If anything we could put in a decking filled with sand to prevent some impact noise but I'm not sure this will be necessary.
Not necessary. And sand is HEAVY! Worst case, build a drum riser for your live room, to keep impact noise out of the structure, and ditto for things like bass cabs.
This Studio will be the first of it's kind in Kenya and we are really hoping to make it better than 'fine' !!
That sure can be done! But it
does require careful design... It can be world-class if you want it, but it ain't so easy to get there!
1) Splaying the front side walls of the control room in this case will obviously make the room narrower at the front
Right! Which is a GOOD thing in your case, as it gives you better angles for attaining a true RFZ style room.
Considering that the room is already quite narrow (4.4m at its widest point), will the benefits of the splaying the side walls for RFZ outweigh the the acoustical advantage of larger room volume.
Absolutely! You still have plenty of room volume in there: ITU specs call for the floor area of critical listening rooms to be in the range 20-60m2. Yours is about 23m2. General "rule of thumb" volume for control rooms is at least 40 m3 up to a maximum of about 180 m3. Yours is roughly 60m3. ITU specs also call for referencing the decay time to a "standard" room with 100m3 volume, using an equation: your room has nearly 60m3 volume, so your decay time should therefore be about 210ms, which is also a very decent time for a control room. Any way you look at it, you are fine.
Another consideration is that splaying these side walls creates dead space that will not be used on either side.
Ahh, but that depends on how intelligently you design the overall facility...
The space does not have to be wasted. When studio designers start looking at possible layout, that's one of the biggies that we take into account: minimize lost space, and then find a secondary use for whatever space turns out to be "lost" anyway.
2) What are you thoughts on positioning the speakers on the other wall so they are firing down the short dimension of the room. I see a lot of RFZ control room designs that are wider than they are longer-
FOr big rooms, that's fine. The issue is this: Can you arrange the room so that the engineer's hear is no further back than 40% of the room depth? If not, then don't do it that way. If it is not possible to get a decent arrangement of speakers, desk, chair, and listening position that meets the above, then it would be a bad idea. If you go further back that that, you start getting your ears into the modal nulls and SBIR artifacts, which is a bad idea. There's another factor: If you want to use diffusion on the rear wall (which is nice, when possible), then the rear wall has to be at least 3m away from the engineer's head. If not, then his ears are still in the lobing artifacts created by the diffuser. The distance might need to be even greater, depending on what frequencies the diffuser is tuned to, and how it is oriented, but regardless of that you still need at least 3m.
In your room, that would be impossible. There's no way to set things up facing the long wall and still have at least 3m from head to rear wall. It would also be hard to set things up with good positions for the speakers, a decent size desk, and still keep your head 60% away from the rear wall. It would also leave very little room for a client couch at the rear.
There's one other issue too: Haas time: For an RFZ room, the spec requires an ITDG of 20ms before the diffuse reverberant field arrives at the engineers ears, to make sure that it is outside of the Haas time window. That means that the path followed by the earliest part of the reverberant field must be 20ms longer than the path taken by the direct sound. That's hard to do accomplish if the back wall is close to the engineers head!
Yes, that kind of layout that you are talking about can be done in large control rooms (and it makes a lot of sense to do so), but for smaller rooms, you are generally stuck with the speakers firing down the long axis.
3) If the a/c will go in the slanted part of the ceiling, is there a problem with having inlet and outlet vents close to each other at the front of the room
Yes there is a problem. I normally try to keep the inlet registers at one end of the room, and the exhaust registers at the other end, to ensure that air moves through most of the room, evenly and smoothly. If the registers are too close, then some parts of the room don't see much air movement. When I'm designing control rooms, I try to get the inlet registers at the back, and the return registers at the front, roughly above the speakers / soffits.
I know this sounds like a stupid question but I don't see how I can run a duct through to the back of the room without going through the CR itself
There's always a way!
HVAC design is a big part of studio design. To be honest, sometimes I spend more time on getting the HVAC right than I do on the actual room acoustics! There are a LOT of calculations that go into HVAC design, and it is critical to get them right. You have to have enough air flow volume for the room size and occupancy, but it has to move slow enough as to not create turbulence and noise where it comes through the registers. You also have to design your silencer boxes such that they allow that volume and speed of air flow while blocking sound from getting through the ducts. You also have to take into account the total static pressure of your design when choosing the AHU and fans, to ensure that you won't be overloading them with too much resistance, and you have to figure the correct cooling/heating/dehumidifying capacity for the system, based on climate, people, gear, lights, sensible heat load, latent heat load, etc. Then you have to make sure that the AHU can handle both extremes: all rooms fully occupied with hot sweaty hard-jamming musicians in mid summer, and also just one single person sitting still, all alone, in mid winter. HAVC is huge, and usually ignored by many studio builders... until it is too late! Please do not make that mistake! Get some with studio experience to do your HVAC design, not just any old guy who knows how to hang a few feet of HVAC duct...
4) For ventilation I am considering two options. I am having a hard time deciding which to go with!
If you aren't sure what you are doing with HVAC, then don't try to do it yourself. That will likely lead to disaster. Either you will over-spec the system, and waste a lot of money, then still have problems because the AHU will only run in short powerful bursts, causing wild swings in temperature and humidity, or you will under-spec some aspect, and the system will be running at full capacity practically all the time while still not cooling or dehumidifying the rooms sufficiently, wasting a huge amount of electricity, causing excessive noise, and burning out early due to the overload. Getting HVAC right is a much, much bigger issue than pointing the speakers in the right direction and putting suitable treatment in the CR (which is pretty big already!). HVAC takes time and care. You can get burned (figuratively!) by not getting it down right.
A) Put a 6 inch fresh air duct running from outside to the return duct for the a/c.
How do you know 6" will be enough? What exchange rate did you use to figure that out? What occupancy? What flow rate? What flow velocity? What static pressure will that produce? Can your fan handle that amount of static pressure while moving the correct volume of air a the correct velocity? Are you going with a CAV system, or a VAV system? Why? Hmmmm..... See what I mean?
There would be a barometric damper here to control fresh air flow. This damper would have to be somehow accessible.
I would not use a barometric damper! I would use a correctly sized electric damper for each room, connected to a system controller and sensors in each room, to regulate the flow rate, temperature and humidity correctly.
B) Keep the ventilation system separate using and HVR unit and ducting at the back of the room. The HVR will save on the a/c bill by regulating humidity and temperature. The downside is again having to run more ducting to back and front of room.
HVR alone is not going to be enough for your facility. The studio will by located in a mild to warm, humid climate, you will have multiple heat sources in each room, some of which are also producing humidity, so heat recovery is not going to do the job. You need a proper AHU that is sized correctly for the job, and can handle all of the rooms in your facility. At the very least, you need a mini-split system in each room plus fresh air ducting. Yes, you can have an HVR, and that's a good idea for saving some operating costs, but it won't be food enough by itself. Far from it.
The downside is again having to run more ducting to back and front of room.
You will need that, regardless. It seems to me, that you are underestimating the importance of HVAC, in general. I cannot emphasize enough just how important it is. It's a major, MAJOR part of building a studio, any studio, and even more so in a world-class studio such as you are trying to do. I would really, REALLY urge you to re-think this, and hire someone with studio HVAC experience to do that design for you. Installing it isn't such a big deal, and any decent HVAC installer should be able to do the job, with some instruction from the designer, but the actual layout and calculations are very, very important.
5) I am considering buying quested vh3208 monitors for soffit mounting - do you think these are suitable to be soffit mounted in a room this small or am I asking for trouble?
Those are nice monitors, but they are BIG! Maybe a bit too big for your room. Also, considering it's size, it doesn't go down very low in frequency: you'd need a sub to go with that, if you want to have a world-class facility. It could be made to work, but it's going to need some pretty deep soffits (it's a deep speaker!), thus eating into your room volume again...
I'd consider something a little smaller. Maybe any Adam A8x or something small from Eve, Yamaha, Event, Dynaudio, JBL, etc. Look for something that is front-ported or un-ported, to make it easier to soffit mount.
I think I said this before: You have a great space there with some excellent potential, and an aggressive but realistic plan to be the best studio in the country: you can achieve that, without doubt, ... provided that you design it carefully, taking into account all the usual practices for high-end studio design, and especially paying attention to layout, acoustics, and HVAC. I noticed several ways you could improve the design, and several ways you could save money. I did a couple of quick mods to your SketchUp, to give you an idea of how studio designers go about reducing lost space, maximizing useful space, improving acoustics, and improving practicality, all at once. Here's where I got after playing around for just a few minutes:
deluxestudios 5-1-V2-S00-1.png
deluxestudios 5-1-V2-S00-2.png
deluxestudios 5-1-V2-S00-3.png
Your CR is now bigger (compare it to the original floor that I left in for reference), the ratio is much better (better modal spread), the lobby is bigger, the live room is easier to build, all rooms have better acoustics, there is space at the rear and sides of the CR for HVAC ducts, the issue with the "passage inside the wall cavity" is gone, the CR wall angles are more suitable for RFZ, the strange "kink" at the rear of the CR is gone... Overall it's a big improvement, but there's still a lot more room for improvement. That was just a few minutes of tinkering, to give you an idea. I can see many more things that could be improved, given enough time.
So my position would be: your facility has great potential: don't waste it with a mediocre design! Spend the time to do it right, and hire people to do the parts that you don't know how to do, and don't have time to learn how to do.
Hope this helps!
- Stuart -
I would not do that. I would either make the CR bigger to close up that gap and put the access door to the LR in the other wall, or I would move the dividing wall over to the CR wall, angle part of it, and put the door in there.