certain industrial applications, some of which used rotary convertors.

 

[pma]

Thanks. I am curious, do you have some statistical timing analysis of these 183Hz distortion occurances? An estimate of how frequent they are [at your place]?

There are more frequencies than one, used for the DSM control (ripple control). I will paste some info in Czech, still hope it would be understandable

(most used frequencies)

Record of daily level in [V] in one town in CZ.

Please note that the signal shape are bursts of impulses. It cannot be simulated by continuous steady state signal as done in post #1. Even if you listen to signal recorded from mains line, it changes with time.

More on ripple control
http://www.cired.net/publications/cired2013/pdfs/CIRED2013_0256_final.pdf