Cable routing into new studio build

thegalleons

New member
Hi I'm currently nearing the end of my studio build and need to run the power, ethernet and some audio cables into the studio from outside.

I should have had them going through the concrete base when I put that down but I've never done this before and it's a bit late now! The construction is a concrete base then a layer of concrete blocks, then a wooden framed structure clad with two layers of 18mm ply, and pallet wood. It's insulated with rockwool, celotex and two layers of sound blocking plasterboard on resbar.

The current plan is for the cable to enter through a small hole I've drilled where two concrete blocks meet at a 45 degree angle at the base. Because the blocks meet at an angle there is quite a large gap as illustrated in the picture attached.

Do people have any ideas on what I should use to fill this gap to keep sound leakage to an absolute minimum whilst also protecting the cables.

The armoured cable should be fine but I've got three XLRS and an ethernet cable. My current plan is to wrap them in gaffer tape where they go through the block to protect them a bit and then fill the gap with pebbles set in mortar.

I could try and put it all in a small pipe and then fill the pipe with expanding foam or something else but I am concerned this would be less effective soundproofing wise.

Alternatively I could try and fill the gap with something else, I've been doing some research to try and find something dense and soundproof(ish) but that might be less harsh on the cable than concrete, something a bit rubbery for example? The gap is between 15 and 20 cm wide at it's widest point, the blocks are standard size. Any ideas or thoughts on my ideas would be welcome.

Many thanks, Ben
 

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Hey Ben, this is one of the most recommended products on the market for stopping sound from escaping via cracks/holes. It is used when building air silencers as well. In the industry, it's often referred to as the "Green Monster".

Acoustical Sound Latex Sealant is a non-flammable, water based sealant specially designed to reduce sound transmission and drafts in all types of wall systems where a sound-rated assembly is requied. function is to achieve and maintain the specific STC (Sound Transmission Class) value of the system designed. The paintable sealant remains flexible and adheres firmly to wood, metal studs, concrete, gypsum board and most other common building materials. The easy-to-use sealant cleans up easily with soap and water.
 
I'd recommend putting a couple of pipes in place, and just seal up the ends with the latex stuff. That way if/when you need to run more cables in, you just drill out the old latex, pull new cables through, and then seal up again with latex. NO matter how you protect those XLR cables, at some point in the future, you're going to need to replace them.
 
Watching some pro acoustic people (Sandy Brown Associates in London) needing to fill a cable access hole, they used a bunch of fabric bags loosely filled with sand. They'd wedge them in nice and tight.

The advantage to this was that, if we ever needed to run another cable or repair an existing one, it was a simple matter to pull out the bags, access the hole, then re-pack it when done.
 
Yeah...put in a pipe and then stuff it with something removable, for future.
Make the pipe big enough for adding additional cables down the road.
 
I had to do this between the recording room and the control room. I just used electrical conduit, ran the cables and stuffed the ends tight with the same sound deadener material I used in the walls and roof, make sure you also seal the outside of the conduit (pipe) with filler and sealant. I also ran separate conduits for audio, electrical and computer.

Alan.
 
Hi guys thanks for the responses. I think a pipe that i then stuff with some Rockwool and seal with green monster sounds like a good bet. I could then use the bags of sand to fill the gap. I guess then I'd be wondering how to seal it from the outside. Or i could just fill the gap premixed mortar and rocks although as you say that would't leave me with many options for later. Do know how the people you mentioned resolved this Bobbsy? I think the gap would be too big for just Green Monster by itself or it would certainly end up being very pricey. Cheers
 
If you have any big gaps you could use expanding foam. Warning use the gloves supplied, as a work mate found out the hard way, if you get it on your hands it does not come off.

Alan.
 
Hi guys thanks for the responses. I think a pipe that i then stuff with some Rockwool and seal with green monster sounds like a good bet. I could then use the bags of sand to fill the gap. I guess then I'd be wondering how to seal it from the outside. Or i could just fill the gap premixed mortar and rocks although as you say that would't leave me with many options for later. Do know how the people you mentioned resolved this Bobbsy? I think the gap would be too big for just Green Monster by itself or it would certainly end up being very pricey. Cheers

In our case the cable duct was, as I said, used the sand bags (loosely packed so they would shape themselves around the cables) shoved in at either end. In our case is was the double wall/floating floor design for great isolation.

The ends of the pipe weren't sealed in themselves. Instead, the control end was beneath raised access compter flooring while the studio end fed into the bottom of a connector box--there were 2 or 3U of blank panel below the actual connectors to allow access to the duct as required. In your case (I assume without computer flooring) you could very cheaply build a small box/access panel.

The goal was NOT to seal the conduit at all (other than the sand bags). This made putting in extra cables a matter of a couple of minutes rather than needed to remove a semi-permanent seal. Despite lots of pre planning and running spare cables, this feature was used all too often.
 
Just to clarify, I was talking about expanding foam on the outside of the pipe to seal to the wall, not inside where the cables are.

Alan.
 
Hi Alan. When you say "cables from outside" do you mean the actual open air? If so I would run them in plastic pipe of some sort.

The armoured mains would probably fit in 30mm HD conduit? So that pokes through the gap and goes into a gasket sealed junction box, very little sound would emerge from that but you could stuff it with GF if you liked.

The Audio can come through 50mm waste pipe and similarly terminate in a sealed box, in fact the box could have XLRs on it you can even buy stock plates pre punched.

Data, get a lot through 30mm cond'. You will want CAT6 but a reel of CAT5e is pretty cheap, even the shielded stuff and that is very useful for tie lines and headphone feeds. 4 pairs in a <6mm sheath! You can even press them into mic line duty but maybe not a 7b on spinet! There are loads of adaptor boxes that allow all sorts of signals down 5e. HMDI, S/PDIF, VGA. I have even put MIDI down 40mtrs. And it worked!

The conduits/pipes can be cemented in but DO put in lots. Also put plenty of cables in but also a couple of 'blue poly' ropes so you can pull more in if required.

So long as things are airtight, both ends for preference, noise should not get in.

Dave.
 
We were wondering if by Outside on the drawing you mean outside the building or outside the studio but within a building.

Alan.
 
Hi guys thanks for your input. I used concrete round the pipe and then filled the pipe with this semi flexible acoustic sealant I found at a hardware store. It'll be a bit of a pain to remove any cables now but hopefully won't be needing to do that too often.

Thanks
 
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