|   speaker cable lenghts...should be the same? | bobbybrady
Apr 17, 2001 3:14 PM | | I've got two surround speakers, and to be frugal, i'd like to get one 35 ft and one 50 ft cable. i've heard it's best to have the same length of cable, for time-delay or something. is this true? will 15 ft length difference matter? thanks. |
| re: speaker cable lenghts...should be the same? | Jon Risch
Apr 17, 2001 7:58 PM | | See:
http://www.AudioAsylum.com/audio/tweaks/messages/1582.html
In this Cable FAQ, I am speaking of the main speakers, so for HT rears/surround, it would certainly not be much of an issue.
In fact, HT rears/surrounds are fairly non-critical, and 12 ga. zip cord is usually going to be all that is needed for best results.
For main speakers, or the center channel, I recommend somthing better, see:
Everyone Should Get Good Cables:
http://www.audioreview.com/message/cgi-bin/dcforum/dcboard.cgi?az=show_thread&omm=0&om=809&forum=DCForumID8
and
The DIY note that started it all
http://members.nbci.com/Jon_Risch/i1.htm
for the companion note to the interconnect note, the one on DIY speaker cables
http://members.nbci.com/Jon_Risch/s1.htm
and
Easy coaxial based speaker cables:
http://www.AudioAsylum.com/audio/cables/messages/7637.html
For more on audio cables, see:
http://www.AudioAsylum.com/audio/cables/messages/19902.html
Jon Risch |
| re: speaker cable lenghts...should be the same? | CE
Apr 18, 2001 8:00 PM | | Even with a new computer and cable modem, thr babble is still unintelligable. You can STILL hear TEFLON? You can hear 15 feet of wire...you are pulling our leg(s). |
| re: speaker cable lenghts...should be the same? | mtrycrafts
Apr 17, 2001 9:10 PM | | Don't worry about that 15ft. Some like to though without any real demonstrable audible differences, just like to worry about nothing. |
| No, not necessary | Eyespy
Apr 17, 2001 10:05 PM | | The delay increments of your receiver/pre-pro's speaker calibration function are enormous, vast actually, in comparison to the completely minute, negligible, practically infinitesimal time delay that the 15 foot difference in wire would cause. You have MUCH better things to worry about. |
| No, not necessary | Tom N.
Apr 18, 2001 7:05 AM | | We should have this tread listed in the all time great and wonderous threads of AR...
Jon, Mtry and Eye all agree....
Of course I just wish to point out that you are all wrong... heheheh (joking).
Tom N. |
| No, not necessary | Eyespy
Apr 18, 2001 7:57 AM | | Doesn't happen very often, does it. Actually, Jon didn't completely agree, but only as far as unequal wire lengths for surrounds are concerned. Mtry and I would carry the logic over to the front main speakers as well regarding a 15 foot differential, whereas Jon definately would not. |
| re: speaker cable lenghts...should be the same? | jAGNER
Apr 18, 2001 2:50 AM | | your 50 ft will havea longer delay than your 35 ft. This may cause echo to your surround sound. If you intend to use these cables, one surround speaker (connected to the 50 ft) will have o be placed closer to the listener to compensate for the delay. |
| "This may cause echo to your surround sound" | Eyespy
Apr 18, 2001 8:01 AM | | You definatley need to review the physics involved here, your concerns are completely unfounded.
"your 50 ft will havea longer delay than your 35 ft"
Just how long a delay do you suppose this will cause?
"one surround speaker (connected to the 50 ft) will have o be placed closer to the listener to compensate for the delay."
What units of distance would you measure this in? |
| I'm amazed . . | Norm Strong
Apr 18, 2001 2:22 PM | | . . at how little useful information one can get by reading this forum. It seems there is no question--no matter how fundamental and simple--that does not turn into the subject of a raging argument. |
| I'm amazed . . | DulceBuzz
Apr 18, 2001 6:26 PM | | I agree. |
| So I see... | Eyespy
Apr 18, 2001 8:03 PM | | But I didn't see where the argument was raging. If you meant my post, which was one comment and two questions, it was meant to provoke a reasoned thought process, not an argument. Sorry if it came across the wrong way; I considered it more useful than the erroneous, if well intentioned, statements by jAGNER. Sometimes, the intended emotive element is difficult to convey with the written word in brief postings, and thus, are prone to being misconstrued. No argument, or offence intended. |
| So I see... | DulceBuzz
Apr 18, 2001 8:42 PM | | I have a feeling its an accumulation of posts. Not just this one. |
| So I see... | Eyespy
Apr 18, 2001 10:05 PM | | Can you back up that feeling with links to such an accumulation? |
| So I see... | DulceBuzz
Apr 20, 2001 1:41 PM | | The accumualation of posts with people bickering is what I meant. |
| Let's do some math shall we | GCM
Apr 18, 2001 9:24 AM | | The signal travelling down the speaker wire is propogating at a rate of approximately 100,000 miles per second. Therefore it takes .00001 seconds to travel a mile. 15 feet is approximately .00284 miles. So the time it takes the signal to travel 15 feet is .00001 * .003 or approximately 2.84e-8 seconds. I'd be kind of surprised if you notice that as an echo.
Some more math.
Using round numbers, the audio signal in the speaker wires is travelling at approximatley 100,000 miles a second. The sound from the speaker is travelling at approximately 700 miles per hour or 12 miles per second. Since sound travels at 12/100,000 the rate of the electical signal, you'd have to move the speaker 15' * 12/100000 which is .0018 feet or approximately .02 inches to compensate. |
| Let's do some math shall we | mtrycrafts
Apr 19, 2001 10:21 PM | | Why do I get a different number? It takes 15 nano sec to travel that 15 ft. How far does sound travel in that time in air if it travels 1ft in a millisecond?
I think I see your error. The speed of sound is about 1100ft per second, not 12 miles per second.
So, th espeaker needs to be moves .000012". He better get a laser measuring device for such accuracy. What will he do to fix his head in such close tolerences? |
| Let's do some math shall we | Eyespy
Apr 19, 2001 11:12 PM | | "What will he do to fix his head in such close tolerences?"
Well, this gets us into the ballpark, at least initially. Unfortunately, the rates for loosening and infection of the pins used in the halo apparatus are high. The commonly recommended amount of torque to be used in applying the pins is 0.68 newton-meter (six inch-pounds). Fortunately, however, the rate for loosening of the pins and the rate for infection at the pin site drops from 36% down to 7% (for loosening) and from 20% down to 2% (for pin tract infection), respectively, if we instead use an increased torque of 0.90 newton-meter (eight inch-pounds). |
| Let's do some math shall we | mtrycrafts
Apr 20, 2001 12:02 PM | | Does one need to remove the skin first to have direct contact with the bone? Is that what you numbers are based on? I love it. :-) |
| Let's do some math shall we | GCM
Apr 20, 2001 9:49 AM | | You are correct sir. My mistake was in converting miles per hour to feet per second for the speed of sound I thought my answer of .02 inches was excessive, but unfortunately didn't check my work. Thank you. |
| Let's do some math shall we | mtrycrafts
Apr 20, 2001 11:59 AM | | Hey, what's a few decimal places among friends :-)
But, Jon likes to worry about such a small numbers, that is why he claims to hear the effects of insulation material; the decimals are in the 4th or 5th place for that effect, in db.
Oh, no need to call me sir:-) |
| Just curious........ | TinHere
Apr 21, 2001 2:27 PM | | What percentage of audial differences are generally being discussed that make hearing them a subject of debate? Shouldn't someone know that number or does it vary? If a tree falls....:) |
| Just curious........ | Eyespy
Apr 22, 2001 4:37 PM | | These are known as JNDs, or Just Noticable Differences, and have been extensively studied. They vary dependant on freq, as our hearing sensitivity is not linear across the auddible spectrum, as shown in Fletcher-Munson curves. |
| Since you asked :-) | mtrycrafts
Apr 22, 2001 8:49 PM | | let me give you some reading material :-)
Clark, David "High-Resolution Subjective Testing Using a Double-Blind Comparator," Journal of the Audio Engineering Society, Vol30, no 5, May82, pg 330-338.
Florentine, Mary, et al 'Level Discrimination as a Function of Level for Tones from .25 to 16khz. Journal of Acoustic Society of America, 81(5) May 1987, pg 1528-1541.
Zwislocki, J and Jordan H. 'On the Relations of Intensity JND's to Loudness and Neural Noise,' Journal of Acoustics Society of America, 79(3), Mar 86, pg 772-780.
Villchur, Edgar, 'Speaker Cables, Measurements vs Psychoacoustic Data,' Audio, Jul 94, pg 34-37. |
| Phon-tasic ......Gents........thx. [nt] | TinHere
Apr 22, 2001 9:42 PM | | |
| Your'e ALL Wrong! | Jon Risch
Apr 21, 2001 9:11 AM | | Not only did you slip some decimal places, but this type of simplistic analysis assumes that there is just a signal traveling down a wire without any other factors.
It seems that you tried to take into account the cable insulation slowing down the propagation fo the signal, as signal speed in a vaccum would be approx. 186,300 miles per second.
However, there are still other factors, such as the cable INDUCTANCE of typical zip cords, and the differing resistance causing differing damping factors.
This will far outweight the effects calculated from velocity of propagation assumptions.
The differences in signal arrival times due to inductance will be on the order of micro-seconds, orders of magnitude higher than what all your simplistic calculations arrive at.
As I correctly note in my FAQ on the subject ( http://www.AudioAsylum.com/audio/tweaks/messages/1582.html
), it is these differences in inductance and resistance for differing lengths that ultimately would cause problems, and the phase shifts and damping factors involved are what are responsible.
For HT rears, it is still a moot point, but for main speakers or a stereo only system, it should be something to keep in mind.
PS. Why is it you guys are just plain WRONG so often?
Come on now, blow it off, trivialize it, redirect and obsfucate.
Jon Risch |
| OK then. | Markw*
Apr 21, 2001 9:53 AM | | Exactly how should he reposition his speaker to compensate for this gross 15 foot disparity.
FWIW, you can argue theory and numbers all you want but I still don't believe that anyone, including dogs and even you, would hear this difference. You are welcome to prove me wrong in front of witnesses if you wish.
It seems that you are trying for the Audio Nervosa poster boy of the year award again. |
| OK then. | Jon Risch
Apr 21, 2001 3:50 PM | | Speaker repositioning is NOT the answer, and all I was pointing out was that an overly simplistic analysis is worse than none at all, due to it being so misleading.
When the cable inductance overshadows the velocity of propagation by orders of magnitude, then calculating and discussing VOP is a red herring, and so is the talk of speaker repositioning.
Speaker repostioning will NOT fix this, as the inductance will cause a phase shift that can not be readily fixed by leading the signal acoustically.
Wrong problem, wrong fix.
Jon Risch |
| So then, | Markw*
Apr 21, 2001 7:28 PM | | You are saying that this will be audiable? Please reread my second paragraph in the above post again.
If not, then an overly simplistic analysis is no more meangless as an over complex analysis.
Or, to put it simply, what's that got to do with the price of tea in a certain Asian country that currently is holding one of our planes? |
| Let us not forget... | Eyespy
Apr 22, 2001 3:51 PM | | Jon can hear one additional foot of Monster cable added in, or so he claims. |
| OK then. | mtrycrafts
Apr 22, 2001 9:03 PM | | <<<Speaker repostioning will NOT fix this, as the inductance will cause a phase shift that can not be readily fixed by leading the signal acoustically. >>>>
But Jon, can you demonstrate and prove that this is audible? Claiming it does is not enough and you have yet to show the simplest of audible differences. How will anyone believe you with all these outlandish claims. |
| So you agree then | GCM
Apr 23, 2001 9:06 AM | | You call us (me) wrong than reaffirm my point, that 15 feet of wire won't result in an echo or require speaker repositioning. |
| So you agree then | Jon Risch
Apr 23, 2001 10:30 AM | | Don't get too smug about being right for the wrong reason, and for overlooking some very basic physics.
That was MY point, simplistic or erroneous analysis can be very misleading.
Jon Risch |
| So you agree then | GCM
Apr 23, 2001 12:24 PM | | I was addressing the guy who spoke of different cable lengths causing an echo because of the different transmission times in the differnt lengths of wire. I was right about that for the right reason. I never attempted to answer the original question. Look at the post my reply was attached to. |
| Your'e ALL Wrong! | mtrycrafts
Apr 22, 2001 8:58 PM | | >>>However, there are still other factors, such as the cable INDUCTANCE of typical zip cords, and the differing resistance causing differing damping factors. <<<<
What a bunch of NONsense. Show me a text book and formula that includes these in the calculation of signal propogation speed. Please.
>>>and the phase shifts and damping factors involved are what are responsible.
<<<<
More silly nonsense. Your buddy tried to measure phase shift and they were very small fractions of a degree. Once again, you are assuming more than you can demonstrate and prove. Kind of tipical for you, isn't it.
>>>Why is it you guys are just plain WRONG so often<<<<
Why is it that you cannot demonstrate any of your audibility claim, Jon? Plain WRONG all the time? |
| Actully.... | brothapig
Apr 22, 2001 9:53 PM | | ...you are correct in that the *electricity* arrives at the speaker at near the speed of light, but the total signal doesn't. The total signal is compised of many many different signals operating at different frequencies, thus the lower frequencies serve as an envelope modulating the higher frequencies. (just add two sine or cosine waves and you'll see what I mean) This is the "beat" heard when two tuning forks of different frequencies vibrate simultaneously. True, the seperate high and low frequencies travel at near the speed of light (or however fast electricity travels thru wire), but the envelope would travel at a much slower velocity, based upon the rate of change of the different original signals. This is called group velocity. Now I'm not trying to say this envelope is part of the music by design, but rather an important part of the way the different sounds of the music interact. I would think this would be a very important part of the "music." Now that the total signal has different velocities, this only supports the concept that wire length would have very little influence on the sound, unless taken to the extreme, of course. |
| Your'e ALL Wrong! | GCM
Apr 23, 2001 9:04 AM | | Mtrycrafts already pointed out the error in my math. I did it quickly and unfortunately didn't go back and check it. The point I was trying to make was that 15 feet of cable wouldn't result in an echo. Do you maintain I'm wrong about that? |
| Not a problem.. | Markw*
Apr 18, 2001 3:31 AM | | The delay situation is purely theoretical here and will not be a problem. That's like worrying about how removing one grain of sand from the beach will affect the tides.
I'd be curious for someone to actually provide figures to substantiate this as a problem, particularly since the speakers distance to your ears would be the limiting factor here. After all, electricity travels through wires much, much faster than sound travels through air but many people tend to forget this. |
| re: Ask yourself this... | Monstrous Mike
Apr 23, 2001 2:27 PM | | If it was true, who would benefit? Well, the listener would benefit because he now has eliminated "time delay". And the cable companies would benefit because now all consumers would have to duplicate their maximum cable length resulting in an increase in sales.
And further to that, if differences in cable lengths caused a time delay, then don't you think that new receivers would have some simply circuitry to compensate for it? |
| re: Ask yourself this... | jAGNER
Apr 23, 2001 8:14 PM | | I never realized I got a lot of reactions because of a simple suggestion, which I based on my personal experience on setting up A/V systems. I don't show stats and other mathematical data. Books, white papers and lectures have these. I learn from them and just do my own tinkering/experimenting based from what I have learned.
Mike, a lot of A/V receivers have time delay switches to compensate for surround sound. They've thought about this problem before that's why they've incorporated it in their equipment. |
| re: Ask yourself this... | Eyespy
Apr 23, 2001 11:09 PM | | "Mike, a lot of A/V receivers have time delay switches to compensate for surround sound"
Yes, that was Mike's point. If unequal cable lengths were going to cause delay times, then there would be circuitry in the receiver to compensate for this, not just to set delay times for center and surround speakers. Afterall, if this were a real problem, why would the manufacturers of these receivers not have thought about that just as much, and then incorporate it into their equipment? |
| Huh??? | Markw*
Apr 24, 2001 4:38 AM | | "...which I based on my personal experience on setting up A/V systems."
Perhqaps you need more experience.
Sorry, no. A 50 foot run will NOT produce an echo when used with a 35 foot run. |
| re: Ask yourself this... | GCM
Apr 24, 2001 7:49 AM | | "Mike, a lot of A/V receivers have time delay switches to compensate for surround sound"
And you think this is to compensate for unequal speaker wire lengths? Hoo boy. Did you learn nothing from the responses to your post? With the signal travelling over 100,000 miles per second, you won't hear 15 feet. The surround sound delay is not to compensate for wire length differences. |
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