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Adding STC values

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Adding STC values

Postby Gerhard Westphalen » Tue Jun 11, 2013 9:14 pm

I am building a new studio which will have 2 doors in 1 frame between my control room and live room. The doors that I plan on using have STC 32 (manufacture's website). I'm wondering what the combined STC or the 2 doors will be so that I don't over spend on increasing the STC of the walls since the doors will be the weak point. I know that STC values involve multiple tests at different frequencies and are hard to calculate but I just want a rough estimate. I will be sealing the doors properly and isolating the HVAC so the doors will be the weakest point.
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Re: Adding STC values

Postby James Perrett » Tue Jun 11, 2013 9:56 pm

I'd suggest that you'll get much better results if you use separate frames for each door - using a single frame will undo much of your efforts to soundproof your room.
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Re: Adding STC values

Postby Gerhard Westphalen » Wed Jun 12, 2013 6:57 pm

I've been using the Rod Gervais book for all of my planning. I was planning to use the diagram which he has of a double door system but several people have recommended that I do 2 separate. I wonder why he doesn't do it as 2 separate.
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Re: Adding STC values

Postby Gerhard Westphalen » Sat Jun 15, 2013 12:45 am

Any ideas on adding the STC?
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Re: Adding STC values

Postby JH Brandt » Sat Jun 15, 2013 4:22 am

Rod's book is great and although I use a different approach and two frames in my designs, the real-world result of using only ONE frame is negligible isolation loss. This is due to many other factors such as flanking, seals, etc.

Also, you can get away with less isolation between CR and TR due to the fact that you will be listening to the same thing.

Have you already bought the STC 32 doors?? The mass of the doors should match or exceed the mass of the wall, AND they should be mounted to optimize the air gap between the two doors. An absorption panel(s) on the inside of the door(s) will improve STL through the closed door partition.

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Re: Adding STC values

Postby Gerhard Westphalen » Sun Jun 16, 2013 4:54 am

I haven't yet bought the doors. They are the best that I can get besides an STC 35 which are $300 more each.
I'm trying to find out the combined STC of the doors in order to find out if it is matching the STC of the wall which is my original question!
I'll be using weatherstripping, gaskets, thresholds, and automatic bottoms on both doors so seals is pretty much the best that I can do.

What do you mean by "mounted to optimize the air gap"?
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Re: Adding STC values

Postby JH Brandt » Sun Jun 16, 2013 1:33 pm

haha.. I guess that my mind was on something else when I said that. ~facepalm~ When you place a door in the frame to swing away from the wall that it is in, it is mounted FLUSH with that wall surface. So, if you have two doors back-to-back and they will swing away from each other. THIS is maximizing the air gap. IOW, place them in the wall so that they are as far from each other as possible. But your going to do that anyway... Sorry for the confusing post.

I have an EXCEL spreadsheet calculator on my publications page called; 'Reflections Boundaries Mass'. Download and play with that. You'll find the mass calculator helpful. There's a lot of stuff in there, so enjoy.

If your wall partitions are very high STL, you may want to go with a sand-filled door. Here is a link to an example. Sand-Filled Door Drawings - JH Brandt
Have fun.

Cheers,
John
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Re: Adding STC values

Postby Gerhard Westphalen » Sun Jun 16, 2013 7:34 pm

Thank you for all your advice! Your website seems to have a lot of useful files!

I'm a bit lost with the spreadsheet. If I get the density from the materials mass page, what do I do after? If there somewhere that tells me the STC of the given density? I don't seem to see anything on that spreadsheet relating to STC.

That sand filled door looks interesting but I think that my contractors wouldn't have the skill to make it and it would be a bit expensive to buy. If the combined STC of my doors are too low then I might consider it. The main problem is that we are trying to keep this renovation fairly "standard". This studio will only be used for 5 years (time that I'll be in university. parents' house) and after that it will become a regular living room. I have the freedom to put in 2 doors, beef up the wall construction, run some cables in the walls, and silence the HVAC but that's about it. Nothing too expensive or impractical (in comparison to "normal" construction).
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Re: Adding STC values

Postby James Perrett » Mon Jun 17, 2013 11:32 am

octilliondollars wrote:I've been using the Rod Gervais book for all of my planning. I was planning to use the diagram which he has of a double door system but several people have recommended that I do 2 separate. I wonder why he doesn't do it as 2 separate.

Possibly there are other details that reduce the effect of flanking in his design. I haven't read his book so I can't really tell you what to watch out for.

Some friends of mine moved into a house that had sand filled doors - it turns out that a previous owner was a radio DJ who worked from home. They just kept the doors as is and used the room as a quiet meditation room.

James.
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Re: Adding STC values

Postby JH Brandt » Tue Jun 18, 2013 7:22 am

Good one James. Meditation room is a great idea! :)

Octillion,
NO STC ratings for materials densities because it depends how those materials are put together. You CAN do a 'calculation' on the Membrane Absorber & MAM Calc tab. Scroll down to line 104 where you see the 'Mass Law for Diffuse Field'. Put the surface density in the yellow block and it will give you a calculated transmission loss for each 1/3 octave frequency band. THIS IS FOR A BALL-PARK figure and field measures can differ greatly due to other factors like flanking noise, etc. This little calculator is for only ONE partition and NOT a MAM system.

For a closer idea of how much STL you can expect from the construction in YOUR building, check out the ir761 document on my pubs page & find the wall configuration that closely matches you own. This will tell you what the LAB did.. real-world, on-site measurements usually never reach the level of the LAB spec.

The door panel is all about mass. You must match the mass of door or window glass with the mass of each wall. If you can not buy a solid core door panel, you can make one. The important part of making a door panel is that it will be rigid and square when finished - and seals are critical.

Following the mass rule, you can build your door from solid hardwood, MDF, or sand-filled by matching the weight of the walls, so that it has the same or (preferably) higher mass than the walls.

You must measure the thickness of the material(s) used in the construction of the wall and divide the density by that thickness to determine the surface density of the partition. If multiple materials are used, do the process for each material and add the results. Take the sum and multiply it times the area of the door to be built. The product will be the total weight required of the door. Build accordingly.

I hope this helps.

Cheers,
John
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Re: Adding STC values

Postby Gerhard Westphalen » Tue Jun 18, 2013 8:10 am

That does help a lot.

I'll find the mass of the doors. To keep it simple I am purchasing a solid core door. I don't have the skill to make it and my contractors would charge a lot more. No worth it for a room only being used for 5 years. Plus, its primarily a composition studio with only a bit of recording so isolation is not critical. There will be many flaking paths as well which I'm still trying to sort out.

Thanks!
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Re: Adding STC values

Postby JH Brandt » Fri Jun 21, 2013 11:44 am

Excellent! Good luck with that! 8-)

All the best.
Cheers,
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Re: Adding STC values

Postby JimWales » Mon Jun 25, 2018 2:27 am

John H brandt is providing incorrect plans and incomplete data
I hired him and he gave me incolplete work that I had to pay upfront and he refused to refund
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