John Sayers' Recording Studio Design Forum Archive

Hi to all, I introduce myself , I am an Italian drummer and recently I bought a new home.
In this new house I was lucky enough to find a place (I choose this home also for this) in which I can put all my things and play drums : I play and study every day and in addition to that I teach (outside , in other structure) but also randomly at home.

Now…unfortunately in previous six month I put my head in reading all what I can find on soundproofing and drum room but UNFORTUNATELY I discover this forum only last week (in which I eat as much topic as possible).
At this point I can only say that there is a lot of disinformation around soundproofing topic (and acoustic in general). I put a lot of effort and money in this project and now I realize that I have a problem : I bUild a three leaf wall, in particoular i build a room within a room within a room (both three totally decoupled)

I am not here to complain myself , and I admit that ignorance is the worst of evil.
When I start the project some month ago I read all the possible , and make comparison with solution offered by company, but sure I was wrong. Now I want only to know if I can make thing work better.

This is what I make is to put a room inside my box :

I make a room with 2 walls : one of 12cm = 4.7“ and one of 8cm = 3,15 with an airgap of 10cm = 4” of rockwool. The problem is that this room that I buid is put inside car-box that make a three leaf room
12cm brick that I use -

8cm brick that I use -

While the exterior wall of the box is 20 cm poroton -


Now , due to the money and time that I have invested and that the room is already finish also in “finishes” I can’t do big important changment….but the room is not finished completely I have to buy (this week) the three (?!?!) door.
Now I imagine that three door are stupid for the same reason as three leaf??
If I close the drum room with only with two door (exterior and interior, without mounting the middle one) can be classified as two leaf room?? Or at least is better than having all the three doors? or should i continue in this way at these point and buy all the three door??

Last but not least things, at the front of the room (where there are the three open space in order to receive the door) .. in this moment the space between the wall (1° wall and 2° wall , and also 2° wall and 3 °wall) is completely free and open (I can put my hand in the air space or touch the rockwool to be clear) should I leave in this way the structure ??

I cry when i discover this forum because i realize my error but also because i wanted to find out sooner.
Please help me to not doing all of these for nothing

Best regards,

Nobody want to help me?

Hi. Please read the forum rules for posting (click here). You seem to be missing something!

- Stuart -

Mmmm ok

I added location...milano , italy
The room inside (finish) is 3m x 2m ( 2m high)
While the initial space was more or less 2,70 x3,70 (2,70 high)

Can i know only one question??
Supposing i have a classic room within a room (4" gap), and without touching anything i will build another room inside ( but very near ...we say 2" of gap) : so i have room within a room within a room.
Now outside ( or from my point of view - neighbor side) with the new construction i will decrease the performance that i had before with only room within a room??
I mean i know that with the same space and mass you can obviously make it better with only two leaf, but my question is without touching the first building i now decrease final isolation ( in comparison to before)?
Thanks to anyone will replay

Supposing i have a classic room within a room (4" gap), and without touching anything i will build another room inside ( but very near ...we say 2" of gap) : so i have room within a room within a room. Now outside ( or from my point of view - neighbor side) with the new construction i will decrease the performance that i had before with only room within a room??

Probably, yes. The exact answer depends on many factors, but assuming that they both have the same overall dimensions and mass, a 3-leaf system will always have worse low-frequency isolation that a 2-leaf system. From looking at your diagram and reading your explanation, I think you are probably OK with isolation. As long as you build your doors and HVAC system correctly, you should be able to get good isolation.

I mean i know that with the same space and mass you can obviously make it better with only two leaf, but my question is without touching the first building i now decrease final isolation ( in comparison to before)?

If you have no choice, and you MUST build like that, then it is still possible to get good isolation: you just need to compensate for the "3-leaf problem" by adding more mass (especially on the "middle" leaf), and making the air gap larger than it would otherwise be.

The only way to find out for sure, is to do the math, but considering the amount of mass you have in there (all three walls are brick!), I would guess that you should be able to get pretty good isolation. It's a pity that the room is smaller than it could have been, but as long as it is still large enough for your needs, that's OK.

I can only say that there is a lot of disinformation around soundproofing topic (and acoustic in general).

Very true!

Now I imagine that three door are stupid for the same reason as three leaf??

I would go with just two doors: one on the original outer-leaf, and one on the inner leaf. If you put one on the middle leaf as well, there's no way to open it!


- Stuart -

Hi stuart thank you very much for your support and replay.. For sure i write not because "i have no choice" but because i already made it.
Unfortunately like i said i am very meticoulus about things and detail but i did this big error of three leaf..and now i dont sleep during the night thinking that this third leaf with 2.5" of air will burn all my plans and my invested money ( i am not seal at the moment the air system so there is this hole in one wall and until that i can t evaluate the final result, only partial)

Ps , yes is possible the 3 door ..because i project them in a way that external one open in one direction while the other two in the other in "matrioska" way

Here a photo :

room is s mall , but is for me and my home

Now here the question that are burning in my head in these days...also if i know that what i am going to say is really hard and complex:
If the last gap ( generating third leaf) is giving me less than the brick 8 and brick 12 alone ( so is only stupid..also if i don t understand how is possible that building a new wall can decrease what you have already have until that point..) do you think i am crazy if i try to call some company asking about filling the gap with concrete?? I will return to 2 leaf and delete that 2.5 " gap...obviously i dont know if is possible but my question is , do you think doing that will give a big improvement to isolation in comparison to actual situation?

I want only to have the maximum performance ( in comparison to what i spend..so money) but with what i have..so nothing like re-do it but if i canhave a big improvement on what i have here...i can think about it
Thanks,
Marco

i don t understand how is possible that building a new wall can decrease what you have already have until that point

It's related to resonance. When you have a leaf of mass next to an air gap, you have a resonant system, that will resonate at a specific frequency, and all of that is governed by the equations for 2-leaf systems, where there is one single resonant frequency. If you add another leaf of mass to that, with another air gap, you now need a different set of equations, which govern 3-leaf walls, and there are now TWO resonant frequencies with that system. Both of those will be higher than the single resonant frequency for the 2-leaf wall, all other parameters being equal. The issue is this: that extra layer of mass and the air gap has it's own resonance, but it also modifies the resonance of the entire system, pushing it up to a higher frequency. Higher frequency leans lower isolation, in general.

This often occurs in old apartment buildings, where there is a two leaf wall between adjacent apartments, but one of the residents plays his TV really loud, and the guy in the next apartment gets annoyed. So he decides to put up some studs and put some drywall on them, thinking that adding more mass will solve the problem... then he gets very confused when he finds that the TV is now LOUDER on his side, especially the low frequencies!

Confusing, but true. Simple laws of physics. Resonance is a powerful thing: it can trash your isolation, or you can use it in your favor, if you tune your walls correctly.

Now, in your case, I would estimate that you are probably going to be OK, since all of your leaves are massive. The air gaps are a bit small, but the bigger gap has mineral wool in it, so that's good. I don't have the time right now to figure out the math, but at a rough guess I would say you should be able to get decent isolation.

do you think i am crazy if i try to call some company asking about filling the gap with concrete??

I don't think that is necessary, or even a good thing. I think that you have enough mass there to still get good isolation. I would suggest that you'd be better off doing a careful job of sealing your final inner-leaf wall with a non-porous treatment. I would suggest maybe a 1cm coating of interior grade acrylic finish render. That adds yet more mass, increases the thickness, and also seals the porosity of the wall, which is important.

- Stuart -

Soundman2020 wrote:

If you add another leaf of mass to that, with another air gap, you now need a different set of equations, which govern 3-leaf walls, and there are now TWO resonant frequencies with that system. Both of those will be higher than the single resonant frequency for the 2-leaf wall, all other parameters being equal. The issue is this: that extra layer of mass and the air gap has it's own resonance, but it also modifies the resonance of the entire system, pushing it up to a higher frequency. Higher frequency leans lower isolation, in general.
This often occurs in old apartment buildings, where there is a two leaf wall between adjacent apartments, but one of the residents plays his TV really loud, and the guy in the next apartment gets annoyed. So he decides to put up some studs and put some drywall on them, thinking that adding more mass will solve the problem... then he gets very confused when he finds that the TV is now LOUDER on his side, especially the low frequencies!

Yes now that i discover john sayers forum and i read everything is clear!!
Ok also for the suggestion of 1 cm coating of interior grade acrylic finish

But due to what you have written here , why you say to me :

Soundman2020 wrote:

Quote:
do you think i am crazy if i try to call some company asking about filling the gap with concrete??
I don't think that is necessary, or even a good thing.

I know i have enough mass to manage but what scares me most is the triple leaf that i created!! After all the hard work and money put in this project (in my house) i dont want to nullify the reasults that i could have without third leaf. The project was started to give me the possibility to play until dinner without neighboor problem (the other house is attached to mine not on the side of the box obviously but on the other side of my house, so out of that room , on the right, there is my living room , more or less 4.5/5m of living room, and after that their living room)
In addition To that , after i discovered that multiple leaf are supreme evil ( less than big big gap), i investigated about the wall that separate the box from my living room, and it's a double leaf wall . So i have three leaf on 4 side (three wall plus ceiling) and a four leaf ( on the right side that separates drum room from my living room).

So , that being said, thenwoodpecker-idea that is in my mind say that if i will pump concreate in 7cm gap of air i will have the correct 2 leaf on 4 side and only one 3 leaf ( so avoiding the big error of the construction) , plus in addition to that i will add mass of the ceiling that is the most "critical part" because was costructed with laminate wood , so less mass in comparison to the brick wall (from in to out the ceiling of drum room is composed like this :6 cm of wood , 10 cm of gap filled with mineral wool, 9 cm of wood , 7 cm of gap only air , and final the original concrete ceiling of the box).
If the evil three leaf problem will disappear maybe i will have a "plus" 10 db of isolation on low frequency ( in comparison to now) with this modification.

But due to the fact that i don t trust anymore my idea ...am i wrong?? I miss something also now? or maybe stuart you mean that the difference between now and after ( in comparison to the hard and big work of filling with concrete) is not so big to justify all of this?!?

Last but not least consideration...at this point also if i haven t seal and finish the 10 cm conduct ( so there is a big hole in the room) i check the actual performance, and the major problem is at first floor.
Directly over the room i think the spl rate is 1.7X/2X in comparison to what i have at the same floor. Is normal his normal? Or is "fault" of ceiling not comparable to brick wall? Or on the other side "fault of the floor inside the cabin"?
Obviously the sound that i perceive is not air sound ( not coming from the stairs) but transmission sound (like in the structure of the house that resonate with wall and floor)
These consideration have some value or no due to the fact that the room is not sealed)?

Ps sorry for all this Questions.

Marco

Seems to me that the difference in frequency of bass drum (if i have only two leaf) is big.
So why is not a good choice?

I check some formula for three leaf construction but it's very intricate and difficult , i think i miss some data that I do not understand.
Can someone help me in understanding with my dimension and weight what's the frequency in which two and three leaf construction intersect?? And maybe how much should be the difference if i will fill in the entire 7 cm gap with sand or concrete ?? What's the resonant frequency of actual system and of "fill in" system?

If I understand you correct, The ceiling of your room is the weak point. That means that filling the walls with sand or concrete is obsolete as the most sound is clearly leaving through the ceiling. That will remain so if you fill the wall cavity.

You also mention that the room isn't sealed yet. I would suggest to do this first. Make sure there's no sound escaping through gaps.