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PostPosted: Wed Jan 25, 2017 8:24 pm 
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Joined: Mon Jan 23, 2017 2:59 am
Posts: 48
Location: Manenberg, Cape Town, South Africa
Short backstory:
Manenberg in Cape Town is known for its gangs, but once it was known for its music. The Abdullah Ibrahim track of the same name was smuggled to Nelson Mandela on Robben Island and became an anthem for the anti-apartheid struggle. I want to create a control room / live room combo to record and mix local musicians, of which I have met many, in order to help tip the balance away from "nothing good comes from Manenberg" by people being proud of the music recorded here. I am not aiming for a professional studio, nor do I have that kind of budget (have ~$3000 for sound isolation and treatment). Also to note that I am also doing film work telling local stories so it will also be my edit suite (which is great as I do my own mixes now).

Room available:
Converted garage with loft above ceiling, solid brick external walls. Currently one non-load bearing wall in middle of room as per floor plan "2 rooms" (dimensions are cm).

Challenges of sound isolation:
- room measures mid 50's on my phone SPL app and mid 60's in the attic (I'm afraid i don't have budget for an omni mic to do REW properly or a proper SPL meter)
- right on main road!
- 2 windows in room + one in bathroom + little window bricks
- 2 doors, bathroom and entrance
- roof
- small single drywall
- floor

Ideas:
- The "1 room" plan shows it without the current dividing wall. The "new wall" plan is my idea of walling off 2/3's of the room for sound isolation of the entrance door and bathroom and for storage of my film gear. The 3D renders are a rough idea of how it might look.
- The roof - I would like to move the ceiling up to the rafters, using fluffy fibreglass and then two layers of drywall with green glue there to isolate. Then I would build a false ceiling with fluffy fibreglass across it for treatment. I have a few threads on this but it isn't common, so I'm not sure about it, particularly whether the roof structure can take the weight. The thin battons are 300mm spaced and the rafters are 114mm x 38mm timber (4”x1.6”). I have costed out doing this vs. beefing up the current ceiling with another layer of drywall with green glue and the costs are not that different. The main cost is the green glue which is twice the price of the UK (where I'm from) as it's imported. But vinyl is 4 times the cost so I'm ruling that out and I haven't found resilient channels anywhere.
- The windows - I had thought to brick up the first one but now I think I will miss the light. So either a DIY plug which I have a thread on or seal it with another layer. I don't tend to open the window anyway.
- The little drywall I want to brick up
- the bass that comes through the floor I think i will live with. (there is some blanket thing under the laminate floor)
- I realise I haven't addressed ventilation, but HVAC isn't used around here and I have been through winter and summer here and had no problems with heat or cold, bar needing an electric heater in winter. I really lose confidence in the whole project when I try to get my head around ventilation. My plan is to open the door sometimes :)

Questions:
1) Any reason not to go for the idea of moving ceiling up to the rafters, e.g. unsafe or waste of money?
2) Do I need additional batons to hold the weight / will the rafters take the weight?
3) When costing the green glue sealant, is it for all edges between drywall boards or do you still tape and mud those joins and just use the sealant at the wall?


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PostPosted: Mon Jan 30, 2017 10:55 pm 
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Joined: Mon Jan 23, 2017 2:59 am
Posts: 48
Location: Manenberg, Cape Town, South Africa
Not trying to bump, just thought I should write up my changed plans.

After a visit from a couple of architect friends, they completely ripped my idea of moving the ceiling up to the roof, pointing out that it would be difficult to isolate the beams as well as the roof tiles. In fact, looking at it again, I think my drywall ceiling is coupled via numbers 1-6 in the diagram to the roof?

So I have moved towards a room-within-a-room design with John's inside out walls design (http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm). As I understand it, with brick walls surrounding the space, I only need one double layer of sheetrock (with green glue) inside in order to create a M-A-M.

So it would be:

Brick wall
small air gap
Fluffy fibreglass
Double sheetrock with green glue
Wooden stud partition
Denser 703 equivalent fibreglass
Cloth
Some covered with slats

I would do this for all 4 walls and the ceiling. But not do a floating floor as I'm on ground level concrete slab (http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8173).

And I will try to get over my fear & ignorance of ventilation to get that sorted (one reference attached in pics)

Does this look good?

Main questions now:

- With just one single wall layer for the inner room, do I then still need to improve TL on all windows and doors in outer room? Would it be better to still have an extra stud wall at the entrance end?
- Could I still let in daylight via a double glass panel in the inner room? Or better to give up on daylight?
- With the inner room ceiling under the current ceiling plus the roof above - is this 3 leafs and therefore a problem?
- Is it worth angling the side walls 6 degrees at the front to help with reflections or is room too narrow? (this post suggests not to http://homerecording.com/bbs/general-discussions/studio-building-and-acoustic-treatment/angled-walls-vs-square-room-324042/
- Should I soffit mount my active Tannoy 501A's with air passage as per John's diagram here? http://www.johnlsayers.com/phpBB2/viewtopic.php?t=66
- Roughly what % to cover with slats and spread over the room or more in the mixing end or the tracking end?


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PostPosted: Fri Feb 03, 2017 2:13 pm 
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Joined: Thu Aug 21, 2008 10:17 am
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Location: Santiago, Chile
HI there "nicklear", and Welcome! :)

Quote:
I am not aiming for a professional studio, nor do I have that kind of budget (have ~$3000 for sound isolation and treatment).
OK; so isolation is out of the question, and you are basically talking about treatment only on that budget.

Quote:
solid brick external walls.
That will give you reasonably decent isolation.

Quote:
- room measures mid 50's on my phone SPL app and mid 60's in the attic
Measuring what and measuring how? There's a big difference between A and C, fast and slow, and also between rock music and general residential ambient noise levels. Please be more specific about what you measured, and how you measured it.

Quote:
I'm afraid i don't have budget for an omni mic to do REW properly
So how are you going to treat and tune your room? If you really do want to prove the ""nothing good comes from Manenberg" myth wrong, instead of just perpetuating it, then you'll need to put a bit more effort into it! :)

A decent acoustic measurement mic costs around $ 100, or even less. It also makes for a great overhead mic on drums, and doesn't do half bad as an ambient mic on many other instruments. As a room mic on electric guitar, for example, it does a pretty acceptable job. I even used one once to record an entire university choir... it's a useful addition to your mic collection, as well as being the only possible way of getting accurate readings from your room, so you can treat it.

Quote:
Challenges of sound isolation:
You don't have the budget to isolate. Sorry.

Quote:
... layers of drywall with green glue there to isolate.
A single crate of Green Glue will eat up 10% of your entire budget, and you would need several crates. That's not a good way of spending it. Green Glue is great stuff, but only if you have the budget for it. I don't normally use it for low-budget studios. Only high-budget.

Quote:
Then I would build a false ceiling with fluffy fibreglass across it for treatment.
The entire ceiling? All tuned to the same frequency?

Quote:
114mm x 38mm timber (4”x1.6”)
Technically, that's a 2x5, which is an unusual size. Mote common is 2x6, which is 140 x 38 mm. Perhaps yours were trimmed down for some reason?

Quote:
I haven't found resilient channels anywhere.
I'm pretty sure you can get normal hat channel in the RSA, so have you looked into RSIC clips or something similar?

Quote:
So either a DIY plug which I have a thread on or seal it with another layer. I don't tend to open the window anyway.
On a tight budget like that, I would go with a removable plug.

Quote:
- the bass that comes through the floor I think i will live with. (there is some blanket thing under the laminate floor)
That's the underlay, and it does nothing to stop sound. It's only useful for a bit of thermal insulation, and reducing impact noise to a certain extent.

Two questions: Why do you have "bass coming through the floor"? And: What is the floor made of?

Quote:
- I realise I haven't addressed ventilation, but HVAC isn't used around here and I have been through winter and summer here and had no problems with heat or cold,
You need to re-think that. Fast. Deep. Building a studio automatically implies that it will be sealed air-tight, twice over, then wrapped in thick insulation. In other words, it will be like working inside a sealed plastic bag, inside a sleeping bag...

People need to breath. If the studio has no ventilation, it will become unpleasant to work in there, very fast.

Also, many musical instruments and some mics are affected by changes in humidity and temperature. The tone changes as the conditions change. If you hope to produce music that is better than "nothing good", then you want to be sure that the instruments and mics sound the same at the end of the session as they did at the beginning... You will need HVAC. You might think you don't, but you do. This is a discussion I have rather often with studio builders, and once they think it through and do the math, the realize that it's a major issue. For a serious recording studio, HVAC is not a luxury: it is a must. It is every bit as necessary as having speakers and a DAW.

Quote:
I really lose confidence in the whole project when I try to get my head around ventilation.
And that should be a major big whopping glaring frantically waving bright red flag! Any time you get to the point in a studio build where you don't understand something, and decide to sweep it under the carpet to forget about it, that's a MAJOR sign that you should stop right there, and not advance even one step further until you figure it out. Ignoring such blatant warning signs can only lead back to "nothing good" coming out of this...

Quote:
My plan is to open the door sometimes
:roll: :cop: :cen: :shock: :|
Think this through: How would opening a door help, if the room is sealed air tight? There is no place for the air to go! If you want air to move, you have to create a pressure difference between two points, but opening the door only provides one point.... How would you create a difference in pressure between one point and itself?

Watch this brief you-tube video to understand the problem: https://www.youtube.com/watch?v=ah5Rm-1bS3U The glass is your studio. The water inside the glass is the air inside your studio. The reason the water does not run out of the glass is the same reason the air will not run out of your studio: it is held in place by air pressure. Think about it...

Quote:
1) Any reason not to go for the idea of moving ceiling up to the rafters, e.g. unsafe or waste of money?
Insufficient budget. You need to save every penny you can, in every possible way.

Quote:
2) Do I need additional batons to hold the weight / will the rafters take the weight?
The only person who can tell you that is a qualified and certified structural engineer. It will cost you money to hire one.


Quote:
After a visit from a couple of architect friends, they completely ripped my idea of moving the ceiling up to the roof, pointing out that it would be difficult to isolate the beams as well as the roof tiles.
They are right! :)

Quote:
In fact, looking at it again, I think my drywall ceiling is coupled via numbers 1-6 in the diagram to the roof?
And also through the walls! The roof rests on the walls. The ceiling rests on the walls. Flanking! No isolation.

Quote:
As I understand it, with brick walls surrounding the space, I only need one double layer of sheetrock (with green glue) inside in order to create a M-A-M.
Correct, but skip the Green Glue. You don't have enough budget for that. You will also need to seal the brick walls, with some type of masonry sealant. Brick is porous, and you need to seal the pores so that the brick surface is fully hermetic.

Quote:
small air gap
Fluffy fibreglass
Why do you want a small air gap? Is that something that is required by local building code? If there is no legal reason why you need the gap, then get rid of it and fill the entire cavity with insulation. Leaving empty space in the cavity robs you of isolation.

Quote:
Fluffy fibreglass
...
Denser 703 equivalent fibreglass
703 is not that dense. It is light. It is 3 PCF, roughly 48 kg/m3. But it is semi.rigid panels, which is not the same acoustically as equivalent ordinary fiberglass. So when you say "703 equivalent", what exactly are you talking about? It would only be equivalent if it really is semi-rigid panels with a density of around 48 kg/m3 and a GFR of around 15,000 rayls and similar surface impedance.

Quote:
Cloth
Some covered with slats

I would do this for all 4 walls and
Slats on the ceiling? Why? Also, it's not usually a good idea to have tuned devices at the front of the room, as they can potentially "color" the sound before it gets to your ears.

Quote:
But not do a floating floor as I'm on ground level concrete slab
Excellent! :thu: !!! But if you are on a slab-on-grade floor then I don't understand the earlier comment: "- the bass that comes through the floor I think i will live with.". What "bass" is "coming up through the floor", if you have a slab on grade?

Quote:
And I will try to get over my fear & ignorance of ventilation to get that sorted
YES!!! Smart move! Very smart.

Quote:
(one reference attached in pics) ... Does this look good?
Ummmm... Nope! Whoever built that "snake in a blanket" box does not have a clue about how to isolate HVAC. All that would accomplish is to greatly increase the static pressure but with no useful insertion loss at all! It would actually make the air flow noisier, not quieter. I'm not sure where you found that monstrosity, but you ca safely ignore whatever other advice they give you... :)

Here is what proper silencers look like:

viewtopic.php?f=2&t=15430&start=45
viewtopic.php?f=2&t=1929&start=74
viewtopic.php?t=8425&start=2
viewtopic.php?f=1&t=11542&start=5
viewtopic.php?f=2&t=9761&start=0
viewtopic.php?f=2&t=11485&start=98
viewtopic.php?f=2&t=11508&start=157
viewtopic.php?f=2&t=13821
viewtopic.php?f=1&t=15378&start=44
viewtopic.php?f=2&t=18202&start=16


Quote:
- With just one single wall layer for the inner room, do I then still need to improve TL on all windows and doors in outer room?
Absolutely! Isolation is not walls. It is not floors. It is not ceilings. It is not windows. It is not doors. It is not HVAC. It is not electrical. It IS all of those! Isolation is the entire complete system of the entire complete studio. Isolation is only as good as the weakest point. If you isolate your walls really well but don't bother about isolating the ceiling to the same level, then you wasted a stack of money on isolating your walls, because the sound will simply get out / in through the ceiling. If you really did do the walls and ceiling well, but didn't do anything about the doors, then you wasted even more money, since the sound will ignore the wonderful ceiling and walls and will enter/exit through the door. If you did the walls, ceiling and door to the same level but forgot the windows, then ditto: you wasted even more money than before and still got the same result, because sound will always take the easiest path in/out: through the windows. And if you did the windows too, but forget to isolate the HVAC ducts, then ditto. And if you did the HVAC ducts along with everything else but forgot to isolate the electrical system, then one again: Ditto! Lots of money wasted, as sound will take the easy path in and out: through the electrical system.

Isolation is the entire studio, not just one part of it. Isolating walls, doors, HVAC and electrical is just as important as isolating walls. And far more complicated. And far more expensive. Doors have to open and close, but they have to be massively heavy, and they also have to seal air-tight. Not easy to do. Expensive. HVAC ducts are basically huge holes in your wall or ceiling: they have to let large volumes of air pass through but somehow prevent the sound from getting through. Complicated. Expensive. Windows have to let light through, but block sound. Obviously, you cannot put insulation in the gap between the two window panes! You would not be able to see if you did that! Yet they have to isolate to the same level as the walls, ceiling, etc. Complicated. Expensive. The electrical system has to allow the wiring to come in through the wall while stopping the sound from coming in. So you cannot do the normal thing of chopping holes in your walls and ceiling to put the electrical boxes and conduit through.... complicated. Expensive.

That's why I said up front that your budget is insufficient to isolate your room. Yes, you might have enough to frame the walls and ceiling, and hang some drywall on it, but I don't see that you'll have enough to also isolate the doors, windows, HVAC system and electrical system, which are more complicated and more expensive. It's been a long time since I last lived in the RSA (30 years or so), so I'm not very up to date on building material costs, but I suspect that they won't be much different from what they are anywhere else in the world. I do not see that your budget is enough to do everything that really needs doing. Note that I said "everything that really needs doing". Not just the things that you have thought of so far, but also the things you thought of then discarded (such as HVAC), and also the things you didn't think of yet, .... such as full perimeter door seals, surface-mount handles, heavy-duty hinges, automatic door closers, mini-split system, structured raceway surface mount electrical system, thick laminated glass with acoustic PCB interlayer, duct liner, HVAC silencer boxes, fans, ducts, registers, crate loads of caulk.... etc. All of that adds up, fast. Those are the unexpected costs that kill underfunded and under-planned projects part way through. Your budget probably does cover the very basic structure itself, but there's no way it can cover all the other stuff, and also your equipment. And we have not even started talking about the cost of the acoustic treatment yet....

So my number one suggestion would be to increase your budget to something more realistic, or scale down the plans to fit the budget. If that budget is as far as you can possibly go, then it is only good for the HVAC system and the basic equipment, nothing else. No isolation, and no treatment.

Quote:
Would it be better to still have an extra stud wall at the entrance end?
If you forgot to include that one as part of your "room-in-a-room" isolation system for the complete studio, then yes!

Quote:
- Could I still let in daylight via a double glass panel in the inner room?
Yes you can, and it's always great to have daylight in a studio! But it costs money to do that. Thick laminated glass with acoustic PVB is not cheap.

Quote:
- With the inner room ceiling under the current ceiling plus the roof above - is this 3 leafs and therefore a problem?
YEs it is 3-leaf, but no it is not a problem. The "air gap" distance to the roof is very large, so the MSM resonant frequency will be very low, and therefore not a problem.

Quote:
- Is it worth angling the side walls 6 degrees at the front to help with reflections
To "help" in what way? :) Angling your walls is another one of those acoustic myths that refuses to die... you do not need to do that to "help with reflections"! The only time that is needed is to deal with flutter echo.... but flutter echo can be dealt with in other ways. The only other time you would need to angle walls (or rather, parts of walls) is if you are doing a true RFZ design concept, or any of its variations, such as CID or NER. And if that's the case, then 6° is way to little. You will need a much larger angle for those.

Some people still think that angling walls somehow helps with modes, standing waves, reflections, SBIR, or just "to make it sound good". All of that is pure garbage. Angled walls do not eliminate modes (standing waves), reflections, nor SBIR, and won't make a room sound better. The ONLY valid reason is for RFZ or derivatives. Or maybe "because it looks cool"! On the own side, it increases costs, wastes space, complicates construction, and makes it much harder to predict the acoustic response.

Quote:
- Should I soffit mount my active Tannoy 501A's
I would, yes. In which case I would also suggest that you do an RFZ-type design for your room.

Quote:
- Roughly what % to cover with slats and spread over the room or more in the mixing end or the tracking end?
You cannot have one single room that is excellent for both tracking and mixing. The two phases require different acoustics. Control rooms for mixing and mastering must be neutral, symmetrical, even, non-specular, etc. Tracking rooms should NOT be symmetrical, nor neutral, nor even, etc. Tracking rooms are supposed to have "character". Control rooms are supposed to NOT have "character". Clearly, you cannot have one room that does both. Either it will be a great control room but lousy for tracking, or a great tracking room that is lousy for mixing.... or you could try to make it both at once and end up with a room that is pretty bad for mixing and also pretty bad for tracking. The only way you can make that work, is by making the acoustics variable. You can design devices that allow you to change the acoustic "signature" of the room, by opening, closing, sliding, flipping, rotating, etc. parts of the device. That is possible, and I have done a few rooms like that, but not on your budget. It's expensive to design, expensive to build, and expensive to test such devices.

Anyway, overall it looks like your biggest problem is budget. You have good plans for the room, but no way to implement them on the budget you mentioned. Raising your budget or lowering your goals are the only two options, realistically.


- Stuart -

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PostPosted: Sat Feb 04, 2017 6:47 am 
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Joined: Mon Jan 23, 2017 2:59 am
Posts: 48
Location: Manenberg, Cape Town, South Africa
Thank you Stuart so much for your reply and for your straight talking. You display endless patience with those like me who come new to this field. And good to know you were here in South Africa a while ago – which province?

I have been reading non-stop for months now and yet still have such large gaps in knowledge. Yet, I really believe in this project and I think with your help we can at the least be producing good demo quality songs that people will be proud of.

I will start with the big picture
:
Quote:
It looks like your biggest problem is budget. You have good plans for the room, but no way to implement them on the budget you mentioned. Raising your budget or lowering your goals are the only two options, realistically.
I will up the budget and do sound isolation & HVAC. I have access to more money than when I started the thread. I can go to at least $6500 for the building and a bit more for kit so will get an omni & give proper REW results. What best if I want to use mic afterwards to record, the ECM8000?

Quote:
You cannot have one single room that is excellent for both tracking and mixing.
I don’t think anyone would argue with this, but the question is what is a better compromise in a small space. The advice I was given on Gearslutz was that on a smaller budget with limited space, the best compromise is a single room & I’ve seen a few of the regulars there suggest that. But I am open to considering a 2 room setup if you push strongly. I don’t need an isolated control room for recording (I know this is not why you were suggesting it, I just wanted to make that clear). With my area, it would be more like a vocal booth and a control room and I had read a lot about how vocal booths can sound boxy. I had planned on a couple of gobo's (see 3D pic).

Other points:

- Your links and info: I will read all and digest and research more
- Bass through floor: ignore that, I was just guessing that was a problem, it’s not. Floor is concrete slab.
- Angled walls: ok, will forget that idea
- Air gap: ok, no air gap, just 50mm fluffy
- Soffit speakers: I feel this may be a bit beyond my/my builders ability to do it right as well as making sure the corner is also a bass trap so I might just use stands. Or must I get over this? Is there no issue with overheating? (NB they are only 5" fairly budget monitors)
- Fibreglass:
Quote:
when you say "703 equivalent", what exactly are you talking about?
It’s called Energylite 47.5 kg/m3 semi-rigid (GFR others have tried to find and failed) I actually bought 75 batts of 50mm (enough to cover all walls and ceiling with 50mm) as the price was going to go up on 1st of Feb. I also bought fluffy Aerolite, 50mm for the gap between inner and outer walls & some 100mm to cut up for 4 corner superchunks.
- Green Glue/drywall: Yes – GG is easily the largest thing in my cost spreadsheet. Compound is $15/m2 here (for standard 2 tubes per board cover) and 12mm drywall is $3/m2 and $8/m2 for 15mm “soundblock”. On my new budget, to glue or not to glue (I know it’s not actually glue)? And is the “soundblock” worth the money?
- Sealant: on my budget do I still spring for Green Glue sealant or is cheaper stuff fine?
- Outer walls:
Quote:
You will also need to seal the brick walls
– when I said they were brick, I should have said all four sides are external house walls of two layers of brick for total depth of 28cm & plastered & painted on both sides, do I still need this?
- Loft: do I do anything here on my budget apart from beef up the hatch door? Is it worth lining it with fluffy 100mm?
- Hat channels:
Quote:
I'm pretty sure you can get normal hat channel in the RSA
Let’s say I can find these, where would I use them? I had thought with a room-within-a-room that the walls were de-coupled already.
- Room background noise: yes sorry I wasn’t in C mode before. Measures average 61dBC background noise. Is 30 a realistic aim for ambient noise? I don’t need to keep drums in or anything, I just need to keep most of the dog and car noise out.
- Extra Wall:
Quote:
Would it be better to still have an extra stud wall at the entrance end? If you forgot to include that one as part of your "room-in-a-room" isolation system for the complete studio, then yes!

I didn’t forget no, I just was doing a normal inner room within the current setup. To be clear I have attached two drawings of the two options. The extra wall does lose me some space, but will do it if you think it’s unrealistic for me to isolate the bathroom and entrance door.


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PostPosted: Sat Feb 04, 2017 2:42 pm 
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Location: Santiago, Chile
Quote:
Thank you Stuart so much for your reply and for your straight talking. You display endless patience with those like me who come new to this field.
Everybody is new to the field at some point! The patience gets a little thin at times, but I do remember that I was also a beginner once, and others were patient with me. Straight talk is the best kind, in my opinion. Waffling and beating about the bush and butterflies and rainbows won't help you get the studio built the best it can be! :)

Quote:
And good to know you were here in South Africa a while ago – which province?
It was called the Transvaal back then, and I lived in Springs, Nigel, and Hillbrow.... back at a time when it was possible to live in Hillbrow ! Not any more, from what I hear....

Quote:
I can go to at least $6500 for the building and a bit more for kit so will get an omni & give proper REW results. What best if I want to use mic afterwards to record, the ECM8000?
Excellent! Not the ECM-8000m but excellent that you can get a decent increase in the budget. The ECM-8000 is not terrible (I own one), but it's not the greatest either. They are prone to developing a fault in the grounding that leads to a huge amount of mains hum. I also have a Presonus PRM1 which I'm very happy with, and costs about the same as the ECM-8000. There's a few other good ones in the same price range, such as Nady, DBX, and a couple of others.

Quote:
The advice I was given on Gearslutz was that on a smaller budget with limited space, the best compromise is a single room & I’ve seen a few of the regulars there suggest that.
Well, a single room setup is possible, yes, but then you have to decide on what your priority is: Do you want to be able to mix accurately, precisely, cleanly, such that your mixes translate very well to other locations but not have tracks that sound really good? Or do you want to record great sounding vocals, guitars, drums, etc., but then not be able to mix them so well? It's a trade-off, and is your decision. If mixing great tracks that don't need much mastering is your number one priority, and you normally add a lot of effects, dynamics and EQ to all of your tracks anyway, then set it up as a control room, with optimum acoustics for mixing. But if capturing every nuance and subtlety of delicate instrumentals and breathy, moving vocals is your thing, with no real need to mix well, then set it up as a tracking room and do your final mixes elsewhere.

Or you could design and install devices that allow you to change the acoustics of the room, so that it can normally be set up for mixing (for example), but by flipping a few panels around you can make it sound much better for tracking (but worse for mixing).

Or you could do two rooms.

You do have options! It's your choice as to what your priorities are.

Quote:
But I am open to considering a 2 room setup if you push strongly.
You mentioned that you've done quite a bit of research already, so you are familiar with the concept of room modes and room ratios. Your available space is long and thin: I don't think you'll find any good ratios in the region around where your "single room" dimensions would be. Long narrow rooms don't have good ratios (with a few exceptions).

Quote:
it would be more like a vocal booth and a control room and I had read a lot about how vocal booths can sound boxy. I had planned on a couple of gobo's (see 3D pic).
Small vocal booths can sound boxy, yes. Bigger ones are better. It seems to me that you do have enough space to do both... barely!

But here's a curve ball: How about if you design the vocal booth such that it has a very large door facing the CR, and then you'll have the option of getting the best of both worlds! If you need a dry sound, close the door, but if you want more ambience, open it! And then when you need to mix, close the door again (in other words, tune the room so it is ideal for mixing with the vocal booth door closed).

That would give you the chance to eat your cake and have it too, so to speak.

Quote:
- Soffit speakers: I feel this may be a bit beyond my/my builders ability to do it right as well as making sure the corner is also a bass trap so I might just use stands
It's not that hard to build: the hard part is designing it! As long as your builders can measure and cut fairly accurately, and follow a plan, it doesn't need extreme carpentry skills. If you look around the forum, you'll see quite a few threads of people with very little building experience who have put together amazing studios, including soffit mounts.

The bass trap part is actually dead easy to do! It's the easiest part of the entire soffit! :)

Quote:
Is there no issue with overheating?
Nope! No issue at all. A good soffit design includes a broad air path up past the rear panel of the speaker, to carry away the heat.

Take a look at this thread: viewtopic.php?f=2&t=20471 Scroll down. Those are Eve SC-407's, soffit mounted. They consume something like 800 watts each, yet even after running the for hours at very high levels, they don't even get warm. We did some tests with an infrared temperature gun, and the air coming out the vent is just a couple of degrees warmer than ambient. The faces are the same temperature as the rest of the soffit around them. If the soffit is designed well, then there should not be an issue with heat.

Quote:
It’s called Energylite 47.5 kg/m3 semi-rigid
Do you have any acoustic test specs on that? A link to the lab reports, for example?

Quote:
GG is easily the largest thing in my cost spreadsheet. Compound is $15/m2 here (for standard 2 tubes per board cover)
As far as I recall, standard coverage is 3 tubes per 4x8 sheet. 2 tubes is reduced coverage, and 1 tube is minimum coverage. So figure out how many square meters of drywall you will need, total (walls and ceiling), and multiply by $22.50. Allow about 5% extra for wastage (you always mess up now and then....). Your ceiling alone is about 6m x 3m = 18m2 * 22.5 = $ 405. Your walls will cost around 800 to 900 additional, so a total of around $ 1200, just for the GG itself. That's more than one third of your original budget, and is still nearly 20% of your updated budget. Unless you need high isolation, or have a problem with low frequencies, then I would recommend skipping the GG. Much as I like it, and think it is a great product, your budget just does not allow for it, realistically. I'm not convince you need it, either.... :)

Quote:
and 12mm drywall is $3/m2 and $8/m2 for 15mm “soundblock”. ... is the “soundblock” worth the money?
That also comes back to the same question: How much isolation do you need? 15mm drywakk will get you better isolation than 12mm, but it certainly won't be three times as good! So it's hard to justify three times the price (or nearly three times). Three layers of 12mm would cost $9/m2 and be 36mm thick, while two layers of 15mm would be $12/m2 and be only 30mm thick... So 30% higher cost for 17% less mass.... :) Draw your conclusions from that!

Quote:
- Sealant: on my budget do I still spring for Green Glue sealant or is cheaper stuff fine?
I love GG compound, but I'm not so fired up about their sealant. It tends to shrink as it dries, and it can crack. A couple of the places I have designed that has happened, meaning that additional work and expense is involved in fixing that. Go with a good quality bathroom or kitchen caulk. Get the type that never hardens, and remains soft and rubbery, even when it is fully cured. I have had good success with Sika brand F11, but if you can't get that then pretty much any good quality bathroom/kitchen caulk will do the trick. Get one that sticks like crazy!.

Quote:
– when I said they were brick, I should have said all four sides are external house walls of two layers of brick for total depth of 28cm & plastered & painted on both sides, do I still need this?
If they are already plastered and painted, then no, you don't need to seal them. They are already very well sealed. I was going on the picture of the walls in your roof cavity, which is why I thought that you would need to seal. But you don't need to.

Quote:
- Loft: do I do anything here on my budget apart from beef up the hatch door? Is it worth lining it with fluffy 100mm?
Yes! If there is no insulation up there already, then yes, it makes a lot of sense to put some in, for both acoustic and thermal reasons.

Quote:
Let’s say I can find these, where would I use them? I had thought with a room-within-a-room that the walls were de-coupled already.
It's an alternative method, useful on tight budgets where very high isolation is not needed. But you won't be able to do that, as you have brick walls at present, not stud walls, so there would be nothing to attach them to! SO you are right: Just go with a stud frame set about 2cm away from the existing wall, and put a couple of layers of drywall on that. Or if you want to go "inside out", then set it up so that the final distance from the existing wall surface across the cavity to the drywall on the inner-leaf, is about 10cm or so (15 wound be better, but I don't think you can afford the lost width).

Quote:
Measures average 61dBC background noise.
That's pretty loud! But then again, townships can be pretty loud places... :)

Quote:
Measures average 61dBC background noise. Is 30 a realistic aim for ambient noise? I don’t need to keep drums in or anything, I just need to keep most of the dog and car noise out.
With your existing brick wall, plus two layers of 12mm drywall on a 10cm air gap filled with insulation, you should be getting in excess of 50 dB, heading towards 60, with a bit of luck. That's very decent isolation. However, that does assume that you do the doors, windows, HVAC, and electrical to the same level...

Quote:
I didn’t forget no, I just was doing a normal inner room within the current setup.
I think you did, yes! :) Without that wall, your bathroom and lobby are inside your wall cavity.... You do need the wall.

It would be a lot better if you start doing your design in SketchUp! It makes a lot more sense like that....

I just noticed that you seem to be showing your inner-leaf walls as being 20cm thick... I'm wondering why so much? 2x4 studs measure 89mm. Two layers of 12mm drywall is 24mm. Total=113mm. Where does the extra 87mm come from? I doubt that you need that much, so unless there's a really good reason for the extra-thick walls, just build them normally. Use 115 as the thickness (allowing for minor variations in materials), plus 20mm for the spacing away from the brick wall, and the final surface of your inner-leaf should end up at around 135mm from the existing wall surface. That gives you a fair bit more width inside the room.

You also need to work on getting your geometry correct, for the speaker/listening relationship! :)


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PostPosted: Thu Feb 09, 2017 6:51 pm 
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Location: Manenberg, Cape Town, South Africa
Quote:
It was called the Transvaal back then, and I lived in Springs, Nigel, and Hillbrow.... back at a time when it was possible to live in Hillbrow ! Not any more, from what I hear.…
Ha – that’s like me saying I can’t do HVAC! People say that about Manenberg too. We have friends who have chosen to live in Hillbrow, we visited them a couple of years back. To be fair they have come close to death, but that is the cost of contributing to the healing of these communities.

Quote:
Well, a single room setup is possible, yes, but then you have to decide on what your priority is: Do you want to be able to mix accurately, precisely, cleanly, such that your mixes translate very well to other locations but not have tracks that sound really good? Or do you want to record great sounding vocals, guitars, drums, etc., but then not be able to mix them so well? It's a trade-off, and is your decision. If mixing great tracks that don't need much mastering is your number one priority, and you normally add a lot of effects, dynamics and EQ to all of your tracks anyway, then set it up as a control room, with optimum acoustics for mixing. But if capturing every nuance and subtlety of delicate instrumentals and breathy, moving vocals is your thing, with no real need to mix well, then set it up as a tracking room and do your final mixes elsewhere.

Or you could do two rooms.
This is a toughy and I need a bit more time on it. I saw from your build thread that you went with two rooms – how did that work out for you? The room modes (see below) might push me in that direction.

Quote:
Or you could design and install devices that allow you to change the acoustics of the room, so that it can normally be set up for mixing (for example), but by flipping a few panels around you can make it sound much better for tracking (but worse for mixing).
I saw a thread where John did this with curved "doors" for the absorbers – very clever. Will have a think about it.

Quote:
You mentioned that you've done quite a bit of research already, so you are familiar with the concept of room modes and room ratios. Your available space is long and thin: I don't think you'll find any good ratios in the region around where your "single room" dimensions would be. Long narrow rooms don't have good ratios (with a few exceptions).
I hadn’t done enough research! I have now taken the time to collate info relevant to me on room sizes into one spreadsheet (attached). I did the calculations based on 2cm or 5cm gap from brick wall to drywall inner leaf (see discussion below - maybe I need 10cm gap?) I've just realised I didn't include the 2.4cm of drywall into the calcs so I will re-do it all, but will wait til I hear from you about the best gap (see below). All of the good ratios within my grasp give a range of 3.5m – 4m for my room length, much shorter than I had. Perhaps this pushes me towards a smallish booth plus control room setup? One big question is whether it's worth lowering the ceiling to get a good room ratio?

Quote:
But here's a curve ball: How about if you design the vocal booth such that it has a very large door facing the CR, and then you'll have the option of getting the best of both worlds! If you need a dry sound, close the door, but if you want more ambience, open it! And then when you need to mix, close the door again (in other words, tune the room so it is ideal for mixing with the vocal booth door closed).
Very interesting idea. I need to find the time to learn SketchUp and work it all out. I did at least find a few skp files on the forum to work from including some John posted. The thing I maybe haven’t mentioned yet is that the control room will double as an edit suite and will need sometimes to have clients come and see a video and so sofa/chairs need to fit somewhere, as well as a TV on the wall. But I suppose control rooms have this requirement anyway?

Quote:
Soffit speakers: I feel this may be a bit beyond my/my builders ability to do it right as well as making sure the corner is also a bass trap so I might just use stands
It's not that hard to build: the hard part is designing it! As long as your builders can measure and cut fairly accurately, and follow a plan, it doesn't need extreme carpentry skills. If you look around the forum, you'll see quite a few threads of people with very little building experience who have put together amazing studios, including soffit mounts.
A good soffit design includes a broad air path up past the rear panel of the speaker, to carry away the heat.
I would like to get this to work if possible. I haven’t fully understood the designs yet but I am working on it. With an air flow design, presumably the speaker box is not airtight? And is it a requirement to be able to drop the bass 6dB? My speakers only have one switch on the back which is HF +-1.5dB. Can it be done in the Monitoring FX bus with EQ? Or is it hardware only?

Quote:
Energylite 47.5 kg/m3 semi-rigid
Do you have any acoustic test specs on that? A link to the lab reports, for example?
No I haven’t found any useful test data yet. The website data sheets aren’t much use (http://www.isover.co.za/products/energylite), except giving an NRC of 0.95 for the 50mm which is similar to 703. Apparently there was a lab called SABS that used to test GFR but it closed.

Quote:
I would recommend skipping the GG.
OK

Quote:
12mm drywall is $3/m2 and $8/m2 for 15mm “soundblock”. ... is the “soundblock” worth the money?
That also comes back to the same question: How much isolation do you need? 15mm drywakk will get you better isolation than 12mm, but it certainly won't be three times as good! So it's hard to justify three times the price (or nearly three times). Three layers of 12mm would cost $9/m2 and be 36mm thick, while two layers of 15mm would be $12/m2 and be only 30mm thick... So 30% higher cost for 17% less mass....  Draw your conclusions from that!
I suppose there is a small chance that the soundblock is special layered drywall like Quietrock, but I doubt it. I will try to find some time to check.

Quote:
Go with a good quality bathroom or kitchen caulk. Get the type that never hardens, and remains soft and rubbery, even when it is fully cured.
OK

Quote:
If they are already plastered and painted, then no, you don't need to seal them.
Great.

Quote:
Loft: do I do anything here on my budget apart from beef up the hatch door? Is it worth lining it with fluffy 100mm?
Yes! If there is no insulation up there already, then yes, it makes a lot of sense to put some in, for both acoustic and thermal reasons.
OK will do.

Quote:
Just go with a stud frame set about 2cm away from the existing wall, and put a couple of layers of drywall on that. Or if you want to go "inside out", then set it up so that the final distance from the existing wall surface across the cavity to the drywall on the inner-leaf, is about 10cm or so (15 wound be better, but I don't think you can afford the lost width).

I just noticed that you seem to be showing your inner-leaf walls as being 20cm thick... I'm wondering why so much? 2x4 studs measure 89mm. Two layers of 12mm drywall is 24mm. Total=113mm. Where does the extra 87mm come from? I doubt that you need that much, so unless there's a really good reason for the extra-thick walls, just build them normally. Use 115 as the thickness (allowing for minor variations in materials), plus 20mm for the spacing away from the brick wall, and the final surface of your inner-leaf should end up at around 135mm from the existing wall surface. That gives you a fair bit more width inside the room.
I had taken the 20cm from John’s diagram (http://johnlsayers.com/Recmanual/Pages/Walls.htm) but as I had drawn it as one whole wall it is confusing. I am going to try to find the time to learn SketchUp and do it properly. But I am a bit confused now about inside out walls – are you saying the drywall is 2cm or 10cm from the brick wall? And given I could only find 50mm insulation, and that you don’t want it too squashed, don’t I need about 5cm gap filled with insulation?

In that diagram that the drywall plus insuation is pictured almost touching the wall. I was thinking to do: Brick wall>50mm insulation>2 x 12mm drywall (24mm) > 2x4 stud (89mm) for total of 163mm. All of this affects the calculations around room modes so I’d love to understand this part.


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PostPosted: Sun Feb 26, 2017 5:57 pm 
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Location: Manenberg, Cape Town, South Africa
Major setback - my office was broken into and my computer and camera equipment and some audio equipment was taken. Not insured or backed up. And I had nearly completed my sketchup file which took ages.

Another update is that I decided in the end to keep a small single bedroom at the back for hospitality and just have one control room (which will be my video editing suite most of the time anyway - I also do my own sound mixes so it will help with that). So the idea is to tune it as well as possible as a control room, but also use it in the short term to record vocals. Then seek funds to build a separate studio that is located more centrally in the community.

As I work again on the sketchup file, if you have time, can you help me with a few outstanding questions which affect how I make it:

- I see from research of other posts that you do normally recommend a 10cm "air" gap between my brick wall and the drywall of the inside out walls. What I've understood is that this lowers the resonant frequency of the M-A-M system to an acceptable degree. I had allowed only 5cm gap in my original design partly to save budget on the insulation, but also to keep as much width as possible in the room. What do you think about me giving 10cm at ends and ceiling, but only 5cm on the width (room is only 3.00m wide to start with)? And what about having 5cm of insulation and 5cm of air in the gap?

- I am strongly considering keeping natural daylight which I understand has cost issues. I think I understand that if building a normal wall you go with 2 leaf. What I don't understand is how 2/3/4 leaf relates to trying to keep natural light when building a room within a room. So if I have a single pane window in the brick wall, and I want a window in the inner wall next to it, do I leave the single pane and also do only a single sheet in the inner wall (in order to be 2 leaf) or do I make both the windows double glazed?

- I read somewhere that a double door system, well sealed, could make a vacuum in between the doors so that you might not be able to get out of your room! Is this ever something you need to plan to avoid?

- It seems to me that there is a clash between trying to have an ideal room shape to minimize modes and the haas thing of wanting the back wall far enough back to not get reflections <20ms from the back. And also with just trying to have a decent sized room to host a few people in. Am I fine to not worry too much about hitting a great ratio, as long as it's not a really bad one? I think I had H:W:L as 2.57m:2.85m:4.10m (1:1.11:1.60) in my plan, which is much longer than ideal, but would suit me much better in having more space.

Will post my sketchup as soon as I can.


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PostPosted: Fri Mar 03, 2017 1:31 am 
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Location: Manenberg, Cape Town, South Africa
My build has started!

Sketchup file here: https://www.dropbox.com/s/bnilphhow383232/Nick%20Studio%20WIP.zip?dl=0 - just can't get it quite right, but hopefully it helps. It certainly helped me no end in deciding where the doors had to go (as this affected the house too)

We have decided to keep the back as a small ensuite single bedroom.

I got a great deal on two panes of glass (8mm and 10mm laminate) so I have taken out my normal window (I need it for another flat anyway) and I will treat the front window exactly as a control room to live room window, just instead of watching a drummer, I am watching the main road!

The electrician is preparing wires and ducting that can feed into the inner leaf and in all cases I will have a gap in the duct and wrap it in neoprene (or duct tape if I can't find any). A/C guy is going to make sure copper curves round for 2m before exiting. I was going to take out one of the glass bricks to get the in duct and a/c tubes as there is a hole already.

Room is not a great ratio:
H W L
255 275 402
1: 1.08: 1.58
28.2m3 = 990 cu feet

It's not too late for me to lower the ceiling height or make it less long if that is important, but otherwise I'd rather keep the volume as large as possible to work in.

HVAC calcs (ref thread: http://johnlsayers.com/phpBB2/viewtopic.php?f=2&t=18726)
Going for a 6 times / hour refresh so 99 cfm (168m3/h)
and a max flow rate of 300 fpm, so duct area = 1/3 sq foot = 48 sq in ~ 7"*7" or 18cm*18cm
plus duct liner of 2.5cm makes 23cm sq internal path
plus wood/osb of 1.5cm makes my silencers 26cm*59cm*100cm - one fitted externally with fan bringing in air near to a/c unit with fan and passive exhaust into house (big open living room / kitchen). Is it fine to have these boxes sitting outside the house?

Only thing I've found mentioned loads of times, but never answered is static pressure so I'll play safe and get a fan rated for a bit higher than 99cfm.

Soffits - still need to work out if I can handle the needed 6dB bass reduction. Only have HF +-1.5dB on speaker. Am hoping I can use the monitoring FX in my DAW and EQ it? Would that be the same as a hardware EQ?


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PostPosted: Sat Mar 04, 2017 5:51 am 
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Knocking through the door into our sitting room.


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PostPosted: Sat Mar 04, 2017 6:24 am 
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Whoaaa! Is that wall load-bearing? The wall where you just chopped out a huge chunk? Does it support something up above, or provide sheer strength to other parts of the house along it's length? Did you check that? If it is load-bearing, then you should immediately insert a lintel across the top of the hole, extending out sideways a certain distance either way. Your structural engineer will tell you what size / type of lintel, and how far it needs to extend.

If you are absolutely certain that the wall is not load-bearing, or structural in any way, then ignore the above... :)


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PostPosted: Sat Mar 04, 2017 6:35 am 
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My man assures me it's not, but I think probably a lintel would be safer you're right. I get the impression that things are a bit more relaxed round here (probably not a good thing when it comes to bearing loads)!

Did you get a chance to see my sketchup file and Q's above?


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PostPosted: Tue Mar 07, 2017 2:35 am 
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Some pics - as noted in the picture notes, I now think it might be a mistake to leave a gap in this part of the outer wall for a silencer - the wall will be not very massive here, though I will double the drywall - could triple - plus it would have the 5/8 OSB, maybe enough?. Or perhaps I should have both silencers externally on the other wall or is that also a no-no to have inlet and exhaust on the same side of the room?


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PostPosted: Tue Mar 07, 2017 6:51 am 
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No Fantech's or the like in South Africa. This fan I think is my best fit so far: http://www.xpelair.co.za/pdf/Xpelair%20Range%20XIM%20Mixed%20Flow.pdf - it is one of two in Xpelair's inline range (along with the XIDP100) that run quiet - 22dbA@3m - and has two speeds, 190 or 251 m3/h at zero pressure (I want about 170m3/h at whatever pressure i will have). Looking at the pdf, it is more clear to me now that static pressure is one of the things you need to know or at least estimate, as air flow is directly proportional. With this fan if my static pressure is much bigger than I think, I could run it on the higher speed, otherwise the lower speed will be fine. I will only have a few meters of duct so I can't imagine the pressure to be that high, though I haven't found a thread yet that explains this well. I imagine it's not just the ducting that builds pressure, but the fact that you're pumping air into a room and then letting it out through a small hole - i.e. the "friction" of the whole system.

Does anyone have an idea in Pascals, what the pressure is for a typical small control room?


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PostPosted: Wed Mar 08, 2017 3:06 am 
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Silencer pieces are cut. Foam sealing tape is for around the glass panes - not sure it's the best thing, but it's all I've found. One solid core door in place. And I decided to do one layer of bricks and leave a hole for the duct.


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PostPosted: Wed Mar 08, 2017 9:22 am 
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How exciting! Looking forward to your pictures of the inner leaf build and particularly your soffit mounted speakers. I'm a way behind you but have a similar room size....

Good luck with it!

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