PMA said:
You're assuming I have RF here...not a valid assumption. The sun puts out RF, but I've never tried to check for it. There's not much else.
Grey
GRollins said:
Usually we ignore something we do not understand.
http://en.wikipedia.org/wiki/RF
the first link goes to
http://en.wikipedia.org/wiki/Radio_frequency
john curl said:Get him off me, SY!
Last I looked, this was a public forum, and I asked you a perfectly legitimate question.
se
PMA, this is a personal matter with SE, and it has been addressed in the past.
I spoke with Bruno (you know who he is don't you?) about it, and he and I have no problem between us over the measurements. Measuring NOTHING, is not measuring anything. It has no substance. Just like when ABX measures nulls. It means NOTHING.
I spoke with Bruno (you know who he is don't you?) about it, and he and I have no problem between us over the measurements. Measuring NOTHING, is not measuring anything. It has no substance. Just like when ABX measures nulls. It means NOTHING.
Then talk to him about it, and please read pp. 130-139 before asking me any more questions about this subject. It is too difficult to continually repeat myself and it gets old.
Steve Eddy said:
Yes, and he can answer or not, as he pleases. 😉
From what I understand of his point, John believes that the AP's grounding and isolation are artificially good, i.e., better than one will encounter with real-world high end products (which often have lousy grounding since they're designed by philosophers rather than engineers). So one potential mechanism for cable differences is eliminated from the test.
I think there's merit to that argument, which is why I listened to you and started using line level input transformers.
john curl said:
Probably. They contaminate line power, even from quite a distance. Rod Elliot has an article up about that. Certainly I've seen it in my own measurements- when I need to do something even remotely sensitive, I have to have every one of those bulbs in the house turned off. You live in an apartment, so you're going to be much worse off.
Engineers will have to spend much more time on line rejection issues than they have in the past, IMO.
john curl said:
Not personal at all.
You said "...we have had bad luck with AP setups, grounding issues I think."
It's not clear what you're saying when you say "bad luck." I simply asked you what you mean by this. You seem to be implying that the AP should be showing distortion but it's not because of grounding issues.
So again, what exactly do you mean when you say this?
No, not just like when ABX measures nulls.
You have claimed to have measured SOMETHING. Yet, when the same cables were measured on a system that's able to see more than 20dB below where you can see, it turned up NOTHING.
Unlike an ABX null result, that NOTHING does indeed mean SOMETHING. It meant the distortion you were seeing when you measured the same cables as Bruno did, was being produced by something other than the cables, contrary to what you had claimed and implied previously.
se
If those interested will turn to pp. 136-137 and read carefully, you will find that the questions now asked are repetitive and personal. Bruno is also mentioned.
SY said:
Some already stepped up to LED lights, also much nicer light than the awfull switchers.
john curl said:
Actually I think one could loop this thread back on itself and it could go on forever. What did Morbius say?, "10 raised literally to the power of infinity "
Nelson Pass said:
Thanks, Nelson. Good experiment. This is the outcome I expected, but it then suggests that if these two resistors are audibly different, the reason is for something which we are not measuring. The old X factor.
I'm guessing that the 0.0003% is the AP residual distortion. What was the test frequency?
Thanks!
Bob
jam said:
Hi Jam,
Are we talking speaker cables here, or interconnects?
It would also seem that each particpant should get two different cables, one sonically known good and one sonically known bad. That would allow for testing not only for possible distortion introduced by a cable, but, perhaps, more importantly, testing for discernable differences in cable distortion or other performance. That is what I liked about what Nelson did with the resistor; his conclusion was a differential conclusion not made too ambiguous by concerns about the performance of the test equipment.
If we are talking about possible distortion in speaker cables, it would seem that we must be driving them with a very low distortion power amplifier into at minimum an 8-ohm resistive load. Ideally the load would be a loudspeaker with a nasty load impedance characteristic, but then there would be concerns about allowable continuous testing power level and, of course, differences among the testers results due to the use of different loudspeakers. Another approach better than an 8-ohm resistive load would be a loudspeaker load model that everyone agreed upon. Maybe as a start, however, we need to settle on a 4-ohm resistive load. Just thinking out loud here.
Cheers,
Bob
SY said:
A realtime Frequency spectrum analyses program is a great tool to monitor the garbage during different periods of the day. I get all sorts of peaks ranging from 150 to 7900 to 12000, 18000 Hz at different times, sometimes 10 to 15dB above noise floor. Later in the evening, things get quite. That’s when I make recordings.
/Hugo
If your system can do that, you could try synchronous time domain averaging, which averages out anything that is not an exact FFT bin frequency if enough average periods are used. In case of hundredths of average periods, this also can increase reslution to 20...30dB below the noise floor. And you can use rectangular FFT windows, resulting in zero skirts around the spectral lines.Netlist said:
- Klaus
I'm not able to do that. fft is 8192 points and shows the peaks rather well. Are you aware of any such program?
Bob Cordell said:
Some of it was noise, the rest was residual distortion of the AP.
I looked at 20-20K, but that figure was 1 Khz.
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