Power cables for active speakers - do they matter?

[RexrothPigeon]

Whatever the difference is - it is very subtle.

The word you're looking for is imagined

 

[Avp1]

Or you could just use a well made power cable and enjoy an adult beverage with the wife while you listen to some music. I know which one I'd choose.

This is exactly what I did.

 

[Sir Sanders Zingmore]

This is exactly what I did.

Did you do a properly blinded test yet?

 

[solderdude]

This is why protection from RFI is more art than science

No ... that is pure engineering. There is no art involved. It only LOOKS that way to people (even engineers) that have not spend enough time in an EMC lab.
It is pure knowledge and experience as well as common sense and measurements.

Or... do you believe that in an EMC lab there are only artists at work and not engineers ?
In that case I have met more artists in my life than I thought I did,

This is only a limited filtering you can fit into active speaker amplifier pack.

There is no filtering at all in the 100A, it does not have an SMPS so is not needed.

Shielded cable works as additional filter.

No it doesn't. You need a filter for that. common mode and/or differential mode.

I now plan to change power cables for preamplifier and DAC, add linear power supply for streamer and use fibre instead of CAT6 to bring network to streamer. I honestly do not know if there will be any advantage from all that. But I try to exclude all possible interference sources.

I am sure it will bring more sonic pleasure but not for the reasons you may believe it does.

 

[Sigberg Audio]

I now plan to change power cables for preamplifier and DAC, add linear power supply for streamer and use fibre instead of CAT6 to bring network to streamer. I honestly do not know if there will be any advantage from all that. But I try to exclude all possible interference sources.

You should use this time and money to do a proper ABX test.

 

[JSmith]

My EE education background

Stick to that and try not to go down this path of power cables making a difference...

AC power is rectified to DC, then it is filtered, and generally regulated to ensure a stable and consistent DC output for the device.

Amir has shown here too in a number of tests that "dirty power" doesn't do anything to the actual audio output and they still measure the same.


JSmith

 

[solderdude]

My EE and EMC background tells me...

Common mode currents can influence the sound and leakage currents between mains and audio ground can be (very) audible.
Have to add... the 'change' in sound manifests itself as 'weird sounds' that should not be there and can be audible when no music is playing, not 'subtle' changes in sound quality.
This is something else than just a 'distorted' (differential) mains waveform though, which is what Amir did test for,

Amir does not test for common mode and leakage currents (though sometimes it seems to creep into his measurements).

Will that change between run of the mill mains cables and DIY mains cables or even shielded mains cables ? No it won't as cables do not change common mode nor leakage currents even when shielded nor will they change the mains 'spectrum' below 20kHz.

 

[boxerfan88]

as has the peanut gallery, I guess

ABx squad too

 

[RexrothPigeon]

ABx squad too

 

[caught gesture]

Your wife’s observations are only classed as being scientifically valid if she could hear any difference from another room. I thought that was a well-established protocol!

 

[Juhazi]

ATC - British hifi is magical! I haven't heard of any other origins being so sensitive to cables, fuses, connectors etc.

Audiogon Discussion Forum

Hello: I've just acquired a pair of ATC SCM100A active speakers, and I'm wondering what other users of ATC actives have done regarding stock PCs versus...

forum.audiogon.com

 

[MarkS]

UMIK-2 and measurements followed by recordings of the music that you find the most reliable to have a difference.

The slightest movement of the microphone will create differences between recordings. Ditto slight changes in ambient noise.

 

[JeremyFife]

I always was skeptical about influence of power cables on sound from well designed audio equipment. My EE education background also made me to believe that all things can be measured. Recently I attended a listening session where we - five members of local audiophile club, compared sound of several "high end audio" power cables. System where we tested them was what I would call mid-range audiophile class setup. All cables (with one exception) were from major brands which are usually advertised in audio related publications. We listened five tracks - each was selected by attending person. What surprised me was that I did hear the difference in sound in all of them. The fact that 4 out of 5 people explained what they heard exactly with the same words surprised me even more. This was not a dealer presentation, so there was no push to choose a specific cable. Actually Chinese knock off version of one of major brands purchased from Ali Express came second and most expensive cable came the dead last.

After that experience, I decided to do my own testing. I use active speakers - ATC SCM100A, where amplifier is located inside each speaker. ATC is a well respected brand and I honestly thought that I would not experience anything similar to what I heard at session described above where audiophile kind amplifiers were in play. Also unlike host of the session, I have a dedicated 30A power line from distribution box to my music room, which should reduce any power related differences even more.

I did not want to spend a lot of money: I needed two cables - one for each speaker. I also wanted to make sure that cable does not have something that may intentionally degrade its performance. Thus I decided to make cables myself from parts I could buy individually. From quick search I found wire and connectors made by Supra Cables - company in Sweden, which specializes on all kind of cable products. They advertise their power cables as the only "audio grade" ones which are UL listed to confirm their safety. I ordered 20 feet of Lorad mains wire plus 5-15P and C13 connectors made by the same company. I did assembly myself, which was rather easy and saved me $30 per cable in cost.

When I finished that assembly work late evening, I replaced my standard 15A rated cables used for ATC speakers before with this newly made ones. I did a quick listen and I felt that there was some difference, but I was not sure if this is a real thing or imagination. I did listen few tracks and went to sleep.

Next day I decided to test if what I hear is a real thing or not. I invited my wife, who does not really into audio hobby but did have some formal music education, to join me for a test session. I selected 5 tracks which I know relatively well, and which represent different kind of sound for this testing. I played track for 3 minutes, then swapped cables, played track again. Then played another track, swap cables again and repeat that tracks. This protocol reduced number of cable swaps and randomized experience a bit since same cable was used for two tracks without swapping.

Both me an my wife agreed that there was a difference between two cables. That difference was consistent throughout all tracks we played and we had the same words to explain what we heard: New cable made sound a bit more transparent, like the scene you see when you clear your glasses. Spacial details like reverb tails were better heard with new cables. This is not what I expected from ATC speakers, but that was real and confirmed by someone who has no stakes in that game.

Tell me: how to quantify that? This is a serious question.

Hi,
I don't doubt that you heard a difference, and on your subsequent tests at home. The question is why, or what is the most likely explanation.

You have an EE background, so you're likely to accept the scientific method for problem solving.
If you have not already, take a look at Psychoacoustics and findings on expectation bias. Don't work from assumptions on what these are but read a bit.

Ask yourself (as an EE) what is it about power cables that could theoretically make such a massive change to an audio signal's frequency, amplitude or distortion that you could actually hear it. Bear in mind the level of filtering going on in your equipment as it receives power and disregard change outside the audible range. We can measure tiny changes, but our hearing is far less sensitive.

If you were to measure your system, the first thing you would do is to make sure that your measurement equipment was calibrated and that measurements were reliable. Measurements made with unverified, uncalibrated instruments would be unreliable - you'd ignore them.
Our ears are terrible measurement / objective evaluation instruments ... we calibrate them by imposing strict listening controls. As a minimum we must match levels, conduct tests blind (preferably double blind), ideally ABX and make repeated tests.

If we don't have controlled listening tests, then we just don't have listening tests

For me, personally, EE theory is compelling that power cables don't make audible differences. Psychoacoustics is similarly compelling in explaining why I would hear a difference anyway (when there isn't one).
If I was bothered/curious enough to challenge that, I know that I would have to conduct a properly controlled listening test or I'm just wasting my time.

The suggestion of recording a few tracks then comparing the recordings is a good one.

 

[Avp1]

If you were to measure your system, the first thing you would do is to make sure that your measurement equipment was calibrated and that measurements were reliable. Measurements made with unverified, uncalibrated instruments would be unreliable - you'd ignore them.
Our ears are terrible measurement / objective evaluation instruments ... we calibrate them by imposing strict listening controls. As a minimum we must match levels, conduct tests blind (preferably double blind), ideally ABX and make repeated tests.

Sometimes ears vs. tools for measurements show strange results. One example was my work on adjustment of cartridge in my turntable. There are two parameters: SRA and azimuth which I had to adjust. With azimuth I measured huge difference when it was less than 1 degree off, but I did not hear that difference at all. For SRA I could not find significant difference in measurements, though I heard difference changing it 1/4 of degree from optimal. Thus our ears and brain sometimes are better than technical measurement instruments, or I rather say that commonly accepted measurement technique is not optimal to identify specific deviations.

 

[Dialectic]

Wife was what is usually called "control group". In the past she was able to hear the difference in different tube brands in amplifier. Her choice for best tube matched my. But different tubes had distinctly different distortion patterns, so no surprise there.

The main problem with your test protocol is that your wife did not tell you she could hear the differences from the kitchen, so it does not conform to the rigorous standards imposed by journals such as The Absolute Sound.

In all seriousness, there is no shame in “hearing” differences where there are none. I formerly made this mistake all the time, and I think even we ardent converts to audio science find ourselves still making this mistake from time to time.

 

[Avp1]

The main problem with your test protocol is that your wife did not tell you she could hear the differences from the kitchen, so it does not conform to the rigorous standards imposed by journals such as The Absolute Sound.

I

The difference is small enough so you cannot hear it from another room. If I did not have treated room, then I probably won't hear it either. We are talking here about 3rd or 4th order difference - very close to noise floor.

 

[Avp1]

No ... that is pure engineering. There is no art involved. It only LOOKS that way to people (even engineers) that have not spend enough time in an EMC lab.
It is pure knowledge and experience as well as common sense and measurements.

Or... do you believe that in an EMC lab there are only artists at work and not engineers ?
In that case I have met more artists in my life than I thought I did,

Engineers usually follow common design pattern and hope that device will measure within requirements in terms of resistance to EMI. In most cases it does. But when it does not - here is where fun stuff begins. Simulations are not precise enough, so engineer starts with physical tweaking: change this and modify that, then measure again. Repeat process again and again until hopefully required result is achieved. Some engineers are better in that - consistently takes less iterations to archive the target parameters. This is why I called that art: you cannot explain why people with formally same credentials produce different results.

 

[JeremyFife]

Sometimes ears vs. tools for measurements show strange results. One example was my work on adjustment of cartridge in my turntable. There are two parameters: SRA and azimuth which I had to adjust. With azimuth I measured huge difference when it was less than 1 degree off, but I did not hear that difference at all. For SRA I could not find significant difference in measurements, though I heard difference changing it 1/4 of degree from optimal. Thus our ears and brain sometimes are better than technical measurement instruments, or I rather say that commonly accepted measurement technique is not optimal to identify specific deviations.

Think about that ...

What were you measuring, and would that have an audible impact?
Always (always), if you hear something but can't measure it with a proper measurement approach and equipment then the change is not there.
It's quite normal to measure a change that you then cannot hear.

First step is always to review your measurement protocol, not to assume that you are hearing something that can't be measured.

 

[Sir Sanders Zingmore]

Sometimes ears vs. tools for measurements show strange results.

To be clear, until you do a properly blinded test, you have *not* performed an ‘ears’ test.

 

[solderdude]

This is why I called that art: you cannot explain why people with formally same credentials produce different results.

I guess I am an artist then... and so are the test engineers and designers..

NO it is engineering and common sense (knowing what the potential issues are) you are free to call it an art... even though it isn't.

And ... ask 10 different designers to design a circuit with a certain functionality and specify minimum requirements and you will get 10 different circuits using different components and PCB layouts.