So asking wheres the ABX testing is an insult? Okay, "a bit of a flake" is an insult, but apparently not enough to get the mods' attention.
The question is whether there's any good evidence for a claim.
The mention of amp oscillation suggests the amp is the problem.
Trying to go past the Rocky Mountains at an elevation of 100 feet above sea level would suggest that the plane is the problem. However, it is just a misapplication of a well engineered product.
If an amp dies because it oscillated with an unloaded low impedance speaker cable, that is because it was not designed to do so... a misapplication of a product.. A zobel is a simple fix for that issue.
Doesn't mean the amp is poorly designed, just misapplied.
John
Perhaps more research is needed?
Since you seem to understand the topic so well, perhaps you could lead the research?
I would assist where needed.
John
PS.. if you need help on the sarcasm end, I can help there as well..just ask
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Actually, I am an EE. But yes, I do that superconducting stuff, as well as design wiring for 2.4 mile and .5 mile circumference machines, motion control to 5 nanometers, EMC problems meeting NEC and , antique clock repair instruction...no wait, that's a hobby... The line starts to get fuzzy.
As I lean towards retirement, I add more hobby skills, and love every minute of it. Oddly enough, the skills I am learning for my retirement hobbies are hugely important for my work...go figure.
I do understand being confused with a nuclear physicist however.. due to pandemic fears (mine), I held off on visiting the barber for about 5 months. My hair was so bad, that Disney called me for the 4th Back To The Future episode.. Doctor Emmitt Brown...
Jn
Thanks for telling us about yourself, but you have worked and tested (possibly) different types of cable, and your qualifications and experience count.
At least your opinions are based on experience, and given the right equipment, your results can be replicated anywhere.
That was also my point, the results should be apparent, quality of sound has many standards in RIAA, DIN, JIS, GOST, maybe others.
If the cable causes change in sound quality, for better or worse, the measurements on equipment must show it.
Nobody took that challenge up...
At least your opinions are based on experience, and given the right equipment, your results can be replicated anywhere.
That was also my point, the results should be apparent, quality of sound has many standards in RIAA, DIN, JIS, GOST, maybe others.
If the cable causes change in sound quality, for better or worse, the measurements on equipment must show it.
Nobody took that challenge up...
There are several solutions that will work. The point is, a good design crosses unity gain before it loses phase margin. If the phase margin is compromised by a low impedance cable terminated with a load that goes high impedance before the unity gain frequency of the amp, bad things happen.
To blame a high bandwidth amp designer because it was unstable with a load it was not designed for is incorrect.
Nowadays, if this happens I would certainly blame the designer for not considering load or cable variations that are well documented.
John
Show me one study that shows ITDs of 10us are audible over stereo speakers in a real room?
Ive been looking and there all done with headphones or:
"noise bursts were presented using an 11-loudspeaker array spanning the subject's frontal 180 degrees arc in an anechoic room."
"interaural phase measurements made on an 87.5-mm sphere in an anechoic room using an array of 13 loudspeakers separated by 7.5°"
Find a ITD test online and hear the difference between HP and stereo speakers.
If the speaker wires are the same length and this delay is the same in both speakers how do you even have a different delay at each ear? Your not even talking ITD anymore so the ITD tests (10us making a difference) might not even apply.
You make the assumption that the speaker impedance is the same at all times and with all stimulus. It is not.
The impedance a voice coil presents at midband frequencies is dependent on the acceleration of the voice coil driven by low frequencies.
If magnetic flux based motors did not do this, then your assumption would be correct.
jn
Ok I can see that. How much does that impedance actually change when theres a xover in between and how much does it actually delay the sound? Some measurements would be nice to see, has anyone done any?
You are dealing with dynamic changes, and delays will vary.
They always do, it is inherent.
If you are very curious, the IEEE may have some useful data, they need you to register (free), and create an account with username and password to see some articles.
They always do, it is inherent.
If you are very curious, the IEEE may have some useful data, they need you to register (free), and create an account with username and password to see some articles.
Separate drivers, I would not worry so much. Yes, the crossover design is important, but I concentrate on only one being driven with multiple signals.
If for example, you have a center stage midrange voice, and the bass is shifted to one side, then there is a possible asymmetry in response.
The first test I recommend when testing a new cable type, is to wire both speakers to one amp channel and first verify that all image is dead center. If it is not, stop, do not proceed.
If perfect, then wire one speaker with the new cable. If all the image remains perfectly centered, stop. The cable made zero difference with these speakers.
If some of the image content shifts to either side, or becomes a non sharp centered image, then you have spotted a difference in response.
If that occurs, reverse the cables and re-try. If the change follows the wire, you can decide if you like what the new cables do, or not. If the change does not, you are chasing a perception ghost.
If you prove to yourself there is a difference, you could get into major blind testing to scientifically prove it. Or, like Hans, just enjoy the music.
In terms of magnetically driven speakers, every single different design will be different in terms of acceleration and velocity induced impedance variation, so a blanket assertion on any cable design vs any speaker is a useless construct.
I have not found any test capable of measuring the impedance modulation, the confounders within a driven speaker are many and complex.
Me, I would just go 25 ohms, roughly 4 twisted zips of 14 or 16 awg wired parallel, and leave it at that.
NAreshBrd,
I have not found any information anywhere on the changing impedance of magnetically driven motors due to acceleration or velocity. I discovered the effect during a tuning run on a motion control system. A system I was characterizing would become unstable during sine wave excitation, and it became unstable only during times of zero acceleration, both directions. I tracked it down to the system response Bode plot changing, and with less magnetic force the phase margin would cross 0 degrees. The variation in magnetic force changed the dynamic impedance.
One solution is an acceleration based PID algorithm, allowing higher gain during acceleration, dropping it down during lower accel.
Understanding this effect gave us bounds on our tuning, we were able to achieve accuracies 200 times better than the requirement without resorting to modulation of the PID parameters. Had we only achieved a factor or 2, I would still be nervous.
The understanding that this occurs within a speaker took about 10 milliseconds to figure out. I just happened to be in the right place at the right time.
John
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I think you have your tongue firmly in cheek...
10 uS differences are 1/100,000 of 1 second...
At least, beyond my ability to differentiate.
10 uS differences are 1/100,000 of 1 second...
At least, beyond my ability to differentiate.
Actually an ITD delay is under some conditions audible.
But it's about a single mid-frequency sound, suddenly being delayed by 10 uS to only one one of the stereo speakers.
It's not about constant time delays at different frequencies.
But it's about a single mid-frequency sound, suddenly being delayed by 10 uS to only one one of the stereo speakers.
It's not about constant time delays at different frequencies.
Humans have a lateralization (headphones) capability of about 1.5 uSec, 1.2 if there is dithering.
Humans have a localization (free field) capability at the 5 uSec level.
This is NOT with two speakers, it is one source relative to another, like 10 feet away, two sources side by side with a distance between.
With two speakers, it becomes more complex. First, the initial arriving sound is exactly correct, left to left and right to right. But then with a small delay, the left gets to right, the right gets to left.
So there is information for each speaker to be localized, then inverse. How we image at all is a wonder in itself.
During final mix, the engineer uses pan (IID) with monitors to place images. Perhaps nowadays they also use ITD for accuracy? (although that kills combining the pair into a mono signal anywhere.)
As an interesting aside.... Last monday I was enjoying oysters and a martini at a local dig, music playing over the house system. Suddenly, three consecutive songs played that were the subtraction of the two channels. All center information was gone, vocals, lead guitar... While I didn't mind at all as I still enjoyed the music, I noted to the bartender this fact.. He said no, it was filtered, and he actually a producer/engineer locally, I think a basement setup.
Having used subtraction in a nightclub when I was a DJ (I built the electronics), I can identify the difference, so detailed a bit to him. note, back in that day, phasing/flanging was done using two copies of the vinyl, so I have two copies of about 50 titles.
Now, I have a local connection. For oysters, martinis, and music production...small world.
John
ITD gained interest in the pro audio & hi-fi communitys with Kunchur's 2007-08 error filled papers on CDs.
In the real world, ITD is about the lateral movement of a single mid-frequency sound.
Some tests move a single loudspeaker or delay a channel of a stereo pair.
j.j. allowed that it might be less than 10 uS in the real world, but tests might have several uncontrolled variables.
I don't recall anything about headphone tests.
In the real world, ITD is about the lateral movement of a single mid-frequency sound.
Some tests move a single loudspeaker or delay a channel of a stereo pair.
j.j. allowed that it might be less than 10 uS in the real world, but tests might have several uncontrolled variables.
I don't recall anything about headphone tests.
Nordmark '72 was headphone and lateralization. It discerned thresholds below which I could not be bothered. If something like a cable made changes below about 2 uSec, I considered it of no concern.
In the 2 to 5 range, I suspect lots of training would be needed, and even then I'm unsure humans could detect that using two speakers.
Above 5, I'm certainly open to that possibility. However, the tests must be tailored to allow discernment between a base reference centered signal and the subject signal shifted by ITD, both presented simultaneously. Just like music that we listen to.
I am also unhappy Greisinger's website is totally different, stuff I found a decade ago I cannot find again.
John
In one of his Power Points, David Griesinger wrote:
From the author’s seat in row F behind the lady in red the string quartet was +-10 degrees in width.
But in the presence of substantial reverberation it was possible to distinctly localize all four players with eyes closed, even when they played together.
This implies a localization acuity of better than three degrees. With just slightly more reverberation it was not possible to localize the musicians at all.
Localizing separated sounds in natural hearing
•It is well known that we localize sounds through:
–the Interaural Level Difference (ILD)
–and the Interaural Time Difference (ITD)
–Experiments with sine tones show that ITD is not useful above 2kHz due to frequency limits on nerve firings.
–And that ILD loses accuracy below 1kHz as head shadowing decreases.
•But high harmonics in the 1kHz to 4kHz range of low frequency fundamentals contain nearly all the information of speech
–And also provide timbre cues that identify musical instruments.
–When these harmonics are present we find that we can localize tones accurately with ILD
–
•To understand our ability to localize speech and music we need to use signals that include harmonics
–When harmonics are present our ability to localize can be extremely acute, +-2 degrees or better
From the author’s seat in row F behind the lady in red the string quartet was +-10 degrees in width.
But in the presence of substantial reverberation it was possible to distinctly localize all four players with eyes closed, even when they played together.
This implies a localization acuity of better than three degrees. With just slightly more reverberation it was not possible to localize the musicians at all.
Localizing separated sounds in natural hearing
•It is well known that we localize sounds through:
–the Interaural Level Difference (ILD)
–and the Interaural Time Difference (ITD)
–Experiments with sine tones show that ITD is not useful above 2kHz due to frequency limits on nerve firings.
–And that ILD loses accuracy below 1kHz as head shadowing decreases.
•But high harmonics in the 1kHz to 4kHz range of low frequency fundamentals contain nearly all the information of speech
–And also provide timbre cues that identify musical instruments.
–When these harmonics are present we find that we can localize tones accurately with ILD
–
•To understand our ability to localize speech and music we need to use signals that include harmonics
–When harmonics are present our ability to localize can be extremely acute, +-2 degrees or better