Impact of AC Distortion & Noise on Audio Equipment

[pma]

What would you call the mains from Amir which was also used ?

Quite "normal" spectrum of mains line as I see it here as well.

 

[Headchef]

The B&K noise simulator is only able to source 300VA of power. For a 120V system, that's only 2.5Amps in a perfect world. Power amplifiers require much more than 300VA to function, hence Amir's test on line-level equipment like the Topping HPA and the tube HPAs. The 300VA B&K noise simulator already costs about $5,500. I shudder to see what a full-blown 3000VA would cost, able to source 25Amps @ 120volts.

you’d think that this was a highly conclusive test that had revealed that there was little to no effect from erratic mains on audio kit by the conclusions being gathered. Let’s be honest shall we, it’s not.

it does however demonstrate that the Topping a90 is a very good headphone amp (and bloody good value by the looks of things)

 

[solderdude]

I'd like to see some huge beats in between 5k and 100k, and listen how sensitive amps input stages, buffers and preamps would render those.

Why, what would that simulate in real world applications ?
Remember this is on the mains side. Everything will be rectified and end up as DC which in most equipment is regulated after smoothing.

 

[b4nt]

Why, what would that simulate in real world applications ?

A fridge motor startup. Fridges being nowadays common in most houses.

Edit... Yeah, I assume if one has a DAC, he has a fridge close to it.

 

[Headchef]

A fridge motor startup. Fridges being nowadays common in most houses.

See my earlier post, if anyone is looking for a test bed for this type of study I’ve got it right here!

 

[David_M]

you’d think that this was a highly conclusive test that had revealed that there was little to no effect from erratic mains on audio kit by the conclusions being gathered. Let’s be honest shall we, it’s not.

it does however demonstrate that the Topping a90 is a very good headphone amp (and bloody good value by the looks of things)

I think it's safe to say that for most line equipment, which SMPS for cost and power dissipation reasons, erratic mains have little to no effect on their audio specs, assuming the mains voltages are within spec of the line-level product specs. As already stated numerous times, the AC-DC conversion filters out all of these gremlins, and the DC voltage outputs are heavily filtered to ensure clean supplies to the circuits downstream.

Its devices such as tube preamps/HPA that use AC mains for filament heating or turn-tables which use AC motors, synchronized to the mains. Both of these product types will experience measurable deleterious effects on their performance.

 

[pma]

Everything will be rectified and end up as DC which in most equipment is regulated after smoothing.

Yes, a non-issue if there is a regulated DC power supply. Calibrated in dBV.

 

[solderdude]

A fridge motor startup. Fridges being nowadays common in most houses.

Edit... Yeah, I assume if one has a DAC, he has a fridge close to it.

How do you know it is differential mode (which was ONLY tested here) and that it must be in the 5k to 100k range ?
I too have a fridge. It is not nearby my DACs though. It is silent. When you hear something 'tick' you can be quite certain it is either coming from a poorly designed audio component or there is a substantial common mode current running around in your audio system.\

Those spikes usually are partly common mode and differential mode. The differential mode is tested here and that's not a problem for the 3 tested devices. These tested devices also were not connected to other components so no common mode spikes or nasties could have made it in the 3 tested devices.
That doesn't mean it does nothing in your or anybody else's home under very different circumstances.

 

[b4nt]

Yes, a non-issue if there is a regulated DC power supply. Calibrated in dBV.

View attachment 145627

Attached being representative of what is occasionnaly flowing in 0V/ground/earth rail in my audio setup.

 

[b4nt]

Those spikes usually are partly common mode and differential mode.

Topic being "& noises". I do not see this in the test Amir did run, he only added some distortion to sine.

Earlier, I added Amir shall run other tests, with noises (5Hz bursts) in diff and common mode.

 

[solderdude]

Topic being "& noises". I do not see this in the test Amir did run, he only added some distortion to sine.

Earlier, I added Amir shall run other tests, with noises (5Hz bursts) in diff and common mode.

No... that was only in the case of the 'dimmer' test. The mains was also used which has a 'normal' amount of distortion and noise.
Common mode noises will only show up when the load or source is connected to something in the ground path.
On top of that it is highly dependent on the used cables, loads and signal routing in said devices.
It will tell little in general and only about that specific test in that specific device.

A regular EMC test with some standard tests and testing all ports will take up several days and will not say much as to how it will perform in your, mine or anyone else's system.

 

[pma]

Attached being representative of what is occasionnaly flowing in 0V/ground/earth rail in my audio setup.

I am not able to comment as I do not know your setup in detail.

For low power components like DAC and preamps, line filters built in the metal box make a good job :

Blue is the filter input, red is output. L measured vs. PE.

 

[b4nt]

No... that was only in the case of the 'dimmer' test. The mains was also used which has a 'normal' amount of distortion and noise.

I don't have a dimmer. But I have the components to build one, and a scope to check. Are you sure the signals Amir has feed to DAC PSUs are representative of dimmer noise?

 

[amirm]

Topic being "& noises". I do not see this in the test Amir did run, he only added some distortion to sine.

You must not have read a fraction of the test then.

I showed you performance of audio devices with AC mains coming into them as is. That mains according to you, is full of noise and distortion. I showed spectrum of such. I then replaced AC mains with BK Precision lab AC generator which produced substantially cleaner AC -- better than anything you hope to do with any noise filtering. Yet the output of no less than three devices, did not change one tiny bit.

This is the spectrum of noise and distortion from my mains:

And Lab generator:

Learn to pay attention to what is presented before polluting the thread over and over again with the same mistaken claims.

 

[amirm]

And from Niagara 1200 Review: https://www.audiosciencereview.com/...view-power-conditioner-surge-protector.25443/

No difference. So your noise filtering did nothing.

 

[b4nt]

I then replaced AC mains with BK Precision lab AC generator which produced substantially cleaner AC -- better than anything you hope to do with any noise filtering.

Add noise

 

[amirm]

From AudioQuest PowerQuest 3 filter review: https://www.audiosciencereview.com/...wer-conditioner-surge-protector-review.14580/

Noise filtering is there. Yet, it makes no difference to your audio equipment, in this case JDS Labs Atom DAC:

Not a tiniest bit of difference.

 

[amirm]

Add noise

I did. Relative to Lab AC, the regular AC source has added noise. Both produce identical performance.

 

[b4nt]

I did. Relative to Lab AC, the regular AC source has added noise. Both produce identical performance.

Then again, it might be non representative of people needs or expectations. Your lab could be an almost ideal one, with DUTs (no more) and with controlled power/sources/listeners. In homes, we have many boxes and wires. One may feel he gets noises from mains, regardless of your conclusions.

And I would have liked at least to see that BK precision to feed common/diff noises and bursts pulses to confirm the DUTs you used really are imune.

 

[Headchef]

I did. Relative to Lab AC, the regular AC source has added noise. Both produce identical performance.

Amir, when you run these tests are they just the devices without a signal or do you play music/test signals when testing? What i’m wondering is if we’re just listening to the electronics or if there’s a modulated wave going through them? As you’d mentioned previously fluctuations in power could lead to drops in peak output, if say there was a sudden sound, a quiet sound then a sudden sound etc whilst power fluctuated this could lead to “degraded recovery of peak output” which could make a system sound “a bit off”?