On the contrary- that's precisely what's being done here. We call that "signal averaging." At 256 samples, you're reducing the residual noise floor to pick out signals by a factor of 16. And the residual floor with that number of averaged samples is an order of magnitude below what John is reporting so is certainly more than adequate to see any phenomena at the level he reports.
The results don't scale with length, though that should be repeated (and I hope to do so with John's setup) with the same cable at different lengths.
SY said:
To add to that SY, what sets the noise floor is measurement bandwidth. Concerning the AP it is sample frequency versus FFT length. Although the kind of windowing plays also a role (makes the effective measurement bandwidth somewhat wider in general).
The advantage of synchronous measuring AND averaging is that it lowers (averages out) all non-signal related noise, including mains hum. In the case of 256 averages indeed 16 times. It has a same effect on noise floor as extra narrowing of measurement bandwidth.
Cheers
I followed a link on AA to this thread and ended up lost of over an hour reading this and other previous ones on the same topic. I really don't understand the passion and anger aroused by whether or not miniscule distortions do or don't exist in cables except for the fact the no one likes to be wrong and will defend their position even in the face of evidence to the contrary. I personally don't believe wires cause non linear distortions but I haven't spent any time trying to prove it. Most if not all DBT has shown that cable effects are insignificant or do not exist at the level of audibility. I had a heated discussion at AA with Mr Curl about Bybee devices that ended up with agreeing to disagree and respecting each others position. Anytime we are measuring near the limit of the measuring equipments capabilities the measurements are suspect and must be taken carefully and repeated by more than one person's setup to be considered factual IMO. I think it is entirely possible that John's measurements reflect distortion in the test gear that are influenced by the cable loading and appear to be in the cable. It is also possible that his measurements are real. At no time in human history have we possessed the complete knowledge of anything. All passive devices exhibit behavior that departs from the theoretical ideal. It is unlikely that wires are different. It is also likely that current knowledge about such behaviors is not complete. Whenever I refuse to believe in the possibility of things that are contrary to my current understanding, I have stopped learning.
"There is a principle which is a bar against all information, which is proof against all arguments and which cannot fail to keep a man in everlasting ignorance -- that principle is contempt prior to investigation."
H. Spencer
"There is a principle which is a bar against all information, which is proof against all arguments and which cannot fail to keep a man in everlasting ignorance -- that principle is contempt prior to investigation."
H. Spencer
Re: Why The Differences In the Graphs ?..........
Correlated to what?
Where has it been established that changing hte level by 0.5dB over a 1/3 octave bandwidth is clearly audible? And please, no amusing anecdotes.
What variation?
Sorry, this thread isn't for empty claims and amusing anecdotes.
And what has the fact that no one to date has yet demonstrated actual audibility of cable direction lead you to think?
Yes, it's fully up to the task of measuring high order distortion products at the levels John has been measuring. In fact, it's more than up to that task as again, the AP's measuring a good 20 dB below where John's able to measure.
Stuart has already set you straight on this one.
But this "irrefutable evidence" has yet to be presented.
Talk is cheap.
Wake me up when someone has something more than empty claims and amusing anecdotes to offer.
se
mrfeedback said:
Correlated to what?
Where has it been established that changing hte level by 0.5dB over a 1/3 octave bandwidth is clearly audible? And please, no amusing anecdotes.
What variation?
Sorry, this thread isn't for empty claims and amusing anecdotes.
And what has the fact that no one to date has yet demonstrated actual audibility of cable direction lead you to think?
Yes, it's fully up to the task of measuring high order distortion products at the levels John has been measuring. In fact, it's more than up to that task as again, the AP's measuring a good 20 dB below where John's able to measure.
Stuart has already set you straight on this one.
But this "irrefutable evidence" has yet to be presented.
Talk is cheap.
Wake me up when someone has something more than empty claims and amusing anecdotes to offer.
se
janneman said:
Nope. That wasn't the original purpose at all.
The original purpose dates back to February 2002 when I first saw John's plots of what he was claiming to be distortion produced by cables.
I'd never believed that cables couldn't produce any distortion at all at any level. What I had doubts of was that the distortion John was measuring, at the levels he was measuring it (higher than some amplifiers) was being produced by the cables as he claimed it to be.
When I questioned John's measurements, he told me:
Steve, you are an insolent fool. You have NOT shown anything! Either seriously attempt to duplicate my results, or find another sandbox to play in.
So what this has been about is seriously attempting to duplicate John's results.
While exploring possible cable distortions in general is interesting, that is not what either of these two threads which I started were intended to address.
So if we want to discuss that topic, let's open a different thread.
That's fine except for the fact that that wasn't the original question.
se
From a scientific point of view (once again ), I am inclined to
agree with Eric that the test should ideally be done with cables
tried in both directions. Some people claim cables to be directed
so if that is actually the case, we cannot rule out the distorsion
being different depending on direction until we have measured
whether it is or not. The tests so far has probably not been
extensive enough to rule out the statistical possibility of Bruno
measuring all cables in the "right" direction and Johns measuring
them in "mixed" directions.
SY,
your previous comment on scaling seems reasonable, but it does
rely on the assumption that distorsion is proportional or at
least a monotonic function of cable length. Although it seems
reasonable to assume that, it may still be an assumption we
shoudln't make. Since we don't know what causes the distorsion
if it is there at all, we also don't really know if that assumption
holds. One possibility could be that the distorsion is caused
in the connector-cable junctions and different cables give
different distorsion here.
), I am inclined toagree with Eric that the test should ideally be done with cables
tried in both directions. Some people claim cables to be directed
so if that is actually the case, we cannot rule out the distorsion
being different depending on direction until we have measured
whether it is or not. The tests so far has probably not been
extensive enough to rule out the statistical possibility of Bruno
measuring all cables in the "right" direction and Johns measuring
them in "mixed" directions.
SY,
your previous comment on scaling seems reasonable, but it does
rely on the assumption that distorsion is proportional or at
least a monotonic function of cable length. Although it seems
reasonable to assume that, it may still be an assumption we
shoudln't make. Since we don't know what causes the distorsion
if it is there at all, we also don't really know if that assumption
holds. One possibility could be that the distorsion is caused
in the connector-cable junctions and different cables give
different distorsion here.
Christer said:From a scientific point of view (once again
agree with Eric that the test should ideally be done with cables
tried in both directions. Some people claim cables to be directed
so if that is actually the case, we cannot rule out the distorsion
being different depending on direction until we have measured
whether it is or not. The tests so far has probably not been
extensive enough to rule out the statistical possibility of Bruno
measuring all cables in the "right" direction and Johns measuring
them in "mixed" directions.
Huh? Even if John's measuring them in "mixed" directions, John's measuring distortion in ALL of the cables I sent him at levels more than 20dB above where the noise floor is in the AP plots. Higher even than the AP's third harmonic residual. So even if Bruno measured the cables in the "right" direction, if the distortion John's measuring even with the cables in the "right" direction is being produced by the cables, we should see high-order distortion products well above the AP's third harmonic residual.
se
Absolutely valid point. So, if true, that means that whatever the mechanism, it's not the wires. IOW, if it doesn't scale, it's some other factor, whether the test set, the plugs, the jacks, external noise, whatever. If it does scale, it's more likely the wires, assuming one does proper controls to exclude increased noise pickup from a larger or smaller loop.
Now go to bed!
Who Listens To Sinewaves ?...............
"Where has it been established that changing the level by 0.5dB over a 1/3 octave bandwidth is clearly audible? And please, no amusing anecdotes."
The other night I did exactly this to the FOH 31 Hz graphic eq fader, and my colleage responded immediately by asking what I did - " That's sitting much better now ! - What did you just move ?"
Go and do some live sound mixing and you will find out quick smart.
While you are at it, try changing foldback eq settings by 0.5 dB and see what happens.
"What variation?"
I said 'possible variation'.
"Sorry, this thread isn't for empty claims and amusing anecdotes."
How about you try this for yourself - the fact that I have encountered this effect many times with speaker wires shows me that there is something going on at system amplifier/speaker level at least.
"And what has the fact that no one to date has yet demonstrated actual audibility of cable direction lead you to think?"
This leads me to believe that the appropriate tests have not been performed correctly yet.
I believe Frank, you and I are co-operating on this, but of course this is not possible until we get the sample set of wires/cables concerned - have they been posted to Frank and I yet ?.
"But this "irrefutable evidence" has yet to be presented."
I assume that this finding has shown up in the TDR testing that Fred and Jocko get into.
You should politely ask them to share what they have found.
The AP test set is showing load dependency according to the graphs.
These test loads are purely resistive, and not properly representative of a typical stereo system that is exhibiting changes according to cable type and direction.
Secondly sine-wave THD testing is a steady state single frequency tone and is not fully representative of dynamic and directional music waveforms.
"Talk is cheap."
And auto nay saying is beneath this - Steve, several of us are saying that we are hearing cable sonics and directional differences in systems.
That the testing described is not showing these up merely leads me to believing that the testing is not fully appropriate to show up these observed differences.
Eric.
"Where has it been established that changing the level by 0.5dB over a 1/3 octave bandwidth is clearly audible? And please, no amusing anecdotes."
The other night I did exactly this to the FOH 31 Hz graphic eq fader, and my colleage responded immediately by asking what I did - " That's sitting much better now ! - What did you just move ?"
Go and do some live sound mixing and you will find out quick smart.
While you are at it, try changing foldback eq settings by 0.5 dB and see what happens.
"What variation?"
I said 'possible variation'.
"Sorry, this thread isn't for empty claims and amusing anecdotes."
How about you try this for yourself - the fact that I have encountered this effect many times with speaker wires shows me that there is something going on at system amplifier/speaker level at least.
"And what has the fact that no one to date has yet demonstrated actual audibility of cable direction lead you to think?"
This leads me to believe that the appropriate tests have not been performed correctly yet.
I believe Frank, you and I are co-operating on this, but of course this is not possible until we get the sample set of wires/cables concerned - have they been posted to Frank and I yet ?.
"But this "irrefutable evidence" has yet to be presented."
I assume that this finding has shown up in the TDR testing that Fred and Jocko get into.
You should politely ask them to share what they have found.
The AP test set is showing load dependency according to the graphs.
These test loads are purely resistive, and not properly representative of a typical stereo system that is exhibiting changes according to cable type and direction.
Secondly sine-wave THD testing is a steady state single frequency tone and is not fully representative of dynamic and directional music waveforms.
"Talk is cheap."
And auto nay saying is beneath this - Steve, several of us are saying that we are hearing cable sonics and directional differences in systems.
That the testing described is not showing these up merely leads me to believing that the testing is not fully appropriate to show up these observed differences.
Eric.
Re: Who Listens To Sinewaves ?...............
Amusing anecdotes are a dime a dozen, Eric. You're on no firmer ground than the amusing anecdotes of photographs in freezers.
Ok, possible variation of what?
Great. So go start a thread about it instead of trying to hijack this one.
Great. So go start a thread about it instead of trying to hijack this one.
Frank's had his for weeks now. As for yours, ask SY. He's the one who's sending them out to you.
It's your assumption. You ask them.
But what's it have to do with the subject of this thread?
What load dependency are you talking about?
And what's it have to do with the subject of this thread?
Exactly how are the loads any different?
And again, what's this have to do with the subject of this thread?
So? What's that have to do with the subject of this thread? The distortion John was measuring he was measuring with steady state sinewaves.
What auto nay saying are you speaking of? I've not done any naysaying, auto or otherwise.
And again, what's this to do with this thread?
So what? That has absolutely nothing to do with this thread.
For the last time, these tests weren't intended to do anything other than try and replicate John's results. Which is what this thread is all about.
Please stop trying to hijack this thread. If you want to discuss those other issues, start a new thread.
se
mrfeedback said:
Amusing anecdotes are a dime a dozen, Eric. You're on no firmer ground than the amusing anecdotes of photographs in freezers.
Ok, possible variation of what?
Great. So go start a thread about it instead of trying to hijack this one.
Great. So go start a thread about it instead of trying to hijack this one.
Frank's had his for weeks now. As for yours, ask SY. He's the one who's sending them out to you.
It's your assumption. You ask them.
But what's it have to do with the subject of this thread?
What load dependency are you talking about?
And what's it have to do with the subject of this thread?
Exactly how are the loads any different?
And again, what's this have to do with the subject of this thread?
So? What's that have to do with the subject of this thread? The distortion John was measuring he was measuring with steady state sinewaves.
What auto nay saying are you speaking of? I've not done any naysaying, auto or otherwise.
And again, what's this to do with this thread?
So what? That has absolutely nothing to do with this thread.
For the last time, these tests weren't intended to do anything other than try and replicate John's results. Which is what this thread is all about.
Please stop trying to hijack this thread. If you want to discuss those other issues, start a new thread.
se
johnferrier said:
I suppose that could be considered some sort of "closure" in a peripheral sort of way. Though not something I've any particular interest in. My interest was in trying to determine whether or not cables were routinely producing distortion on the order of what John was measuring and attributing to the cables.
It's become rather apparent that they're not. Why John's 1700B is behaving the way it is and producing the levels of distortion that it is is John's problem, not mine.
se
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