questionable interpretations of how things work
@theaudioamp You're new here. What an insulting statement.
@jea48 's knowledge and advice is above reproach. Jim's interest and expertise has helped solve the issues of many members over the years. In order to troubleshoot, one must ask questions.
I wholeheartedly agree that the receptacles have not had breakin time. A Rhodium duplex takes 200 to 400hrs. of run-in time. Manufacturers such as Furutech state this requirement.
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Jim, ( @lowrider57 ) ,
Thanks for the kind words.
Jim
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@theaudioamp You’re new here. What an insulting statement.
And you don’t read well. My comment was not to the person who posted the link, obviously, but to the person who put on the non-peer reviewed presentation to the AES that was linked. There are absolutely some questionable things in that presentation that would not stand up to scrutiny. Questioning the accuracy of what someone links to is not rude, and being here for a long time does not make your posts any more accurate than anyone else and immune to criticism. This is not a professional forum where the accuracy of someone’s posts are validated by equally qualified people.
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but to the person who put on the non-peer reviewed presentation to the AES that was linked. There are absolutely some questionable things in that presentation that would not stand up to scrutiny.
@theaudioamp
Please point out the questionable things.
Jim
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At higher frequencies, where inductance dominates, using thicker wire has virtually noeffect on impedance. At 1 MHz, replacing the #12 wire with a ½” solid copper rod has little effect (as noted in the plot).
- Misleading and erroneous in the framework of the discussion. For a single wire, in free space, this is true. However, we don't use wires in free space, we use conductors. For a given insulation thickness, increasing wire diameter reduces inductance by increasing area between the two wires. For instance, 2mm wire, with 1mm insulation (4mm on centers) would have about 50uH/meter inductance. If I increase the diameter to 10mm, but keep the same insulation thickness, the inductance
Conduit Transformer (Voltage is directly proportional to load current, wire length, and rate of change in current or ∆I/∆t)
- For a transformer company, I would have hoped they understood transformers better. If you look at their drawing, the output of the transformer is 1.5K in series into a volt-meter, with a 2.2nF load. Essentially that is an open circuit. If it is a transformer, the open loop output voltage of a transformer is independent of the frequency. i.e. in their experiment, the output voltage should not have changed with frequency. If they had shorted the output (very low resistance), then the output voltage would be affected by frequency. They didn't, so their experimental results do not match their proposed transformer model.
- What would match their model? -- parasitic capacitance. I expect there are aspects of both. Either way, their experiment is flawed which means any conclusions are suspect.
They assign the source of all noise to this "conduit transformer" and discuss lamp dimmers. The also say leakage current are very small as a partial justification of this. Use a 2.2nF capacitor as an example
- At 60Hz, impedance = 1.2M ohm
- at 70KHz, impedance = 1000 ohms
When you swing 120V (or 220) with 1000 ohms impedance, you can no longer claim low leakage current. Parasitic capacitance provides a nice path for noise in the line/neutral to get into the ground.
- As a point of discussion, a dimmer can also generate audible noise in an audio device with no ground connection.
- 90 degree conduction angle for a dimmer is 50% voltage, not 50% brightness. I think it is closer to 10%. Yes, I am being intentionally pedantic.
For most cord connected equipment, 2 or 3 prong, the leakage limit is 0.5mA and 0.75mA, but again, that is pedantic to the discussion. I am just illustrating a trend.
Even installing a “cheater” (3-to-2 prong adapter) or cutting off a safety ground pin from one of the power cords would still leave as much as 3.5 mA flowing in the interface cable ... that’s 10 times the current of the previous 2-prong example, so a serious noise problem would still exist ... as well as a much more serious safety hazard!
- Both unlikely to due real limits on leakage in 3 prong audio equipment, and practically wrong as well. How many ground loops have been eliminated by clipping a ground pin? The reason is the configuration of EMI filter capacitors and typical parasitics causing case ground to now be equipotential between line/neutral and little current to flow through the capacitors into chassis ground. However, don't disconnect the safety ground. It is a bad idea.
Zcm tolerance of real-world drivers typically determined by ± 5%
series resistors and ± 20% (or worse) coupling capacitors
- Appropriate for this point is that the tolerance of the coupling capacitors is only important w.r.t. the impedance at the frequency of interest. i.e. in audio, at 60Hz, we would typically ensure the capacitance is large enough, so that the impedance is low enough that tolerance is not a significant factor. 20% of 0 is still 0 (exaggerating obviously).
Strange that cable manufacturers still don’t “get it” ... they seem to think “floobydust” is more important.
- I don't have any issue with this. I just think it is funny. I like them even if I disagree with some of what they say. I think the discussion on cables is really good. I think most cable vendors could learn something from it.
Keep cables short and do not coil the excess
- The reason for not coiling is due to coupling of external magnetic fields into the cable. While obviously this is 100% true for a single wire, a coiled cable is a common mode inductor so will reject most external magnetic fields.
- I will give the benefit of the doubt for any cable with a double terminated shield as that would be worse coiled.
Page 150
- This absolutely could provide benefit. It all comes down to implementation. If a short RCA is used between the single ended equipment and the transformer, then effectively there is no ground voltage on the single ended side to cause a ground loop noise issue even if high current flows in the ground.
Page 202
- While technically true, in most equipment, the capacitors are not parasitic but intentional for emi and noise.
Page 211
- Accuses others of fear mongering while doing some himself. Any half decent designed equipment has ESD and similar protection on I/O lines. Since the I/O lines are high impedance w.r.t. ground, the protection circuitry limits the excursion for the required amount of time.
Page 212
- Series suppressors do dump current into the safety ground, they just do not dump as much. Simple logic should reveal that. If the inductor is connected to an open circuit, the full voltage is transmitted. Hence there must be a low impedance path for the current.
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