I was wondering can anyone explain t me how a upgraded power cord can help? - Page 25 - AVS Forum
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post #721 of 969 Old 11-15-2011, 07:51 PM
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The power cord with the shells removed for easy acess. about 7 ft

Attachment 228112

Plugged into the overhead drop. about another 8 ft of SO hanging from the ceiling. The scope ground and probe shorted together.

Attachment 228113

The reading on the scope with the ground and probe shorted together.

Attachment 228115

The scope is connected across the ground wire the receiver is not plugged in to the cord yet.


Attachment 228116

The reveiver is now plugged in but the power swith on the receiver is not on.

Attachment 228117
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post #722 of 969 Old 11-15-2011, 08:04 PM
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The volume is turned up to the point of just short of breaking into distortion.

Attachment 228121

The set up

Attachment 228122

So this has about 15 ft of SO cable connected and I cannot see any visible signs of induce currents in the ground from the current conductors. The frequency was 5M Hz. Some even higher frequency hash. Voltage was varing between 2.7mv ans 3.0 mv. Hash riding on the fundamental was also varing.
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post #723 of 969 Old 11-15-2011, 08:46 PM
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Good grief Cruising. Can't you afford a better camera??? Maybe we can pass the hat and collect money for you . I stopped looking after the first two out of focus shots....

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post #724 of 969 Old 11-15-2011, 09:17 PM
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Quote:
Originally Posted by jneutron View Post

Actually, my concern is that by neglecting the human localization adaptation response time constant, differences can easily be missed. In essence, I am concerned that the test design is skewed unfairly towards finding no differences.

Wait, what test design? Surely you don't think that simply controlling a test necessitates this problem you imagine?

Quote:


One classic test is to put an ABX box in...
... introduction of the box removes the difference.

Then don't use ABX.

I fail to see how this rather narrow example effects my argument. Which leads me to conclude you simply misunderstood it.

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post #725 of 969 Old 11-15-2011, 09:21 PM
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Originally Posted by amirm View Post

Good grief Cruising. Can't you afford a better camera??? Maybe we can pass the hat and collect money for you . I stopped looking after the first two out of focus shots....

Thanks for the offer. What brand and model do you have in mind?
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post #726 of 969 Old 11-15-2011, 09:27 PM
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Originally Posted by Just cruising View Post

Thanks for the offer. What brand and model do you have in mind?

I think a pinhole camera would be an improvement

Seriously, holding the camera/phone parallel to the subject will maximize depth of field. And be mindful of minimum focusing distance.

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post #727 of 969 Old 11-16-2011, 05:46 AM
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Originally Posted by amirm View Post

I think a pinhole camera would be an improvement

Seriously, holding the camera/phone parallel to the subject will maximize depth of field. And be mindful of minimum focusing distance.

Thanks for the advice Amirm. However one of the issues I was trying to work around was the harsh florescent string of lights above the benches. It was creating a wicked glare on the scope face. I was out in the process lab area and the light is not as soft as in the electronics lab. I should have turn off a couple light strings instead of adjusting the camera angle. I do apologize for the quality of the pictures but hope you can see the screen well enough to get the information. But don’t let that hold you up on that offer of a new camera.
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post #728 of 969 Old 11-16-2011, 06:46 AM
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Quote:
Originally Posted by Glimmie View Post

So you are saying that a $19K power cord could actually make the problem worse?

I Agree!

But this just further endorses the snake oil behind these marketing claims!

I have stated all along, it is a random, hacking process. Attempts to solve a problem that is not understood, using solutions which are also not understood, generally leaves one with a 50-50 shot.

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Originally Posted by diomania View Post

I'm pointing out your problem so that there will be less of it here, a communication problem to be specific.

Your hopelessly redundent attempts at characterizing anybody you do not agree with smacks of desperation. World reknowned experts with decades of experience that does not conform to your slanted view, you dismiss as hacks.

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Originally Posted by diomania View Post

It's been pointed out to you more than once by a few members that what you are doing on this thread aids those snake oil power cord vendors.

OOOOH, scary.

So, lets see. Any technological analysis, discussion, test, solution which could conceivably be misconstrued as aiding and abetting a power cord vendor, MUST be denounced regardless of it's scientific accuracy.

That is your position. And historically speaking, you will denounce anyone and any science which could possibly aid and abet that enemy.

Perhaps you would be better served by discussing actual engineering/science/physics... But that would require knowledge, no? You've not demonstrated such that I am aware of.

Your only viable option appears to be..attack the individual, not the message..
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Originally Posted by diomania View Post

jneutron, just pointing it out to you that your reading and writing (communication) problem coupled with denial, arrogance and condescension really stink up the thread.

Being too lazy to engage a technical discussion is your forte. Attacking the individual is all you got..
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Originally Posted by Just cruising View Post

It is nice to actually have a dialog and not the over spoken language with the condemnation that you normally present.

It is good to see you not blasting in with "let's end all the BS. That was unexpected, unpleasant, and not an avenue which would bear fruit. As well as terribly premature and inaccurate.

As for "overspoken", I initially assumed your e/m theory level was higher. I am afraid there is no way to state that without appearing condescending, so I only state it as fact with apology.. As I said, on-forum one can only guess the level of an intended audience.

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Originally Posted by Just cruising View Post

So when you say couple to the line I can only assume you mean through the transformer?

There are quite a few things which can couple.

Producing field possibilities: Within the equipment, transformer, internal AC runs, line filter, power supply wires, cap bank layout, wires to the on/off switch...outside, a poorly designed line cord's inductance could couple to the ground loop, the romex run feeding the duplex outlet,

Receiving field: ground loop.

What can alter the ground current:
Line cord resistance, IC shield resistance, chassis resistances RCA jack to IEC safety bond, connection contact resistances, outled ground resistance, contacts again

where the ground loop current can impact the analog signal:

Interchassis potential from IR drop of IC shield, internal coupling loop in amplifier input run, ground current passing by input pair base/emitter pair, injecting error signals at the input differential nodes, feedback network grounding connection. The OUTPUT loop of the source component (this is always neglected, btw..)

Because there are just too many things here, the best and easiest thing to do is treat the units as black boxes when troubleshooting a system. It only pays to troubleshoot a component AFTER identifying a measureable problem. If there is no measureable problem, there is nothing to troubleshoot.

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Originally Posted by Just cruising View Post

And I am quite aware of how power supplies work.

I did not say anything along that line which would indicate otherwise. Why did you state this?

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Originally Posted by Just cruising View Post

Now we are back to the bulb? I would think thermal stability of the bulbs is fairly good since they are common every day incandescent and the mechanical stress of low thermal stability would result in premature failure. It is typically less that 1/8 and tungsten is the most common if I remember correctly. It looks like you have figured out one of the labs for the light bulb circuit.

It appears that one bulb vendor doesn't see it your way. Bought six 40 watt medium base clears a few weeks ago, all 6 failed within 2 to 3 hours. Clearly a manu issue. The 1/8th number is from memory and several decades ago, so typical could indeed be less. I remember a 100 watt bulb that was very close. The HD guy says incandescents will be no longer available here in december, leaving CFL's and LED's. Wonderful, new spectra to deal with..

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Originally Posted by Just cruising View Post

OK now we are back on the control panels? Man you like to jump around!

It's all one system. Am I gonna hafta publish a program?? By control panel, are you talking about the load panel? Service panel, load panel, control panel, breaker panel, load distribution panel, I guess we can lump it all for residential discussions, no?

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Originally Posted by Just cruising View Post

I agree that the high input Z and sensitivity of a phono input could pick up noise here but I am not about to stick my turn table it to the control panel.

Hmm? T-table ground wires work the best if one wraps the wire around the t-table IC's. That minimizes loop area for external fields. But the sensitivity is kinda out there for our discussion, and I didn't follow your "stick it to the control panel" statement.

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Originally Posted by Just cruising View Post

There are many high Z meters out there that will give frequency. However the voltage has to be of sufficient magnitude and decently clean. Why make that comment?

Because when discussing what for all purposes is noise level signals, it is important to distinguish between 60 hz, 120 hz, 180 hz,45 hz, 70 hz, 15 plus khz, or 2 Mhz. The spectra usually gives an excellent indicator as to the source.


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Originally Posted by Just cruising View Post

This comment alone makes me seriously question your understanding of meters?

Why? see above...
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Originally Posted by Just cruising View Post

No doubt the environment is considerably different. For one the branch circuits in a commercial industrial environment is made up of a single conductor in poly phase system with the 4th wire of the distribution as the return conductor. All the return conductors connect back to the same point and therefore any induced voltage due to noise and or current imbalance can be seen throughout the system as each phase is 120 degrees apart and neutral currents in individual branches can be swapping back and forth from different phases .

Agreed, that is actually what I said with the 208/line to neutral. Further embellishment was nice, I didn't need it...

And in addition to all that, there is the safety bonded ground.

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Originally Posted by Just cruising View Post

At home this is not the case. The transformer at the pole is a true single phase system. Typically the output is 240 across the full secondary winding with a center tap acting as the neutral. This puts each line to neutral exactly 180 degrees apart. Due to how the panel is configured all the major loads like your AC/heat pump, resistive heating on you range, water heater, etc… pulls current across the whole secondary winding and unless a low/120v control in needed the neutral is not conducting anything. In the event a120v is needed for control it is usually very small to power electronics or small control circuits. This would be the only current that would return through the neutral on the 240v loads. That means the remaining loads in your house that do require the neutral for return are the for the most part the lite stuff, lights, blow dryers, electronics, refrigerator, the current circulates in only one side of the transformer at the pole. In other words the current that travels in the neutral for any given load is not shared like in an unbalance 3 phase system. This means all the fields you keep talking about are at equal but opposite strength at any given time and cancel each others effect.

Everything you stated was accurate up to but not including the last sentence.

All romex creates a dipole magnetic field. Your verbage essentially precludes all possibility of ground loop hum. Clearly, experience by darn near everybody conflicts with the "canel each other effect" you stated.
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Originally Posted by Just cruising View Post

I have in affect by doing this in a industrial environment supplied a much worst overall condition that is by far more likely to create the results you are looking for.

Actually, no. Conduit stops external dipole fields at 60 hz. Power strips with metal housings having relative magnetic permeability in the 100 range, and conductivity in the 10-20% OFHC range, prevent external dipole fields. So in fact, many things in the industrial enviro are by accident of design, lower in coupling capability than a residential.

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Originally Posted by Just cruising View Post

If you care to know I have worked on a wide variety of systems, controls, and electronics for many years including UPS systems. I am not talking about the kind you plug you desktop into. I consider myself to be very lucky to have had such varied and interesting career. And to think I have done this all while only using 120V!!!

I do care to know, thanks for the info. I work code in building a really big machine, I build and test supeconducting magnets, I occasionally consult across the ponds for of all things....soldering..sigh. I play with an 11 axis motion control widgit (designed, wired, programmed)..as I told Joe, big and fun toys.

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Originally Posted by Just cruising View Post

Did you measure this with a high Z meter? What was the frequency?

I used my fluke handheld. Given the possibility of rf intrusion, I checked it's frequency response...it works up to about a kilo.

So I then used a scope. One of those portable battery capable ones. It confirmed both the 60 hz nature of the voltage, and the wildy varying level vs time. Some waveform distortion of course with noise, but the fundamental was not far off the meter read. There was hash due to the flourescents in the ceiling, and other stuff in the 120/180 hz range probalby the computer supply. I really love that little toy scope, the battery option saved my butt many times..

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Originally Posted by Just cruising View Post

Yes, this sounds right, it has been many years but if I recall correctly it is using 2 different transformer configurations to feed the convertor, a wye and a delta together on the same feeds. It appears to the converter there are 6 phases and with full wave rectification this should give you 12 pulse ripple on the DC link.

Sounds right to me. But I seem to recall somewhere 3 transformers running phase to phase to produce a derived phase shift, the secondaries put into series with the second transformer phase runs, the sum used as either a leading or lagging source. Again, not my normal bailiwick (sp). Nonetheless, having 12 2 inch hockey puck SCR's is less reliable than 6 3 inchers, as well as re-torquing the clamping hardware every year or so..that, I do...I've played with 3 inch diameter diodes as well.

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Originally Posted by Just cruising View Post

So in other words…no… you have no idea if all your equipment has connected grounds or not. Yet when I mention this with the test piece you ask why I have an aversion to using grounded equipment.

Huh? All wiring meets code, all equipment meets UL..Of course I know all the equipment.. That was a weird statement. Where did I say you have an aversion to grounded equipment? Are we reading the same verbage??

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Originally Posted by Just cruising View Post

I use to think you were an objective but I have come to realize you a closet subjective like Amirm. A joke to both of you since ya'll share so much in common.

I don't know him. Many times I've no clue what he talks about..And frankly (sorry amirm), some of the posts are so long my eyes glaze over and I fall asleep.. (unlike my long ones which are real page turners)

Quote:
Originally Posted by Bigus View Post

Wait, what test design? Surely you don't think that simply controlling a test necessitates this problem you imagine?

Not controlling for human response time delays means not having full control over confounding issues. If I wished to determine for example, the impact a power cord had over imaging within a soundfield, I would have to control for my time dependent localization re-configuration..

Remember, we human beasts in the wild, use ITD and IID to determine the horizontal location of sounds. In the listening room we have to adapt to a stimulus which does not necessarily follow the natural sound propagation patterns..we adapt.

How fast? who knows, who has cared? It is a confounder. One which I would be concerned with if I were to build a test design. Note that Gresinger did indeed build a test design to accomodate at least one aspect of this issue, it was a 3rd speaker used as a localization reference standard, he arrived at some great results because of that.

Cheers, John

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post #729 of 969 Old 11-16-2011, 08:44 AM
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Quote:
Originally Posted by Just cruising View Post

Thanks for the advice Amirm. However one of the issues I was trying to work around was the harsh florescent string of lights above the benches. It was creating a wicked glare on the scope face. I was out in the process lab area and the light is not as soft as in the electronics lab. I should have turn off a couple light strings instead of adjusting the camera angle. I do apologize for the quality of the pictures but hope you can see the screen well enough to get the information.

Understood. Perhaps use of screen capture in your portable scope, or PC interface would be a better bet.

Quote:


But don't let that hold you up on that offer of a new camera.

Oh, I already gave you one. It was the pinhole camera (http://en.wikipedia.org/wiki/Pinhole_camera). All it takes a box and well, a pinhole! If you don't have a box, I am sure we can manage to send you one.

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post #730 of 969 Old 11-16-2011, 09:02 AM
 
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Quote:
Originally Posted by jneutron View Post

Your hopelessly redundent attempts at characterizing anybody you do not agree with smacks of desperation. World reknowned experts with decades of experience that does not conform to your slanted view, you dismiss as hacks.


OOOOH, scary.

So, lets see. Any technological analysis, discussion, test, solution which could conceivably be misconstrued as aiding and abetting a power cord vendor, MUST be denounced regardless of it's scientific accuracy.

That is your position. And historically speaking, you will denounce anyone and any science which could possibly aid and abet that enemy.

Perhaps you would be better served by discussing actual engineering/science/physics... But that would require knowledge, no? You've not demonstrated such that I am aware of.

Your only viable option appears to be..attack the individual, not the message..

Being too lazy to engage a technical discussion is your forte. Attacking the individual is all you got..

You posted something vague so I asked for a clarification. You couldn't clarify it because your post was based on something that doesn't exist. Now all you are doing is copying amirm dance moves, deflect, redirect, complain, make things up as you go 1, 2, 3, 4

Cheers,
too lazy to engage a technical discussion guy (formerly known as a very lazy person)


PS. JC, your call, "closet subjective" is looking more accurate than ever.
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post #731 of 969 Old 11-16-2011, 09:13 AM
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Quote:
Originally Posted by diomania View Post

You posted something vague so I asked for a clarification. You couldn't clarify it because your post was based on something that doesn't exist. Now all you are doing is copying amirm dance moves, deflect, redirect, complain, make things up as you go 1, 2, 3, 4

Cheers,
too lazy to engage a technical discussion guy (formerly known as a very lazy person)


PS. JC, your call, "closet subjective" is looking more accurate than ever.

You remind me of westom. Are you a sockpuppet of him? Or are you just copying his rather interesting "style"?

jn

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post #732 of 969 Old 11-16-2011, 09:32 AM
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Quote:
Originally Posted by Bigus View Post

I fail to see how this rather narrow example effects my argument. Which leads me to conclude you simply misunderstood it.

Lets review the history of this context, so that it doesn't get confused. I will hilite the important (to me) points. And dear me, I hope I sequence it right...

Quote:
Originally Posted by Bigus View Post

Which is interesting, but I'm not sure it matters. You could conduct such research to further understand human hearing/perception, and strengthen the case against audible cable differences (for everyone but amir)... or you could just conduct controlled tests to see if anyone could hear the difference. I've read your arguments against ABX before... fine, there are many other ways to conduct such tests. It only takes one positive.

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Originally Posted by jneutron View Post

Actually, my concern is that by neglecting the human localization adaptation response time constant, differences can easily be missed. In essence, I am concerned that the test design is skewed unfairly towards finding no differences.

You say "strengthen the case against"... That is not a valid scientific method in my opinion. Preconceived notions are not allowed within the testing of a hypothesis. I don't think you meant that.

I point out issues I see which can spoil the outcome of the test..skew the results..

Quote:
Originally Posted by Bigus View Post

I think I missed your point. A controlled test (of the sort I speak of) doesn't care what causes the effect, the only goal is to determine perceptibility. If it is the geometry that is different between two cables, fine. Prove there is an audible difference, then go about identifying the cause.

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Originally Posted by jneutron View Post

One classic test is to put an ABX..... In this specific case, introduction of the box removes the difference.

Here, you say controlled test. I have pointed out the lack of control of the testing I've seen, in two specific areas. First, the tests do not consider how long humans require to adapt to a changed soundstage from an artificially derived stereo image. And second, all the testing I've seen which are "fast switch" spoil the actual entity that would need controlling...in this discussion, the ground loop geometry and the loop resistive and inductive values, as well as how we respond to localization parametric changes.

edit: with ground loops, they have low impedance. Measuring them accurately is not easy. Trying to measure the current is not possible with a resistor in series, as the resistance added will change the loop characteristics..that is why I mention a clamp on current measurement scheme.

Trying to play games with IC's and PC's in those loops will also change the parameters. However, since nobody performs any kind of listening tests where they absolutely control the resistance of the connections and the loop geometry of the connections, nor consider how we actually would hear a change in soundfield localization parametrics, rigorous conclusions cannot be justified one way or the other. As I said, the test scenario's are skewed against positive findings.

I am not saying there are always (or even ever) going to be positive findings, I am stating that the test design is skewed against it.

Without control over the testing, no matter how many tests performed, no matter how many decades of history are there, if the confounders to a test are not controlled, the results must be questioned.

cheers, jn

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post #733 of 969 Old 11-16-2011, 09:39 AM
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I've followed this thread with interest. Being an (electrical and telecoms) engineer myself I am always interested to read about test methods etc.
So far, I haven't read an argument that would make me re-mortgage the house to get some expensive cables in.
Price: I am not surprised that the cables are more expensive than the one that comes in the box, as it looks like more expensive material (and quite a variety of materials) goes into producing the cables (like some fancy special copper, silver, very special rubber etc) as well as quite some effort is put in in twisting the stuff in whatever special way.
I can't see however how this would bring the price of 1m of cable into the thousand's of dollars, but maybe the special rubber is just really wicked epensive.

Anyway, all the measurements on the cables on its own are in my opinion pointless as it doesn't say anything how it would influence what comes out of the speaker - and that is what it's all about at the end.

Maybe a full range frequency spectrum analysis of the signal leaving the speakers would help.
Pick whatever song and equipment you like, play the song and run the analysis. Then change nothing but the power cable and do it again.
I am wondering if you would expect to see a change in the spectrum (I wouldn't to be honest, assuming you don't have a broken cable to start with).

And keep going please....
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post #734 of 969 Old 11-16-2011, 09:55 AM
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Quote:
Originally Posted by Just cruising View Post

The volume is turned up to the point of just short of breaking into distortion.

Attachment 228121

The set up

Attachment 228122

So this has about 15 ft of SO cable connected and I cannot see any visible signs of induce currents in the ground from the current conductors. The frequency was 5M Hz. Some even higher frequency hash. Voltage was varing between 2.7mv ans 3.0 mv. Hash riding on the fundamental was also varing.

Thanks for the work..coupla Q's.

1. The fundamental is 5 Mhz? I couldn't see the timescale on the screen.
2. The amp was two prong, yes?
3. Was the ground reconnected for the scope pics?
4. If you connect the scope between the amp chassis and the ground at another duplex of that branch located 10 feet away, what do you see?
5. If you see 60 or 180 hz using #4, what does it read if you go to current? In other words, what would be the equivalent source resistance for the 60 hz?

Maybe if you turn off the flash, you could go normal to the screen. It works for me, but it means I have to remain very steady.

Cheers, jn

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post #735 of 969 Old 11-16-2011, 10:02 AM
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Quote:
Originally Posted by newirishman View Post

Anyway, all the measurements on the cables on its own are in my opinion pointless as it doesn't say anything how it would influence what comes out of the speaker - and that is what it's all about at the end.

What jc and I are discussing is the aggressor portion of a coupling scenario between what a power amp draws, and a resultant change to the analog output. The second thing required is the coupling mechanism..the third thing is the victim sensitivity.
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Originally Posted by newirishman View Post

Maybe a full range frequency spectrum analysis of the signal leaving the speakers would help.

As I recall, really good guys have detailed the problems associated with this. Room measurements are reported as not repeatable at the level we'd like to see.
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Originally Posted by newirishman View Post

Pick whatever song and equipment you like, play the song and run the analysis. Then change nothing but the power cable and do it again.
I am wondering if you would expect to see a change in the spectrum (I wouldn't to be honest, assuming you don't have a broken cable to start with).

I wouldn't expect a change either. Unfortunately, some things won't be seen in a spectrum analyzer..for example, if some (but not all) content of one channel were timeshifted 20 uSec from the other (say, harmonics of a vocal), imaging would change location for that portion of the image with respect to the fundamental, but spectra would'nt.

How we hear is not very simple, so testing of it is the same.

Pure listening tests are really the best way to go, but it is important to consider anything which can skew the results.
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Originally Posted by newirishman View Post

And keep going please....

My guess? That is a given.

Cheers, jn

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post #736 of 969 Old 11-16-2011, 10:14 AM
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Originally Posted by newirishman View Post

Price: I am not surprised that the cables are more expensive than the one that comes in the box, as it looks like more expensive material (and quite a variety of materials) goes into producing the cables (like some fancy special copper, silver, very special rubber etc) as well as quite some effort is put in in twisting the stuff in whatever special way.
I can't see however how this would bring the price of 1m of cable into the thousand's of dollars, but maybe the special rubber is just really wicked expensive.

You're forgetting the cost of research and development, the "leading edge" of cable technology aspects. Proprietary breakthroughs don't come cheap. Somebody has to pay for it.

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post #737 of 969 Old 11-16-2011, 10:15 AM
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You know in your heart it's all bling and puffery, John.

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post #738 of 969 Old 11-16-2011, 11:10 AM
 
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You remind me of westom. Are you a sockpuppet of him? Or are you just copying his rather interesting "style"?

jn

This soon after posting this:
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Being too lazy to engage a technical discussion is your forte. Attacking the individual is all you got..



Cheers (you need it).
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post #739 of 969 Old 11-16-2011, 12:24 PM
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jn, as I suspected I think we're talking past one another. I've read about your concerns with localization adaptation to non-natural sounds. I agree, interesting stuff.

But you keep posting about past tests, and decades of history. I probably wasn't clear but that isn't where my original point was rooted. I'm simply pointing out that if people claim to hear these differences (clearly, obviously, easily, in many cases I might add), a controlled test can be designed to replicate how they achieve this feat.

I'm not referring to a specific test design. Not ABX. Not quick switching. Just the general principle that if they hear it, we should be able to reproduce it. And whilel localization adaptation response is interesting, it doesn't really matter, except that it is but one reason to allow people to listen in the way they have already demonstrated this ability. You can still control months long extended listening sessions.

Now, I provided my belief that ABX gives the best chance of hearing differences. I know you have a few specific concerns. I understand. You may be right, or you may not, but it is a minor, nearly irrelvant point in the bigger picture.

As to "scientific method" I'm simply pointing out that if research keeps piling on evidence as to the likely explanation, the burden is ever greater on the party claiming an alternative explanation to prove the positive. This happens all the time, in all areas of science, so yeah... I meant that. Probably just wasn't clear in wording it.

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post #740 of 969 Old 11-16-2011, 01:08 PM
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This soon after posting this:



Cheers (you need it).

As I said, attacking the individual is all you've got. You never engage a technical discussion.

To me, calling you westom-like...is a perk. He posted so many things over and over, that everybody suspected he was a bot. You strike me the same way in the way you attack others.

It strikes me that I've never seen a post of yours with technical content. Have you ever? Can you link to some technical post where you were not attacking another who doesn't share your POV?

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post #741 of 969 Old 11-16-2011, 01:12 PM
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Originally Posted by Chu Gai View Post

You know in your heart it's all bling and puffery, John.

So much of it really is...sigh.

Grain boundaries, dielectric absorbtion in a power cable, 7 nines silver, cryo treatment changing metal conduction..even that power test thingy where they push 300 amp spikes in the line cord...sheesh.

So much randomness.

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post #742 of 969 Old 11-16-2011, 01:24 PM
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jn, as I suspected I think we're talking past one another.

I agree..

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I'm simply pointing out that if people claim to hear these differences (clearly, obviously, easily, in many cases I might add), a controlled test can be designed to replicate how they achieve this feat.

You would think that it would be that easy. The ridiculous claims always fall apart in rigorous testing.

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Just the general principle that if they hear it, we should be able to reproduce it. And whilel localization adaptation response is interesting, it doesn't really matter, except that it is but one reason to allow people to listen in the way they have already demonstrated this ability. You can still control months long extended listening sessions.

We certainly agree in principle. I worry about really long tests though, as I find I change preference month to month, so I think I'd be a poor candidate for long term testing.

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Now, I provided my belief that ABX gives the best chance of hearing differences. I know you have a few specific concerns. I understand. You may be right, or you may not, but it is a minor, nearly irrelvant point in the bigger picture.

Actually, my feeling is that rapid switching between a correct reference and the two choices is probably better. Greisinger used a moveable reference speaker, and the subject selected between that and the stereo pair. That normalized the subject's hearing response.

All that said, what I really prefer is the actual measurement. Reproduceable tests which can be used for standardization.. Things like measurement of an amplifier's susceptibility to ground loop currents through the audio band, and the amplifier's ability to inject into a ground loop, any current at all. The hearing stuff is really interesting, but the electrical is just so much more solid..

Cheers, jn

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post #743 of 969 Old 11-16-2011, 01:33 PM
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As I recall, really good guys have detailed the problems associated with this. Room measurements are reported as not repeatable at the level we'd like to see.

So are you saying that the differences the cable is supposed to make are so detailed that the settings of a proper sound lab is not good enough to allow for a repeatable test? I do find that hard to believe.

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I wouldn't expect a change either. Unfortunately, some things won't be seen in a spectrum analyzer..for example, if some (but not all) content of one channel were timeshifted 20 uSec from the other (say, harmonics of a vocal), imaging would change location for that portion of the image with respect to the fundamental, but spectra would'nt.
How we hear is not very simple, so testing of it is the same.

While recent research shows that the human ear is indeed able to hear a timeshift down to 5uSec in lab conditions [1], I can't see how the power supply cable could possibly cause a timeshift of some content on one channel but not the other. I'd appreciate any links to the theory behind it.

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Pure listening tests are really the best way to go, but it is important to consider anything which can skew the results.

That is a difficult statement. Above you mentioned that room measurements are not repeatable on a good enough level. I would think that the same thing that makes the measurements not repeatable makes the listening experience not repeatable, especially as you add an additional factor into the equation: the human ear and the attached body.
This makes me doubt that any quality gain from power cable is more drastic than any other aspect. It sound like the influence of the cable will be lost in the "general variation" of things anyway.

I have met people who have excellent hearing, so I cannot rule out (read not disprove) that for some people in some circumstances there might be a difference. However, you probably need to spend hundreds of thousands of dollars on amps, speakers, DAC's, etc before any problem potentially fixed by the power cable would be bigger than what is caused by the general processing noise of less expensive components.
Which means that for most of the even very audiophile people (who might spent several K's for an amp, or dozens for speakers) an expensive power cable is simply put not worth the money.

BTW - Reminds me of the short discussion I had when I bought new speakers recently - the shop assistant was adamant that the length of the cable for my stereo speakers must be the same for both channels. I did not understand why he was so insistent, and he couldn't come up with one convincing reason. So - the cable to the right speaker is about 60cm and the other is about 240cm - so I don't have any cable laying around. Can't hear a problem, but that's probably because the electrons travel the additional 180cm in less than the potentially discernible 5uSec

[1] Temporal resolution of hearing probed by bandwidth restriction, M. N. Kunchur, Acta Acustica united with Acustica 94, 594-603 (2008) link
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post #744 of 969 Old 11-16-2011, 01:47 PM
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So are you saying that the differences the cable is supposed to make are so detailed that the settings of a proper sound lab is not good enough to allow for a repeatable test? I do find that hard to believe.

Don't shoot the messenger. May higher level audio guys talk about how they can't get run to run repeatablility across the audio spectrum.
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While recent research shows that the human ear is indeed able to hear a timeshift down to 5uSec in lab conditions [1], I can't see how the power supply cable could possibly cause a timeshift of some content on one channel but not the other. I'd appreciate any links to the theory behind it.

edit: Nordmark demonstrated 1.5 uSec discernment in 1974, Kuncher's two speaker setup alters the vertical dispersion by inter-driver displacement, a confounder IMHO.

The closest I'll be able to get you that way would be EMC stuff, like Tom Van Doren. Ground currents from the RCA's to the IEC travel in rather strange ways...For DC, the currents go path of least resistance and spread across the metal... For AC, the currents go path of least reactance as frequency goes up, and this transition occurs in the 1Khz type area. So any hf ground current that couples either into the star ground or the pc traces will affect by proximity. If one channel is in closer proximity to the path, voila.

A lot of things have to happen at the same time of course, but this can be easily tested should one wish. I've attached one method..With the amp and source on, drive audio currents into the loop using the transformer (red). Measure the loop current to verify, and with the amp and preamp/source on, look for output signal caused by the loop currents. An amplifier/source combo which is not susceptible to coupling in this scenario, has no problems. One that outputs the ground loop signal may have a problem. If it is susceptible, then additional testing of the amp to determine if it couples it's power draw to the ground loop is needed.

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Can't hear a problem, but that's probably because the electrons travel the additional 180cm in less than the potentially discernible 5uSec

One must be careful in comparing the prop velocity of the cable (quarter to half lightspeed) with the mm per second velocity of the electrons.. AS well as consideration of the cable impedance with reflections, or equivalently, use of the cable lumped parameters..But I wouldn't worry about a meter or two of wire length difference either..

While Kunchar does work with superconductors (so I gotta like him), I'm not confident with his methodology or test design..

Cheers, jn
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post #745 of 969 Old 11-16-2011, 01:56 PM
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One must be careful in comparing the prop velocity of the cable (quarter to half lightspeed) with the mm per second velocity of the electrons.. AS well as consideration of the cable impedance with reflections, or equivalently, use of the cable lumped parameters..But I wouldn't worry about a meter or two of wire length difference either..
Cheers, jn

We are still talking about kHz frequency, so I would not worry at all about reflections etc. Even at 1/10 of light speed we would probably need a kilometer of cable to come up with any relevance (that is of course just an over-the-thump assumption).
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post #746 of 969 Old 11-16-2011, 02:08 PM
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We are still talking about kHz frequency, so I would not worry at all about reflections etc. Even at 1/10 of light speed we would probably need a kilometer of cable to come up with any relevance (that is of course just an over-the-thump assumption).

A rigorous analysis of the prop velocity of a speaker cable, it's characteristic impedance, and the load impedance can demonstrate signal delays consistent with low microsecond , frequency dependent delays. The alternative method, the use of the cable lumped L and R, will arrive at the same results.

The only signal that can propagate along a wire at the prop velocity of the wire, is a signal which has the V to I ratio of the cable impedance. Zip cable runs in the 100 to 150 ohm range, and the speaker loads run the 2 to 100 ohm range, frequency dependent. Again, a good RL analysis will show the same thing.

But as I said, I wouldn't worry about a meter or so at all..

Cheers, jn

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post #747 of 969 Old 11-16-2011, 02:43 PM
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I've followed this thread with interest. Being an (electrical and telecoms) engineer myself I am always interested to read about test methods etc.
So far, I haven't read an argument that would make me re-mortgage the house to get some expensive cables in.
Price: I am not surprised that the cables are more expensive than the one that comes in the box, as it looks like more expensive material (and quite a variety of materials) goes into producing the cables (like some fancy special copper, silver, very special rubber etc) as well as quite some effort is put in in twisting the stuff in whatever special way.
I can't see however how this would bring the price of 1m of cable into the thousand's of dollars, but maybe the special rubber is just really wicked epensive.

I have explained this before. So here it is again. Courtesy of all of us becoming cheap bastards that shop our electronics to death, we have pushed the profit margin to zero or negative for retailers and with the exception of Apple, for almost all electronics manufacturers. Since you can't run a huge best buy store on negative margin, you can't leave the place without being pushed to buy an expensive cable and or maintenance agreement. Needless to say, the higher the margin, the better this arrangement works for all concerned. Net, net, profit margins for cables have to, by definition, be high or the retailer will not carry them. After all, his main intention for selling them is to make up for losses elsewhere.

So please, let's not keep comparing the cost of wholesale/Chinese cables for retail branded cables. You don't see Apple selling its products for cost of its components. Let's not forget economics and compare MSRP with wholesale costs here.

Quote:


Anyway, all the measurements on the cables on its own are in my opinion pointless as it doesn't say anything how it would influence what comes out of the speaker - and that is what it's all about at the end.

Maybe a full range frequency spectrum analysis of the signal leaving the speakers would help.

And wouldn't you know it, someone has done that and is the cable companies no less! The work has fair number of holes in it as all tests do. But it is food for thought. Alas, for some reason almost all mentions of it have vanished and the one site that has video of it has malware on it . Here is the thread but DO NOT click on the video link in it as my Chrome browser giving me strong warnings on the web site hosting the video: Objective Test of Power Cables on Whatsbestforum.com

The text of the thread is fine of course. Before you go there then, read through this pdf. I am providing the cached version since Nordost has removed the link there too. Thankfully Google cache works although the doc preview is a bit fuzzy:

https://docs.google.com/viewer?a=v&q...KVvs-1YQ&pli=1

They test AC cables, AC conditioner, etc. and find differences in measured samples (timing). You can read my comments in the WBF thread (which is mostly negative toward the test although I could not dismiss it all). If there is an explanation for what they found, it actually has to do with what JN has been telling us. Read about my points on using a PC and shared ground and such with the audio gear.

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post #748 of 969 Old 11-16-2011, 04:31 PM
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You posted something vague so I asked for a clarification. You couldn't clarify it because your post was based on something that doesn't exist. Now all you are doing is copying amirm dance moves, deflect, redirect, complain, make things up as you go 1, 2, 3, 4

Cheers,
too lazy to engage a technical discussion guy (formerly known as a very lazy person)


PS. JC, your call, "closet subjective" is looking more accurate than ever.

You seem to be here only to fight, and not to (unable to?) engage in technical discussions or answer questions.

I have asked you the same question, over and again, at least five times. You respond to me but continue to dance around the question.

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post #749 of 969 Old 11-16-2011, 05:31 PM
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Best Buy's profit margin is around 1.5%. By way of comparison, Staples is 2x and Walgreens is 3x more. Any idea how much of BB's profit margin comes from accessories and service contracts, Amir?

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post #750 of 969 Old 11-16-2011, 05:45 PM
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Best Buy's profit margin is around 1.5%. By way of comparison, Staples is 2x and Walgreens is 3x more. Any idea how much of BB's profit margin comes from accessories and service contracts, Amir?

1.5%??? Gross margin for BBY is around 25%. Net margin is in about 3% from what I recall. Big company, lots of overhead.

And no, I don't have specifics to share beyond what they do . I meet with their execs often but not on this topic.

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