Login / Register
 
Existing stud wall with speaker - help
New Reply
Subscribe
ex_directory
Thread Starter
#1
25th August 2013
Old 25th August 2013
  #1
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Existing stud wall with speaker - help

Hey all,
First post - been reading and learning a lot from you guys so first thank you!

I have built a stud wall (in the UK), it has...

acoustic plasterboard 12mm (0.5")
OSB 12mm (0.5")
cavity 80mm (3") (including stud), filled with cheap acoustic insulation fibre glass (yellow stuff)
OSB 12mm (0.5")
acoustic plasterboard 12mm (0.5")

I have now put two in-wall speakers in the cavity (with opening of 200mmx300mm 8" x 12") and want to minimise noise in the next room.

As I need to fill the cavity from the hole I was thinking of using something like rockwool RWA45 75mm flexible fibre glass slabs (45kg/m3) in just that part of the cavity, is this my best option?

Andy

Last edited by ex_directory; 26th August 2013 at 08:49 AM.. Reason: correction
ex_directory
Thread Starter
#2
26th August 2013
Old 26th August 2013
  #2
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Also, do such things as a shock absorber exist, aka 'giant rubber washer' between the speaker and wall. When I turn the speakers up I am getting some small bass vibration on the wall in the next room - this could be my inferior building skills though!
#3
26th August 2013
Old 26th August 2013
  #3
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,979

DanDan is offline
Diaphragm

ex, thump your plasterboard wall with the soft edge of your fist. Boom right?
Like a large bass drum head. A diaphragm. Now you have bolted a speaker, a vibrating source, to this diaphragm......
First thought is that this is a situation without hope of solution. But that really depends on how much bass is getting through etc. etc.
The solution would be to created an isolated chamber for each speaker. In english, put them in boxes! Then these boxes need to be NOT attached directly to studs or plasterboard.
Floating or hanging on springs or some such.
DD
#4
26th August 2013
Old 26th August 2013
  #4
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Dan - what you suggest is challenging at best given his situation.........

He has a wall with only 3" of depth inside face of drywall to inside face of drywall........

The he cut holes through the faces to install his speaker, so now he has only 1 layer of mass on one side of the wall - and a very VERY narrow space behind the back of the speaker to place any isolating assembly........

Given his starting point (3" stud frame) he should probably begin with forgetting the in-wall speaker (which looks better) and infilling the drywall........ then he would need to construct some sort of (attractive) isolation boxes for the speakers to mount within (most flush in-wall speakers I've worked with in hotels/offices/etc. did not include speaker cabinets as a part of the equation) - which he could then hang with some isolation mounts to the face of the walls.

I might be reading more into this than exists - however I cannot picture how you would otherwise mount speakers in cabinets inside of a 3" wall cavity........

What he describes sounds to me more like this:

http://www.speakerworks.com/6_5_150_...h_p/t46915.htm

He can correct me if I'm mistaken.........

Rod
ex_directory
Thread Starter
#5
26th August 2013
Old 26th August 2013
  #5
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Thanks for your replies...

I have had to cut away the OSB board just for the magnet on the bass speaker which then gives me the depth I need of 105mm (4"), the rest of the speaker is less than 3" deep. They are speakercraft AIM7 MT3, similar to the ones linked by Rod.

I guess I am trying to make the best of a bad situation, as in reality it is not so bad I am ready to tear down the wall

I still could put extra timber in the wall to create a speaker box or isolation box, but this would be connected to the OSB board on both sides, I did not get the impression from other threads this would help with reducing noise in the next room though?
#6
27th August 2013
Old 27th August 2013
  #6
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,979

DanDan is offline
Alternative

I think we are both trying to gently say there is really no way this will work out. My plan is desperate, Rod's would certainly work if you can find some effective way to resiliently mount perhaps more suitable speakers.
Your current speakers would probably work out if you could mount them in the ceiling, presuming IF there is a seal, wall, above the ceilings between the rooms.
DD
#7
27th August 2013
Old 27th August 2013
  #7
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Quote:
Originally Posted by ex_directory View Post
I have had to cut away the OSB board just for the magnet on the bass speaker which then gives me the depth I need of 105mm (4"), the rest of the speaker is less than 3" deep. They are speakercraft AIM7 MT3, similar to the ones linked by Rod.

I guess I am trying to make the best of a bad situation, as in reality it is not so bad I am ready to tear down the wall

I still could put extra timber in the wall to create a speaker box or isolation box, but this would be connected to the OSB board on both sides, I did not get the impression from other threads this would help with reducing noise in the next room though?
That would be a pretty good impression........ I wish I had an answer that would solve your problem - but there isn't any I can see given your current set-up........

Rod
#8
27th August 2013
Old 27th August 2013
  #8
Lives for gear
 
boggy's Avatar
 
Joined: Feb 2007
Location: Belgrade
Posts: 2,087

Send a message via Skype™ to boggy
boggy is offline
Quote:
Originally Posted by ex_directory View Post
........
I have now put two in-wall speakers in the cavity (with opening of 200mmx300mm 8" x 12") and want to minimise noise in the next room.
.......
There will be two sources of noise which will be transferred to the next room. One from air moved by cone from back of the driver and second from vibrations of loudspeaker driver cone-spider-surround-magnet construction through its basket. Both of this sources are roughly more intensive than mounting method with the speaker driver in the box but without touching the plaster wall, resting on the floor.
Third reason not to do this is possibility to ruin sound insulation system formed by membranes, plaster+osb+fibreglass+osb+plaster... because cutting it and include additional weight will damage insulation for sound not only came from this particular speaker, but other sound sources (talking, other speakers etc).
__________________
-BP

Facebook: @MyRoomAcoustics
Email: boggy@myroom-acoustics.com
--"We can never see past the choices we don't understand." (Oracle, The Matrix Reloaded)
ex_directory
Thread Starter
#9
27th August 2013
Old 27th August 2013
  #9
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Like I said, best of a bad sit...

If it were you and it were trivual to put in an isolation box (i.e. I think it would take < 1 hour per speaker to put in some stud timber), would you bother?

Also, the upgrade to the rockwool RWA45 is only a few pounds.
#10
27th August 2013
Old 27th August 2013
  #10
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Quote:
Originally Posted by ex_directory View Post
Like I said, best of a bad sit...

If it were you and it were trivual to put in an isolation box (i.e. I think it would take < 1 hour per speaker to put in some stud timber), would you bother?

Also, the upgrade to the rockwool RWA45 is only a few pounds.
You do not have the room or the construction to develop an isolation box in the wall......

To begin with - it would have to be suspended in some manner that assured is was not in contact with the existing structure in order to be effective.....

It would also have to either be so massive that is was an effective isolator all by itself - or you would need some distance between the back of that box and the wall behind in order to create some isolation.....

In either case - there will be a large body of "something" that has to surround/isolate the speaker from the wall behind) that places this inside of the interior face of the wall finish.......

That being the case you might just as well forgo the hole in the wall and transition to being completely inside of the room.

As much as you might like this to work - you cannot have both the concealed speaker AND the isolation.... this is a case of "pick your poison." You will have either one - or the other - I cannot envision (and I have a pretty vivid imagination) what you could possible do to achieve both......

Rod
ex_directory
Thread Starter
#11
27th August 2013
Old 27th August 2013
  #11
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Quote:
Originally Posted by Rod Gervais View Post
You do not have the room or the construction to develop an isolation box in the wall......
Rod, my bad, I don't mean an isolation box, what I mean is a box! i.e. by adding some timber in the hole, instead of the cavity the speaker sits in being 2ft wide by 4ft high (i.e. between the existing studs), I can make it 8" by 12", i.e. the size of the speaker.
ex_directory
Thread Starter
#12
27th August 2013
Old 27th August 2013
  #12
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
I made a picture, speaker on left without box, speaker on right with box (effectively 4 bits of stud added through the hole and pinned)

My diy skills are better than my drawing skills!
#13
27th August 2013
Old 27th August 2013
  #13
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Quote:
Originally Posted by ex_directory View Post
Rod, my bad, I don't mean an isolation box, what I mean is a box! i.e. by adding some timber in the hole, instead of the cavity the speaker sits in being 2ft wide by 4ft high (i.e. between the existing studs), I can make it 8" by 12", i.e. the size of the speaker.
That won't help - in fact it may well make it ever worse - as you will now have even more energy inside of a smaller "box" that is directly contacting the opposite wall surface...... and there is no avoiding that.

Listen, I really do wish there was some way I could help you with this....... but there isn't........

You have 3 options open to you - the first is to decide on appearance - and live with the loss in isolation - the 2nd is to opt for isolation and live with the appearance of the speakers inside of the room........

If you want to get into some construction you might be able to get both (option 3) - but it could be both relatively extensive and fairly expensive - and would mean you would have to lose some area inside of the room.....

In other words - if you were willing to spend the cash - and live with the area lost when you finished - you could remove the drywall inside of the space in the locations of the speakers (1 stud bay in width - full height of the wall) - build out some pilasters inside of the room - add some mass in the stud cavities behind the pilasters, let the pilasters "float" free of the existing walls (via the use of isolation clips to lock them in place) and construct the pilasters in such a manner as to create the necessary isolation....... then simply finish everything up so that the end result matches the room's finishes..........

An alternate means would be isolating walls the full length of the space in front of the walls with the speakers - again structurally isolated from the existing walls - which would make the entire room smaller - but would not draw attention to the build out in the same manner that the pilasters would.....

Either way it will cost you some time - some money - and some floor space.... but outside of that you simply cannot make it from "A" to "B" with what you have.......

Rod
ex_directory
Thread Starter
#14
27th August 2013
Old 27th August 2013
  #14
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Rod - really appreciate you taking your time and explaining things so well So no box, and apparently no easy way to improve things a little.

As a matter of interest, in your replies were you say ...

Quote:
Originally Posted by Rod Gervais View Post
That won't help - in fact it may well make it ever worse
Is 'it' referring to the bass vibration on the wall, the level of noise in the next room or both?
#15
27th August 2013
Old 27th August 2013
  #15
Gear Guru
 
DanDan's Avatar
 
Joined: Aug 2003
Location: Cork Ireland
Posts: 10,979

DanDan is offline
Acoustics

Quote:
Then these boxes need to be NOT attached directly to studs or plasterboard.
Floating or hanging on springs or some such.
Ex, my suggestion of a box had the main goal of providing decoupling from the structure. If MDF and sealed it will also contain the back pressure from the speaker. I think you need to accept that is not a long term prospect.
Have you ever heard what a pumped shower attached to a stud wall does......

DD
#16
27th August 2013
Old 27th August 2013
  #16
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Quote:
Originally Posted by ex_directory View Post
Is 'it' referring to the bass vibration on the wall, the level of noise in the next room or both?
"It" would be both.....

In order to get your head around it, start by looking at an extreme to the opposite:

Take a wall cavity..... it's 5' deep with coupled wall surfaces and the inside of the cavity is 10' square....

You have a speaker that will radiate "X" amplitude at any particular frequency (which we will refer to as "Y") off the back of the speaker.

All of this energy will disperse into an area that is 500 cf in volume....... and that energy will then have 100 sf of wall surface that it has to pass through.....

Now - let's shrink that cavity (with exactly the same amount of energy) to a box that is only 1' wide x 1' tall x 3" deep........ the energy build up in the area of the box will now be much greater as a whole (due to the decreased volume) and the concentrated energy will then have only 1 square foot of wall that will absorb it..... the concentrated energy will have far more impact on what passes through the wall than the dispersed energy in the 1st case would have.

Rod
ex_directory
Thread Starter
#17
28th August 2013
Old 28th August 2013
  #17
Gear interested
 
Joined: Aug 2013
Posts: 8

Thread Starter
ex_directory is offline
Quote:
Originally Posted by Rod Gervais View Post
"It" would be both.....
Makes sense, the idea actually came from the Acoustacell product which speakercraft sell as the solution to all world problems! Rather than link I will quote...

"When Installed behind the Speakers..., it Forms a Precision Sonic Chamber, Eliminates Reverse-phase Cancellation Caused by Sound Waves from the Rear of the Speaker Passing through the Drywall and Mixing with and Cancelling Those from the Front of the Speaker, Virtually Eliminates Helmholtz Resonance and Standing Waves, Subdues Out-of-Phase Drywall Resonance, Layers of Mass-Loaded Dampening Material Reduce the Transmission of Sound into Adjacent Rooms"

Note that it only surrounds the speaker in the cavity and adds nothing to the back! i.e. the depth required is not increased when using this product.

Are we talking sales hype???
#18
28th August 2013
Old 28th August 2013
  #18
Lives for gear
 
boggy's Avatar
 
Joined: Feb 2007
Location: Belgrade
Posts: 2,087

Send a message via Skype™ to boggy
boggy is offline
Quote:
Originally Posted by ex_directory View Post
..........
"When Installed behind the Speakers..., it Forms a Precision Sonic Chamber, Eliminates Reverse-phase Cancellation Caused by Sound Waves from the Rear of the Speaker Passing through the Drywall and Mixing with and Cancelling Those from the Front of the Speaker, Virtually Eliminates Helmholtz Resonance and Standing Waves, Subdues Out-of-Phase Drywall Resonance, Layers of Mass-Loaded Dampening Material Reduce the Transmission of Sound into Adjacent Rooms"
....
Are we talking sales hype???
[bolded by me]
may be even something stronger than only (sales) hype... IMHO

EDIT: Ask for actual measurements of all noted benefits... so you will see by yourself...




#19
28th August 2013
Old 28th August 2013
  #19
Lives for gear
 
Rod Gervais's Avatar
 
Joined: Jul 2003
Location: Central Village CT
Posts: 4,730

Rod Gervais is online now
Quote:
Originally Posted by boggy View Post
[bolded by me]
may be even something stronger than only (sales) hype... IMHO

EDIT: Ask for actual measurements of all noted benefits... so you will see by yourself...




+1 to the above........

The term "sales hype" for the quote you provided would more than kind......

I wouldn't be surprised if they also sell magic beans and fairy dust.........

Rod
New Reply Submit Thread to Facebook Facebook  Submit Thread to Twitter Twitter  Submit Thread to LinkedIn LinkedIn  Submit Thread to Google+ Google+ 
 
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump

SEO by vBSEO ©2011, Crawlability, Inc.