The Drum Bubble - Leaks in my space

Ekimtoor1

Member
If I could get some opinions

I want to improve the leakage into my granddaughter’s living room. Her wall is a standard 2x4 wall with r13 and faces the bubble with a 2” gap. I have pieces of 5/8” that I can add to the bubble wall that faces her living room. Should I add 2” of rockwool before or after the 5/8” or does it not matter?
 

ecc83

Well-known member
My front door is an Everest DG unit (with no glass in it!) and has a 'cam' system. You can close the door as normal and it clicks shut but then if you raise the handle about 45dgs dogs cam the door into the frames seals producing a light-tight and therefore gas tight seal.
I have often thought such a door with beefier panels would be ideal for a studio especially if you had two? I bet you could pickup some cosmetically damaged ones at a salvage yard?

Dave.
 

Ekimtoor1

Member
Thanks, Dave.

My door, which is already built and installed, has something similar to yours. There are rollers top and bottom that press the door into the seal as it closes. Friction is a bit of a problem, but not a deal breaker once the rollers are adjusted. My door is also light tight. It’s extremely heavy at 300 pounds of framing and four layers of drywall with green glue, so it takes a serious tug to open and close. But it works!

Mike
 

Slouching Raymond

Well-known member
have often thought such a door with beefier panels would be ideal for a studio
I've been drawing up plans to build a studio at the bottom of the garden.
This is my approach. Both door and windows would each be double doors, and double windows
having a total of 1" of glass between inside and outside.
 

Ekimtoor1

Member
It’s certainly clever but if it slides horizontally what compresses the join? Surely at some point it must move towards the hole in the wall? I can’t see how this happens. My thinking is that if a heavy door can glide past the opening easily, then the seal thickness and material is the only barrier to sound. I’ve probably just not been able to see how you‘ve sealed this in your mechanism
I’m doing tests on my project and will post results in my other thread, but I wanted to ask you about the screws.

I am not concerned about noise getting in, I only want to block noise from getting out to whatever extent I can do that.

So, in regard to noise transmitting out, are the screws transmitting to the studs and then the studs transmitting to the exterior drywall layer?
 

rob aylestone

Well-known member
Yep. Transmission is note directional. There is always coupling, the question is the amount. An isolated panel, with green glue, foams or even air gets this isolation compromised when the soft compliant coupling is overridden by something strong and rigid. Worse, the more you have to use to make it suitable for vertical fixings, working against gravity, negates the isolation. In fact, you van hear this if you knock your knuckles on a wall. In my home I have some walls that are one layer of plasterboard onto 75x50 timber. The builder was very enthusiastic with the screws. The sound, mid point between the studs is very different. The studs making that joint sound different. In my studio with three layers and no glue, the sound is totally different. I guess it’s like a drum skins but far less movement. Green glue is a sound shock absorber. I like your amazing quest for the mega door, but I’d bet the weak links are however is slides. Better seals mean more friction, and more friction suggests to me that if the sealing is good, you can’t open it. This was the reason for my earlier comment that asked if it moved across then got compressed was because of this. Rod Gervais in his book mentions windows and points out that if you have them, this is usually the weak link. No point making walls better than the windows? The law of diminishing returns also plays a part.
 

Ekimtoor1

Member
Yep. Transmission is note directional. There is always coupling, the question is the amount. An isolated panel, with green glue, foams or even air gets this isolation compromised when the soft compliant coupling is overridden by something strong and rigid. Worse, the more you have to use to make it suitable for vertical fixings, working against gravity, negates the isolation. In fact, you van hear this if you knock your knuckles on a wall. In my home I have some walls that are one layer of plasterboard onto 75x50 timber. The builder was very enthusiastic with the screws. The sound, mid point between the studs is very different. The studs making that joint sound different. In my studio with three layers and no glue, the sound is totally different. I guess it’s like a drum skins but far less movement. Green glue is a sound shock absorber. I like your amazing quest for the mega door, but I’d bet the weak links are however is slides. Better seals mean more friction, and more friction suggests to me that if the sealing is good, you can’t open it. This was the reason for my earlier comment that asked if it moved across then got compressed was because of this. Rod Gervais in his book mentions windows and points out that if you have them, this is usually the weak link. No point making walls better than the windows? The law of diminishing returns also plays a part.
As always, thank you for the reply.

This would be a last resort, but I could remove the screws on the innermost and outermost layers, except for the ceiling. While GG may not be glue, once it cures, the drywall is permanently bonded. I tried to separate a piece and it is not possible. So I would not have any mechanical concerns about removing those 2nd layer screws, which are large #8.

Would removing some screws get me an incremental improvement? I think the answer is yes but I’m skeptical as to whether it would be worth it. I have a list of easier things to try. As my motorcycle mechanic told me about working on motors, always try the easy things first.

The door seals well. That is, it is light tight. Friction is annoying and it takes some strength to open and close. Even with lubricating the seals I still have to get my whole body into it. I have some other ideas such as a nylon C channel with a mating I piece. But it seems to work for now.

Thanks again!
Mike
 

Stewart Adam

New member
My room build got to the point where I could actually start testing. The initial results are disappointing, but fixable I think.

Originally I installed a window AC up on one wall which was inexpensive at $180 and did a great job of cooling the room. But in my tests it was clearly leaking a LOT. Not sure what I was thinking as it is plain to me now that a window AC can never be adequately sealed. Fortunately, I was able to return it.

My next attempt will be using a portable AC which has a single 6” exhaust duct and I think I’ll have a lot more control over that. I’m thinking about how to line the duct with MLV and I can envision a baffle device on the outside wall, also constructed of MLV. I’m not expecting perfection, but it will certainly be quieter than the window unit.

If that fails, then I’m onto a mini split which is very expensive compared to these other options. But if that’s what it takes…
I have an LG split AC in my studio. It is very quiet, I never did any tests regarding noise level, but you can record vocals and acoustic instruments and not hear the AC.
 

rob aylestone

Well-known member
Mike - I suspect the screws might make so little difference you won't notice. Once a panel starts to get thick and heavy, it's really good at doing it's job, so you have a really good panel, as a moveable door. That's unusual. I have a small confession - in my studio at home, the performance is quite good. Late at night when it's quiet, I can just hear the kick drum - and it's not something people would identify as a drum, but due to a measuring mistake, the fire exit heavy type door I bought didn't fit. This door now seals the blocked off area where the computers sit behind, built because the fans were too noisy to have in the room. The door I intended for that area was a cheap plain door that has no bottom end reduction at all. One of those masonite things with cardboard as the link between inside and outside. It was the right size (I mixed up the two door sizes) so temporarily, that is the door to my studio - terrible noise reduction specs. I meant to change it but never did as the reduction in sound escaping was good enough! This is one reason why I no longer get carried away by chasing the figures. Leakage in the wrong place is terminal, but in other places, very workable.
 

Ekimtoor1

Member
Taking into account the possibility that fixtures or screws driven into the framing of a structure may transmit sound through the sheathing or drywall and outside the structure, I did a test. Very unscientific and maybe it means nothing but I thought it was interesting.

My speakers were mounted on wall mounts attached to the corners with two 6” lag bolts each. See the attached photo. I did a series of sound tests by turning up some pink noise and music to 100db and then measuring with a db meter at a few different positions inside and outside the house.

I then removed the mounts and put the speakers on stands in about the same position, a little lower, and did the same tests.

The result is that there is little or no difference. In one test the stands were actually a db or two louder. But the overall average is insignificant. I expected to see at least some small improvement with the stands, but there really was none.

The wall mounts are more convenient for my tiny space so I’m going back to those.
 

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Ekimtoor1

Member
I have an LG split AC in my studio. It is very quiet, I never did any tests regarding noise level, but you can record vocals and acoustic instruments and not hear the AC.
Yes, as soon as I can decide on a unit I’m going to go with one. I’ll definitely consider the LG as I’ve heard good things about it.
 

Ekimtoor1

Member
Here is a video of my door in action. I really don’t know if this result is good, bad or just ugly. How does it compare with spaces you may have built? Trying to determine if I have got all I can get or if I should keep chasing improvements.

The short answer is I’m seeing a 42db reduction from 100db in this video.

 
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rob aylestone

Well-known member
You covered an extra ‘phenomeno’. The fact that physical rigid fixing did virtually nothing also shows the hi fi enthusiast’s oft repeated comment about speaker can movement is equally pointless. They spend lots of money on resilient mounts, or sharp spikes, and other gizmos, and one type allows the speaker to move, spoiling the sound and one keeps it absolutely steady. Your test suggests that speaker movement does not transmit through the structure, making the coupling almost undetectable.
 

Ekimtoor1

Member
You covered an extra ‘phenomeno’. The fact that physical rigid fixing did virtually nothing also shows the hi fi enthusiast’s oft repeated comment about speaker can movement is equally pointless. They spend lots of money on resilient mounts, or sharp spikes, and other gizmos, and one type allows the speaker to move, spoiling the sound and one keeps it absolutely steady. Your test suggests that speaker movement does not transmit through the structure, making the coupling almost undetectable.
If I understand you correctly, you’re saying using a fixed mount is better than allowing it to move a bit on some resilient type mount. Is that because the movement of the drivers can be slightly cancelled out by a flexing mount?
 

mjbphotos

What?!?
Taking into account the possibility that fixtures or screws driven into the framing of a structure may transmit sound through the sheathing or drywall and outside the structure, I did a test. Very unscientific and maybe it means nothing but I thought it was interesting.

My speakers were mounted on wall mounts attached to the corners with two 6” lag bolts each. See the attached photo. I did a series of sound tests by turning up some pink noise and music to 100db and then measuring with a db meter at a few different positions inside and outside the house.

I then removed the mounts and put the speakers on stands in about the same position, a little lower, and did the same tests.

The result is that there is little or no difference. In one test the stands were actually a db or two louder. But the overall average is insignificant. I expected to see at least some small improvement with the stands, but there really was none.

The wall mounts are more convenient for my tiny space so I’m going back to those.
Can't tell from the pics on what your speakers are - what is their low end frequency? And what gets transmitted from the speaker cabinet through the mounting points is not the same as direct sound (as in soundwaves hitting the sheetrock wall).
 

Ekimtoor1

Member
Can't tell from the pics on what your speakers are - what is their low end frequency? And what gets transmitted from the speaker cabinet through the mounting points is not the same as direct sound (as in soundwaves hitting the sheetrock wall).
They are Rockville DPM6W. The test was intended to compare transmission through the mounting points vs stands.
 

mjbphotos

What?!?
They are Rockville DPM6W. The test was intended to compare transmission through the mounting points vs stands.
In theory, a good plan, but in practicality.... The low end on those speakers is mfr-rated at 50Hz (at what dB drop off?), and low frequency transmission is really what you want to be looking at in this test.
 
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