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Author Topic: Pre-painted EMT conduit  (Read 14551 times)

Adam Kane

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Re: Pre-painted EMT conduit
« Reply #10 on: December 10, 2004, 05:17:19 PM »

The auditorium was built back in the 20's and they don't want add/change anything more than they have to...which is strange that they don't have a problem with a couple of speaker clusters hanging from the ceiling???

long story short, they don't want anything there that wasn't original except conduit that's painted.  All of the existing trim is very ornate hand carved wood or plaster...would be very hard and probably expensive to duplicate that.

wierd customers... Confused

thanks again everyone

adam
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Tim Padrick

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Re: Pre-painted EMT conduit
« Reply #11 on: December 12, 2004, 10:47:25 PM »

If code allows, put the speaker cables in non-metallic conduit.  Running them in metallic conduit can sound pretty bad.

Blake Courtney

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Re: Pre-painted EMT conduit
« Reply #12 on: February 21, 2005, 10:41:14 PM »

Curious about speaker wire in conduit sounding bad? I had several thoughts about that but what's your reasoning for that?
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Blake Courtney

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Re: Pre-painted EMT conduit
« Reply #13 on: February 21, 2005, 10:41:48 PM »

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Hal Bissinger/COMSYSTEC

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Re: Pre-painted EMT conduit
« Reply #14 on: February 22, 2005, 12:02:42 PM »

There is no evidence to suggest that metallic conduit has any effect on speaker wiring. Any thoughts on it are the result of an active imagination.

-Hal

Blake Courtney

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Re: Pre-painted EMT conduit
« Reply #15 on: February 23, 2005, 10:48:03 AM »

Good. Not in the mood to relplace miles of wiring because of snake oil theroys. Also I don't think that plastic conduit would pass inspection.
             Blake
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Tim Padrick

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Re: Pre-painted EMT conduit
« Reply #16 on: February 25, 2005, 01:28:18 AM »

I've been the victim of this.  I thought it would be handy to just run the cable along some metal HVAC ductwork.  System did not sound right.  Replaced the cables on a whim (with the replacements just lying on the floor), and all was well.  Rerouted the original cables and all was well.

I should think that running a cable in or on metal is akin to using shielded cable - much more capacitive than the norm.  The more capacitive the cable, the lower the impedance at high frequencies (and on transients - you have to charge that capacitor).  Many amps have an inductor in series with the output to counteract the capacitance of the load, but apparently this is often not enough.)  

mark ahlenius

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Re: Pre-painted EMT conduit
« Reply #17 on: February 25, 2005, 05:57:12 AM »

Interesting, I have never heard of running speaker wire in pipe as being a problem.  Putting speaker wires in EMT would be "potential" capacitance to ground and unless the amp/speaker is tied to the EMT ground, I am wondering what effect that would have.  Perhaps the original wiring for the speakers was bad and replacing it with anything would sound better.

Anyhow back on the subject of painted EMT - one caution is that if you are relying on the EMT itself to act as a ground, pre-painting it will probably interfere and cause a high resistance connection. That said I have learned over the years with residential and commercial AC wiring to always include a green #14 or #12 wire in the pipe to carry the ground.  Connectors often become loose or are not installed properly. That way you have a double fail safe - if the pipe gets loose you still have a high integrity ground.  

just my 2 cents...
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John Roberts {JR}

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Re: Pre-painted EMT conduit
« Reply #18 on: February 25, 2005, 07:34:43 AM »

TimmyP wrote on Fri, 25 February 2005 00:28

I've been the victim of this.  I thought it would be handy to just run the cable along some metal HVAC ductwork.  System did not sound right.  Replaced the cables on a whim (with the replacements just lying on the floor), and all was well.  Rerouted the original cables and all was well.

I should think that running a cable in or on metal is akin to using shielded cable - much more capacitive than the norm.  The more capacitive the cable, the lower the impedance at high frequencies (and on transients - you have to charge that capacitor).  Many amps have an inductor in series with the output to counteract the capacitance of the load, but apparently this is often not enough.)  


I am not aware of any sound problems from running speaker wire in "pipe". Please describe precisely what you heard that you attribute to the "pipe"?

JR
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dpaton

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Re: Pre-painted EMT conduit
« Reply #19 on: February 25, 2005, 09:21:58 AM »

I'm with JR. The capacitive effect of having the pipe around the speaker cable will be minimal, and probably will not even approach the capacitance of the cable alone, unless the pipe is grounded to the amp's groudn att he back where the speaker cable connects, which is pretty rare  Rolling Eyes

-dave
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