Quantcast
Dilemma: mass or gap? - Gearspace.com
The No.1 Website for Pro Audio
Dilemma: mass or gap?
Old 3rd March 2014
  #1
Gear Maniac
 
🎧 10 years
Dilemma: mass or gap?

Hi all, I'm building a home studio from scratch, and have the choice of single skin 100mm concrete blockwork, or doubling them up (a 'nine inch wall').

My first thought was -great, 9 inches of concrete should stop a lot, 6dB more than single skin, but as I won't be able to make the roof anything like that massive will it just be wasted? the roof being the weakest link?

Would I be better off making the wall thinner and increasing the width of the gap? The inner wall will be two shets of 16mm acoustic plasterboard plus green glue.

I'll be keeping a diary of the build. Should I do it here, any interest? All I have at present is photos of a stonking great hole in the ground full of mud (it's clay round these parts; wet, wet, sticky clay )
Old 5th March 2014
  #2
Gear Maniac
 
🎧 10 years
Anyone? Should I be offering more detail?
Old 5th March 2014
  #3
Gear Guru
 
1 Review written
🎧 15 years
Gap

I would go with the plasterboard. Mount it on studs which are entirely separated from the wall, not tied to it, and 'floating' on neoprene or other footers. Steel studs can be good. Damp the gap by filling entirely but loosely with light insulation blankets. Make sure it cannot sag down over time. The benefit of the gap and floating damped internal wall would be that you now have some LF absorption caused by the floating plasterboard. That's a lot of heavy expensive plasterboard and Green Glue. Perhaps a tad overkill if your roof is light, but it should work well.
DD
Old 5th March 2014
  #4
Gear Maniac
 
🎧 10 years
Cheers for the reply, Dandan (and you might like to know my phone attempted to autocorrect your name to "fandango").

I was always intending to do a m-s-m construction with isolated plasterboard and fiberglass. The dilemma is, do I do 200mm concrete with 150mm gap, or 100mm concrete with 250mm gap?

Am I right in thinking that 200mm of concrete on a wall is a waste of mass if the roof isn't also made of 200mm concrete (or equivalent mass)?
Old 6th March 2014
  #5
Gear Maniac
 
🎧 10 years
Incidentally, the lower third of the wall is a metre below ground level so I'm hoping the earth will damp the walls and slab sufficiently that I wont need to decouple the inner walls from the floor.
Old 7th March 2014
  #6
Gear Maniac
 
🎧 10 years
Ok...Can anyone point me at the calculations so I can work out the resonant frequency of a m-s-m assembly for myself?
Old 7th March 2014
  #7
Gear Guru
 
1 Review written
🎧 15 years
Calculation

Google will find that for you. I suggest real world tests might give a much better indication of what happens in reality. Again a quick google reveals this http://archive.nrc-cnrc.gc.ca/obj/ir...r586/ir586.pdf
If this particular doc is not on target they have many many more.

DD
Old 7th March 2014
  #8
Gear Maniac
 
🎧 10 years
That is the actual motherlode of answers to my questions :-)

You say 'a quick google' but clearly some people are better at googling than others. Many thanks.
πŸ“ Reply
Post Reply

Welcome to the Gearspace Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…

Forum Jump
Forum Jump