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Effect of Length [message #63531]

Mon, 26 July 2010 13:24

Lancelot
Messages: 99
Registered: February 2010

Viscount

Does the length of a audio cord affects the quality of the sound produced? I know that this is true with the internet connection but how about with audio connection?

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Re: Effect of Length [message #63532 is a reply to message #63531]

Mon, 26 July 2010 13:39

Wayne Parham
Messages: 18677
Registered: January 2001

Illuminati (33rd Degree)

Certainly. As length increases, so does resistance and reactance. For loudspeakers, it's the resistance that usually matters most and for interconnects, the reactance (capacitance and inductance).

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Re: Effect of Length [message #63536 is a reply to message #63531]

Mon, 26 July 2010 21:40

Adveser
Messages: 434
Registered: July 2009
Location: USA

Illuminati (1st Degree)

Very very little. Let me know what you are dealing with, such as AWG and the specific length and I can give you exactly what the specs should be as far as Resistance. My circuits book has this stuff in there and i'll be glad to let you know.

http://adveser.webs.com/

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Re: Effect of Length [message #63539 is a reply to message #63536]

Mon, 26 July 2010 22:56

Wayne Parham
Messages: 18677
Registered: January 2001

Illuminati (33rd Degree)

Let's say a guy doesn't really know the effects of speaker wire resistance and buys a spool of this stuff to wire his home:

22 guage speaker wire

Two rooms are pretty close to his 100 watt per channel home theater, and can be run up the wall, over the celing, and down the other wall with relatively short runs, 25 feet on one and 40 feet on the other. Another room takes 60 feet and the longest run takes 100 feet. Then he decides to wire some outdoor speakers that need 150 foot runs.

Since the speaker cable is a wire pair, the conductor length is twice the run length. In other words, the room that requires a 100 foot run has 200 feet of wire in the line...

...I think probably it would be best to understand that larger guage wire is going to be necessary, at least for the longer runs. The length of wire is enough to modify the response of the speakers by introducing a few ohms resistance, having a similar effect as raising Qes.

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Re: Effect of Length [message #63564 is a reply to message #63531]

Thu, 29 July 2010 21:25

jesstasy
Messages: 6
Registered: July 2010
Location: New York

Esquire

There seems to be a confusion on the proper way to answer this question. One says it certainly matters. Someone else says it matters very, very little. Which is correct? I am also very curious about this matter as well but need some clarification.

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Re: Effect of Length [message #63587 is a reply to message #63564]

Sat, 31 July 2010 09:46

Keith Larson
Messages: 34
Registered: May 2009
Location: Boston

Baron

Electrically you have a series connection of an amplifier, wire and speaker, so it comes down to ohms law, and thats nothing more than impedance ratios. Anyhow, if the wire impedance is high compared to the speaker (and amplifier) some of the signal will be show up in the wire instead of the load. This is calculated using the equation

dB(loss) = 20*log(Rload/(Rload+Rwire+Ramp))

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Re: Effect of Length [message #63591 is a reply to message #63564]

Sat, 31 July 2010 23:17

Adveser
Messages: 434
Registered: July 2009
Location: USA

Illuminati (1st Degree)

Well, that is because the difference is typically very small. When I asked my teacher about this, he looked at me like I was crazy because he knows I am talking in the sense of a 16awg wire being a half inch shorter on one speaker. Naturally there are always conditions where it would become a bigger deal, but in a more general way, it isn't an issue, but some think it extremely important to correct even the slightest thing. Just use the chart and move the decimal places correctly. If it falls somewhere between the usual 10% tolerance, it is not worth the hassle. If you wanna be really accurate maybe go 2-5% tolerance. There is a calculator down at the bottom that might help.

Here is the chart:
http://www.powerstream.com/Wire_Size.htm

http://adveser.webs.com/

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Re: Effect of Length [message #63596 is a reply to message #63531]

Sun, 01 August 2010 20:59

Lancelot
Messages: 99
Registered: February 2010

Viscount

Thank you guys for those inputs. I ask this question because of the speakers on my workplace. I work in a school and there are speakers in all buildings so everyone will hear any announcements. Some speakers sounded loud and some are not so loud. I guess I have the answer from the chart.

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Re: Effect of Length [message #63600 is a reply to message #63596]

Sun, 01 August 2010 21:48

Shane
Messages: 1117
Registered: May 2009

Illuminati (3rd Degree)

Ummm....in our workspace we have volume adjustments on each of the ceiling mounted speakers....just a thought?

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Re: Effect of Length [message #63605 is a reply to message #63600]

Sun, 01 August 2010 22:08

Wayne Parham
Messages: 18677
Registered: January 2001

Illuminati (33rd Degree)

I'm not really as concerned about power loss as I am with modifying the response. When the electrical resistance is increased, it reduces damping, much like what you get from a SET amplifier. In some cases, it isn't a problem but in some cases, it is.

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