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post #91 of 534 Old 05-24-2011, 01:49 PM
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A little knowledge is a dangerous thing.

I have little knowlege, but I am pretty harmless
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post #92 of 534 Old 05-24-2011, 02:06 PM
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Originally Posted by Randy Bessinger View Post

That will go on until someone does the tests...

Just because no one has measured it yet down to the threshold of human perception doesn't mean it cannot be perceived... just means we haven't got the gear to measure it yet.

Like I know from my hobby of astrophotography that no recorded photo of the surface of the moon comes close to what it looks like visually through a telescope.

Sadly many visual observations have gone ignored until the ability to measure/record it has caught up.

Like the discovery of 'spokes' in Saturn's Rings...
http://youtu.be/nkArqtto3m0
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post #93 of 534 Old 05-24-2011, 02:09 PM
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You ask relevent and good questions.

Because humans can discern in the 1.5 usec and up differentially, system delays must be considered to that level. Faster than that can easily be ignored. I suspect even 2 to 5 uSec can be ignored, but my suspicions are not a basis of fact in that regard, it should be tested.

Back of the envelope:
343m/s * 1.5 uSec = 5cm

seems about right based on the size of our heads.
And explains why we do not have to hear above 20khz (about 2 cm)

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I've limited my analysis to pure resistive loads. So, I can only determine the lower bound of the settling time...reality will be slower.

Thinking of a driver which can have lower reactance at frequency only makes the situation worse. When the driver matches the cable, there is no settling time, just prop delays in the nanosecond realm... which to quote a wise sage, ""are trivial and irrelevant""..

I've never seen a pure resistive load.

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Given our lack of sensitivity to ITD at low frequencies, I'd go simply guage for the woofs. But where we have better discernment, I'd go for matching cable to driver. So, if I were so inclined, I'd bi-wire and make a tweet cable that matches tweeter Z, and a woofer cable out of 4/0 twisted pair.

Why? Do you think it would make a difference? I know you are not inclined to find out. But I'm not sure what this might possibly gain you.

For the record, I think initial impulse and sustained sound are what is important for localization. By the time the sound has decayed, the wild man does not care anymore. Which means Bob is probably right, settling time does not matter (as long as it is not also related to rise time).



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Steven Hawking does not use bi-wiring. He uses 16 AWG lamp cord. So, I'd go by his direction. He doesn't sweat the small stuff.

I know he has problems talking, how are his ears ?
(disclaimer, 16 gauge zip cord is probably fine except for high power or low impedance)

Edit: now you've got me thinking about, Lets pretend we had a horrible speaker wire - as long as right and left were about the same, wouldn't localization remain the same?

Everything I say here is my opinion. It is not my employers opinion, it is not my wife's opinion, it is not my neighbors opinion, it is My Opinion.
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post #94 of 534 Old 05-24-2011, 02:32 PM
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Originally Posted by dknightd View Post

Back of the envelope:
343m/s * 1.5 uSec = 5cm

seems about right based on the size of our heads.
And explains why we do not have to hear above 20khz (about 2 cm)

343 meters/sec times 1.5 10e-6 sec

(343 *1.5)/10e6 ~ 500 / 10e6 ~ 50/10e5 ~5 / 10e4 ~.5/10e3

I think it's about half a mm.

Absurdly small if you ask me. But well within the excursion distance of a single wideband driver. But this is why many people come up with the old head in the vice argument...not correct of course, but the distance is very small.
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I've never seen a pure resistive load.

Nor I. But I've made 1, 4, and 8 ohm power resistors that don't overshoot a square wave in the 250 picosecond realm..I think that for audio and 1.5 uSec measurement, that might be good enough...

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Why? Do you think it would make a difference? I know you are not inclined to find out. But I'm not sure what this might possibly gain you.

For LF, we are not very sensitive to interaural delays. So, I wouldn't worry about what the wire does.

For 500 hz up, we are sensitive. So, if I use a wire design that keeps the settling time in the nanosecond realm (by matching impedance), then I have removed by design, any possibility that there is something audible. No guessing, no random shots..by design.
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For the record, I think initial impulse and sustained sound are what is important for localization. By the time the sound has decayed, the wild man does not care anymore. Which means Bob is probably right, settling time does not matter (as long as it is not also related to rise time).

Ah...a little confusion. no problem.

The settling time is the amount of time required for the system to get close to final value. I've provided analysis using a step function (leading edge of a square wave), so what I speak of is directly related to rise time.

As for Hawking...as I recall, he was wrong..

Well, at least he said that he was wrong...I can only take him at his word..


Cheers, John

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post #95 of 534 Old 05-24-2011, 02:48 PM
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Edit: now you've got me thinking about, Lets pretend we had a horrible speaker wire - as long as right and left were about the same, wouldn't localization remain the same?

Ah...you have cut to the most important question.

Let's assume amplitude is unaffected.

Also, a source (vocal, percussion, whatever) which contains content at 100 hz and 5 Khz..

If the cables delay 5khz with respect to 100 hz say, 50 microseconds as a result of the load to cable mismatch, what happens.

If the image presents at center stage (like a mono signal) , the 5khz content and image will present 50 microseconds behind the image of the 100 hz signal. 50 usec represents roughly half a foot straight back.

If this is done to a signal that presents 45 degrees to the right of center, how does that manifest? At the 45 degree point, the line of constant interaural delay is not straight back as it is for a central image..it curves.

The gross manifestation would be that some of the content will be perceived as behind and off to a side...this is consistent with image smearing.

Cheers, John

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post #96 of 534 Old 05-24-2011, 02:48 PM
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Clearly I need a new envelope!

So why are these differences not obvious - like my error was?

Everything I say here is my opinion. It is not my employers opinion, it is not my wife's opinion, it is not my neighbors opinion, it is My Opinion.
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post #97 of 534 Old 05-24-2011, 02:49 PM
 
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Hi John,

Why would audible spatial shifts be missed by audiophiles during a blind test of wires?
What would cause them to notice(hear) this sighted, between wire A and wire B....but miss it blind?

cheers,

AJ
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post #98 of 534 Old 05-24-2011, 02:53 PM
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Originally Posted by dknightd View Post

Clearly I need a new envelope!


Nah, just forever stamps...
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Originally Posted by dknightd View Post

So why are these differences not obvious - like my error was?

Because if they were, we'd have nothing to argue about...duh...

Simple...we adapt.

Think of the pan pot. to move an image right or left, just tweak that knob, and lo and behold, you can move the image.

Yet, there does not exist in nature a sound source which has different amplitudes but same arrival time. We perceive an image off center, but we do so with a constructed soundfield which is entirely synthetic. An artificial construct..

How long does it take for our brain to adapt to this change....if we put a speaker in the image location, and A/B'd between the synthetic image and the single speaker at the same spot, what happens?

Cheers, John

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post #99 of 534 Old 05-24-2011, 02:56 PM
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Originally Posted by AJinFLA View Post

Hi John,

Why would audible spatial shifts be missed by audiophiles during a blind test of wires?
What would cause them to notice(hear) this sighted, between wire A and wire B....but miss it blind?

cheers,

AJ

Adaptation. Human hearing adapts, and settles into the adaptation over time.

Pressure to perform. no need to elaborate there...

And of course, let's not forget...it may not be audible.

Cheers, John

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post #100 of 534 Old 05-24-2011, 03:00 PM
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LOL...
As usual, the wire wars begin. Simple opening post and it goes to peacock feather display.
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post #101 of 534 Old 05-24-2011, 03:05 PM
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LOL...
As usual, the wire wars begin. Simple opening post and it goes to peacock feather display.

What thread are you looking at?

To me, the statement "peacock feather display" implies people are tossing their own credentials about. I've see no such behaviour here.

Rather disingenuous statement..any possibility of contribution there instead, dude?

Cheers, John

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post #102 of 534 Old 05-24-2011, 03:26 PM
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Originally Posted by jneutron View Post

Nah, just forever stamps...




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Originally Posted by jneutron View Post

Because if they were, we'd have nothing to argue about...duh...
Simple...we adapt.

I call it discussing, but it could be called arguing. But as you say, we adapt.

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Think of the pan pot. to move an image right or left, just tweak that knob, and lo and behold, you can move the image.

Yet, there does not exist in nature a sound source which has different amplitudes but same arrival time. We perceive an image off center, but we do so with a constructed soundfield which is entirely synthetic. An artificial construct..

Strange it works as well as it does. Suggests to me our feeble brains will use amplitude first if possible. Or perhaps this is lucky !

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How long does it take for our brain to adapt to this change....if we put a speaker in the image location, and A/B'd between the synthetic image and the single speaker at the same spot, what happens?

I suspect my wife would divorce me, and my kids would run away, if I asked them to carry speakers around as the performer moved around the stage. And I run out of people if the band had more than three players.
I prefer live shows - the ironic thing is most of these use "reinforcement" which basically means moving things through a mixing board. Probably with a pan pot involved.

I really like simple two channel recordings - recorded with just two mikes - but they no doubt suffer from the same things you are describing.

You would think I'd only go listen to live music, with no amplifiers or mixing boards involved - and do like doing that - but is it not very convenient.

Frankly I think you are concerned about things that might make a difference, but in practice do not. Of course I could be wrong

Everything I say here is my opinion. It is not my employers opinion, it is not my wife's opinion, it is not my neighbors opinion, it is My Opinion.
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post #103 of 534 Old 05-24-2011, 03:31 PM
 
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Adaptation. Human hearing adapts, and settles into the adaptation over time.

Yes, just like with some optical illusions.
Which is why I asked earlier about what type of signal the JND studies used.
Of course, as you know, in a blind test like Mike Lavigne(sp) did over at the Mad House (asylum), only the switch is fast. You have as much time to "settle" as needed. But the music is dynamic, changing....the environment is reverberant, speakers have their own image smearing delays like diffraction.
Can't remember the exact wires or loudspeakers, but then again, I'm usually not paying too much attention, when reading about audiophile "hearing" wires playing back an artificial construct.
Maybe I'll pay closer attention next time....

cheers,

AJ
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post #104 of 534 Old 05-24-2011, 05:04 PM
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Originally Posted by jneutron View Post

What thread are you looking at?

Post #1:

http://www.avsforum.com/avs-vb/showt...5#post20337125

Dude! The OP's question was answered in the first few responses.
Cheers, Ratman
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post #105 of 534 Old 05-24-2011, 06:48 PM
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@John -- Thanks for the pix; is the article on-line somewhere? And I just missed it (senility)?

Are you comparing settling differences in the output sound waves to dispersion? Interesting analogy, seems apropos...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #106 of 534 Old 05-24-2011, 08:18 PM
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Is there any way to create a recording where we can delay the 5kHz signal WRT the 100Hz signal by varying degrees to estimate the point where a person can pick it up? Also is any of this relevant to interconnects?

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post #107 of 534 Old 05-24-2011, 09:40 PM
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An appropriate combination of filters should do the trick. However, if we are to test just two tones, the easiest way would be to generate them (digitally) phase-shifted and play them back. Catch is, two tones in isolation probably won't tell us anything; there isn't any cohesive image to be smeared. A better test might be to generate a pulse/square wave with components delayed appropriately, and see how the sound changes.

Interconnects, hmmm... If I ever get time to set up a test I plan to try both in simulation. Interconnect source and load (especially load) impedances tend to be much higher and lengths shorter. The simple speaker'ish test I did earlier showed settling to 0.1% in about 1.2 us; using the same FDTD program with 100 ohm source and 10k ohm load a 6' cable (RG-59-class) settles to 0.1% in about 0.03 us, so it would not seem to be an issue (or as much) in interconnects. As John notes, real source and load impedances (rather than purely resistive models) would change the settling time (make it longer).

One thing potentially lost in this discussion is the impact of system damping/ringing on the settling, particularly in the speakers. Might that not mask the effect? Of course, if the speakers are linear enough, or just repeatable enough, the effect would still come through, superimposed upon the ringing/hangover. Another place for ringing/slower settling is in the system's filters (analog and digital), DAC outputs, etc. etc. etc. There are a lot of places that don't have 1 MHz+ BW and do have ringing that could impact the settling in much the same way that reflections might, though signal correlation might (probably will) be different.

YACOM -- yet another can of worms! - Don

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post #108 of 534 Old 05-25-2011, 03:39 AM
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An appropriate combination of filters should do the trick. However, if we are to test just two tones, the easiest way would be to generate them (digitally) phase-shifted and play them back. Catch is, two tones in isolation probably won't tell us anything; there isn't any cohesive image to be smeared. A better test might be to generate a pulse/square wave with components delayed appropriately, and see how the sound changes.

If tones are ugly, square waves are even more so. What about two different instruments playing a single note the 'nominal' frequencies which are separated by more or less that same amount?

Quote:


Interconnects, hmmm... If I ever get time to set up a test I plan to try both in simulation. Interconnect source and load (especially load) impedances tend to be much higher and lengths shorter. The simple speaker'ish test I did earlier showed settling to 0.1% in about 1.2 us; using the same FDTD program with 100 ohm source and 10k ohm load a 6' cable (RG-59-class) settles to 0.1% in about 0.03 us, so it would not seem to be an issue (or as much) in interconnects. As John notes, real source and load impedances (rather than purely resistive models) would change the settling time (make it longer).

Well, you can have long interconnects and short speaker wire.

Quote:


One thing potentially lost in this discussion is the impact of system damping/ringing on the settling, particularly in the speakers. Might that not mask the effect? Of course, if the speakers are linear enough, or just repeatable enough, the effect would still come through, superimposed upon the ringing/hangover. Another place for ringing/slower settling is in the system's filters (analog and digital), DAC outputs, etc. etc. etc. There are a lot of places that don't have 1 MHz+ BW and do have ringing that could impact the settling in much the same way that reflections might, though signal correlation might (probably will) be different.

So now the ability to hear this potentially audible effect is predicated on what alignment the speaker designer chose?

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post #109 of 534 Old 05-25-2011, 06:19 AM
 
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A better test might be to...

No. The best test is to have a Golden Ear audiophile use their own system and track where they heard the effect in the first place, repeat, but under blind protocols spelled out by jneutron, to account for settling time and all other confounders.
We only need one single person on earth to produce a statistically relevant positive to investigate further. Doesn't matter if everyone else on earth can't hear it with their or anyone else's system.
Any volunteers?

cheers,

AJ
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post #110 of 534 Old 05-25-2011, 06:43 AM
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Is there any way to create a recording where we can delay the 5kHz signal WRT the 100Hz signal by varying degrees to estimate the point where a person can pick it up?
Isn't that possible by time alignment of the tweet/woof? Granted, in the region where both drivers contribute, the pattern would collapse into anarchy..but with 1.5 usec being half a mm, 15 is 5mm, 50 is 1.5 cm, seems easy enough to do.. the confounder here would certainly be the crossover region, so the source spectra would need a hole at the crossover region. I hate test tones, but that might be the only way.

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One thing potentially lost in this discussion is the impact of system damping/ringing on the settling, particularly in the speakers. Might that not mask the effect? Of course, if the speakers are linear enough, or just repeatable enough, the effect would still come through, superimposed upon the ringing/hangover.
Or, the impact the cable has on the damping/ringing...isn't damping pretty much the resistive ratio? The crux of my argument is that control over the load current is lost a bit as a result of the settling time, so the essence of damping should also be affected..That should be easily measurable though..

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YACOM -- yet another can of worms! - Don
I've never heard that...but I love it..

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No. The best test is to have a Golden Ear audiophile use their own system and track where they heard the effect in the first place, repeat, but under blind protocols spelled out by jneutron, to account for settling time and all other confounders.
The essence is to consider how we adapt to the different ITD/IID stimulus, and figure out how to eliminate it as a confounder.
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We only need one single person on earth to produce a statistically relevant positive to investigate further. Doesn't matter if everyone else on earth can't hear it with their or anyone else's system.
Actually, one person with stat relevant positive is only the start. The protocol must be robust enough so that the result can be duplicated. One statistically relevant positive isn't good enough to accept blindly, but certainly good enough to publish..

Cheers, John

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post #111 of 534 Old 05-25-2011, 06:55 AM
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Quote:
Originally Posted by Ratman View Post
Post #1:

http://www.avsforum.com/avs-vb/showt...5#post20337125

Dude! The OP's question was answered in the first few responses.
Cheers, Ratman
Is there a mechanism on this forum where the moderators can find out if you consider the OP question answered so they can close the thread?

My point is, you've accused contributors of a "peacock feather display". So your basically accusing people who are contributing into a rather technical discussion, of doing so for personal gain or king of the hill childs play.

As such, I consider your comment to be entirely off base, and diversionary.

Please contribute technically if you can, or ask questions if you wish..

Thanks.

John

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post #112 of 534 Old 05-25-2011, 07:35 AM
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No problem. The OP seemed satisfied at post #7 and hasn't come back to this particular thread for more info or questions.

Just an observation. Enjoy and have fun. Sorry for my diversion.
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post #113 of 534 Old 05-25-2011, 08:20 AM
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Quote:
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Isn't that possible by time alignment of the tweet/woof? Granted, in the region where both drivers contribute, the pattern would collapse into anarchy..but with 1.5 usec being half a mm, 15 is 5mm, 50 is 1.5 cm, seems easy enough to do.. the confounder here would certainly be the crossover region, so the source spectra would need a hole at the crossover region. I hate test tones, but that might be the only way.
Do you propose to do that by having a speaker where one could vary the acoustic centers? If so, won't that introduce other unintended changes in the speaker's performance?

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post #114 of 534 Old 05-25-2011, 09:21 AM
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Do you propose to do that by having a speaker where one could vary the acoustic centers? If so, won't that introduce other unintended changes in the speaker's performance?
Yes, if by acoustic centers you mean time alignment.

And yes, it would be worrisome if it changes the speaker performance.

If the cable/load mismatch causes a delay/settling of 50 usec for example, perhaps that is exactly like backing the tweeter 1.5 cm?

And 5 usec as 1.5 mm?

How do they test audibility of time-alignment speakers vs common mounting plane?

Cheers, John

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post #115 of 534 Old 05-25-2011, 09:40 AM
 
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Originally Posted by jneutron View Post
How do they test audibility of time-alignment speakers vs common mounting plane?
Don't get me started John .
So called "time alignment" requires more than physical alignment of the measured acoustic centers, as filters introduce delays themselves. Not to mention that this must all be on (only) a specified "design" axis, problematic with a (multi-axis) polar field/reverberant environment and an unclamped listener with 2 ears.
I could type more, but I prefer less, so check this out.
Check audibility you say...??

cheers,

AJ
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post #116 of 534 Old 05-25-2011, 10:29 AM
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Originally Posted by jneutron View Post

Yes, if by acoustic centers you mean time alignment.

And yes, it would be worrisome if it changes the speaker performance.

If the cable/load mismatch causes a delay/settling of 50 usec for example, perhaps that is exactly like backing the tweeter 1.5 cm?

And 5 usec as 1.5 mm?

How do they test audibility of time-alignment speakers vs common mounting plane?

Cheers, John

To my knowledge it isn't done, John. A speaker manufacturer will have a philosophy when building speakers and if it's time alignment they'll direct the reader's attention to those aspects of their design that illustrate their skill at slaying the beast.

My gut feeling on this speaker wire delay thing is that it falls into the trivial many bin. Interesting to read about though.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #117 of 534 Old 05-25-2011, 06:30 PM
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...isn't damping pretty much the resistive ratio?

Yep. And if you include the speaker wire resistance as part of the source impedance (which I think you should) then amplifiers that have extremely high damping factors may be a waste of time. Notice I say MAY.

From the amplifier end the wire would be considered part of the load. From the speaker end, the wire would be considered part of the source. All wires have resistance (and inductance/capacitance), and it is not clear to me if they are always small enough to be neglected.

My envelope has proven to be unreliable, but just for fun calculate the effect of 20 feet of 14 gauge wire on the effective output impedance of an amplifier with a "damping" factor of 1000. I think you'll find the wire has significantly more "resistance" than the amp output.

Everything I say here is my opinion. It is not my employers opinion, it is not my wife's opinion, it is not my neighbors opinion, it is My Opinion.
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post #118 of 534 Old 05-25-2011, 07:01 PM
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14 AWG = 2.525 mohms/ft so 20' = 50.5 mohms (Reference Data for Radio Engineers, 5th ed) and DF = 1000 into 8 ohms implies Rout = 8 mohms. So, for your example, the wire dominates. However, I think a more realistic DF is closer to 100, giving amplifier output resistance of 80 mohms, comparable to 14 gauge and more than 12 gauge. Good connections add a few mohms, too; bad, more... Finally, most amps only have very high DF at lower frequencies; DF rises with frequency and by 10 kHz or so could easily be 5 - 10 or less.

Resistance in the wire lowers the Q and increases the damping factor (it's a little more complex than just the resistance but the equation depends upon the order of the system). The net effect in a T-line is more loss, less peak but longer ringing/settling, and more dispersion (smearing in time as different frequencies propagate at different rates and arrive with different amplitudes).

I don't think two independent tones phase-shifted would tell us anything about settling time by ear; we are looking for a cohesive signal that is corrupted (distorted) by the settling effects. A pulse would show that clearly in a measurement, thus my suggestion to use a square wave and listen for differences. Easily measured, probably harder to hear.

The impact of settling time due to reflections back and forth is relatively independent of damping factor; a perfect (zero-ohm output) amplifier with zero-ohm (d.c.) transmission line would still exhibit settling issues from the reflections between source (amp) and load (speaker). Except that resistance changes the characteristics of the transmission line, of course, as well as the driving-point impedance of the amp. We are still talking about two different things, however.

All imo, fwiwfm, my 0.000001 cent (microcent), etc. - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #119 of 534 Old 05-26-2011, 06:27 AM
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Originally Posted by DonH50 View Post

I don't think two independent tones phase-shifted would tell us anything about settling time by ear; we are looking for a cohesive signal that is corrupted (distorted) by the settling effects. A pulse would show that clearly in a measurement, thus my suggestion to use a square wave and listen for differences. Easily measured, probably harder to hear.

Concur. One vendor provided a square wave response to contrast normal wire and theirs. They had low Z cable, so the rise and ring was better for their cable of course. The verbage said this sounded better, but there were no controlled listening tests documented to back that assertion up, so no possibility of reproducing results.. Just marketing verbage.

I can't discount their assertion of better sound, but I also cannot support it given the information presented. I can agree from a T line analysis with what they provided, but that is not an audibility analysis.

Honestly, why should they bother with backup documentation? To satisfy geeks like me? Under no circumstances could I be considered a member of their target market.

Cheers, John

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post #120 of 534 Old 05-26-2011, 04:58 PM
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Hi John,
Bottom line for me, since you say this settling thing matters, it is up to you to show it matters. Otherwise is just like all other marketing (even though I know you are not marketing). You have math to show there might be a difference. And NO doubt there is a difference. It can be measured no doubt. But if it can not be heard, what is the point? I guess the point is to suggest something else to listen for. Which is, or course, a good thing. I secretly hope that one day somebody will be able to hear the difference between two cables we might think are "good enough". If you can suggest the test that does this you'd be an instant hero to many people.
Cheers, David

Everything I say here is my opinion. It is not my employers opinion, it is not my wife's opinion, it is not my neighbors opinion, it is My Opinion.
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