you don't have to.
You can use this simplified example in 2d space with straight lines
-
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Electromagnetic Interference in Speaker Cables? (video)
- Thread starter amirm
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You can use this simplified example in 2d space with straight lines
PM me I'll give you my PayPal.
Your want payment todo?
Better do a cured test and interpret the results so they fitt the preconceived ideas.
I mean that's what Danny did
.
Oh and don't forget to use argumentum ad hominem if someone is questioning the conclusions from the experiments.
what a bummer this would be actually an helpfully peace of evidence and somewhat "scientific" if someone could actually be bothered to do the math.
Better do a cured test and interpret the results so they fitt the preconceived ideas.
I mean that's what Danny did
.Oh and don't forget to use argumentum ad hominem if someone is questioning the conclusions from the experiments.
DualTriode
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Not a good test!
There was no current through that power cord.
It is really difficult to demonstrate inductive fields without current. (yes there is minimal current with no connected load, however nothing like having a load attached.)
Thanks DT
There was no current through that power cord.
It is really difficult to demonstrate inductive fields without current. (yes there is minimal current with no connected load, however nothing like having a load attached.)
Thanks DT
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If that extension cable you used coiled with the speaker wire was under load and had a current of a few amps in it the speaker wire would show a lot more pick up, right?
Darth Bubba
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Please consider reviewing the SMSL M200, and perhaps any SMSL DACs that have been upgraded (i.e., V2, MkII, etc.) since any previous review.
Darth Bubba
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Actually, if Amir had used cryogenically relieved speaker cable he would have measured a difference!
Remember, keep it fun!
Remember, keep it fun!
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Anyone interested in my Faraday sleeved speaker cables?
Kennyknetter
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Come to think of it, I have first hand experience with a much worse scenario than this.
I've installed the current speaker system at the gym that I work out at. The speaker cables have varying lengths between 20 and 30 meters. All the cables are laid out alongside the power cables for the lighting in the gym. That lighting draws about 5kw of power, and there are three long rows of lighting, so let's say that there is 1,7kw running along each line.
Now, what does 30m of speaker cable laid alongside 1,7kw of lighting sound like?
Nothing. Nothing at all.
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i watched a video in yotube once, where power cable and speaker cable where crossed like this + , and it was adviced that dont do that.. ( some lab video showing interference..)
dont remember was could it been audiable or anything but that was the config. that resulted the biggest interference...
dont remember was could it been audiable or anything but that was the config. that resulted the biggest interference...
Interesting. My guess is that if you substituted counter-rotated braided cables, and then visit the empty gym at midnight, and really concentrate, you could experience an entirely new level of nothingness, an infinite black chasm of silence that may redefine the nothing concept for eternity.
Plus, if you didn't experience that, at least the included rope would provide additional socially distanced aerobic exercise opportunities.
Invinoveritasty
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This has quickly become my favorite audio website. Amir is father every audiophool needed growing up, but never had. There are a lot of wire lickers out there ("Son, don't lick the wires...")
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Has to be a class A or tube amp for that warm sound.
Helicopter
Major Contributor
I like the 'concentrate alone at night' angle. Bad recordings with a high noise floor will make it easier to hear differences in the noise level compared to good non-noisy recordings. Sighted tests will also help.Interesting. My guess is that if you substituted counter-rotated braided cables, and then visit the empty gym at midnight, and really concentrate, you could experience an entirely new level of nothingness, an infinite black chasm of silence that may redefine the nothing concept for eternity.
Plus, if you didn't experience that, at least the included rope would provide additional socially distanced aerobic exercise opportunities.
Invinoveritasty
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Does this mean I can get away with fewer speaker cable risers?
Does this mean I can get away with fewer speaker cable risers?
No, it means that the noise is lower than previously thought and therefore reducing that last bit is even more important!
Darth Bubba
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Does this mean I can get away with fewer speaker cable risers?
No, you need the cable risers to get the music in the wire above the noise floor!
As I watched the video, the thought that I had is that I would have taken a somewhat different fundamental approach (not with the measurements per se). I would start by working out the minimal voltage required by a typical speaker in order to produce sound pressure that humans can hear. I would use this voltage threshold to assess whether the amount of noise picked up in speaker wires will be audible.
At the reference voltage of 2.83 V, SPL for a typical speaker will be about 85 dB. This information is found in most any ordinary plot of sensitivity vs. frequency (i.e., “frequency response”) for most any speaker that anyone has measured in the past half-century or more. It is also available in the spec sheet for any off-the-shelf driver. The 85 dB value is typical, and although there are notable exceptions, the great majority of commercially available speakers are within a few decibels of this value. What this means is that at this reference voltage, 2.83 V rms, the sound pressure from a typical speaker will be +85 dB relative to the threshold of audibility, for a young person with perfectly normal young-person hearing, and at frequency near the peak of our hearing sensitivity. (It means this partly because the standard reference value for sound pressure in decibels, which determines the 0 dB point, was chosen to be 20 uPa, which value had been deemed the threshold of audibility for sound pressure.)
Now we need to figure out the voltage corresponding to 0 dB, given that 2.83 V corresponds to 85 dB. In other words: what voltage is -85 dB relative to 2.83 V? We use this equation: -85 = 20 x LOG(V/2.83). Solving this equation for V, we have V = 2.83 x 10^(-85/20). The answer is 159 uV. Thus, in order for a typical loudspeaker to produce a sound that a young person with perfectly good hearing can hear, the RMS voltage presented to the speaker needs to be around 160 uV at least. You could probably be generous and call it 150 uV, but there isn’t any readily identifiable reason to make it lower than than this.
That’s a good start, but the sensitivity of our hearing is about -35 dB at 60 Hz compared to 1 kHz, in the peak-sensitivity range. This means that the voltage presented to the speaker at 60 Hz needs to be +35 dB relative to the voltage presented at 1 kHz, in order for the 60 Hz hum to be at or above the threshold of audibility. The equation we now want to use is: +35 = 20 x LOG(V/160E-6). Solving for V, we have V = 160E-6 x 10^(35/20). The answer is 9 mV. At 60 Hz, the signal to a typical speaker needs to be at least 9 mV in order for the 60 Hz hum to be loud enough to be heard by a young person with good hearing in ideal, quiet conditions.
Now comes these questions: What voltage did Amir measure? Did he take the measurement in a way that was realistic? The second question is difficult, and I’ll leave it for others to answer. As for the first question, the display on his analyzer indicated -130 db referenced to 4 Vrms. We can calculate the voltage by starting with this: -130 = 20 x LOG(V/4). Solving for V, we get this: V = 4 x 10^(-130/20). The answer is 1.3 uV (microvolt, or 1.3E-6 V). [There is another way to solve this, making use of the fact that each increment of +/- 6.02 dB corresponds to a doubling or halving of voltage. Since -130/6.02 = -21.6, the measured voltage is 4V / (2^21.6) = 1.3 uV.]
It is useful to use decibels to compare the measured value (1.3 uV) to the 9 mV threshold value. This: 20 x LOG(.0013 mV / 9 mV) = 20 x LOG(.00013). The voltage that Amir measured is -77 dB relative to the voltage for which a 60 Hz signal played through a typical speaker will just barely be audible.
At the reference voltage of 2.83 V, SPL for a typical speaker will be about 85 dB. This information is found in most any ordinary plot of sensitivity vs. frequency (i.e., “frequency response”) for most any speaker that anyone has measured in the past half-century or more. It is also available in the spec sheet for any off-the-shelf driver. The 85 dB value is typical, and although there are notable exceptions, the great majority of commercially available speakers are within a few decibels of this value. What this means is that at this reference voltage, 2.83 V rms, the sound pressure from a typical speaker will be +85 dB relative to the threshold of audibility, for a young person with perfectly normal young-person hearing, and at frequency near the peak of our hearing sensitivity. (It means this partly because the standard reference value for sound pressure in decibels, which determines the 0 dB point, was chosen to be 20 uPa, which value had been deemed the threshold of audibility for sound pressure.)
Now we need to figure out the voltage corresponding to 0 dB, given that 2.83 V corresponds to 85 dB. In other words: what voltage is -85 dB relative to 2.83 V? We use this equation: -85 = 20 x LOG(V/2.83). Solving this equation for V, we have V = 2.83 x 10^(-85/20). The answer is 159 uV. Thus, in order for a typical loudspeaker to produce a sound that a young person with perfectly good hearing can hear, the RMS voltage presented to the speaker needs to be around 160 uV at least. You could probably be generous and call it 150 uV, but there isn’t any readily identifiable reason to make it lower than than this.
That’s a good start, but the sensitivity of our hearing is about -35 dB at 60 Hz compared to 1 kHz, in the peak-sensitivity range. This means that the voltage presented to the speaker at 60 Hz needs to be +35 dB relative to the voltage presented at 1 kHz, in order for the 60 Hz hum to be at or above the threshold of audibility. The equation we now want to use is: +35 = 20 x LOG(V/160E-6). Solving for V, we have V = 160E-6 x 10^(35/20). The answer is 9 mV. At 60 Hz, the signal to a typical speaker needs to be at least 9 mV in order for the 60 Hz hum to be loud enough to be heard by a young person with good hearing in ideal, quiet conditions.
Now comes these questions: What voltage did Amir measure? Did he take the measurement in a way that was realistic? The second question is difficult, and I’ll leave it for others to answer. As for the first question, the display on his analyzer indicated -130 db referenced to 4 Vrms. We can calculate the voltage by starting with this: -130 = 20 x LOG(V/4). Solving for V, we get this: V = 4 x 10^(-130/20). The answer is 1.3 uV (microvolt, or 1.3E-6 V). [There is another way to solve this, making use of the fact that each increment of +/- 6.02 dB corresponds to a doubling or halving of voltage. Since -130/6.02 = -21.6, the measured voltage is 4V / (2^21.6) = 1.3 uV.]
It is useful to use decibels to compare the measured value (1.3 uV) to the 9 mV threshold value. This: 20 x LOG(.0013 mV / 9 mV) = 20 x LOG(.00013). The voltage that Amir measured is -77 dB relative to the voltage for which a 60 Hz signal played through a typical speaker will just barely be audible.
Hi @amirm
In one of your videos you mentioned an AC power transformer near analogue cables can measurably interfere with audio band.
And you showed it here (includes timestamp):
And you mentioned our threshold for hearing is very high at low frequency noise and the noise levels are low anyway.
But does the same AC transformer wand measurement also show changes over unshielded ethernet cable? For something like a Matrix Audio Element DAC with ethernet input?
Again, I'm not concerned about audibility but do you get a ~15dB increase in noise like you did with the generic (shielded) RCA interconnect?
In one of your videos you mentioned an AC power transformer near analogue cables can measurably interfere with audio band.
And you showed it here (includes timestamp):
And you mentioned our threshold for hearing is very high at low frequency noise and the noise levels are low anyway.
But does the same AC transformer wand measurement also show changes over unshielded ethernet cable? For something like a Matrix Audio Element DAC with ethernet input?
Again, I'm not concerned about audibility but do you get a ~15dB increase in noise like you did with the generic (shielded) RCA interconnect?
Helicopter
Major Contributor
Yeah, but like with my suggestions on methodology, it is still a wash, and some simple math still shows you will not hear this stuff.
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