Attic Shaped Studio

#151

Dr Space wrote:Source of the post I will also have some exciting news and pictures soon as well. Good luck and look forward to keep an close eye. Lucky for me I have huge granite stone walls surrounding my studio on three sides and no one lives closer than 300m from the studio...

I look forward to reading those, it sounds amazing!

#152

Contemplating soffit design this occurred to me;

The speaker shelf is connected to the OSB board on the knee wall, and should provide three benefits;

1) Decouple the speaker from the soffit structure and baffles.
3) Decouple the speaker from the floor, reducing structural sound transmission to the room below.
2) Act as a counterweight to the cantilever force exerted by the silencer on the wall.

I'm using structural OSB-3 for the wall, which is rated for walking on, so hopefully it will be strong enough. If not I could double up the OSB layer.

Comments welcome!

I had initially planned to float the speaker in the manner Stuart suggests, but my budget, time and skills are not up to this task just now. When I make my fortune (hah!) I'll be upgrading to Neumann KH310s anyway, so the old school simpler but not quite effective method is more realistic right now

Cheers,
Jennifer

#153

Hi Jennifer
I think you may end up with quite wobbly shelves with that design meaning that when the bass drum kicks through the speakers they move rather than just playing the sound. Perhaps this could be upgraded with a few 4x2 timbers (or offcuts) going from floor to the underside of the shelf to stop potential movement?

I do think you’ll be surprised at the difference soffit mounting makes so I would encourage you to try with your offcuts sooner rather than later!

By the way I’ve found a Sorbothane retailer in the UK: http://www.gelmec.co.uk/

Cheers
Gareth

#154

Cheers Gareth, good plan, I will make sure the shelves are beefy enough. Thanks for the link to the sorbothane supplier.

So the soffits really do make a big difference in your experience? Excellent!

Cheers,
Jennifer

#155

All the materials & components have arrived and I've started.

First is the builtin bass traps on the rear wall. I made a circular saw guide similar to Starlight's one but with the straight factory edge from a piece of plywood instead of a rail. I used it to cut some of the angled side parts and it works really well.

Also a big shout out to Gareth for recommending the TX screws. These are amazing, so much faster and more accurate that posidrive or phillips heads. And much easier to drive in straight. If I had known about them back in the day I reckon I'd have saved several months of work over my life. Quite seriously!

https://www.screwfix.com/p/turbo-ii-tx-double-self-countersunk-multipurpose-screws-grab-pack-850-pcs/7282h

Cheers!
Jennifer

#156

endorka wrote:Source of the postI made a circular saw guide similar to Starlight's one but with the straight factory edge from a piece of plywood instead of a rail.

Smart move! I bought some plywood recently and the same thought occured to me - as you got there first it will be as the saying goes: Great minds think alike; you're the great mind and I think alike.

And +1 to TX screws. Jag94's use of a pocket hole jig persuaded me to buy one and it came with a long TX bit. I am impressed at how much we are learning we are getting from each other, it is so helpful.

Jennifer, I kept revisiting your reply, no. 152, about the speaker shelves. On the basis that this is a temporary setup before you get a pair of Neumann KH310s I couldn't find anything really helpful to add to Gareth's comments apart from something I picked up from RyanC over on GS - he buys sorbothane hempispheres that are rated for heavier work and then puts weights on top of his monitors until the sorbothane has a good degree of compression.

#157

from RyanC over on GS - he buys sorbothane hempispheres that are rated for heavier work and then puts weights on top of his monitors until the sorbothane has a good degree of compression.

Yes, I read that too. Seems like a really sensible approach.

#158

SoWhat wrote:Source of the post
from RyanC over on GS - he buys sorbothane hempispheres that are rated for heavier work and then puts weights on top of his monitors until the sorbothane has a good degree of compression.

Yes, I read that too. Seems like a really sensible approach.

I also remember seeing a setup with T-nuts, threaded rods & nuts to exert pressure on the sorbothane pads. You could alter the amount by tightening. Very clever.

Cheers,
Jennifer

#159

Attachments are back so here is some work in progress.

Recessed bass traps built in to the eaves up first! Before;

Plasterboard removed. Oh no! There is some horizontal wood in the way!

Not to worry though. The old wood along the top was just dwangs for the knee wall plasterboard. As I'll be running OSB along there the can be removed.

For the other bits, I checked with my neighbour who built several houses in our cul-de-sac of a similar design. He said the old wood bar on the right of the photo would have just been used as a temporary fixing to keep the rafters aligned during assembly, and could be safely removed now.

The wood on the left of the photo looks a lot more intentional, and after a bit of puzzling it became obvious that it was intended to be a dwang for mounting a radiator. The radiator has been fixed round the corner though, so it was left unused. So it could also be safely removed.

There are a couple of central heating pipes & electrical cable runs, all fortunately out the way of the planned bass trap boxes. I'm going to add extra clips to the cable to ensure they stay flat on the bit of wood they run on. There was a good amount of insulation in the eaves, there won't be room for it all once the bass trap boxes go in, I can reuse it in the bass traps though.

The wall will have one layer of 18mm OSB with 15mm plasterboard on top, so the wooden floor has to be cut back a bit. I remember a tip Stuart mentioned a while back about doing this with a circular saw. I did it this way, set cutting depth to 18mm so it removed only the top layer of wood, leaving the floor board below intact. It was easy and worked well. Had to chisel out the last few inches into the corner.

Workshop ready for action!

Circular saw guide as per Starlight's recipe;

First cuts are the sides of the "bass bins" :-)

#160

Looking good! It's great to see progress isn't it. Glad the torx screws worked for you - I don't think I can take credit for recommending them to you though - it was Paul (SoWhat).

I think the design for sorbothane hemispheres where they can be compressed by tightening a threaded bar is part of Stuart's design for soffit mounting - I'm sure I've seen it in a picture of old. I've decided just to set the gap between speaker and box the right size to allow the hemispheres to be compressed correctly. They're surprisingly expensive, though - £100 for mine!

Looking forward to seeing the build come together.

Cheers
Gareth

#161

Built in bass trap update.

There are six in total, all different widths to fit in the eaves. Outer layer for all has been built with 18mm OSB-3, sealed with mould resistant caulk along the joins. The corner bracket jigs are worth their weight in gold for this task.

The inner layer will be 15mm plasterboard, except for the base which is 18mm plywood. I've danish oiled this for a nice finish to match the room floor. It will be hidden by absorption of course, but if the studio ever stops being a studio I thought these would make cool built in storage, so might as well do it properly while access is simple.

I'm contemplating a trial of some waveguides like Starlight showed in his recent post. A read of the attached paper got me thinking. Fitting them vertically wouldn't do much, but how about horizontally, a bit like the ceiling in the paper? I'll keep you all posted.

#162

Nice and neat, well done!

#163

I think the design for sorbothane hemispheres where they can be compressed by tightening a threaded bar is part of Stuart's design for soffit mounting - I'm sure I've seen it in a picture of old. I've decided just to set the gap between speaker and box the right size to allow the hemispheres to be compressed correctly.

Apparently the hemispheres are flawed in that they're not linear (the surface area & thus shape factor increases as the load increases) so it's harder to calculate isolation.
Would be better to get a sheet or several strips of Sorbothane that you can cut into cubes. Discs are apparently fine too
The retailer that Gareth recommended are good (Gelmec) but there's also these guys: https://www.dexineleyland.com (similar pricing)
Use the engineering guide pdf on Sorbothane's website to figure out the number, dimensions, duro, position & exact compression that you need (they have a calculator too but I've heard it has problems)

#164

I've built the outer layer of OSB for all the rear builtin bass traps, and got the top and backs of the inner plasterboard fitted to them all. Some tricky angles to work out and cut there; the plasterboard rasp was excellent for this. Green glue between layers. The mass should be equal to the mass of the wood floor & floorboards. With that and the Green Glue it should provide at least as much sound transmission loss.

Is there any benefit to it being more than the floor? I've no idea. It occurred to me that since those are a corner, the room modes "accumulate" there - certainly you can hear more bass in those areas - so it might be useful to have more sound attenuation to the room below if there is more "sound volume" there. Perhaps totally incorrect, but I already have the Green Glue, and there is no way I'll be able to add it after the build. Someone please say if this is bunkum, I won't mind and it would save someone else from making the same mistake if so

Got the first side of plasterboard cut too. Measure 10 times, cut once. Fortunately it fits.

By the way, the plasterboard is excellent stuff. "Gyproc Soundbloc Plasterboard Tapered Edge - 2.4m x 1.2m x 15mm".

These boards are heavy - the specified density is 12.6 kg/m2 - but the mass marked on the board is 44 kg, which would give 15.2 kg/m2. I'll try to remember to put a board on the scales to confirm either way.

#165

That looks a right pain to cut at the right angles! I know I wouldn’t have bothered getting the edges angled so good on you for going the extra mile.

I’m now regretting my plasterboard choice as my 15mm boards were marked as being 33kg. That’s a significant difference to yours, which makes me scared for my sound reduction!! I didn’t realise there was such differences between plasterboard ‘models’ at the same thickness. Hey ho. At least you can be confident you’ve got something decent.

With no theory behind it I’m with you on the conclusion that more mass in the areas where bass is more pronounced is a good thing...

Cheers
Gareth

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