Speaker/interconnect /power cord routing

[doitmyself]

Regarding home theater wiring, can someone educate me about routing power cords close to other cables such as low voltage, interconnects, and speaker cables.

I know the codes don't allow them to share the same box and that signal cables should not run alongside power wires.

What about the wire/cable mess around your components? How does one keep power cords away from the other types?

And one specific question: can I run my surround speaker cables through a shared floor hole with the satellite coax (touching each other)?

Thanks

 

[eljefino]

Originally Posted By: doitmyself

And one specific question: can I run my surround speaker cables through a shared floor hole with the satellite coax (touching each other)?

Thanks


This you absolutely can do. RG6 is shielded.

As far as power cables, try to cross signal ones at a 90 degree angle if you have to. You'll know a 60 Hz hum; it's unmistakable, and if you go back there and wiggle the wires when it's doing it you'll find it.

 

[Stu_Rock]

There aren't many requirements for low-voltage in-wall wiring. You have most of it already. One more thing: use fire-resistant cable. Go for plenum-rated cable if it enters a space where air moves.

On long runs of line-level audio, I like to use shielded single-wire cable. Sometimes I notice faint crosstalk if multiple wires share the same shield.

As far as interconnects go, it's up to you. I like using keystones, but it seems like most homeowners just run the cable through a wall plate with a hole. That looks sloppy to me.

Near the components, organize cables however you like. I sometimes use split-loom tubing if there's a long span. I've never had problems bundling AC cords with signal cables in an AV cabinet.

 

[doitmyself]

Thanks for the comments. I was aware of the 90 degree rule and have studied the NEC regarding running low voltage wires near high voltage.

According to Blue Jean cables, speaker wires with low impedance and high current are relatively immune from EMI noise. Yet, many references recommend keeping them as much as 16 inches away from high voltage (110/120v).

My question about rear surround speaker cables near dish satellite came from the following link (and others) that say that satellite coax can pick up EMI in the shield and/or be improperly grounded to cause sub woofer or speaker hum:

http://oreilly.com/pub/h/4241

I'm re-working my modest system and am just trying to learn more. But, if something works, I won't change it!

 

[Volvohead]

If you have any EFI concerns, coil the offending cable in a figure eight pattern. Despite shielding, I try to keep sensitive signal line level, RF and network lines away from mains lines when possible in any higher end system. Otherwise, a "messy" cable layout is less prone to cross-interference than the neatly bundled ones (that often unwittingly run parallel to each other) in my experience.

You're correct about in-wall wiring; mains voltage and low voltage can't share the same "box". But there are two gang enclosures and separator plates that will allow both AC and low voltage.

More importantly, don't run power cords though the walls. That's a big no-no under the code. Yet many folks will still do it, especially with wall-mounted flat panel TVs.

If you encounter hum, most often it is a ground loop issue. Happens all the time if anything is coming from the cable co. I've encountered ground differentials as high as 25 volts. Installing an isolator usually resolves it.

 

[Papa Bear]

Originally Posted By: Volvohead


If you encounter hum, most often it is a ground loop issue. Happens all the time if anything is coming from the cable co.


+1

 

[doitmyself]

Originally Posted By: Volvohead
If you have any EFI concerns, coil the offending cable in a figure eight pattern. Despite shielding, I try to keep sensitive signal line level, RF and network lines away from mains lines when possible in any higher end system. Otherwise, a "messy" cable layout is less prone to cross-interference than the neatly bundled ones (that often unwittingly run parallel to each other) in my experience.

If you encounter hum, most often it is a ground loop issue. Happens all the time if anything is coming from the cable co. I've encountered ground differentials as high as 25 volts. Installing an isolator usually resolves it.


-Is EMI and EFI the same thing?

- Regarding the figure 8 comment, is it true that coiling cable in a circle can create problems? When and how?

- Does one figure 8 the "offending" cable or the one you are trying to protect? Should all excess cable be figure 8'ed....i.e power cords, speaker, etc.. Please explain the figure 8 rational.

- Regarding messy vs. neat behind your rack. Is it o.k. to bundle similar cables (all your components power cords) or should they be helter skelter? Bundle speaker cables together?

- Is Blue Jean cables assertion that speaker cables are fairly immune to EMI noise correct. Others (and you) say that its the interconnects that are much more sensitive.

- What's your stance on the idea of having the shield on a sub cable connected only on one end to reduce "noise" problems.

 

[Quest]

Originally Posted By: doitmyself


-Is EMI and EFI the same thing?

Q: Nope. EMI stands for Electromagnetic interference; EFI maybe (in automobile terms) stands for electronic fuel injection? (lol!)

- Regarding the figure 8 comment, is it true that coiling cable in a circle can create problems? When and how?

Q; if you coil it into a circle, it will act as a loop antenna, picking up radio signals (although in practicality terms, not much being picked up unless you live close to an AM radio broadcast tower, close proximity to power transformer substation, or close to industrial section of your neighbourhood.


- Does one figure 8 the "offending" cable or the one you are trying to protect? Should all excess cable be figure 8'ed....i.e power cords, speaker, etc.. Please explain the figure 8 rational.


- Regarding messy vs. neat behind your rack. Is it o.k. to bundle similar cables (all your components power cords) or should they be helter skelter? Bundle speaker cables together?

Q: me it doesn't matter.

- Is Blue Jean cables assertion that speaker cables are fairly immune to EMI noise correct. Others (and you) say that its the interconnects that are much more sensitive.

most speaker cables, due to low loading resistance and the lack of need to pass signal to the next gain stage (but to drive speakers), they are not well known to pick up enough EMI to be of serious concern (again, the only time I can tell if this is the case would be what I mentioned before: power substation, seriously dirty power line, "dirty" environment due to close proximity to industrial sections or radio broadcast tower, etc.)

- What's your stance on the idea of having the shield on a sub cable connected only on one end to reduce "noise" problems.

Q: again, see my above response.




Bottomline: speaker cables does not pick up any significant enough EMI to be of any audio concern. You can go fancy with multi-shielded speaker cables (waste of $$$ anyways) and not get the same kind of performance out of some fair-priced OFC cables.

I'd spend more on high quality OFC (or PC-OCC varieties) speaker cables from known vendor (reputable foundrys) then wasting my hard-earned $$$ doing silly things.

Q.

 

[doitmyself]

Thanks Quest and others.

Some ten years ago I somewhat bought in to some of the cable hype. I over spent on an Audioquest sub cable (even on clearance). They are one of the worst offenders regarding hype, in my opinion (Monster being very bad too).

I now have a more balanced view. I.E., regarding HDMI cable the cheap mono price ones work well for me. I really like much of the Blue Jean cables offerings for their balance of fair price vs. apparent quality, without too much hype.

 

[daves66nova]

Originally Posted By: Stu_Rock
One more thing: use fire-resistant cable. Go for plenum-rated cable if it enters a space where air moves.
Isn't plenum rated only because when it does burn,it doesn't emit toxic fumes like pvc? If that's burning,i think the whole house would be starting to burn already.

 

[brianl703]

Plenum cable does not emit visible smoke when it burns. What it does emit, although invisible, is quite toxic.