John Sayers' Recording Studio Design Forum Archive

Hi Stuart, hows it going?

We've been busy over the past week and accomplished a few things:
- the floor has been removed entirely and rubber matting cut out (that stuff was not made for cutting!).
- the ceiling has been taken out, exposing the OSB of the floor above (there are joists, insulation and plyboard above that)
- the remaining stud walls were bolted to the ground to keep them secure

What is left is essentially a lidless box within the outer/external shell (80mm high density concrete block walls, and OSB celing as mentioned).

We are now ready to start building again! But there are a couple of consideration that have now presented themselves:

1) I neglected to mention there are practice rooms 'behind' the front wall of our control room (i.e. the unit next to ours), and they kick out a lot of noise. This was made worse by the floating floor, and is less of a problem now that has gone, but still present.

This led to our building the second wall at the front (the stud wall with the exposed rockwool in one of the photos in an earlier post). The second/new wall itself has 50mm rockwall stuck on to 50mm double-layer office wall dividers (it has something like 12mm plasterboard, 36mm honeycombed stiff card, 12mm plasterboard), then 50mm timber which is filled with instulation. As mentioned, we intend (or intended ) to clad this with resonator slats, but will wait on the final verdict of the REW tests.

This is what a cross section looks like:
And in place:
While we are keen to get more mass between us and them, and such a wall seems the best/only course of action, our concern is that this may create more 'leaves' than is good with regard to acoustics within the room. Working from the external unit/building wall inwards, there is high density concrete block, 50mm celotex, 50mm insulation (maybe a little air gap between the two), plasterboard, 50mm air gap (this is the pre-existing inner shell wall), then our wall. This is what it currently looks like:
We also intend to add another lay of plasterboard on all walls to add some extra mass, but again are wary of the above, i.e. wrong number of leaves.

2) With the old ceiling gone (which, as my friend Donk mentioned in this thread, was coupled to the rest of the external shell and thus the rest of the building!), we intend to build a new one on top of the now decoupled walls using a similar approach to the design/build of the new wall, mentioned above. Within this, we are thinking of mounting the cloud we built (mentioned in an earlier post), effectively as a panel. This would positioned above the listening position, angled and dropped down about 70-100mm from the height of the rest of the ceiling, which would be plasterboarded.

Does this sound like a good move, or should we just plasterboard the lot and then mount the cloud within that?

3) As you mentioned in your very helpful designs on soffitt mounting our speakers, to do so would encroach into the window. Measuring up in the room, it would cover just under half!
The vertical line going up to the window shows where we calculated the soffitt panel would go to.

In this respect, we think having soffitt mounted speakers is going to be problematic. But here are the few options:

a) simply have monitors in the room, either on/above the meterbridge, or just behind. I remember reading somewhere on here that, in a small room, monitors can be placed right up against the front wall so as to alleviate low freq reflections off of it (or suck them up?). This is fine with us, and any problems associated with doing so can be addressed in the treatment stage i guess.

b) build a box/recess/alcove into the flat wall to house each of the monitors, but at the same angle as they would be if soffitt mounted. They would stick out of the wall, but have the bulk of their volume within the wall. A kind of happy medium!

From my limited understanding, i guess the shortfall of such an approach would be the potential for soundwaves radiating from behind the monitors to reflect back into the room and interfere with reflections coming from elsewhere.

c) build the walls for the soffitts but 'rebate' the space for the window out of the wall/panel, i.e. create an opening in the panel for the window. This would have to be mirrored on the opposite wall to ensure symmetry of course. I envisage the shortfall of this approach would be the potential of a having such a reflective surface so close to the monitor. Indeed, are the panels in which the monitors are flush mounted integral to the effect of the monitors themselves? If so, would the absence of a 'complete' panel cause issues beyond any potential reflectivity from the window?

d) just build the bloody soffitts! If so, how do we calculate the angle at which they should tilted on the horizontal, i.e. towards the listening position? We worked out that, due to the height of the desk, meter bridge etc., they would end up above the 1.2m threshold mentioned in the Recording Manual. Indeed, this may actually take it above the height of the window, so we may be in luck there. Ill let you know.

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So, as stated, after the destructive phase we are ready to start building but would greatly appreciate a little guidance on what the best steps should be next. We've started over too many times to go down the wrong path again, but feel, with your help, weve got to a solid base (quite literally, ho! ho!). I keep kicking myself we werent at this stage a year ago!

Many thanks in advance

Chris

Another little update:

We've calculated what we think is our optimal position for the soffit mounting, and reckon it should be 1305mm at speaker centre (42% down from ceiling), with a tilt down at 4.5 degrees. This should hopefully put it enough out of the way of the window and minimise reflections. This should also reduce the reflections off the desk.

In the diagrams you provided, monitor centres work out at 1250mm, but you dont specify a tilt, so we assumed they should be flat horizontally. Our higher level precipitates angling down, as specified in the Sayer Recording Manual, but keeps it within the 5 degree maximum tilt you and others have mentioned here.

Does this sound any good?

This should also reduce the reflections off the desk.

Actually, no! If you raise the speaker and tilt it down, you will get MORE reflections from the desk, not less... Work it out in 3D, using SketchUp....

In the diagrams you provided, monitor centres work out at 1250mm, but you dont specify a tilt, so we assumed they should be flat horizontally.

Correct. No tilt.

Why do you want to raise yours higher and tilt?


- Stuart -

Soundman2020 wrote:Why do you want to raise yours higher and tilt?

We worked out the height of the top of the desk (which we understand is too big for the room, but will live with it for now) to be 1245mm, which required us to push the speakers up a bit from your specs, bearing in mind they put the speaker centre at 1250mm. This places half the speaker below the meterbridge.

By moving the centre of the speakers up, ensuring they are above 50% of wall height, it took it above the 1.2m threshold for tilting monitored specified in the Recording Manual. We then worked out the angle that would fire the sound to ear height, using 1.2m at the listening position, which came to 4.5 degrees:

Donk's bit of CSI blood splatter analysis we used to work it out:
We do understand the probability of reflections off the desk, but they would most likely be there anyway given the size of it. We may be able to mitigate it, but have been using the desk for best part of 10 years and most likely had reflections off it during that time. And in rooms far far worse than what this should hopefully become!

Chris