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Analysis of Paper on Measurements of RCA Cables by Kunchur (Video)

Blumlein 88

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The meta-analysis he referenced by Reiss referenced in regard to time smearing the Craven papers related to MQA. So that is part of what he is taking as a tested and settled issue on time smear. I must say this response mostly makes me think a lot less of the JAES. What does it mean to say lower rate digital sampling can only place where the start of a waveform is within sub-microseconds, but not the fine structure of the waveform between sample points. I also noticed he said the finest inter-aural timing of the ear was known to be microseconds around 900 hz. This was one of my criticisms of his earlier work. It was known this sensitivity was greatest in the 8-900 hz range and pretty much insensitive above 1500 hz while he once tested with 7 khz squarewaves.
 

SIY

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I'm surprised by the very existence of the response.
I thought multiple MSc/BSc/PHd's followed the unwritten law to not answer critique but by their peers.
That's REALLY strange.
He's not really acting as an academic when outside of his actual specialty. He's working as a commercial shill for profit, and this is exactly what one expects of a commercial shill.
 

odarg64

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He's not really acting as an academic when outside of his actual specialty.

Areas of expertise can, and very often do, change over time due to any number of reasons, including change of interest. I have would have difficulty naming an advisor or former colleague whose area didn't change significantly over the years.

Whether or not this applies to the subject of discussion, and if they are a shill, can only be answered directly by the author or possibly through their work.

I've always viewed people who list degrees after their names as insecure. The listing of honors after the author's response to Amir's work says a bit more than that.
 
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Easternlethal

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The meta-analysis he referenced by Reiss referenced in regard to time smearing the Craven papers related to MQA. So that is part of what he is taking as a tested and settled issue on time smear. I must say this response mostly makes me think a lot less of the JAES. What does it mean to say lower rate digital sampling can only place where the start of a waveform is within sub-microseconds, but not the fine structure of the waveform between sample points. I also noticed he said the finest inter-aural timing of the ear was known to be microseconds around 900 hz. This was one of my criticisms of his earlier work. It was known this sensitivity was greatest in the 8-900 hz range and pretty much insensitive above 1500 hz while he once tested with 7 khz squarewaves.
Whenever someone points out that the measured frequency response or SNR of a product doesn't support its claims, 9 times out 10 I will hear 'cause the problem is in the time domain and not frequency domain because humans have evolved to can notice differences in microsecond yadayadayada...'. This argument has been around for decades and made by manufacturers too. But other than studies which show that humans CAN notice temporal delays (e.g. HRTF. phase) I haven't come across any papers or demos which show what perceptible changes to audio quality that can cause. So I have no idea what time smearing sounds like. People don't even agree on how jitter affects sound.

Maybe because I'm not a JAES member and missed out on all the amazing revelations in their events..

So Amir - pls do an educational video on time smearing. I will donate some more money..
 

SIY

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Whenever someone points out that the measured frequency response or SNR of a product doesn't support its claims, 9 times out 10 I will hear 'cause the problem is in the time domain and not frequency domain because humans have evolved to can notice differences in microsecond yadayadayada...'. This argument has been around for decades and made by manufacturers too. But other than studies which show that humans CAN notice temporal delays (e.g. HRTF. phase) I haven't come across any papers or demos which show what perceptible changes to audio quality that can cause. So I have no idea what time smearing sounds like. People don't even agree on how jitter affects sound.

Maybe because I'm not a JAES member and missed out on all the amazing revelations in their events..

So Amir - pls do an educational video on time smearing. I will donate some more money..
"Time smearing" is a marketing term, not a technical one.
 
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So Amir - pls do an educational video on time smearing. I will donate some more money..
As SIY correctly says, it is a marketing thing as otherwise it would be backed by proper listening tests and measurements. It is the old myth that people catch a cold in winter because it is cold. Not because they are more apt to catch the virus that causes it. It makes perfect lay sense but has no scientific foundation.

But sure, I will see if I can put together something.
 

Peluvius

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images


Its just so you buy more stuff ;)
 

Easternlethal

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Here's kuncher's video on this. He mentions the calculations for time delays and frequency.

He starts off by explaining that time delays affect timbre and makes a very interesting comparison of the frequency spectrum between a piano sounds played forwards then backwards to demonstrate frequency spectrum doesn't show this differences.

But then he kind of lost me when he started to explain how the ear works because that's all in the frequency domain!
 

SIY

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Here's kuncher's video on this. He mentions the calculations for time delays and frequency.

He starts off by explaining that time delays affect timbre and makes a very interesting comparison of the frequency spectrum between a piano sounds played forwards then backwards to demonstrate frequency spectrum doesn't show this differences.

But then he kind of lost me when he started to explain how the ear works because that's all in the frequency domain!
Ironically, he originally and notoriously demonstrated his extreme incompetence talking about this very issue- that made him the darling of the "high end" ripoff sector where it's the FUD, not the facts that's important.

Well, I have to hand it to him, he's found his grift.
 

JSmith

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He's not really acting as an academic when outside of his actual specialty. He's working as a commercial shill for profit, and this is exactly what one expects of a commercial shill.
I'm tending to agree with this now after the unprofessional spray at Amir and ASR, as if his "research" is above reproach. Comments like this are certainly not productive;
Mr. Majidimehr’s instrumentation and basis of analyzing audio fidelity is fundamentally flawed.


JSmith
 

GXAlan

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You cannot get to complete silence due to thermal noise. You can get results in the -100 to -110 db level. With better ADCs you can do better. Amir has gotten down around -115 db and near -120 db, but he has the APx 555 to work with. You get the same results whether comparing cable A to itself 5 minutes later or cable B to cable A. Also it might interest people to know the left and right channels of even very expensive DACs don't null this deep.

Challenge accepted!
 

ctrl

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Here's kuncher's video on this. He mentions the calculations for time delays and frequency.

He starts off by explaining that time delays affect timbre and makes a very interesting comparison of the frequency spectrum between a piano sounds played forwards then backwards to demonstrate frequency spectrum doesn't show this differences.

1. Time delay affects timbre
The popular example with the offset of tweeter and woofer (or woofer and mid-woofer).
1663414869549.png
Source: Loudspeaker Design Book, Vance Dickason

The offset should be in 99% of cases in the range 0.01 - 0.05m for tweeter and mid-woofer.
With 3-way speakers, the offset of woofer and midrange driver may be 0.1m.

If we take the maximum offset of 0.1m for woofer and midrange, then we get a time delay of about 0.1:344 = 0.3ms between the two drivers.
Keep these two values (0.1m offset or 0.3ms delay) in mind, we will need them later.

From Prof. Kunchur's video I have now recorded and analyzed the example (C) with the two tones at 440Hz and 880Hz with delay.
1663415166477.png

To do this, I plot the impulse response for the left channel in Arta (by importing the recorded .wav file).
1663417367709.png

We can tell when the first tone starts, the time at which the second tone is added, and determine from the wavelength that the frequency of the first tone is 440Hz.

If we look at the end of the impulse response, only the 880Hz tone is still playing (obviously because of the delay).
1663416970681.png

Now we have to remember the two values from above. For a realistic scenario for playing the 440Hz and 880Hz tones, the delay should be around 0.3ms which corresponds to an offset of woofer and midrange by about 0.1m.
Then let's have a look at the delay value Prof. Kunchur has chosen for his demonstration:
1663418731015.png



The chosen time delay is completely insane and amounts to 5m. This means that the woofer of a loudspeaker would have to be five meters (196'') behind the midrange driver to have the effect shown in Prof. Kunchur's demonstration.

Why didn't he take a realistic value? Everyone is likely to know the answer. It is disgusting with which means inexperienced consumers are deceived.



2. frequency spectrum doesn't show this differences
This is misleading again, there is no gotcha! The recorded impulse response of a measurement contains the (amplitude) frequency and phase frequency response. Only both together (FR and Phase response) correspond to the impulse response.

If the impulse response is inverted, the frequency response does not change, that is correct, but the phase frequency response does. The example is trivial and shows nothing relevant for loudspeakers.

When measuring loudspeakers, the phase frequency response is usually not shown, because only a few people can do something with it*** and the information is not decisive for the sound of reasonably designed loudspeakers. For example, you can often determine the filter slope order and the crossover frequency from the phase frequency response.

Here is an example of an ideal speaker (FR + Phase) with normally connected drivers and both drivers connected with reverse polarity.
The FR does not change, but the phase frequency response does.
1663420881956.png 1663420896665.png

UPDATE***: An example of what information the phase frequency response contains can be found here.
 
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Easternlethal

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which is why he says phase integrity is so important we should all be rushing out to buy Wilson Audio Chronosonics
 

Cbdb2

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He's not really acting as an academic when outside of his actual specialty. He's working as a commercial shill for profit, and this is exactly what one expects of a commercial shill.
I wonder what he would think if I bought a telescope and wrote a paper on astrophysics, which I know little about.
 

SIY

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astrophysics, which I know little about.
Neither does he. His specialty is solid state physics.

If there were a grift angle in astrophysics, I imagine he would suddenly become an "expert" in it.
 

Human Bass

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Here is video proof that short interconnect cables can affect the sound. I live in San Francisco where Sutro tower also exists, a large TV and radio broadcast tower.

These Internet cables from China were purchased from eBay as “audiophile “flat ribbon cable. These are silver plated copper with a Teflon dielectric. All the right subjective buzzwords.

Switching back to generic shielded cable fixed the problem.

Given that @amirm has shown that cheap Amazon Basics shielded RCA interconnects work, that’s a good strategy. I have had Monoprice XLR cables break on me from too much strain on the connector. That is also where more expensive cables may have avoided a problem. That said, Monoprice stood by their lifetime warranty and are replacing that broken cable after 10 years.

If you want something special with a brand, Nelson Pass uses the gold Radio Shack cables.
Well, unshielded singled ended cables picking up noise from a powerful source is expected.

Especially those flat ribbon cable that have a lot of unshielded surface area. They are the exact opposite of what I recommend for rca: heavily shielded coaxial.
 

GXAlan

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Well, unshielded singled ended cables picking up noise from a powerful source is expected.

Especially those flat ribbon cable that have a lot of unshielded surface area. They are the exact opposite of what I recommend for rca: heavily shielded coaxial.
Yeah, if you look at my notes, I make that same recommendation. There are a lot of “expectations” but the video provides fact.

What is interesting is that in Amir’s video mentions that RF/EMI adds sparkle and high frequency noise which can in fact contribute to the subjective sound.
 

noiseangel

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You didn't escape the wrath of that worthless non testing website Stereonet. Having another dig at ASR trying hard to defend some cable guru. They don't own a multi meter between them.

 
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