Impact of AC Distortion & Noise on Audio Equipment

[b4nt]

That aside, what you state is very rare.

A motor starting being a sort of short AC distortion...

But I mainly wanted to add that if nothing is audible in the audio, there is nothing to tweak on mains side, nor in other cables used.

 

[b4nt]

@amirm I have no more noises in audio on my side. Using RCA cables.

Since, I checked the currents flowing between my low noise DAC 5V PSU and my DAC, on the OV line. This is what I saw.

I assume the minimal variations are representative of the DAC current (switching supplies inside the DAC). And that the other signals I noticed came from mains, via the PSU and its EMI filter.

And since, I'm just wondering why I bought a low noise PSU

 

[Martigane]

I'm disturbed by the fact that the worst case distortion is introduced near zero crossing, right where a linear PSU diode bridge will not be conducting. Or is it just me?
Then this only exposes residual transformer ringing and other capacitive phenomenon, no?

In my view, It would have been better to destroy the upper and lower peaks of the sine wave which not only is closer to reality, but also has probably more impact on typical PSU as described above.

 

[Grumpish]

A motor starting being a sort of short AC distortion...

I have a refrigerator and an airbrush compressor that both make their presence known, on some (but not all) of my kit. I do have surge protection, fitted after being woken up early one morning by lights that were switched off flickering on and off and a noise like Old Marley dragging his chains around, caused by the truck sized step down transformer across the road dying and taking out all the power locally for most of the rest of the day. Bizarrely, I just rolled over and went back to sleep, I think I must have thought I was dreaming.

 

[b4nt]

I have a refrigerator and an airbrush compressor that both make their presence known

I would use that AC test source to generate 5Hz pulsed signals and so, a bit to far above 220V. In diff and in common mode, and see....

 

[Angsty]

This is how the sudden change of mains line load is detected at the amplifier output noise voltage. I am just monitoring the real life situation.

View attachment 145457

That’s not really a line main noise issue; that looks like a voltage sag. Sags have different solutions than noise would have.

 

[Angsty]

Very interesting. Almost two decades ago I bought a used Sound Application CF-X power line conditioner on Audiogon. It retailed for over $5K, I picked it up used for under $1K. At that time I was a fairly new "audiophile" and I was buying up all sorts of snake oil "tweaks": silver plated copper speaker wires, pure silver interconnects, Bybee AC filters, vibrapods, all sorts of different power cords, etc...

Apparently the Sound Application power conditioners are big with mastering and recording engineers (and Audiophiles ). They definitely offer better protection for your gear than a standard "surge protector", but $5k+ MSRP is pretty big leap if they don't technically improve anything.

I'd be interested to see a test of run of the mill surge protectors and power strips to see if they do any harm? Where is the sweet spot of protecting your gear without buying into the "audiophile tweaks" segment? Also, my understanding is that some of the basic surge protectors and power conditioners limit current and shouldn't be used with power amplifiers?

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?

Surge suppressors can do harm to power amplifier fidelity if they dramatically constrict in-rush current. My SurgeX does this which is why I connect my other devices to it, but my power amp gets plugged into the wall.

 

[b4nt]

@amirm I beleive many of us have got more or less noise in their audio, and suspected mains. May you perhaps simply add a test with a bad wiring example around a DAC, but not hum, showing what the output could so be? This would then show:

- no impact, for acceptable/common wiring and hardware (what you have done)
- impact, and how noticeable it would get in audio if a wiring/setup is incorrect

Any impact for that alternate test should quickly get audible up to loud. Would point so to setup, and not to mains nor a DAC.

 

[Spkrdctr]

Who cares? On any properly functioning, non-piece of crap audio product, it is not audible. Audibility is everything. If you do have a known problem with your AC current in your house, get it fixed. Way, way too many subjectivists trying to pose ideas that "might' make it possible to see something on an O-scope. Those scope readings are useless, when the noise is not audible. Regenerators are just another expensive tweak that is a waste of money.

Now if I sound a bit unhinged, it is because i just read 9 pages of this thread and it bounces between about 4 basic possible testing ideas. All 4 or 5 mean nothing with non-junk gear. Sorry, maybe I should have taken a break in the reading. I will now go to my happy place. I feel the need for Popcorn!

 

[Francis Vaughan]

If you do have a known problem with your AC current in your house, get it fixed.

How do you propose that the mains borne control signals be fixed? They are fed into your house from the street supply. What about local electrical equipment, your next door neighbour's welder, the motor switching noise from the factory in the next block. Getting it fixed is not always possible. Or rather the fix is to buy a power conditioner. Seriously, power conditioners are not some weird snake oil invented to fleece audiophools. The Audio branded ones are, but reputable manufactures make power conditioners for sensible reasons and have done so for decades. I have used them for sensitive (non audio) equipment for my job in the past. This idea of "just get it fixed" is naive.

There is a scientific disconnect occurring in this thread. On one hand you have the desire to prove the audiophools and purveys of snake oil as wrong, and this has become something of a tail wagging the dog problem. On the other hand there are clear legitimate problems in the mains that many, but not all have. If you are fortunate enough to live somewhere where the mains is of reasonably consistent quality, then enjoy your good luck. Don't assume you can apply your experience to others. Especially when there is no science to back up the assertion.

There have been a number of quite blatant logical fallacies in argument here, so much so I feel quite depressed about the entire exercise. People who are smart enough to know better are making some really poor arguments and blunders because they are blinkered in their desire to disprove yet another audiophool myth.

Syllogistic fallacies abound. It probably isn't the place to educate people on the rules of logic and argument, but I do wish people would apply a bit more care in their arguments.

 

[AndreaT]

Marvelous test inspired by the logic extension that if less AC distortion is better more AC distortion must be worse. As me moved from analog to digital, some of the mental habits we had (wow & flutter, errors in the precision of the 33.333 rpm of the LP) were more clearly linked to the less is better more is worse paradigm. Marketing spins are often still inspired by these old habits, and extended to whatever device might be sold to fools at the highest possible price. After extinction of cassette tape players and severe slimming of turntable market, these new myths are money makers: transparent cables, dirty AC, energy dissipation, room tuning devices. Few have a solid understanding of power supplies and electronic circuits to rationally steer far away from useless and costly "improvements", and Amir's tests help to separate what matters from what does not in improving our listening experience. Great review. Amir, it might be time to consider a body guard when you go grocery shopping.

 

[AndreaT]

I have a set of 300B amps. I can hear differences in sound quality at different times of the day. I've always attributed it to noise on the power line.

Same here, I also taste flavors differently in the morning and process thoughts much, much better after my cup of triple Espresso.

 

[amirm]

Since, I checked the currents flowing between my low noise DAC 5V PSU and my DAC, on the OV line. This is what I saw.

Do you mean current or voltage?

 

[b4nt]

If you do have a known problem with your AC current in your house, get it fixed.

No AC current is clean or to be fixed.

How do you propose that the mains borne control signals be fixed? They are fed into your house from the street supply. What about local electrical equipment, your next door neighbour's welder, the motor switching noise from the factory in the next block. Getting it fixed is not always possible. Or rather the fix is to buy a power conditioner.

One of my noises source was my fridge motor, at startup. I fixed my audio setup, didn't buy a mains conditionner, neither switched off my fridge.

 

[amirm]

How do you propose that the mains borne control signals be fixed?

What do you mean? Everyone in the entire country with such control signals is getting audible problems in their stereos? If so, it should be trivial to get the problem fixed at the source.

 

[MaxBuck]

In my view, a power conditioner is an unnecessary expense and nothing other than a glorified over-priced power bar with fancy lights; another myth from the audiophile world that bites the dust thanks to Amir's enlightening reviews.

OK, so I'm going to open myself up to some ridicule here. I bought an APC H-10 power conditioner and surge protector for my new system; paid about $200. I'm aware that it's highly unlikely to have any benefit to the sound quality from the speakers, and its overvoltage protection circuitry is maybe no better than I could get from something I could get off the shelf at Home Depot. But doggone it, those fancy blue lights are so pretty!

 

[Labjr]

Same here, I also taste flavors differently in the morning and process thoughts much, much better after my cup of triple Espresso.

I've been able to hear differences for 25 years and demoed it for friends. It's not my ears.

 

[b4nt]

Do you mean current or voltage?

That was the voltage at my 0V wire, going from PSU 0V to the DAC 0V.

See the pics I added. You will notice the shape of the DAC current. What additionnaly flows so comes from mains, I think, and goes to earth (my amp side 0V being earthed). You see on those attachements:
- the PSU/DAC current shape (U=RxI)
- the superposed noises, coming out from DAC PSU 0V line, going to amp, to earth

I beleive it is that. I would not know from where else those additionnal signals could come from.

But I have no (more) noise so. I fixed this with basic copper wires, rewirings.

 

[beeface]

Is it only a matter of time until an audio company starts marketing an off-the-grid system including "audiophile grade" solar panels, battery storage and inverter?

 

[John B]

I live in a big apartment building where I believe someone runs a cyclotron at various times of day. My regenerator stabilizes voltage and the neat sine waves going to the turntable help me think maybe it’s running more consistently. Aside from this, it acts as a nice replacement for a fireplace and the dog loves it ; )