HUB Studio

[Hub]

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And just to put it in context with the existing walls...

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[Hub]

We are looking at supporting the walls with High Density Closed Cell EPDM rubber to isolate the walls. Below is a detail view. We are also considering the drum riser method for our floor.

floor & wall detail.jpg

Any comments appreciated.

[Soundman2020]

Just looking back over your thread again, and a couple of things caught my eye:

I have a pad of 70mm x 50mm which I have tested under load. The compression is as follows:
Original thickness - 14.75mm
25kg load - 14.2mm
55kg load - 13.6mm
105kg load - 12.5
155kg load - 11.2
185kg load - 11.2
Since the approximate load on the bottom of the frame around the entire perimeter is 250kg per lineal meter( this is including studs, gyprock, insulation, joists, beams, room diffusers) I am thinking of placing 3 pads every metre. This would compress my pads to about 13mm which equates to about 12% compression. The product seems to bottom out at about 25% compression at 185kg.

That's all well and good, but what does the MANUFACTURER of that product say? What is the optimal loading? What is range it needs to be in to float? You can't just guess: if it is an acoustic product, the manufacture will have published charts, tables and maybe graphs that show the performance for different load factors. If the manufacturer does not publish those, then the material is not meant for acoustic purposes. You also need to know other things, such as how it reacts over time: For example, if you load it to 14 kg/cm2 (which is what you said you think will work), and that compresses 13mm now (what you tested it at), how much will that be after 6 months? A year? 5 years? If the material does not have good resilience characteristics, it will continue to compress over time, with the load on it, and eventually bottom out anyway.

You also mention that you calculated your load as "250kg per lineal meter", but lineal meters is not what you need to know! You need to know the load per square centimeter, since that is what matters. You need enough square cm of resilient pads to support the total load. At 3 pads per meter, you are talking about 10cm2 for 250 kg load, which is 25kg/m2, not the 14kg/m2 you mentioned... It is nearly twice the load you should have. It is very close to bottoming out like that...

But all of the above is a moot point anyway, since your diagram of October 6 shows that you are not anchoring the wall to the subfloor! You cannot just sit the entire wall on rubber pads without anchoring it in place!!! There MUST be bolts, nails or screws going through the sole plate, through the air gap where the rubber pads are, through the "other plate" (not sure what the purpose of that is?) and into the sub-floor. It is not safe (and will not pass inspection) if the wall is not anchored to the floor in some way.

I would suggest that, instead of trying to re-invent the wheel on your own, and become your own acoustic test lab, it would be better for you to look into floating your walls correctly using commercially available products that are specifically designed for this purpose, such as IsoSill:

Isosil-anchor-bolt-decoupling-isolation-collar-and-pad.jpg

There are other similar products, but that's the one I happened to have on hand.

including ... room diffusers

That room looks borderline for diffusers, if you are talking about Schroeder type diffusers (numeric sequence based). They might be appropriate, if designed and placed correctly, since the room does seem to be almost big enough for that, but it still might be better to go mostly with absorption, especially seeing that you show the wall built conventionally, not inside-out.

What is the distance from the mix position (engineer's head) to the rear wall? What cut-off frequencies did you use for your diffuser design?


- Stuart -

[Hub]

The product we are using is a EPDM class of rubber that comes in 50mm wide at 14.75mm thick in rolls. We have cut this strip into 70mm long to lay across the 70mm wide frame. The manufacturer does not have acoustic information for this product. The only information is as follows: High Density Closed Cell EPDM Sponge rubber, UV Stabilised and Automotive Use, Temperature range -30C up to 130C.

The reference to lineal meters is based on placing 3 pucks across 1 lineal meter of wall framing. Since 3 pucks spaced over this distance would theoretically support about 240kg this seems correct. In fact we are really spacing them every stud which are spaced at 450mm centers which means it can support a little more load.


The anchoring in the photo you show is what we are doing with ours.

Isosil-anchor-bolt-decoupling-isolation-collar-and-pad.jpg

The purpose of the bottom plate is to bridge the areas where there would be no bearer supporting under the puck. We came up with placing a fixing a bottom plate first which meant we could put the rubber pucks on top nearly anywhere along the frame even if there was no direct support from a bearer under the floor. The existing floor is 19mm thick plywood.
Then we built the frame on top of this with the pucks in between.

So really the bottom plate (probably not the right name) is really just a part of the existing floor say(just a thickening to help support if a puck happened to be placed in between bearers) then the pucks and then the bottom plate(you say sole plate). This is the fixed with the method you described.

The listening position is about 2.7m from the back wall.

Anthony

[Hub]

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[Hub]

Hi everyone. Stay tuned . We will be sending more construction pics soon.

[Soundman2020]

I just noticed something in the previous set of photos: Is that carpet under the sole plate? If so, that MUST be removed. No seal at all with that... Potential big problem...

- Stuart -

[Hub]

Oh. Sorry for not updating. Here is the wall floor detail as it stands. We figured the carpet could stay as it did not effect the sealing.

Floor wall detail.jpg

[Hub]

We are designing the door construction. We are thinking of two 25mm thick MDF boards glued together. We like the refrigerator seal idea. I have drawn the fridge seal with a metal strip glued to the frame and then a second seal. What do you think? The wall has 1 layer of 16mm firecheck plasterboard - green glue and 1 layer of 16mm mdf. The wall thickness is about 34mm in total but I believe the greenglue potentially adds another layer so in theory the wall could be 45mm thick.

Door section 1.jpg

[Soundman2020]

We are thinking of two 25mm thick MDF boards glued together.

Rather than just glue, I would screw them together, possibly with some type of additional layer between them. Do you have Rod's book? He shows how to build doors in there.

We like the refrigerator seal idea. I have drawn the fridge seal with a metal strip glued to the frame and then a second seal. What do you think?

That would also work, but do take a look at the Zero International catalog: they have ready-made seals specially designed for acoustic doors, on all sides, including the threshold seals, which are hard to make yourself.

The wall thickness is about 34mm in total but I believe the greenglue potentially adds another layer so in theory the wall could be 45mm thick.

Weelleelll... sort of! It's equivalent in the sense of increasing isolation in the low end about as much as adding an extra layer of drywall would, but it's not really the same as having the leaf 45mm thick.

Still, two layers of 16mm drywall with Green Glue in between is a very good way of doing it. Should work well, provided that the rest of the structure is done in a similar manner.

- Stuart -

[Hub]

Thank you for the reply.

What and where is rods book? I must of missed it!

I was thinking of a 2mm or 5mm soft acoustic rubber in between like the material they place under the timber floors.

[Soundman2020]

Rod's book: http://www.amazon.com/Home-Recording-St ... e+the+pros

For the door: 2mm would be fine.


- Stuart -

[Hub]

Would 2mm be also good for the window doors? Or do i increase the thickness?
I can get a 3 mm acoustic underlay that is used underneath timber flooring.
It does come in 6mm thickness.

[Hub]

Here are a few update photos of our studio build.


We have got the 1st layer of 16mm Gyprock on the walls and ceiling and one layer of 16mm mdf on the ceiling so far. We have used Quiteglue in between the Gyprock & mdf.

Outside windows in control room.jpg

[Hub]

We have fixed all the doors and just have to paint the edges and attach the double seals. We got a good deal on Dorma door closers. Installed one and just 5 more to go.

Control - Live room doors.jpg