The frequency regularity of the spike anomolies suggests that they are the result of externally induced fields or the result of parasitic signals in the test equipment itself. A wider bandwidth cable might be more susceptable to them than one with deliberatly high shunt capacitance. Shielding from externally induced fields can be substantially improved by adding a bare drain wire and a foil wrap. That's how many of the best cables are shielded. Generally the industry reference standard for comparison is not RS but Belden. However, in recent years I've switched away from RS. My customary source these days is The Dollar Store.
The frequency regularity of the spike anomolies suggests that they are the result of externally induced fields or the result of parasitic signals in the test equipment itself. A wider bandwidth cable might be more susceptable to them than one with deliberatly high shunt capacitance. Shielding from externally induced fields can be substantially improved by adding a bare drain wire and a foil wrap. That's how many of the best cables are shielded. Generally the industry reference standard for comparison is not RS but Belden. However, in recent years I've switched away from RS. My customary source these days is The Dollar Store.
So then you're measuring shield effectiveness and not distortion or noise floor?
Why measure a cable in such an enviorment?
Agreed, my point exactly. The test is defective because it does not isolate two entirely different variables. There is no way to know what the results actually mean. Disappointing, especially considering the source.
To quote Wikipedia "[citation needed]."
This whole section sounds like speculation and nostalgia. Are you presenting it as fact, or merely your conjecture and musing? Both are welcome, but it's helpful if they are clearly identified. Thanks.
The frequency regularity of the spike anomolies suggests that they are the result of externally induced fields or the result of parasitic signals in the test equipment itself. A wider bandwidth cable might be more susceptable to them than one with deliberatly high shunt capacitance. Shielding from externally induced fields can be substantially improved by adding a bare drain wire and a foil wrap. That's how many of the best cables are shielded. Generally the industry reference standard for comparison is not RS but Belden. However, in recent years I've switched away from RS. My customary source these days is The Dollar Store.
I remember when RS first began, they were like a dollar store and were called "Radio Spares" and carried all sorts of bin end stuff.
Wrinkle
It took me a while to finally get enough information out of John to figure it out, but the noise floor is around -120dB.
se
No indication of which part of the universe is your home, but a common mix-up is between RS = radioshack in the US and (what was) Radiospares in the UK.
Rs (US) branded iteself as Tandy in the UK - now displaced by Maplins, ISTM, who are also rapidly going down the pan.
Back OT!
Steve,
Actually I think John got this wrong! The ST should be capable of a 100db distortion reading minimum and from those nice pictures you posted the test tone was reading about -45 so at minimum spec' the noise level is -120 to -125 as you concluded.
But I suspect the null really is 120db or more! Which is what the notch filter section by itself in an ST can do. That would put his spikes at -140 or lower.
So why don't you drop by his place and check out how deep the null really is.
I was impressed by the null used with the AP measurements. Those nulls were -150 ish!
By the way your number didn't win the lottery yesterday!
ES
What do you think the term "high fidelity" means? fidelity to what? The goal was clear. So were the shortcomings. Today there is a pretense that they don't exist. But the emperor has no clothes. At least not to those who are old enough to remember what it was like before the age of me-too ism took hold. I don't think there has been a single truly innovative idea in this industry in nearly thirty years.
Then how could he have claimed that in the best cable he measured that the distortion of the seventh harmonic of five kilohertz was -135 db? That's orders of magnitude lower. At the time he reported it, he said the $1 RS cable was down only 120 db. I took his word for it then. Was he wrong then or is he wrong now? Or is there a way to reconcile this?
Pavel,
You just asked the best question that came out of my results. (A few others did ask it also.)
The results are the same with or without the Faraday shield.
But what I did not do was use the same connectors and swap the actual wires around.
As I have learned a lot since I did those test, I will probably revist them, but right now things are a bit too busy to spend the weeks it would take.
ES
If the middle graph is correct, then when I turn up the gain to +70 db I should hear a whole series of distinct tones with peaks of nearly 30 db between 500 hz and 1 Khz when there is no source signal to mask it. I should also hear tones of distinct frequencies across the audio band as well, not just pink or white random noise. But I don't. Why do you suppose that is true? Maybe my Tru-sonic Dollar Store cables are better than RS....and the ones in the other two graphs as well which have the same tones to a lesser degree. Or the graphs are not representative of what is actualy happening. Doesn't it seem strange that all of the cables show the same noise signals at the same frequencies even if their amplitudes are different?
The tests told me nothing I could hold of value. The only legitimate test I can think of is an A/B test against a shunt. If a shunt sounds identical then the cable is performing perfectly. It's doing exacly what it is supposed to do. At what point is low noise low enough? In the audiophile way of thinking as I've come to understand it, that point doesn't exist. The only other considerations for me would be reliability related to quality of build and cost.
Once again, I doubt any 'cable harmonic distortion'. Let me show you another example. It is an output from SACD player, playing -120dBFS test signal. The analog output is amplified +60dB. Look at the plot. You can see base frequency, noise floor (both amplified +60dB), and some player artifacts, again amplified +60dB. No 'cable distortion'.
Attachments
Surely you ask a rhetorical question. With the results as shown, there should be an immediate alarm bell and the measurement discarded.
Don't know why people still show this without a trace of embarassement....
jan didden
Surely you ask a rhetorical question. With the results as shown, there should be an immediate alarm bell and the measurement discarded.
Don't know why people still show this without a trace of embarassement....
jan didden
Yes but people get angry when I simply and overtly state the obvious. These kinds of postings say worlds about those who present them or fail to challenge them, little if anything about the topic at hand. Critical thinking seems to be a dying art and those who practice it are not merely out of favor but condemned for their blasphemy. We are supposed to take everything we read at face value especially if it is attributed to someone who is famous.
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