Back in my automotive installer days, we always knew to run RCA and power wires on opposite sides of the car to avoid electrical noise. Here is my question:

I need to hide the electrical cord and sub cable in tubing to get to my outlet and amp. WAF right now is very low having those cables exposed, and it is too late to bury them behind the wall.

I have the Aperion Sub Cable and a Monster HTS-1000 MKIII (thanks Aperion, great promotion!).

If I put them in the same tubing, am I risking noise? My initial thought is the shielding on your sub cable would be good enough to shield any noise. But I cannot get the old days out of my head. It just seems wrong.

WAF would be pretty low running two tubes. I know I could trial and error, but thought one of you Gurus may know the answer and save me another trip to the hardware store.

Thanks guys!

Scott,

The following is in reference to say a complex 4 axis metal cutting machine tool with multiple motor drives and feedback devices such as resolvers or encoders and inductive scales.

Back in the “old days” it was s good idea to run 480/240/120 VAC wires in a physically isolated conduit separated by some distance from low-level feedback signals. The magnitude of EMF noise induction is proportional to the amount of current flowing through the wires. The stronger the current the stronger becomes the magnetic field.

Since your Sub should draw less than 3 amps, the chance of inducing noise into a high quality Sub input cable should be null.

My S-10 sub LFE cable runs parallel with two separate 120 VAC power cords one of which is the 805’s power cord which can draw 9.5 amps. I have no problems with induced noise to the S-10.

To prove this to yourself before you decide, run the power cable and LFE cable parallel to each other in close proximity. Test the application. I doubt you will see a problem.

I think I have been wrong before so that is why I say that personal observation is the best answer to your question.

Hey, thanks for the reply Jack. Makes perfect sense to me. With automotive running @ 12 volt, amperage obviously was much higher.

Let's say, no news is good news. I am sure it will be fine.

Thanks again for the reassurance.

Scott,

I’ll chime in and agree with Jack.  My experience in a similar industry parallels his and I’ve had to run power and control circuits in close proximity numerous times and have seldom experienced problems with noise, feedback, coupling, etc. (and some of the power circuits were 20-25 amps at 480 VAC/3-phase, with control circuits in the milli-volt range).  While it’s always preferable to separate power and control circuits, sometimes you don’t have a choice: wireways in electrical cabinets, cable trays, etc.  In cases such as these, you give them as much separation as you can, then live with the result (unless there’s a problem, then you address it).  Like Jack says, run them together (tape them together if you want a worst-case scenario) and see what happens.  Push your system hard (max amperage) and listen to the result.  At the low amperages we’re discussing, I (like Jack) would be surprised if you notice anything objectionable.  Let us know what happens after you try this. 

Not to get too technical, but the reason you ran audio and power cables on opposite sides of the car is that the audio was AC and the power was DC.  Shielding (wire braid, wrapped foil, etc.) is very effective at shunting “noise” to ground in AC circuits, but useless in a DC circuit.  AC signals (the fields Jack mentions) are constantly expanding and collapsing as the polarity changes, which shielding is designed for.  DC fields are constant (never changing polarity but can vary in magnitude), and the fields generated in these circuits will saturate adjacent conductors for which shielding offers no protection.  For these applications, separation of the conductors is the only answer (I learned this on the railroad where traction motors used to be powered by DC, with some motors drawing 1,500 amps each…and four to six per locomotive amounted to a BUNCH of current!).

And most definitely let us know how much “smoke” you generate during this experiment (and this one’s meant to be a joke…no kidding!).

Fred