[ScottMayo]

I'm on planning installing plastic pipes for wire channels in the walls of my HT room, just to make it easy to add stuff over time. Whenever I've seen this done, it's been some sort of plastic PVC tube. So I have a question. What about iron pipes? Choose one:

1. You're insane. Running cable through an iron pipe guarantees all sorts of capacitor effects. Why don't you just run your signals into a vintage 1960's transistor radio, and be done? It would sound the same.

2. You're brilliant! You'll never be troubled by magnetic or RF interference again. I guarantee improved soundstage, blacker than black space between notes, and a 3db increase in efficiency. And as an added bonus, neither the NSA nor space aliens will be able to electronically eavesdrop on your listening habits! Plus if your cables catch fire, your house is saved!

3. You're clueless. Unless you are using antenna wire for your interconnects and you live next to a shortwave transmitter, things like this have zero measurable effect.

Comments?

[JoshK]

I am thinking about doing the same in my place when I move in.  I had just planned to use PVC pipe, hadn't even thought of Iron.  

I personally don't think I want to work with iron piping.   Not much fun when I have done it in the past.  It *may* add a capacitive effect.  Probably nothing to worry about for your rear channels but for the Front mains I probably wouldn't try it.  

How far do you need to run piping for the mains and center?  I like to use starquad wiring anyway which naturally rejects some EMI/RFI so I think PVC will be adequate in my application.

[Ethan Winer]

Scott,

> You're insane. Running cable through an iron pipe guarantees all sorts of capacitor effects. <

I like that one, but it's not my first choice.

The real issue is what kind of wire and what kind of signals they carry, which you didn't mention.

For speaker wires, the added capacitance of being in a metal pipe is insignificant. And for shielded audio cable, it's already enclosed in metal that's in close proximity, so adding more metal outside the shield is irrelevant.

I vote for PVC because it's cheaper and easier to work with. Obviously, the larger the pipe, the easier it will be to add more wires later. If you're smart you'll also leave a piece of string inside the pipe so you can more easily pull additional wires later. But be sure to pull more string through for the time after that!

--Ethan

[Carlman]

This is more of a question for the lab or 2-channel and not really acoustics.  So, I'll move it in hopes to get a few more responses.

I have the same question but relating to power cords.  I want to run power from my breaker to my outlets and sheath the cables in conduit.  However, I was going to do it to be neat only.... and to be extra safe.  But then I started thinking about what might happen if moisture gets into the pipe.... what then?  How would I avoid that?

In any case, good question.

-C

[JoshK]

I guess you could get some pliable soft wax and form a cap around the cables and the ends of the piping.  This might seal it from moisture.  Calking might work too, but wax might be easier to take off and on again.

[WerTicus]

ill take number 2 scott

2. You're brilliant! You'll never be troubled by magnetic or RF interference again.

and ill buy a vowel.

I would say this though... why are you worried about capacitance anyhows.... its going to be minor and inductance is what you DONT want in your speaker cable.  all the good cables have low inductance and relatively high capacitance and low resistance... you cant have everything!

[beat]

people use metal conduit all the time for cables. It is thin walled and galvanized. I was thinking maybe copper because it is easy to work with, light, and you wont have to worry about rust that you could get from iron or "black" pipe. Of course what would really rock is running multiples so each would be isolated from the next!

[mgalusha]

I wouldn't run speaker cables through any magnetic material either conduit (steel) or iron pipe. I suspect it will raise the inductance significantly, especially if the run was very long. Copper would probably be just fine and even better if you grounded it.

I do have a couple 6ft pieces of black iron pipe in the garage. I'm willing to drop a piece of cable through them and see how much the inductance changes if anyone is interested.

mike g.

[ScottMayo]

I do have a couple 6ft pieces of black iron pipe in the garage. I'm willing to drop a piece of cable through them and see how much the inductance changes if anyone is interested.

mike g.

Sounds like a worthwhile experiment to me...

[WerTicus]

good idea to test that ... maybe the inductance will decrease and we will find the holy grail!