Speaker cable - interference?

[extracampine]

I know that it's best to avoid rolling up unused speaker cable, or running speaker cable along side mains cables.

 

I was wondering if it would be OK to run the cable for one of the speakers alongside a Sky cable (which connects the satellite to the Sky Box)? I'd imagine that the Sky cable is low-powered so should be OK, but just wondering on your thoughts.

 

Thanks!

 

[davidR]

I think you'll be good Dan. Take a listen after connecting and if everything sounds good, it is good.

 

[Christopher]

Hi Dan,

 

Most satellite coaxial cable, such as your Sky cable, is shielded with both foam polyethylene insulation and aluminum foil sheathing. This shielding helps protect against electromagnetic and radio frequency interference (the noises and hums you are worried about).

 

I’ve heard that using coaxial cable as an interconnect between certain pieces of equipment can create an electrical connection between them. This sometimes results in a ground loop and you will hear a hum.

 

I agree with David (above post) - it’s very unlikely that you will have a problem running your speaker cable next to your Sky cable. In the end, you should trust your ears. If there is nothing audible, you’re probably fine.

 

On a side note, make sure that your speaker cable is the same length for both L+R channels.

 

Enjoy the music,

Chris

 

 

 

[sastusbulbas]

I was under the impression that unless there is a huge difference the length of each cable will not matter.

 

As for running it by other cables, It will be fine, I have just such a cable running along my wall next to a speaker cable with no audible problems, along with a few other cables.

 

[mikesmith11]

You should be fine. Just make sure you have good speaker cables. I buy mine from here

 

[realafrica]

What if one is using 5 or more speakers? Should cables lengths be equal for all?

The amp is never in the centre of the room is it! So usually there is one speaker pretty close to the amp and the diagonally opposite one could be at least 20 feet further in cable run.

What do you do (if cables are all equal length) with the extra 20 foot of cable for the speaker next to the amp, other than coil it?

 

[One and a half]

The Sky cable as others pointed out, makes sure the noise form the outside doesn't get into the cable. The loads on a skycable signal are so small, the voltage is in the microvolt range, and their impedance is moderate, 50 Ohms or 75Ohms, constant.

A speaker circuit is very low impedance (ie a short circuit capable), and the amplifier which is the source has also low impedance. Any RF noise would be likley to attract the coax, since RF noise propogates along the sheilds very well and will ignore the low impedance circuits totally, regardless of length.

 

[realafrica]

To clarify my previous question or maybe just put it another way, which may or may not make it clearer:

 

Can one have speaker cable runs of equal lengths to front speakers, and longer runs to rear speakers but still keeping lengths equal in their respective pairs?

For example, the amp is in right hand corner of a room, as is one of the front speakers, the run from amp to other front speaker is 12 foot. So keeping pairs of speakers cabled with equal length the speaker in the right corner (with the amp) has maybe 9 foot of spare cable coiled there. The cable run from this right-hand corner to the diagonally opposite corner could be about 25 foot, but only 15 foot to its pair (as rears).

If all cable runs are supposed to be equal to all 4 corners, then in this very common scenario you have 25 foot of cable to the furthest speaker from the amp (in diagonally opposite corners) but only 3 foot required to reach from amp to speaker in the same corner as the amp.

 

To sum up, there are 4 points:-

1) What is the best thing to do about speaker cable lengths?

2) Is it proper to coil the excess cable behind some speakers/amps.?

3) Can you make shorter yet equal runs to the front pair, say both 12 foot, but have 2 x 25 foot runs to the rear pair? Or should all cable runs be equal to all speakers?

4) Should the centre speaker have the same length as the front pair?

 

 

[Audio_ELF]

Ideally cables should be the same length so they present identical load to the Power Amp. If there is a difference there may be a marginal difference in the sound quality between left and right. In practical terms though with most power amps there is little noticeable difference. If you can keep the left and right identical.

 

The issue with front / rear cable lengths is different. For a variety of reasons you are less likely to notice if you have long rear cables. In most setups people tend to use higher quality cables for the front two or three than the rear ones. One thing is that most people don't have identical rear speakers, so you already have a difference in sound between front and rear and the addition of an extra 13ft of cable (in your case) is unlikely to add anything more.

 

Eloise

 

[realafrica]

Audio_ELF:

Thanks for taking the time to give your opinion on this matter. To sum up, you suggest that having longer runs of speaker cable to the rears in a surround system has little effect on the sound, as long as the cable lengths to left and right are equal. Is that right?

 

Any other opinions from other people.

 

[Christopher]

Speaker wire discussions often involve significant debate. There are varying opinions and different approaches when testing the performance of speaker wire. What is quantitatively measurable in some tests may not be audible for all listeners. In addition to perceived performance, there are other factors (such as cost and aesthetics) that will make some speaker wire more desirable than others. Ultimately, what is considered to be a good approach and best practice for some may not be considered important or significant for others.

 

Regardless of what speaker wire we select, some of us will have room design elements and placement configurations that will render the location of an amplifier in a place that is not equidistant to left and right channel speaker locations. This also holds true for multi-channel configurations, such as home theater applications.

 

If we are confronted with such challenges, should we cut speaker wires to length, or coil the excess? Do different speaker wire lengths matter? For example, do different length speaker wires result in undesirable effects, such as audible phase disparity? With these questions in mind, I will offer my opinion concerning different length speaker wire.

 

There are certain aspects of speaker wire that are relevant to this discussion. Below are four parameters that can impact speaker wire performance:

 

Resistance >> a function of wire gauge or thickness (measured here in AWG)

Capacitance >> a function of length and distance

Inductance >> a function of length and distance between leads, twists and loops

Terminations >> the quality of contacts and pressure points where speaker wire meet equipment

 

In a perfect world, speaker wire will have no resistance, no capacitance, no inductance and oxidation-free terminations. Since theoretical perfection is not possible, low resistance is usually considered to be one of the most important aspects of speaker wire performance.

 

In general, thicker wire reduces resistance. Certain tests suggest that the resistance of 16AWG wire has no detectable effect in runs of 48 feet or less for standard speaker connections with 8ohm speakers. Some studies suggest that resistance begins to have an audible effect when resistance exceeds 5% of the speaker's impedance. (see Roger Russell link below for further reading)

 

Shortening the length of speaker cable can help reduce resistance. Increasing the gauge of speaker wire (i.e., going from 16AWG to 10AWG) can also help compensate for longer runs between amplifiers and speakers.

 

What if we have different speaker wire lengths between the amplifier and each speaker? Should we cut or coil the excess?

 

Assuming resistance is low (for example, using 10AWG speaker wire), a very long distance would be needed to produce an audible difference in speaker cable length. Some studies suggest that a 10-foot difference in length of 10AWG speaker cable is approximately equal to an acoustic delay of 0.003mm. In relative terms, a human hair has a diameter of about 0.05mm. This would suggest that a 10-foot difference in speaker wire length is the equivalent of moving a speaker one tenth of a hair's width.

 

When using thinner wire (such as 22AWG), you should probably be more concerned with not exceeding 5% of the speaker's impedance. Roger Russell, a former McIntosh Laboratory loudspeaker designer, has produced research that recommends runs of 12 feet or less when using 22AWG speaker wire with 8ohm speakers.

 

Personally, I prefer to keep speaker wire lengths as equal as reasonably possible. I’ve invested in speaker wire that has silver factory termination points that would be a shame to cut. My computer audio system has some excess speaker wire concerning the right channel. Instead of cutting or looping the excess, I run the cable in a serpentine snake-line formation on the floor to avoid bunching and coiling.

 

My home theater system, on the other hand, has a much greater difference in speaker wire length concerning rear channels. Since I only run wire along one side of the room, the distance of wire between rear speakers is significant. In this case, I decided to use thicker wire and cut the excess. Surround-sound speaker wires are well within 5% of the speaker's impedance and, so far, performance has been good.

 

Another key difference in my home theater system is the length of center channel speaker wire. Since the center channel speaker sits on top of the stereo rack, speaker wire is very short when compared to the length of left and right channels (main and rear). I’ve compensated for this with DSP programming. It seems to work fine.

 

Aside from speaker wire length observations, I find that termination points are an important maintenance opportunity. Every year or so I re-cut and bind contact points involving speaker wires that do not have factory terminations. Avoiding oxidation is a simple and cost-free way to help preserve and protect audio quality.

 

Wishing you happy holidays and much music enjoyment.

 

Best regards,

Chris

 

Sources and further reading:

http://www.roger-russell.com/wire/wire.htm

http://procosound.com/downloads/whitepapers/Understanding%20Speaker%20Cables.pdf

 

 

[extracampine]

Thanks for all the excellent info!