Cable Pathways Between Audio Components Can Affect Perceived Sound Quality

[March Audio]

I have just had a quick squiz through the paper so I may well have missed pertinent things, so dont shoot me, but I raise the same concerns as others have already stated.  

 

1. Comparing different types of cable i.e. RCA and XLR.  The cables behave fundamentally differently with respect to noise rejection.  The electronics driving each, balanced V single ended perform differently WRT noise and distortion.  RCA will be more susceptible to noise currents which can be flowing in the low signal conductor (shield).

 

2.  The noise measurement was performed incorrectly.  It was driven with a 100 ohm source impedance (quite representative) however the far end was only terminated by the oscilloscope which will have a very high input impedance of typically 1Mohm.  This is not representative of real world amplifiers which may typical range from 10kohms to 100kohms.

Secondly scopes are generally useless for measuring noise.  The one used has an 8 bit resolution.  Its own noise floor is way to high.

 

[jventer]

Let's make it simple: he was trying to see if people can reliably hear differences between 2 sets of interconnects. His paper say they can.

 

The only other possible variable in the system is/was what the dac does with outputs via balanced and single ended. The author assumed / measured certain things: 

"This DAC’s total distortion (all products) at the present output level is specified at -120 dB of full scale. 10 This DAC’s absolute voltages at the left and right RCA outputs and the XLR inverted and non-inverted outputs (pins 3 and 2 relative to pin 1) are equal within a standard deviation of 0.13% (i.e., 0.011 dB). The six voltages were measured at the pins while playing a -12 dB (25.12% of full scale) 1 kHz sinusoidal tone from a 16 bit, 44.1 kHz wave file.

 

I am not experienced with this dac or qualified enough to know what other measurements should /could have been done to measure that the outputs were the same?

 

Assuming the outputs were the same, the author proved that people can hear differences in interconnects.

 

If we go off on tangents about the quaility of the interconnects, their cost, their lengths etc., which may all influence the why people heard a difference, it still does not refute the fact that the majority of the people in this experience reliably heard a difference.

 

(The paper do raise many further questions re larger sample size, measuring of noise etc., but it does point in the direction that further tests are necessary to fully understand how our ears and brains work.) 

 

[March Audio]

38 minutes ago, jventer said:

Let's make it simple: he was trying to see if people can reliably hear differences between 2 sets of interconnects. His paper say they can.

 

The only other possible variable in the system is/was what the dac does with outputs via balanced and single ended. The author assumed / measured certain things: 

"This DAC’s total distortion (all products) at the present output level is specified at -120 dB of full scale. 10 This DAC’s absolute voltages at the left and right RCA outputs and the XLR inverted and non-inverted outputs (pins 3 and 2 relative to pin 1) are equal within a standard deviation of 0.13% (i.e., 0.011 dB). The six voltages were measured at the pins while playing a -12 dB (25.12% of full scale) 1 kHz sinusoidal tone from a 16 bit, 44.1 kHz wave file.

 

I am not experienced with this dac or qualified enough to know what other measurements should /could have been done to measure that the outputs were the same?

 

Assuming the outputs were the same, the author proved that people can hear differences in interconnects.

 

If we go off on tangents about the quaility of the interconnects, their cost, their lengths etc., which may all influence the why people heard a difference, it still does not refute the fact that the majority of the people in this experience reliably heard a difference.

 

(The paper do raise many further questions re larger sample size, measuring of noise etc., but it does point in the direction that further tests are necessary to fully understand how our ears and brains work.) 

 

I hear what you say but the problem with the paper is that it is testing a system of components which will behave fundamentally different in the two configurations.  

 

As such it isn't testing just the cables, it's testing the whole system. 

[lucretius]

On 6/9/2021 at 5:56 PM, Kal Rubinson said:

Pretty clear:

"(A) a Straight-Wire Virtuoso higher-end (retail price ~$500 for 0.5 m) 0.5 m long balanced XLR-to-XLR cable with polytetrafluoroethylene insulation and (B) a MonsterCable11 Interlink 400 entry-level (retail price ~$50 for 2 m) 2 m long RCA-to-RCA cable with polyethylene insulation."

 

He had to prove to the wife that the $500 was money well spent? I have a few sets of balanced cables 2m long (star quad and regular twisted pair) all costing within the $50 mark that I could have loaned to the investigator.

[March Audio]

On 6/10/2021 at 9:55 AM, The Computer Audiophile said:

I still have an open mind about it but more questions the more I read. 
 

I found it very interesting he used Spectral amplification. Spectral “requires” using MIT cables and has ultra wide bandwidth. Great stuff, but perhaps not idea for such a test?

 

Would you say he really tested for a difference between a single ended route and balanced route, rather than a difference in cables per say?

Well a radio receiver has the potential to suffer problems other amps may not.  I was surprised to see they even admit to this in their own literature:

 "To prevent oscillations in the Spectral system, conventional "wire" cables have been replaced with precision tuned cable "networks" developed by MIT. The modular terminations of the MIT cables tune them to function like ideal low-pass filters"

 

So I agree it was a dubious choice of amplifier for the test.  That's not a criticism of spectral, just whether it was appropriate for the test as it has special requirements to keep it stable. Requirements the tested cables would not meet.

 

 

 

I would possibly suggest that he tested for neither because it's difficult to differentiate between the effect of the balanced v single ended electronics compared to the effect of balanced v single ended cable.

[Kal Rubinson]

7 hours ago, lucretius said:

 

He had to prove to the wife that the $500 was money well spent? I have a few sets of balanced cables 2m long (star quad and regular twisted pair) all costing within the $50 mark that I could have loaned to the investigator.

He made a number of choices and comments that should be inappropriate in a "scientific" publication. 

[Archimago]

52 minutes ago, fas42 said:

Note,

...

The author says, in the introduction,     Therefore, doing the carefully controlled test to verify this, and publish the results, is fully justified.   As I implied earlier,we now have adequate research, that is the first step. Next step, don't change the

 

Let's get into the details Frank.

 

Yes, the author sets out to find a difference in audibility between 2 cable paths. One with a 2m RCA cable and the other with a 0.5m XLR cable. Both plugged in simultaneously as far as I can tell to the same Berkeley Audio Alpha 2 DAC.  Both cables connected to the same Spectral DMA-250S Amplifier.

 

Potential causes of differences between the RCA and XLR outputs:

1. The Berkeley DAC may perform differently between the single-ended and balanced outputs - distortion levels, frequency response can be different. Even as output level controlled.

2. I didn't see a measurement of the output impedance of the Berkeley DAC and the input impedance of the Spectral amp; I assume they're OK for both balanced and unbalanced operation.

3. Odd that RCA cable longer than XLR. Unbalanced cables obviously more susceptible to noise which is what they found. No surprise. (And no surprise that this could be audible.)

4. Even more strange, why did he choose an expensive $500 XLR short cable vs. $50 RCA long cable?

 

If we give the benefit to the Straight Wire Virtuoso cable as better built with better connectors since it is 10x the price for 1/4 the length, then he's totally stacking the listening test against the RCA output! And guess what, the RCA output path sounds worse with more noise which he concluded as "However, the electrical measurements conducted here indicate that noise levels may be one determining factor of sonic performance".

 

"May be"!? Why doesn't he just show us an FFT of the noise floor from the RCA output vs. the XLR from 20Hz-20kHz? Let's see the level difference between the 60Hz hum for a start... 

 

What exactly is the new "scientific" finding here or the uniqueness of this experiment?

 

35 minutes ago, fas42 said:

 

Well, two different ways of connecting the component parts of an audio chain are audible - demonstrated in a rigorous trial. Which counters the usual cry of objectivists, "Well, I just connected my audio stuff together with very ordinary, cheap cable - because that's all that's needed; fancier stuff will make no audible difference".

 

The result is not surprising to "objectivists" or any audiophiles, period! It still doesn't mean he could not have replaced that $500 XLR cable with a $20 Monoprice XLR and found that this still sounds better than the $50 RCA, right?

 

Actually, I want to see Kunchur try that and tell us whether the RCA wins in that experiment 🤨.

 

Might as well keep another post-grad student busy and get another paper under his name to tell the University of S. Carolina that he's working hard doing science.

 

By the way, here's the measurable difference between three 10' XLR cables - 2 Monoprice and generic SRADIO vs. short 4' Amazon Basics RCA cable:

 

 

Check out the noise level (and small amount of crosstalk difference). This is the noise difference coming out of the outputs from my RME ADI-2 Pro FS as DAC. As you can see, I even stacked it against the XLR cables with more than twice the length versus RCA... (Original article here.)

 

Yes. This difference is audible with appropriate conditions. You honestly think "objectivists" don't believe cable types (and balanced vs. unbalanced operation specifically in this case) make a difference?

[botrytis]

Problem being, if that is the quality of AES papers, they really need to rethink how they review papers. In most reviewed journals, that paper would never have been published because it had so many OBVIOUS flaws. One wonders, now, if this is how mQa papers passed, just based on the reputation of the author, w/o any review.

 

Frank, if you are using that paper as proof of anything, well, that explains much.

[kumakuma]

@The Computer Audiophile

 

I thought you booted Frank from this thread on Thursday.

[botrytis]

Frank that paper, putting it bluntly, isn't worth the paper it was written on. Many scholars do make their names, early on, but then they just slide on their reputations, rather than actually doing anything worthy. I have seen this many times in my career. 

 

No squirming - just a fact.

[The Computer Audiophile]

5 minutes ago, kumakuma said:

@The Computer Audiophile

 

I thought you booted Frank from this thread on Thursday.

And, he’s gone… from this thread. 

[Archimago]

28 minutes ago, fas42 said:

 

Thanks for the solid response.

 

 

Great. So there's no problem, right? Everything's pretty clear?

 

28 minutes ago, fas42 said:

 

The uniqueness that it's now a published paper  - rather than rule of thumb thinking. I thought that's the point in science: someone publishes findings, which allows others to confirm or refute, or extend - or have I got it wrong, 🙂?

 

As @pkane2001said, balanced cabling was designed to reduce susceptibility to noise. Kunchur presumably proved it with this paper (other variables still possible because the research design wasn't great).

 

28 minutes ago, fas42 said:

So why do they just throw in the comment, "A cable that happened to be lying around was plugged in, and was fine - of course!"

 

Alright all you "objectivist" jokers... Which one of you said: "A cable that happened to be lying around was plugged in, and was fine - of course!" just so @fas42 could quote this???!!! Hope I didn't say that over the years... 🤣

 

Got a reference/link to that comment there Frank?

[botrytis]

10 hours ago, Archimago said:

 

Great. So there's no problem, right? Everything's pretty clear?

 

 

As @pkane2001said, balanced cabling was designed to reduce susceptibility to noise. Kunchur presumably proved it with this paper (other variables still possible because the research design wasn't great).

 

 

Alright all you "objectivist" jokers... Which one of you said: "A cable that happened to be lying around was plugged in, and was fine - of course!" just so @fas42 could quote this???!!! Hope I didn't say that over the years... 🤣

 

Got a reference/link to that comment there Frank?

 

 

 

"A cable that happened to be lying around was plugged in, and was fine - of course!"

 

Will this do? 🤣

[Kal Rubinson]

12 hours ago, botrytis said:

Frank that paper, putting it bluntly, isn't worth the paper it was written on. Many scholars do make their names, early on, but then they just slide on their reputations, rather than actually doing anything worthy. I have seen this many times in my career. 

 

No squirming - just a fact.

That is not uncommon but nor is a more relevant issue.  Kunchar's training and previous experience is in an entirely different academic area.  He is a Professor of Physics and Astronomy and his main field of endeavor is in " in superconducting nanowires and thin films."  In this audio stuff, those credentials are not particularly relevant.

[lucretius]

1 minute ago, Kal Rubinson said:

That is not uncommon but nor is a more relevant issue.  Kunchar's training and previous experience is in an entirely different academic area.  He is a Professor of Physics and Astronomy and his main field of endeavor is in " in superconducting nanowires and thin films."  In this audio stuff, those credentials are not particularly relevant.

 

Likely, he's an audiophile who wanted to prove the worth of his $500 cable.

[botrytis]

1 hour ago, Kal Rubinson said:

That is not uncommon but nor is a more relevant issue.  Kunchar's training and previous experience is in an entirely different academic area.  He is a Professor of Physics and Astronomy and his main field of endeavor is in " in superconducting nanowires and thin films."  In this audio stuff, those credentials are not particularly relevant.

 

Well, Just because a person's ORIGNAL expertise is not in audio, does not mean they can't work and get expertise in that area. One only has to look at all the work that has been done by PHYSICYST in the field of Cancer research, HIV, etc.

 

That argument is a red herring and is part of the problem with science today and companies in general. Some of the best innovations are from people who think outside the box.

 

From my background, I had a BS in biology. In the current way big companies hire, I would have never worked in Petrochemicals research nor got my name on a patent for the research I was doing. 

 

Again, that attitude is what is wrong with current situations, not what is right. It also shows how tech like mQa are released w/o any review or research into it. I feel it was based on name only, not the actual technology.

[Kal Rubinson]

21 minutes ago, botrytis said:

Well, Just because a person's ORIGNAL expertise is not in audio, does not mean they can't work and get expertise in that area.

Of course.  Training and expertise in one area of science can allow one more easily to "get expertise" in another but that is not assured.  I do not see that Kunchar has successfully applied basic scientific principles to this audio work.

[botrytis]

1 minute ago, Kal Rubinson said:

Of course.  Training and expertise in one area of science can allow one more easily to "get expertise" in another but that is not assured.  I do not see that Kunchar has successfully applied basic scientific principles to this audio work.

 

Not really. Some great technology comes out of people who have no training in a particular area. We tend to pidgeonhole people rather than allow them to fail. Failing is a learning process. If one doesn't fail, how can one succeed at anything?

 

I think the Kunchar paper, shows exactly what I was saying, based on name rather then innovation or tech. That paper should have never been published.

[Kal Rubinson]

5 hours ago, botrytis said:

Not really. Some great technology comes out of people who have no training in a particular area. We tend to pidgeonhole people rather than allow them to fail. Failing is a learning process. If one doesn't fail, how can one succeed at anything?

I don't know why you keep at this since we are not disagreeing.  I said that "Training and expertise in one area of science can allow one more easily to "get expertise" in another" but that is not assured. (Emphasis added.)

5 hours ago, botrytis said:

I think the Kunchar paper, shows exactly what I was saying, based on name rather then innovation or tech. That paper should have never been published.

Again, I agree.