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Impact of AC Distortion & Noise on Audio Equipment

b4nt

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I took many precautions in running these tests and checked and double checked every time I energized a line. Watches and rings were taken off hands and I stayed insulated form ground.

Just dealing with our boxes without modifying neither opening them and with non hurted power cables shall always be safe.

Live mains (or using a test tool, with probes), or even opening an amplifier where you have more than 50V DC inside and big caps can be lethal. There are a lot of risks off injuries, includings severe burns, due to high voltages or currents.

The worst I experienced where not shocks (often over years), but a short with probes on 50V 32A. My probes blowed, and I was dazzled/blind for an hour.

One may also fall and so get severly hurted if he gets shocked...

There are specific knowledges, trainings and equipements (helmets, isolated tools, strict procedures, gloves, eyeglasses, isolation pads, ...) for such activities, either with live mains, or high DC (from 50V) and caps or batteries (high to very currents).
 
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amirm

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The worst I experienced where not shocks (often over years), but a short with probes on 50V 32A. My probes blowed, and I was dazzled/blind for an hour.
I had a different version of this. Was wiring up lights for our garage. Decided half-way through the project to test the already installed ones. They worked. I then forgot that the power was still on and went to cut a live romex wire with pliers. It created a dead short across the wires. Thankfully the breaker tripped but not before completely pulverizing the cutters! And it was all in my hands but luckily was wearing gloves.
 

GeorgeBynum

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An isolation transformer does several things, of which eliminating ground loops is just one. It does that by isolating the secondary neutral from the safety (earth) ground as John stated.
And while on that subject, the use of (USA) balanced power, 60-0-60 volts has been mentioned. It's worth realizing that transformers for this, whether conventional (E-I core) or toroidal will optimally wind the secondary "bifilar" with a pair wound and the center tap created so that both secondary windings are as identical as practical.

I suspect, but have zero experience, that an electrostatic shield will be used between primary and secondary.
 

b4nt

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And while on that subject, the use of (USA) balanced power, 60-0-60 volts has been mentioned. It's worth realizing that transformers for this, whether conventional (E-I core) or toroidal will optimally wind the secondary "bifilar" with a pair wound and the center tap created so that both secondary windings are as identical as practical.

I suspect, but have zero experience, that an electrostatic shield will be used between primary and secondary.

I had never heared about that (I'm not in the US). But last days, I found a scholar thesis about balanced in audio, including for power.


AttemptWithBalanced.PNG
 

Wes

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I had a different version of this. Was wiring up lights for our garage. Decided half-way through the project to test the already installed ones. They worked. I then forgot that the power was still on and went to cut a live romex wire with pliers. It created a dead short across the wires. Thankfully the breaker tripped but not before completely pulverizing the cutters! And it was all in my hands but luckily was wearing gloves.

pics of the cutters?
 

Grooved

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I had a different version of this. Was wiring up lights for our garage. Decided half-way through the project to test the already installed ones. They worked. I then forgot that the power was still on and went to cut a live romex wire with pliers. It created a dead short across the wires. Thankfully the breaker tripped but not before completely pulverizing the cutters! And it was all in my hands but luckily was wearing gloves.
Got a similar case once, and got shocks three other times in my life, and it was never while working but at home, being tired or getting a small attention from something else, it was not hard maybe because I was trying to take care of everything and knowing what I was doing, but it shows that even with the knowledge, it's easy to do a bad move/forget something and getting a shock.
So if someone don't know anything about this and doesn't have the right tools, better stay away from anything like that.
 

Grooved

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@b4nt , if you have free time to check files, go ahead and play with them, I have done some captures yesterday.

Note that no amp was involved.

In the same circuit, TV, AVR, Sub, light with dimmer, and a fan were turned on.

Devices under test:
Node2i (Coax out), Topping E30, Topping L30, Focusrite Forte, and laptop for using Reaper to capture.

Plugged to wall
Vs
Plugged to Furman Elite 15 Power Factor i. It is just a conditioner and not a generator.

The files null well together. Clock drift seems again slightly more for wall powered chain. Null results seem slightly better for Furman chain.

Against the orig, left null worse than right. It seems Furman left channel (capture 1) did several dB better than wall plugged capture1.

I already spent hour got the things setup, captures, and done a bit of comparisons. But there are still too much to compare....


Here are the captured files with orig:

https://wetransfer.com/downloads/aa...f866f6db573ab5c7baa565c120210814170320/e270cb

Tested in DeltaWave on the first capture of each case, and you were closer to the original on without the Furman than with :

Without Furman :
DW 1 Wall Jack.PNG


With Furman :
DW 1 Furman.PNG


Question : did you have any synchronisation between DAC and ADC ?
 
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amirm

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I had never heared about that (I'm not in the US). But last days, I found a scholar thesis about balanced in audio, including for power.
That's Bill Whitlock's presentation. It is one of the most lucid and authoritative presentations there is on AC power, ground loops, etc.
 

b4nt

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Tested in DeltaWave on the first capture of each case, and you were closer to the original on without the Furman than with :

Without Furman :
View attachment 147530

With Furman :
View attachment 147531

Question : did you have any synchronisation between DAC and ADC ?

I tested, but didn't want to comment so far. I beleive he had a setup issue. The furman shall perform better, it filters out EMI/RF.
 

Grooved

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I tested, but didn't want to comment so far. I beleive he had a setup issue. The furman shall perform better, it filters out EMI/RF.
I see that the difference level is more consistent with the Furman, but it's a bigger difference, so less close to the original.
I would say we can comment, but we can't get any conclusion from this test ;)

I did test some different things one day but with DAC-ADC interface and different audio cables, USB cables..., all the results were closer than what he got on his recordings, but when I tried with the same interface as ADC and a different DAC without any possibility to sync both together, the results were really bad even if the file sounded well... I will do it one more time these next days to check
 
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b4nt

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That's Bill Whitlock's presentation. It is one of the most lucid and authoritative presentations there is on AC power, ground loops, etc.

But I felt not so confortable with the content. It discusses isolation from mains, and earthing. Depending of what is done so, it could be dangerous.

This will again require some expertise. Seems some isolate so their audio from mains, setting up a separate but efficient/safe earthing.

I have a isolation transformer for tests on mains, never used it. Wouldn't use it without a current sense to cut its power in case of leakages.
 

Jim Matthews

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... cut a live romex wire with pliers. It created a dead short across the wires. Thankfully the breaker tripped but not before completely pulverizing the cutters! And it was all in my hands but luckily was wearing gloves.

Ah, the smell of vaporized Klein steel in the morning.

Remind me to never lend you my Knipex.
 

Blumlein 88

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Tested in DeltaWave on the first capture of each case, and you were closer to the original on without the Furman than with :

Without Furman :
View attachment 147530

With Furman :
View attachment 147531

Question : did you have any synchronisation between DAC and ADC ?
What did you get if you run this without phase and EQ engaged? Looks like you might want to trim the last 4 seconds too.
 

b4nt

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I did test some different things one day but with DAC-ADC interface and different audio cables, USB cables..., all the results were closer than what he got on his recordings, but when I tried with the same interface as ADC and a different DAC without any possibility to sync both together, the results were really bad even if the file sounded well... I will do it one more time these next days to check

I got also better results with my DAC supposed to be good, but worther than D30 pro or x16.

I beleive the results can be better using synched DAC/ADC to test pure analog systems.

If you test a DAC, the ADC cannot be synched to it, they will shift away. DW will have to calculate to deal with that. From what I've noticed, the recording level has an impact here. If it is high enough and close to original levels (not clipping), the resolved jitter is better, and the PKM also.
 

b4nt

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What did you get if you run this without phase and EQ engaged? Looks like you might want to trim the last 4 seconds too.

I think there is something wrong with the records PdxW took. With the Furman (an EMI/RF filter), the results are worther. I would have expected the inverse. And I beleive there was something wrong during recordings (maybe cables crosstalk/coupling). At least, they shall have shown equal.
 

Blumlein 88

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I think there is something wrong with the records PdxW took. With the Furman (an EMI/RF filter), the results are worther. I would have expected the inverse. And I beleive there was something wrong during recordings (maybe cables crosstalk/coupling). At least, they shall have shown equal.
If you measure, and get consistent results over several measurements, does not matter what you believe. Assuming the Furman would improve this test is not something assured by any means.
 

b4nt

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If you measure, and get consistent results over several measurements, does not matter what you believe. Assuming the Furman would improve this test is not something assured by any means.

See #712 #715
 

Pdxwayne

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Tested in DeltaWave on the first capture of each case, and you were closer to the original on without the Furman than with :

Without Furman :
View attachment 147530

With Furman :
View attachment 147531

Question : did you have any synchronisation between DAC and ADC ?
I wanted to check a new headphones amp just now. I tried to check 1khz tone using E30 in my computer room and I couldn't get good THD plus noise result. Always very high noise level in the -50db. It sounded ok, but the noise level as measured by REW RTA bugs me. Something is not quite right. Maybe using RCA to XLR adapter to connect to the ADC is the problem.....So my captures from yesterday may not be quite right....
 

b4nt

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I wanted to check a new headphones amp just now. I tried to check 1khz tone using E30 in my computer room and I couldn't get good THD plus noise result. Always very high noise level in the -50db. It sounded ok, but the noise level as measured by REW RTA bugs me. Something is not quite right. Maybe using RCA to XLR adapter to connect to the ADC is the problem.....So my captures from yesterday may not be quite right....

Thanks to be transparent.

@Blumlein 88 It would be better if one would have more reliable results over days and weeks. Nothing ensuring 10 times the same being a reference.
 

audio2design

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CISPR 14-1 (or EN 5504-1) is defining the emission requirements for household appliances, electric tools and similar apparatus. CISPR 14-2 (EN 55014-2) is defining the immunity requirements for the products which are under this standard.

Of course there is no immunity testing for audiophiles but there is for household appliances which home audio falls under.

I know. I am signing the checks regularly for test services. Meaningless wrt audio equipment. Is no indication of meaningful performance.
 
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