Does length matter....or only width?

[Teeza]

I confess I have not scoured these forums to see if this question has already been addressed, so apologies if it has.

Should speaker cable lengths be kept equal between left and right channels? My left front is much closed to the amp then the right so I could have un-equal cable lengths but instead have chosen to coil up the excess.

My schoolboy physics falls well short of trying to figure this out logically but it would seem that having the same thickness of cable could be important. If so, is that just L to R or also F to B in a surround configuration.

(Presumably amps that self configure could overcome any issues associated with diverse cable lengths/widths?)

 

[Anonymous]

The difference in length would have to be very substantial for you to notice any change in sound quality at all. What kind of difference are you talking about?

 

[idc]

I would recommend you keep the lengths equal for two reasons; firstly the ear is very sensitive and without realising it can notice minute differences such as one speaker sounding out of time with another and secondly what if you move house, your furniture and/or your hifi about, you would need to start again.

 

[Anonymous]

idc:the ear is very sensitive and without realising it can notice minute differences such as one speaker sounding out of time with another

So how fast does the music signal move down a speaker cable?!!

 

[The_Lhc]

AIUI the issue with speaker cable length is not one of timing, it's load. The speaker cable impedance adds to the impedance of the speaker itself and thus the total load placed on the amplifier stage, with different lengths of cable either side you'll get different loads on each side of the amp, which could result in a different sound (and possibly volume, thinking about it) from each speaker, which is obviously to be avoided. How much difference it makes will depend largely on the speaker cable in use I'd expect.

Does that sound plausible?

 

[Anonymous]

Yep

 

[Anonymous]

In scientific terms. Like I said, the difference in length would have to be very large for you to hear any difference.

 

[The_Lhc]

trevor79:the_lhc: Does that sound plausible?

Yep

Blimey, I thought I'd made it all up!

 

[Anonymous]

the_lhc:
trevor79:the_lhc: Does that sound plausible?

Yep

Blimey, I thought I'd made it all up!

After 25 years in management / business I find that blagging or appearing to know what you are talking about (even though you dont) works wonders!

 

[idc]

heystak:idc:the ear is very sensitive and without realising it can notice minute differences such as one speaker sounding out of time with another So how fast does the music signal move down a speaker cable?!!

I stand by my comment that the ear can notice minute differences in sound which is why it is better to keep cable lengths the same, and I can blag just as well as the_lhc;

when electric current in a material is proportional to the voltage across it, the material is said to be "ohmic", or to obey Ohm's Law. A microscopic view suggests that this proportionality comes from the fact that an applied electric field superimposes a small drift velocity on the free electrons in a metal. For ordinary currents, this drift velocity is on the order of millimeters per second in contrast to the speeds of the electrons themselves which are on the order of a million meters per second. Even the electron speeds are themselves small compared to the speed of transmission of an electrical signal down a wire, which is on the order of the speed of light, 300 million meters per second.

So Heystak, the answer is just short of the speed of light.

 

[Anonymous]

idc:
So Heystak, the answer is just short of the speed of light.

I would agree that ideally cables should be of equal length but in a typical domestic setup the odd metre is nothing to worry about at these sorts of speeds.

 

[aliEnRIK]

"Does length matter....or only width?"

My girlfriend says BOTH

 

[Teeza]

Thanks for the quick replies guys.

I'll go with the notion that normal domestic cable lengths are unlikely to make an appreciable difference. FYI from my amps manual it says that the initial reflected sound hits the ears between 50-100ms after the direct source sound - and I'm not sure that I am normally aware of them.

The impedance bit about the load on the amp - how do cable thicknesses affect impedance/load in terms of what we hear? Although I have equal length cables L/R and F/R the thickness of the cables to the rear (under the carpet) are very different to the front cables.

This wasn't really a concern in a pro-logic set-up where the rears were just mono effects channels, but now I am in the process of upgrading to a 5.1 digital system do I need 6 identical lengths of identical cable?

 

[Anonymous]

Usually recommendation for equal length is for two main front speakers. You can use different cable and different length for the rears, in fact most people do.

 

[The_Lhc]

chainrock: Usually recommendation for equal length is for two main front speakers. You can use different cable and different length for the rears, in fact most people do.

Yeah I've never worried about front to rear matching really, the rear is so much more unfocussed it'll be much harder to notice any differences between cables compared to the fronts.