Cable Pass-throughs?

barefoot · Post by **barefoot** » Sat Jul 24, 2004 2:31 am

Ok, I'll start off the questioning.

Aaron,

Can you illustrate some basic methods/devices for passing cables between rooms, yet still maintaining good sound isolation?

Thanks!
Thomas

Post by **Aaronw** » Sat Jul 24, 2004 4:51 am

Hello Barefoot...(Isn't this a "construction" question...

)

I've seen several different ways, but the most common would be to run PVC conduits to be able to pull your lines/snakes through after your done w/ construction.

First off, when running conduits, be sure to run a "Pull String" through the conduit as you're assembling it. Nothing is more frustrating than trying to run cable through a conduit that's already sealed up in a wall or floor and no way to pull it.

Second, don't run cables or cable conduits parallel to electrical wires or conduits.

Third, don't run amplified wires such as headphone sends, speaker monitors, etc. in the same conduit as mic lines.

Now, back to answering your question Barefoot. If you're running conduits, you need to be aware of flanking sound "coming down the pipe" (literally). When running the conduits, don't make it a straight conduit from one room to the other. Have some length between them and a couple turns, either 45 or 90 degrees. Be sure to use the long elbows for pipe, or you're wire will get hung up when pulling it through. After pulling your wire through, stuff insulation on both ends of the conduit to help reduce the chance of sound coming through. Often times you'll have a panel on the wall in the tracking rooms w/ all your connectors. You can add additional insulation in here as well.

Be sure to use acoustical sealant where any penetrations may be in your wall. As far as decoupling the conduit from room to room, you can do a couple things. As Steve mentioned in some other threads here, you can use the large rubber coupling w/ steel bands, and this will reduce some vibrations, but these are pretty thick rubber and may or may not work well. The best thing (in my opinion for the day) is to leave a small gap between the pipes between walls if possible, but not so far apart where the cable will get hung up when pulling it through. You'll want to secure it well so it doesn't move when pulling the cable.

In some situations, you may have a wire trough built into or under your floor. When doing this, line the trough w/ rigid insulation like 703, and where ever it makes the penetration through or under the wall, be sure to insulate it well.

The main thing is to not have a direct line of sight for sound to come traveling through. You want angles, bends, curves to reduce the amount of energy of the sound waves coming through any penetrations.

That's a start...

Aaron

Sen · Post by **Sen** » Sat Jul 24, 2004 10:52 am

That's a great post Aaron...Thanks very much for the info...I like the idea of "breaking" the conduit between the two walls to stop (minimize) flanking. Very simple but never occured to me...

cheers

knightfly · Post by **knightfly** » Sat Jul 24, 2004 3:08 pm

Yeah, I like that better than the rubber "union" thing too - looks like a lot of things that work with AC ducting can be used in similar ways for wiring ducts.

In fact, if we were all rich enough to afford plenum-rated cables for everything, we could just USE the AC ducts

OK, maybe not... Steve

Sen · Post by **Sen** » Sun Jul 25, 2004 12:14 am

Yeah, I like that better than the rubber "union" thing

yeah, I don't like the "rubber union" thing too often my self

cfuehrer · Post by **cfuehrer** » Sun Jul 25, 2004 12:46 am

So what do you suggest for running a powered line for headphones? Install another pipe next to the main line one for it?

cfuehrer · Post by **cfuehrer** » Mon Jul 26, 2004 8:54 am

What? No one cares to help or comment?

giles117 · Post by **giles117** » Mon Jul 26, 2004 6:21 pm

Powered Line. Elaborate. an AC Run to power a head phone amp??? Not sure what you mean.

I Used the same mic snake I ran for the mic lines to pass the Headphone signal back into my Live rooms. It';s all low power signal. (correction I ran 2 snakes, 1 snake for mic lines, and 1 snake for headphone returns)

Post by **Aaronw** » Mon Jul 26, 2004 11:26 pm

So what do you suggest for running a powered line for headphones? Install another pipe next to the main line one for it?

If you're referring to the amplified signal from the amp...Yes. I would suggest running another conduit. This helps to space the amplified wire from the mic lines.

Aaron

barefoot · Post by **barefoot** » Tue Jul 27, 2004 3:40 am

Headphone signals aren't that hot. You should be able to get away with a shielded cable, No?

Thomas

knightfly · Post by **knightfly** » Tue Jul 27, 2004 3:43 am

Definite agreement there - years ago we were practicing for a gig in my living room, kept getting feedback - tried moving mics, speakers, it was a small room so couldn't do a lot that way - the guitar player's friend, who used to be a roady for Jefferson Starship, walked over and moved a speaker lead out of the mess of wires and about 8" away, and the feedback STOPPED... Steve

Post by **Aaronw** » Tue Jul 27, 2004 5:32 am

Headphone signals aren't that hot. You should be able to get away with a shielded cable, No?

Sometimes you won't have any issues...BUT...chances are, you will at some point in time.

Here's the reason...even though you may have a shielded line, it will not always protect from "bleed through or crosstalk".

Some mic's have a low output, thus you have to crank up the mic pre. If there's any slight amount of signal crossing into the mic line, when you crank up the pre, you'll also turn up the level of the signal from the headphone line. Then you have a problem.

Aaron

Jester · Post by **Jester** » Tue Sep 07, 2004 12:57 pm

I am going back and forth on whether to float the my floors. If I don't float them can I run conduits in the walls? Would I still be able to put wire through?

If I float the floor and lay my 2x4s flat will I have enough room to run conduits?

Post by **Aaronw** » Tue Sep 07, 2004 11:46 pm

If I float the floor and lay my 2x4s flat will I have enough room to run conduits?

You might get 3/4" or 1" if you're lucky. Unless you let the conduits rest directly on the floor below the floating floor, you might get a little larger, but you'll have to be careful to not short out the floor w/ too large of a conduit.

What size snakes will you be running?

Hummarstra · Post by **Hummarstra** » Sun Nov 14, 2004 4:55 am

I'm wondering the same thing as I'm gonna have to keep as much ceiling space as possible. I don't know what size snake I'll be running, yet, but if the snake would fit are you saying it would be OK to just let it lay on the floor?