John Sayers' Recording Studio Design Forum Archive

Sorry, me again

...just quickly: Is there a minimum width I shouldn't go under on the vent at the top / bottom of the speaker box? I was thinking an opening 30mm x 220mm. Would that be ok to allow enough air circulation for my speakers?

Thanks !

Simo

What speakers?

Personally, I'd take a look at the heat sink on the back of your speaker, and make it quite a bit wider and deeper than that. If there is no heat sink, then I'd go for at least 2/3 the width of the speaker and 3 or 4 cm deep.

When the speaker is sitting on a stand, there's plenty of space for air to circulate, but when it's in the soffit there's no space at all, so be generous with vent dimensions.

- Stuart -

They are Genelec 1031A.
The speaker dimensions are: 393mm (H) x 251mm (W) x 291mm (D).

I was proposing a 220mm x 30mm vent, so it can't be much wider than that. But I guess I could make it slightly deeper, say 4-5 cm? (unfortunately I can't make it deeper than 4cm - 5cm max, otherwise the box will end touching the wall on the back )

Simo

Hello,

I've made the speaker boxes (pics to come).
I haven't placed the sorbothane lining inside yet (I'm going to glue it with some strong glue / contact cement).
Since that the sorbothane isn't very hard, I'm worried that if I have to pull the speakers out and push them back in their box the sorbothane layer would tear off.

So here my question:
Does the speaker case need to be screwed to the plane is resting on?
Because if not, I could have the "pulling straps" around the case (instead than around the speakers) and be able to pull out the box + the speakers as a joined thing?
I would of course restrict the movement (sideways and back to front) of the speaker case with a frame around it which will be screwed to the resting plane. Would that work?

Thanks

ciao
Simo

…slight bump perhaps?…

Any idea if the approach with the strap around the box (which won't be screwed to the plane underneath) will not compromise the effectiveness ?

Sorry for being insistent . It's just that I've got a some free time before a busy patch at work, and would love to get as much done as possible before that.

Many thanks

ciao
Simo

I'm not so sure that would work. If the box is not screwed, nailed, or bolted down, I suspect it will vibrate, shake, move and do other unpleasant things.

I wonder if you could put something like a sheet of paper between the rubber and the speaker, so that it slides in and out more easily? I think part of the problem is that the rubber "sticks" or "grabs" the sides of the speaker cabinet, but if you put something in between, then it should go in and out a lot easier. Maybe?


- Stuart -

yeah that could work, yes… perhaps the only concern would be the heat from the cabinet after hours of operation (?)… but the idea is good, I'll definitively play with it. Grazie Stuart

Hi all,

I'm about to finish the ceiling for the control room (pics to come soon).. I know I know... I'm soooo   s  l  o  w, but work is keeping me busy (without which this project wouldn't go much further anyway) and two little girls need quite a bit of time - most of you know what I mean I'm sure !

So, looking ahead:
I wanted to build something to break the reflections between the floor and the ceiling - with them both being  flat, i.e parallel to each other.
The options I'm considering are:

1) A cloud hard-backed with a layer of 18mm plywood angled downwards on the front of the CR, hung on heavy duty chains and hooks, with a gap of 30cm circa from the walls.
This will start from behind the sitting position (highest point) and descend with a 12 degree angle to the front of the CR (lowest point). The only concern here is its weight and how I can trust the strength of the hooks and chains...


2) A modification of the previous point:
Basically all the same as described above apart from having the highest point (behind the sitting position) attached to the existing CR ceiling frame. I was thinking of doing it this way in order to save same room height, which is not much already

(Note):  Would it be a problem not having the cloud completely "free standing"? just guessing here, as I'm not sure if that is a requirement for the cloud to work properly or that doesn't really matter?


3) Build a sloped false ceiling (just the frame, not hard-backed with plywood), directly connected to the walls all around, with the cavity between this and the flat ceiling filled with insulation and then acoustic hangers at the front of the room (space permitting - otherwise all insulation).

(Note):  This obviously won't break the reflections between floor and ceiling as the two will still be parallel, but has the advantage of having a greater quantity of absorption material (soft insulation in the cavity and rockwool slabs between the framing).
I guess I could add a plywood layer at the top of the frame (and then insulation between the beams), but wouldn't that create a 3-leaf structure? sorry - getting confused here


Which one would you recommend?

Really hope you can point me in the right direction.

Many Thanks in anticipation !

Ciao
Simo

I don't see how "option B" can be hard-backed, since the backing would be interfering with the ceiling joists. Sure, you could cut slots out of the backing, but that kind of defeats the purpose of the backing! And if you happen to need to change the angle, you'd need to cut deeper slots or fill them in again...

I think I'd go with "option A".

My $0.02...


- Stuart -

Thanks Stuart,

yes I think I'll go with option A… easier to build, adjust, remove (if needed).

I read somewhere that a 18mm plywood layer and a 18mm MDF layer screwed and glue together should be used for the back of the cloud (the MDF adds mass and the ply adds stability)… but I'm a bit worried about its final weight as I will spend quite a bit of time sitting under it
(I was planning of using 100mm x 20mm timber for the framing just to minimize that)

What type of hooks should I use ?

Thanks
Simo

I read somewhere that a 18mm plywood layer and a 18mm MDF layer screwed and glue together should be used for the back of the cloud (the MDF adds mass and the ply adds stability)…

I don't think it needs to be that massive. The density of plywood and MDF are pretty similar, while MDF is slightly more dense, so that "wisdom" you read seems to be a bit off. I'd go with just a single layer of plywood.

What type of hooks should I use ?

Heavy duty ones! Good enough that each one can take the entire weight of the cloud, if possible. You do NOT want that thing coming down on your head, so make sure you have plenty of safety margin in your hooks and chains, such that no single or double point of failure can cause it to fall.

- Stuart -

Just to mention ...

'Gullfo' did the design for my hard backed clouds, and recommended the combination of MDF and plywood.

It worked out very nicely, as the MDF provided mass, and the plywood [with its mass] also allowed for attaching my aluminum frames AND the ability to staple the fabric cover to the top side of the plywood. MDF alone is not as easy to work with.

Here's a link to my section on the cloud construction and mounting design:
http://www.johnlsayers.com/phpBB2/viewt ... &start=390

just additional info

Thanks Stuart and RJ for your advice. Much appreciated !

I'll calculate what will be the weight of the cloud (as it's quite big) and then decide… I might divide the front cloud in two instead of a big one...

Also, I was planning to have three smaller clouds at the rear of the room. So, clarified that a hard-backed cloud is the way to go at the front of the room (being my ceiling flat), I was wondering if I'll need to have these three smaller ones at the back hard-backed as well?


By the way - Fantastic build RJ !!

Ciao
SImo

Hello

hope all is well.

It's been a while since my last post. It seems I'm going to have a quiet time in front of me now so I'm hoping to get a lot done.
I thought it was time for a little update:

I built a plate/structure to attach the AC wall mount indoor unit…this required some "particular" cuts Removed the plasterboard layers between two studs to pass pipes/cables through Outer-leaf penetrations drilled at the bottom, inner-leaf penetrations drilled at the top. This gave me an offset between the two penetrations of 1.8m.

I made the holes few mm larger than the pipes, then I filled that gap with insulation, backer rod and caulked.
The space between outer and inner walls was filled with soft insulation, and I placed 5cm rockwool slabs between the studs.
Finally I re-attached the usual two layer of plasterboard from inside the room.

CR:Having that single stud bay NON inside-out (unlike everywhere else in the construction) shouldn't be a problem because the top part will be the backing of the angle superchunk (so it will have insulation in front of it again), whereas the bottom part will have a sofa in front of it.

LR: Then, Inner ceiling construction:

- 50x150cm rafters resting on walls top plates - 25x45 mm timber ledgers screwed to ceiling rafters and caulked
CR:LR: - to close each bay I used two plasterboard "plugs" (1x 15mm fireline, 1x 15mm sounbloc) screwed to ledgers from below and caulked
CR:LR: - view from above - wire penetrations were filled with insulation, backer rod and caulked from above and below ....to be continued....

.....

- 5cm rockwool placed above the plasterboard "plugs" between the ledgersand then completely filled the rest of the void (which varies from 5cm at the rear of the room to 30cm at the front) with soft insulation
Fresh air system:

This consists of two paths per room:

A. the INCOMING FRESH AIR PATH with fan (at a rate of 60 l/sec, allowing 10 l/sec per person)with inline silencer(note: in this pic you'll notice that the circular connection - to connect the silencer to the duct - is in the wrong place… I temporarily put it there just to take a photo without realizing it , but then it was fixed correctly at the end of the internal bent - top left)

The fans will be connected to a weather proof 20 amp 1-phase isolators (not done yet, I hope next week), so I can switch them off either from there or from the main electrical panel.

B. the OUTGOING STALE AIR PATH with silencer.


As the void between outer and inner ceiling was way to small to install the silencers on the inside, I decided to have them on the outside of the building (like "realdoyle" did on his build: http://www.johnlsayers.com/phpBB2/viewt ... 8&start=30):(I will build some sort of weather cover for these)


I did used the small void between ceilings though to run the 80mm flexible insulated ducts(with as many bents as I could to minimize noise turbulence) to connect the fans and silencers to the inside vents. This is one of the entrance from silencer to duct (again the gap around the connection was filled with insulation, backer rod and then caulked): .......