[Ted White]

Wall studs would not contact concrete wall = decoupled

There are two types of clips. One decouples the frames wall from the joists overhead. This is the DC-04 clip.

The other clip you may be more familiar with is the sound isolation clips like the PAC RSIC-1 or WhisperClip. These isolate the drywall from the stud wall

If the wall itself is separated from the concrete you would benefit from the DC-04s but not the Sound isolation clips

 

[Ted White]

Every 3-4 feet along the top plate of that wall. Again, the stud wall is maybe 1" from the concrete. With a little R13 fiberglass. Then drywall right to that stud wall.

The heavier that wall is, the better. Double 5/8" drywall is perfect

 

[Ted White]

I agree you should have a plan before the nails and screws fly. Not convinced anything would come out of measuring the sound beforehand. 95% of the time casual HT-ers are looking to simply keep as much sound in as possible, not vise-versa.

There are space conserving sound isolation construction techniques.

 

[Ted White]

What would come out of measurements Ted, is knowledge. Knowledge that you are up against a specific noise level. That in itself allows others that can help, like you, to know with better accuracy what the build will require.

You would spend $ in this budget build to buy equipment to measure the noise coming off the washing machine?

I could be all wrong here, but I believe LGL is looking to keep sound in, not out. A background sound measurement isn't helping.

 

[Ted White]

Keep in mind you're still going to hear subs.
Posted via Mobile Device

 

[Ted White]

This is getting a bit overboard for lgl.

There's nothing to measure up front, since you have no specific sound you're looking to block.

You can incorporate treatments and traps after you build.

Just follow the basics of room construction (as inumerable others have) and build the best walls and ceilings you can. Decouple, absorption, mass and damping.

 

[Ted White]

What a great reply. I agree with all these points. Maybe not so much the measuring part, I'll admit. But for sure very good point about the decoupled system absorbing low frequencies.

You rarely hear about this. The max absorption occurs at whatever low frequency resonance point is present in a given partition. And you have the bell curve move out from there. Further away from the fundamental LF resonance point and absorption drops as well. I was involved with testing this very thing at Orfield Labs in Minneapolis.

This is all excellent that you brought this up as we're seeing amazingly large IB systems much more routinely, and of course this means they need more LF absorption as you say.

Do you like to use theater risers as bass traps? I'm not an in-room acoustics person but this topic comes up frequently.

 

[Ted White]

I`ll build the room airtight with no leaks,

Tough, but you know that obviously​

floating ceiling on floating walls

You mean independent ceiling joists as in the article? That's better than clips if you can do this.​

... floating walls attached with resilient clips to the concrete

Clips on stone = 1 5/8" air cavity. That small air space with clips and drywall will improve your high frequency performance but your low frequency isolation will worsen. I have the data on that if anyone's interested. There are other issues with that air cavity and the resonance point of that stone wall, but that's another post​

and a floating floor inside the wall.

This is for comfort? Getting the carpet and pad off the concrete?​

I`ll have two airtight doors.

When these two doors are closed, are they side by side or is there an airlock created?​

 

[Ted White]

Ted will be the first to say that before a build starts you should add additional mass to any and all areas that are part of the exterior leaf if possible. The interior leaf will not be effective enough to completely isolate the heavy rumblings of a sub woofer if this attention is not granted.

Is that not a fair assessment Mr. White?

That's fair, sure enough. Having said that, you could mass load the existing structure, decouple, mass load the second inner structure and still hear bass. It is not likely that the resonance point of the resulting new assembly will be lower than 30Hz. This means we won't have as much effect on frequencies below 45Hz.

That's what I was meaning several posts ago. You're still going to hear the low bass, since it just isn't practical to build partitions whose resonance point is extremely low. Too much air cavity depth and mass is needed.

 

[Ted White]

I would not take up valuable headroom for that floor.

 

[Ted White]

You're below ground? Or no? Cold in the states and canada as well but a few feet below ground it's all same temp all year. Small point, as many do this for thermal comfort nonetheless.

 

[Ted White]

Adding the mass as you pointed out is a good idea. I am saying that you cannot build a room in any basement that will completely stop low frequencies even after adding said mass.

 

[Ted White]

So I assume the Holiday went OK?

 

[Ted White]

Are you suggesting removing the concrete floor and re-pouring? I'm confused... sorry.

7cm isn't a lot of height to gain considering the work involved. Again, I'm probably misunderstanding

 

[Ted White]

Well ceiling height is always a desired thing. So I would see if you could avoid losing the 7cm

 

[Ted White]

This can be calculated, but it's along the lines of a foor or two of airspace and 6-7 sheets of drywall on each side. Shocking, really

 

[Ted White]

Not really. The resonance of the system is defined by the whole system, not the parts. Mass is mass. If well damped, there's no advantage to using dissimilar densities of mass in a leaf.

The LF resonance point calculation looks at:

Decoupled leaves?

Total Mass added

Absorption in cavity?

Air cavity depth (which is related to absorption).

 

[Ted White]

Absorber is a term generally used to describe a treatment of sound remaining in the room. The sound we're describing has sufficient energy to enter (and leave) the room.

The object is to build partitions with as low of a resonance point as is practical.

Decouple the framing with a double stud wall.

Have as large a gap as possible between the two frames

Add absorption with standard R13 iberglass.

Add mass, generally double 5/8" drywall

These are the factors that lower that resonance point. Keep in mind that we're only able to significantly affect frequencies at 1.5X the resonance point and up. So if a wall had a resonance point of 60Hz, we're going to start to see a drop in performance at 90Hz and below.

Also your earlier question about a 45 Hz wall would be more along the lines of a 1' air cavity and 3-4 sheets of drywall. That's a guesstimate this morning.

 

[Ted White]

I admire your thoughts and questions patchesj

 

[Ted White]

So this is a 1/2" total thickness product? If so, I really recommend to increase the mass by adding a thick sheet of drywall behind that finished material.

Are you planning to incorporate acoustic treatments on the walls? Often the walls are completely covered with treatments. In that case there's not much use in applying a finished panel like you're showing.

Just trying to fully understand what you're goals are.

Thanks,