The heat is on – a rant about eggboxes

control-1The baffle (which will be above the planned twin Mac screens) is under construction – plasterboard and timber form the frame, and the final layer will be the same as the ceiling – rockwool and fabric. Behind this (at the bottom left of the vertical plan below) is the air circulation routing. This, again, is something of a trade secret, so I’ll confine myself to a description of the underlying physics and a plug for Jeff’s ingenuity (and Artis’ estimable craftsmanship). Basically, high frequencies are absorbed by ‘soft stuff’ and low frequencies are absorbed by ‘dense stuff’. But isolation and damping are two entirely different things. You may have heard of the urban myth about studios putting eggboxes on the wall. This does actually work to some extent in that it provides high-frequency damping and stops reverb (sound bounces less easily off rough non-uniform cardboard surfaces than it does off flat surfaces like tiling or plasterboard) but in my experience, this just has the same effect as a thick curtain or other soft furnishings. What eggboxes (or any similar lightweight materials) don’t provide is isolation – i.e. soundproofing – this can only be achieved through very dense/heavy materials that don’t resonate with uniform wavelengths; hence all the earlier variations in thicknesses and materials (rockwool, air, SterlingOSB, plasterboard etc).

picture-12This, of course, becomes a problem when you come to design air conditioning systems. Any air con system requires a duct – or hole – through which air of different temperatures can pass. And sound travels rather easily through holes! So the challenge is to create a construction that extracts air while preventing sound leakage into the rooms. The ducting needs to have some soft interior lining (to stop high frequencies) and a wavelength-averse construction (to stop low frequencies). And it goes without saying that the fans themselves need to be completely silent. Oh, and this studio is done on a very tight budget, so we can’t afford a top-of-the range air cooling system.

All of this secret construction cleverness is hidden behind the baffle in this picture – and you’re not allowed to see it, I’m afraid, but I’ve seen Jeff and Artis building the ducts, and it’s very impressive so far.

Will the guys solve all these problems and deliver silent aircon without breaking the bank? Tune in next time!

Standing in the way of control

The inner shells are in – this is the actual shape of the studio interior. You can now see the ‘V’ shape that forms the centre point between the midfield monitors. Above is the wooden frame for the panel that will contain some of the lights.
In the other picture you can see the lateral ceiling struts. These will have soft Rockwool between them then finishes with acoustic fabric (hessian). We’re on a tight budget so I will have to choose whatever fabric colour Jeff has left over from other jobs. Unlikely to be pink đŸ˜¦

Talking of recycling, we had a catflap fitted this week in the kitchen. It needed a custom glass panel for the door, so the glazing guy took out the old double glazed door panel, which is about 60cm x 80cm. I was going to get rid of this, but thought I’d offer it to Jeff. Sure enough, he said “that’s perfect for your live room window, that is…”. I asked him “how big was the window going to be?”. He looked at the window panel and said “errr… that big”. Great music is all about improvisation, I guess.

You’ve been framed

All the isolation (on three sides, and floor/ceiling) is now complete, with the final layer of SterlingOSB providing (another) different density in the ceiling, which now consists of so much plasterboard, OSB, rockwool and timber that the ceiling is now almost as low as it was before the roof was raised.

This is where, according to Jeff, the ‘studio building begins’. Artis and Jeff have made the frames that will form the interior shell of the live room. Their construction methods and measurements are a trade secret, and I’m under strict instructions not to blog them – you can contact Howard if you want to discuss commissioning a design. I can tell you it’s a particular combination of rockwool, timber and plasterboard of various specified grades, thicknesses and measurements, with particular bracings. What you end up with is a dense/heavy stud wall, onto which, eventually, will go another timber frame, which will be filled with rockwool of a different grade then covered with fabric. There will be bass traps in the control room, but the dimensions of the live room may make this unnecessary – Howard plans to run spectrum analysis on it before we make this decision.

I’ve said too much. If you print this out, you must eat the paper. Don’t let it fall into enemy hands. In fact, I suspect they will be coming to get me right n

It takes two

The ceiling now has two layers of plasterboard – one widthways and another lengthways. Right now there’s noticeable isolation in the room, even with thin garage doors forming one of the walls.

Jeff pointed out that the raised floor in the lobby gives us a bit of a dilemma. If we raise the floor level, we won’t have an interior step up. This means the cosmetic/fake garage doors on the outside would have to be some two or three inches off the floor – creating a ‘lip’ at ground level that wouldn’t suggest to an observer that this was a garage for anyone but the owner of the most rugged of 4x4s – who liked a bumpy offeoad experience when putting the car away at night.
So in order to make the studio look suitably garage-like from the outside (to avoid advertising the nickable guitars therein) we may need to rethink the interior step.

In order to create the ceiling height specified in Howard’s drawings, Jeff has decided to raise the roof one more time. Not by a whole block’s worth, but just by a couple of inches. In the picture above you can see where the roof has been screwed to the wooden batons, and the batons fixed to the concrete with metal strips.
According to Jeff, the guys haven’t really started work yet; “All this is just basic construction – we haven’t made the boxes for the actual rooms yet. We’ll have this finished in a day or two – THAT’S when we’ll start building you a studio!”.

Isolation (plastic? Oh, no – banned!)

FlooringThe sand/cement (screed) floor is now dry enough to create the floor proper. We’ve deviated slightly from the drawings in terms of construction materials – Jeff describes Howard’s flooring drawing (right) as ‘just a guide’ (I’ll let them fight this out!). So we’ve used the following materials for the floor (from the ground upwards);

  • screed (with PVA to help it stick to original concrete floor)
  • damp-proof plastic membrane (stops damp soaking into the rockwool)
  • compressed rockwool (1 inch)
  • lengthwise chipboard
  • widthwise chipboard (these last two are for strength as well as isolation)
  • rubber-backed carpet

I’ve just, er, bounced on the floor, and it has that curiously springy solidity that you get in studios – feels like the bass drum/bass cab wouldn’t resonate at all, but there’s a feeling of ‘give’ underfoot.

Here’s a close-up of the membrane/compressed rockwool and first layer of chipboard..

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floor-ceiling-isolation52Two and a half metres higher, the roof timbers have been wood-treated (with whatever the modern equivalent of creosote is – I shall call it creosote in tribute to the many Derbyshire chicken sheds I painted with the evil stuff in the 1970s). Artis has now added nearly all the lower-density rockwool – the stuff that actually looks like wool. floor-ceiling-isolation42Rockwool is, apparently, the best material for sound  isolation, because it contains a combination of rock and air (as, indeed, will the studio itself ;-). He cuts the stuff with amazing expertise – it’s a millimetre-accurate job because if the slabs are too thin, they fall out of the gap between the timbers; if they’re too thick, they buckle. The control room ceiling is now filled; here’s a picture of it, and of the half-completed live room timbers.

Spirit (level) in the sky

floor-levelling1We discovered that the garage was slightly sloping, front to back. No surprise there – it’s a flat roof and the water has got to run off somehow. More mysteriously, the floor was sloping in exactly the same proportion. As I didn’t fancy taking office-chair rides from the control room mixing desk to the sofa (not while anyone was looking, anyway), Jeff suggested that the floor should be completely level. So he’s started at the back of the building where the level is highest, and gradually poured in sand and cement to make a new floor.

floor-levelling2On a related note – here’s a link to my favourite application of the moment – the ‘A Level’ is a spirit level for the iPhone. Oh, the lengths to which human beings will go to make a better world…

Walls and bridges

wall-and-ceiling2The roof-raising is now finished – concrete blocks all the way around. The modern blocks we’re using are a lot slimmer than the original (1970s?) ones, and this works in our favour. You can see in the photo how the thin line of blocks at the top is set back from the interior wall, giving us a ‘shelf’ at the top of the lower blocks. This is where Jeff’s going to run the pipes for the (silent) air circulation system.

wall-and-ceiling1Meanwhile, the old dividing wall has gone, and the new one is complete. We’re keeping this little ‘stub’ of the old wall as extra support (the rear wall is soil-retaining on the other side) – the stub is going to be hidden by a bass trap in the control room. So the ‘stub’ in the photo is roughly where the left-side monitor speaker will be, in front of the corner bass trap. The music keyboard will go under the window, on the left of the picture, giving line-of-sight communication between keyboard player and vocalist (or drummer). I find this kind of sight/talkback/keyboard communication is really handy when doing a lot of backing vocals (50% of the job is teaching the singer the part IME).

Jeff and Artis are leveling the concrete floors today, but he won’t let me show you a photo until these are complete. Artists, eh?!!