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Measurements of speaker cables in frequency and time domain

MrPeabody

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I did. The statement was addressed to the post #1 in the Morrow cable review thread. That review included only measurement of cable FR with AP (40 ohm source impedance and 200 kohm load impedance) and measurement of “cable distortion”, the phenomenon that does not exist. This review then resulted in anecdotal comments without any background. This is what I criticized and I would do it again.

I'm not following and would like for you to make this clearer. Please provide a link to the post you wrote where you explained (in greater detail than you have here) what was wrong with how Amir did the measurements of the Morrow cable review. Please note that the reason he measured distortion was to address distortion-related claims made by the manufacturer. Those measurements are of no consequence. You clearly have specific criteria by which cables should be measured. So far as I can tell you have not clearly identified those criteria and have not explained why the method that Amir used doesn't meet that criteria. What is it that you find unsatisfactory about the setup he used when he used the cable to connect signal source to the speaker he used (a Klipsch if I recall)?

Additionally, what point do you think you have made when all you really do is demonstrate that the affect on voltage at the speaker terminals is not the same for every combination of speaker and cable? This was already well known, and what have you demonstrated other than this?
 

Pdxwayne

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:facepalm: You're just upset because I won't let you bait me. Go try that with someone else.
It was to educate you. Sorry if you don't want to learn. I will ignore your comments going forward. Not worth it.
 

FrantzM

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I also made a simulation of FR of the 5m zipcord loaded with a dummy load as of the post #14. The simulation gave almost same plot as the measurement:
View attachment 127063
which proves that the measurements are correct.

I would like to mention that the speaker cable, though often underestimated and laughed, may have much bigger impact to the sound than a change of average DAC or preamplifier. This observation might be interesting in the light of attention that is paid to preamp and DAC tests and to tiny differences in the SINAD. The speaker cable in fact is a kind of EQ with respect to the speaker used and its influence might be eliminated by using software EQ.
Ok.
 

Ashley Salmond

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You may be drawing the wrong inference from these test results. While cables CAN measure differently and, when not used appropriately in a given circumstance (amplifier, speaker load, distance) - all things being equal, different cables will NOT sound audibly different.
I watched a YouTube video of the, Steropolice, and he showed by way of a resistance formula calculation and a sine wave sweep that clearly showed how cable with high resistance cause distortion you in a signal that causes a loss of voltage in the lower frequency causing a reduction bass. I would urge you to watch his video.
 

preload

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@pma, your measurements of FR deviations across speaker cables are consistent with those published by Davis in JAES 1991;39:461- "Effects of Cable, Loudspeaker, and Amplifier Interactions." He measured the resulting FR of various commercially available cables on two different power amps and reported the FR curves. And the degree of variation Davis reported is absolutely expected by applying simple circuit analysis, knowing the LCR values of each "component" and treating it like a voltage divider.

1619881123076.png


Note the magnitude of the response deviation (-0.75dB at 20khz for the Krell cable) and the up to 0.6dB difference across cables. Note also that the x-scale is 10Hz to 20kHz.

Audioholics also reports the predicted FR deviation at 20khz based on LCR measurements into a fixed 4 ohm load. Also, note the differences:
1619881955939.png


This makes me question why Amir's Morrow review is not showing ANY appreciable FR deviation using his measurement method. That's not to say that Amir's measurements are not also correct, but from a scientific standpoint, I would want to reconcile why we're seeing different results. The OP's measurements,, measurements from a JAES paper, and an analysis from Audioholics are showing differences that would be predicted by the LCR properties interacting with a non-smooth impedance curve (OP and JAES) forming a voltage divider. Amir's measurement is showing essentially no deviation from flat (i.e. <<0.1dB). Could it be a property of the purifi amp that was used? Could there have been a calibration or setting issue on the AP software? Wrong input selected?
 
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NTK

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@pma, your measurements of FR deviations across speaker cables are consistent with those published by Davis in JAES 1991;39:461- "Effects of Cable, Loudspeaker, and Amplifier Interactions." He measured the resulting FR of various commercially available cables on two different power amps and reported the FR curves. And the degree of variation Davis reported is absolutely expected by applying simple circuit analysis, knowing the LCR values of each "component" and treating it like a voltage divider.

View attachment 127432

Note the magnitude of the response deviation (-0.75dB at 20khz for the Krell cable) and the up to 0.6dB difference across cables. Note also that the x-scale is 10Hz to 20kHz.

Audioholics also reports the predicted FR deviation at 20khz based on LCR measurements into a fixed 4 ohm load. Also, note the differences:
View attachment 127433

This makes me question why Amir's Morrow review is not showing ANY appreciable FR deviation using his measurement method. That's not to say that Amir's measurements are not also correct, but from a scientific standpoint, I would want to reconcile why we're seeing different results. The OP's measurements,, measurements from a JAES paper, and an analysis from Audioholics are showing differences that would be predicted by the LCR properties interacting with a non-smooth impedance curve (OP and JAES) forming a voltage divider. Amir's measurement is showing essentially no deviation from flat (i.e. <<0.1dB). Could it be a property of the purifi amp that was used? Could there have been a calibration or setting issue on the AP software? Wrong input selected?

The cable Amir tested was significantly shorter than 50 ft. The attenuation at 20 kHz was 0.08 dB. Assuming the length of the tested cable was 5 ft, a 50 ft one would give an attenuation of ~0.8 dB at 20 kHz.

Morrow SP3 Bi-wire review Speaker Cable.jpg Morrow SP3 Bi-wire differential wire Measurements Speaker Cable.png
 

preload

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The cable Amir tested was significantly shorter than 50 ft. The attenuation at 20 kHz was 0.08 dB. Assuming the length of the tested cable was 5 ft, a 50 ft one would give an attenuation of ~0.8 dB at 20 kHz.

View attachment 127436 View attachment 127437
True. This may account for some of the difference. However, the AES paper tested 10 ft (3m) lengths.
 

NTK

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The attenuation of the cables in the AES paper ranged from 0.1 to 0.8 dB. The cables Amir tested (if you double their lengths) were within the range.

[Edit] The impedance of the speaker used (load) will also make a difference. I.e. if the load has a lower impedance, the cable attenuation will be higher.
 
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preload

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The attenuation of the cables in the AES paper ranged from 0.1 to 0.8 dB. The cables Amir tested (if you double their lengths) were within the range.

This is true. So it's possible that the cables that Amir picked to test just happened to not have a while lot of deviation (likely lower dcr and lower inductance). However, this also implies that the OP's measurements here are valid as well. There is a ton of scientifically sound data out there from reputable sources (yes from ASR level standards) that confirm FR variation on the order of 0.5dB-1dB that can be introduced by different loudspeaker cables at ordinary lengths (like 10 ft). People can choose to accept this or not but the evidence is there and it has been replicated in every which way.
 
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NTK

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I totally believe OP's measurements and conclusion are valid.
 

BluesDaddy

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I watched a YouTube video of the, Steropolice, and he showed by way of a resistance formula calculation and a sine wave sweep that clearly showed how cable with high resistance cause distortion you in a signal that causes a loss of voltage in the lower frequency causing a reduction bass. I would urge you to watch his video.
I've never claimed that you can't create a situation where cables create an audible problem. The caveat has always been "properly used" and "all things being equal" (i.e. same distance, same impedance, same speaker load, same amplifier, same gauge) two different cables will NOT "sound" differently. And unless you've been running 16 gauge at over 25' runs, you're not going to hear a difference in 16 gauge or lower cable. Unless the cable that it replaces was improperly used and creating distortion (which is entirely measurable as well as audible) a speaker cable cannot IMPROVE the sound.
 

BluesDaddy

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The cable Amir tested was significantly shorter than 50 ft. The attenuation at 20 kHz was 0.08 dB. Assuming the length of the tested cable was 5 ft, a 50 ft one would give an attenuation of ~0.8 dB at 20 kHz.

View attachment 127436 View attachment 127437
I am curious as to how many people could hear a less than 1 DB difference at 20 kHz? I'm curious as to how many people, even those in their aural prime, can hear 20 kHz to begin with. I know I haven't been able to even approach it in a LONG time.
 

NTK

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I am curious as to how many people could hear a less than 1 DB difference at 20 kHz? I'm curious as to how many people, even those in their aural prime, can hear 20 kHz to begin with. I know I haven't been able to even approach it in a LONG time.
I agree with you that these differences aren't likely to be audible, as have been shown in numerous blind tests. However, IMHO, I believe OP's point that the effects from speaker cables on the FR is quantitatively more significant than, say, the effects of different DAC reconstruction filters, is valid.

[Edit] And of course, all these are dwarfed by the FR irregularities of loudspeaker and headphones.
 

BluesDaddy

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I agree with you that these differences aren't likely to be audible, as have been shown in numerous blind tests. However, IMHO, I believe OP's point that the effects from speaker cables on the FR is quantitatively more significant than, say, the effects of different DAC reconstruction filters, is valid.
Yes, but also irrelevant and seems to lead people into believing "ah ha, see, cables DO make a difference (i.e. as in audible, "lift a veil", reduce distortion I'm hearing, etc. kind of difference), and so justify high price cable scamming.
 

preload

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I agree with you that these differences aren't likely to be audible, as have been shown in numerous blind tests. However, IMHO, I believe OP's point that the effects from speaker cables on the FR is quantitatively more significant than, say, the effects of different DAC reconstruction filters, is valid.

Exactly. And when folks obsess over differences in -115dB vs. -120dB SINAD on DACS and dismiss the fact that speaker cables can introduce +/- 0.5dB deviations across the audio spectrum, it seems rather inconsistent to me.

Yes, but also irrelevant and seems to lead people into believing "ah ha, see, cables DO make a difference (i.e. as in audible, "lift a veil", reduce distortion I'm hearing, etc. kind of difference), and so justify high price cable scamming.

Yes and I'd like to add two things:
1) The type of people who have the background to understand that +/- 0.5dB is unlikely to be audible are also the same people who are unlikely to be scammed by the "large audible differences" myth.
2) There IS evidence that longer stretches of cables that are not unheard of (20ft, 30 ft) in a domestic setting, particularly when coupled with relatively smaller gauge cable (i.e. 16GA), and particularly if using exotic geometrics that do not prioritize low inductance, CAN result in FR deviations that most people here would agree are audible (i.e. 1-2dB or more over wide frequency ranges).
 

ctrl

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Any fact-based explanations are a boon.
I like @pma's detailed technical knowledge, but would have liked him to present his facts in a less "sensationalistic" manner.

The first few posts set up a bit of a straw man argument, namely that "It is impossible to say that cables make no difference". Nobody claims that "cables make no difference" at all.

Nevertheless, it is written:
Two speakers cables were tested:
1) a flat cable, length 2m
2) a zip-cord, cross section 2x1.5mm2, length 5m
It is impossible to say that "cables make no difference". It is not true. The cables depending on length, construction and speaker used may make an audible difference,...
I would like to mention that the speaker cable, though often underestimated and laughed,

Nobody doubts that there is a measurable difference between speaker cables with 2m/2x4mm² and 5m/2x1.5mm² and possibly even audible differences. There are probably hundreds of articles on the Internet that point out the relationship between speaker cable diameter and length.
But that's not the point.

But rather that a "reasonable" speaker cable with 2x4mm² or 2x6mm² (from 0.1mm copper strands) for <2-6€ per meter is quite sufficient (for short lengths, a 2x2.5mm² cable should do too).
1619892666671.png
Luxury high-end speaker cables, with the same common length and comparable conductor cross-sectional area, bring no audible (20Hz-20kHz) advantage. That's what all the discussions are about.
The way the facts are presented, it gives the impression, as others have said, that 3m of high-end cable for $500 really makes an audible difference.
 

MarkS

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And when folks obsess over differences in -115dB vs. -120dB SINAD on DACS and dismiss the fact that speaker cables can introduce +/- 0.5dB deviations across the audio spectrum, it seems rather inconsistent to me.
It is absolutely inconsistent. IMO, there is no point at all to measuring modern electronics, they are all essentially perfect.
 

NTK

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It is absolutely inconsistent. IMO, there is no point at all to measuring modern electronics, they are all essentially perfect.
As an engineer myself, the point of these measurements is to assess the competency of the engineering and execution. There is no excuse not to achieve datasheet performance. It shouldn't cost more, and only require competent engineering and manufacturing. If a DAC performs significantly poorer than the datasheet and its competitors using the same or similar ICs, it raises a red flag to me.
 
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