I don't know those guys, i make my own measurements with the real cables on long distances.
When it is about symmetrical cabling, the first important thing is EMI/RFI protection. Then, ground loops (racks) and AC leakages. Never forget that you have >60db common mode rejection, reason why symmetrical is 1000X better.
We compared this one with 5 others and it was our choice. Now, make measurments on *this* cable, to prove *this* cable have poor symmetry:. You will be very surprised
All this controversy is like talking about -140dB distortion.
Now, the reason why this cable does not suffer from the 'current centroid asymmetry* is the foils has less Z than the drain, and the *twisted pair* VS strait drain *null* any remaining asymmetry.
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No, that would be two words.
Greater than 25 meters? What, are you wiring up a small concert hall or something?
se
I really enjoyed his remark "electrons don’t care and they don’t read schematics!", which may have been a quote from D. Gerke and W. Kimmel in the references.
Video has changed since 2005, (in ways that only increase the importance of low inter-equipment "ground" voltages), and jneutron's thoughts about proximity of AC power and signal wiring has refined my viewpoint, but that's still a terrific paper. And very accessible.
Thanks,
Chris
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I have given talks back to back with B.Whitlock and other talks with ac power designers. [And, worked for years in the ac power field for high power experimental machines.] Anyway, in both cases I thought they knew thier stuff as they did about me. But I never heard anything new... that is to say, something that I had not read or seen in practice elsewhere before.. a generation earlier. His patent(s) not withstanding.
Recycling info is important to do. There are many good technical books on the subject.... Bill W. has foot noted and referred to many of them for his material. He is an excellent teacher of the subject. Thx-RNMarsh
Recycling info is important to do. There are many good technical books on the subject.... Bill W. has foot noted and referred to many of them for his material. He is an excellent teacher of the subject. Thx-RNMarsh
About ground loop problems, and noise induced in connections, the first thing i do, when i build any system, is to find the good AC sens of any equipment, to minimize the Ac leakage between us.
We gone work with a dedicated AC distributor for our Hifi equipment. We need access to the cabling of the AC power plugs in-it.
CAUTION of electric shocks: isolate yourself, and do not touch any chassis or wire with hands, while you do it. When you do any wiring operation, unplug the distributor from the wall. Remember you play with your life, verify there is not AC twice before to touch anything including chassis. Each time you will connect the signal cables between equipment, disconnect the distributor from the wall.
Remove the earth wire from the AC plug in the distributor where you will connect your preamp and plug the power of your preamp (or the equipment where all signal connections comes in) in the distributor,.
Measure the Voltage between it and the disconnected earth wire. Change the sens of the 2 AC wires in your distributor for this plug, and measure again. Chose the sens where you have less AC leakage between the earth pin and the earth wire ( reading your voltmeter). Reconnect the earth of this plug in your distributor and mark the plug for this device.
Now, plug AC of your second equipment, don't connect the signal cables, while disconnecting the earth wire inside the AC distributor. Measure the leakage between the pin earth and the wire's earth (or between the chassis) find the best AC sens to minimize the voltage between them. Reconnect the earth wire in your AC distributor. Mark your plug for this device. disconnect the distributor from the wall.
Connect the devices and connect the signal cords between them. reconnect the distributor in the wall.
Do the same for each device, one after the other.
When everything is connected and grounded, you can do the same operation between the main earth and the earth of the wall outlet.
Now your system is optimized for the less AC leakages between the equipments, means signals as clean as possible in your situation.
We gone work with a dedicated AC distributor for our Hifi equipment. We need access to the cabling of the AC power plugs in-it.
CAUTION of electric shocks: isolate yourself, and do not touch any chassis or wire with hands, while you do it. When you do any wiring operation, unplug the distributor from the wall. Remember you play with your life, verify there is not AC twice before to touch anything including chassis. Each time you will connect the signal cables between equipment, disconnect the distributor from the wall.
Remove the earth wire from the AC plug in the distributor where you will connect your preamp and plug the power of your preamp (or the equipment where all signal connections comes in) in the distributor,.
Measure the Voltage between it and the disconnected earth wire. Change the sens of the 2 AC wires in your distributor for this plug, and measure again. Chose the sens where you have less AC leakage between the earth pin and the earth wire ( reading your voltmeter). Reconnect the earth of this plug in your distributor and mark the plug for this device.
Now, plug AC of your second equipment, don't connect the signal cables, while disconnecting the earth wire inside the AC distributor. Measure the leakage between the pin earth and the wire's earth (or between the chassis) find the best AC sens to minimize the voltage between them. Reconnect the earth wire in your AC distributor. Mark your plug for this device. disconnect the distributor from the wall.
Connect the devices and connect the signal cords between them. reconnect the distributor in the wall.
Do the same for each device, one after the other.
When everything is connected and grounded, you can do the same operation between the main earth and the earth of the wall outlet.
Now your system is optimized for the less AC leakages between the equipments, means signals as clean as possible in your situation.
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An other and safer method to do it is to use 2 distributors.The second will be plugged in the first one, in such a way that the power AC wires will be inverted. You will plug you devices alternatively in each distributor, and measure the leakages between the chassis to chose the AC distributor with the less leakage for the device.
Actually, what he stated was correct. Indeed, it is not possible to have a twisted diff cable where the shield centroid is coincident with the signal centroid at audio frequencies. As one climbs into the Mhz area, the hf will try to overlap the centroids, but that requires conductivity around the entire cable. Foil may be adequate, I don't know. However, the twisted pair will share a common centroid by integration along the cable length.
If you were trying to troubleshoot a pin one problem in an audio system, it would be more significant than -140dB.
Actually, as described, the shield current would redistribute at hf, so signal containment in both directions (inward or outward) would be complete.
jn
I don't know how you do things over in France, but over here, you should NEVER change the sense of the AC mains hot and neutral.
They should always be wired like this:
se
Finally, some common sense about ground leakage! That is another 'tweak' that we did with the Parasound JC-1 when we designed it. As it has multiple transformers, we oriented each transformer to be lowest leakage when the power cable was connected normally. This is different from the HCA3500, that did NOT have properly oriented transformers. It was one of the first things that we changed.
Just another 'tweak' to get best performance. Interestingly enough, Hi Fi books from the '50's used to suggest the same thing. It was easier then, with just two leads, and no 3'rd wire ground, at the time.
Just another 'tweak' to get best performance. Interestingly enough, Hi Fi books from the '50's used to suggest the same thing. It was easier then, with just two leads, and no 3'rd wire ground, at the time.
Especially when the electricians have wired your lab benches with alternate phases of 220.
What is the practice with those two round prongs that go in either way?
If you consider swapping hot and neutral at the AC mains outlet to be "common sense," you should get out of the business.
And in the 50's, it was common to wire the equipment chassis to neutral. So yeah, now let's go and flip the plug around on one piece of equipment.
*sigh*
se
I don't know how you do things over in France, but over here, you should NEVER change the sense of the AC mains hot and neutral.
They should always be wired like this:
se
What he is talking about is the winding closest to the transformer core should be connected to the neutral. To conform to code this should be corrected inside the piece of gear.
Most transformers pay no attention to which primary wire is the winding start.
I do have a sample of a Chinese R core power transformer where the 120 Volt hot lead is color coded green!!!!
The other issue is the use of Belden 1023A cable. It is a shielded twisted pair with a foil shield. HOWEVER one conductor is copper the other is constantan! It is intended to attach to thermocouple and not introduce any voltage errors.
Actually I think it is the leakage to the core that is more of a concern.
Yes, but he wasn't talking about doing it inside the piece of gear. He was talking about doing it at the AC outlet.
Not surprising. A Chinese amp and DAC maker (Audio g-d) was shipping his gear with power cords that had the hot and neutral reversed.
se
In the '50's and '60's, almost all hi fi and other appliance AC plugs were just 2 and NOT 3. AND they were NOT polarized.
I worked at UL Labs, about 50 years ago, for about 1 year as a test tech. Which way you plugged in the plug just was not a concern at the time. So many 'far fetched' conditions had to occur before any serious injury, that extreme measures did not seem to be important enough to consider. You could even suffer a mild 'shock' from a guitar amp, for example, and it was considered OK, so long as it could not be fatal. Of course 3 prong plugs existed in restaurant appliances and such, when exposure to water and water pipes was much more common.
Later, plugs became polarized, and then 3 prong plugs became more standard, especially with metal cased audio equipment.
The most dangerous appliance I have seen in today's world is a toaster.
I worked at UL Labs, about 50 years ago, for about 1 year as a test tech. Which way you plugged in the plug just was not a concern at the time. So many 'far fetched' conditions had to occur before any serious injury, that extreme measures did not seem to be important enough to consider. You could even suffer a mild 'shock' from a guitar amp, for example, and it was considered OK, so long as it could not be fatal. Of course 3 prong plugs existed in restaurant appliances and such, when exposure to water and water pipes was much more common.
Later, plugs became polarized, and then 3 prong plugs became more standard, especially with metal cased audio equipment.
The most dangerous appliance I have seen in today's world is a toaster.
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That's what i was trying to explain. Same thing if the two wires are strait and the drain symmetrically situated all the way.
Belden take care of those details, as, by example, the way wires are shielded, for they don't change their geometry when the cable is creased.
One other thing, i don't know if it is the metals used, (Coper, Constantan), but the sound is very neutral and detailed comparing the whole box length with a short circuit.
About the grounding tip, i suppose we have some norm about hot and neutral, never respected. But norm is severe with earths diameter and impedance. my suggestion was not to modify wall outlet, but what you call "Power distribution units" ? Right ?
An externally hosted image should be here but it was not working when we last tested it.
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