Music studio in Berlin - Design phase - Build coming soon!

[timo6600]

Dear all,

Firstly, thanks to all who contribute here, have been obsessively reading and enjoying for some time.

Now the time has finally come to build my own studio. I have a studio elsewhere at present but plan to move to my basement as I have a lil one due in May (hooray!) hence the deadline!

Apologies if some of this post belongs in the construction forum - I plan to do a new post there once I start building.

So, the studio will be located in Berlin, as I mentioned in a basement space (called keller in German). Our apartment is immediately above and the space is accessed through a trapdoor.

studio5-_Page_2.jpg

space1.jpg

space2.jpg

The ceiling (floor above) appears to be made of some kind of concrete bricks, and I know from renovating the kitchen above, there are large wooden (and some metal) beams, cavities filled with some kind of rubble (building is from 1912) then thick pine floorboards above that.

The keller has a floor which appears to be concrete layer over more fine rubble with some areas which seem a bit hollow. I intend to fill these areas.

floor.jpg

The studio will be a control room for making electronic music with plenty of bass. At present I have Tannoy Reveal speakers (for soffit?), Genelec 1029a (will change to Adam F5 perhaps) and an Achat 12" subwoofer.

So here is my design so far:

studio5-_Page_1.jpg

studio5-_Page_4.jpg

studio5-_Page_5.jpg

A few questions:

1 – General design
a) – am I going to too much effort for a small space (ie taking up too much room) creating this internal geometry? Is there an easier/better/cheaper/faster way to do this?
b) – How can I make a door through the back? Would it be problematic to hinge the entire bass trap from towards the centre of the room?
c) – does soffit mounting really make sense in such a small space? If not, what would be in these corners – just bass traps I guess?
The areas aren't really deep enough for the speaker unless I offset them towards the outer walls. Should they normally be centred?
To be honest, this would be a perfect place for windows to the side windows in the keller.

2 – Materials

a) I am trying to use materials that have less of an environmental footprint. Whilst Gips is recycled well, there is no carbon uptake and the footprint to manufacture is huge. OSB board (particle board) has carbon uptake, uses about 1/10th of the carbon footprint to process and will be from FESC certified sustainable plantations. Does this have any bearing on sound proofing compared to GIPS? On the outer layers I will also add reclaimed laminate to add mass and change material density which I hope will help.

b) I intend to use short supply chain recycled fabric batting instead of rockwool.

Specs here:

PRICE_LIST_2015-2_pdf__page_2_of_3_.jpg

anyone see any problems?

As I understand recycled PVC insulation is no good due to closed cell structure?

3) Ceiling

So far I have just planned to use the same as the wall structure – one ceiling on the inner walls, and another ceiling on the outer walls – does this make sense or is there a better way to do this? The total height of the keller is 2480mm and I'm 198cm tall so really trying to save headroom here!

4) Floor

As this will be concrete below, what structure should I put on it? I had thought of using U-boats, beams and OSB plates on top. Would this be a good idea? Or is it a waste of money and I should just go direct onto the concrete? Or perhaps just a layer of insulation and then OSB on top? I suspect floating on a basement slab is a waste of time and money!

5) Walls

Any comments on the structure? I guess the walls should also sit on a rubber base?

6) Ventilation

So far I have planned to use PVC flexi tubing (with wire in), 10cm. I have yet to find a really good thread on simple ventilation (lots on HVAC).

As it is in the keller the temperature is quite constant so I'm not too worried about adding heat/cold. What I still struggle is with how to silence this hole. My plan was to have 2 x 10cm holes in the ceiling, back and front for in and out. Then 3m of tubing, wrapped in insulation. Then the fans.

I guess I would try to couple these with Rubber between the walls. And use a plenum or muffler like the one below

air.jpg

The space is around 20 cubic meters with a 'working' space around 17 I guess. The fan is 90 cubic meters per hour and 38db.

Any suggestions or comments?

Greatly appreciated - many thanks!
Tim

[Soundman2020]

Hi Tim, and welcome!

First thing I noticed is that "possible future wall - not in out control". If you have no control over whether or not that wall will appear, then you have a problem. If you build a 2-leaf wall just short of that location, and somebody then build another wall, you will have a 3-leaf or 4-leaf system, potentially reducing your isolation. (Yes, reducing: acoustics is not intuitive in many aspects, and this is one of them.

To compensate for that possible future situation, you will need to make your outer-leaf wall across that area very massive (very heavy), and leave a slightly larger air gap.

The trapdoor is also going to be a problem. That will be very hard to isolate. Can you block that off completely, and seal it up? It is also in the exact place where you are going to need bass trapping...

The keller has a floor which appears to be concrete layer over more fine rubble with some areas which seem a bit hollow. I intend to fill these areas.

If there are hollow areas, you need to break into those and find out why they are hollow, then fix any issues, and fill them with concrete back up to floor level.

So here is my design so far:

There are several problems with that layout, and they are mostly related to the geometry of the speakers and listening position. You need to get that correct first.

To start with, you are showing your mix position exactly in the middle of the room, 50% of the distance between the front wall and back wall. That is the worst possible position in the room! It is precisely where all the modal peaks and nulls will be at their maximum values. The correct location is about 33% to 38% of the distance from the front wall to the back wall.

You also show that the dimensions of the finished room make it square, and perhaps even a perfect cube! That is the worst possible shape for a room. With a cube, all of the modes in all three axial directions will line up perfectly, multiplying each other, and creating large gaps between each other in the modal spread. You should set the dimensions to be close to one of the known good ratios, or at least to be inside the Bolt area, in order to have reasonable modal response.

Also, you have your door in the corner of the room, which is a really bad place to put it, as that is where your bass traps need to go. Rather, put the door in the middle of the back wall.

You also seem to be creating some 3-leaf and maybe 4-leaf situations yourself, plus you are not making the most of the outer leaf that is already in place.

a) – am I going to too much effort for a small space (ie taking up too much room) creating this internal geometry?

Not at all! You are doing the right thing there. You do need to create an isolation system, and you do need to create symmetry for the room, so that is fine.

Is there an easier/better/cheaper/faster way to do this?

Your design can be improved, and maybe simplified a bit, but with studio building, there is no such things as "easy / cheap / fast" and also "good". You can choose only ONE of those...

b) – How can I make a door through the back?

Put it in the middle of the rear wall, not in the corner. Problem solved.

Would it be problematic to hinge the entire bass trap from towards the centre of the room?

Yes, that would be problematic.

c) – does soffit mounting really make sense in such a small space?

Absolutely! It makes sense anywhere. And the bottom of the soffit unit can still be used for bass trapping.

However, the soffit does have to be designed correctly for the room (yours isn't)...

The areas aren't really deep enough for the speaker unless I offset them towards the outer walls. Should they normally be centred?

The room must be symmetrical, so the soffits must be the same distance to the left and right of the center line that runs down the middle of the room. The soffits must be deep enough to fit your speakers in, and must be angled correctly to create the right geometry for the listening position, and they must be positioned correctly to minimize unwanted artifacts and to produce the cleanest sweet spot.

To be honest, this would be a perfect place for windows to the side windows in the keller.

You can still have a window in the middle, if you want, in between the soffits. Many studios do that.

a) I am trying to use materials that have less of an environmental footprint. Whilst Gips is recycled well, there is no carbon uptake and the footprint to manufacture is huge. OSB board (particle board) has carbon uptake, uses about 1/10th of the carbon footprint to process and will be from FESC certified sustainable plantations. Does this have any bearing on sound proofing compared to GIPS? On the outer layers

The density of drywall (gypsum board) is around 680 kg/m3. The density of MDF is around 750 kg/m3. So there is no problem with substituting MDF for drywall. It is harder to cut, of course, and more problematic to build with, but it's a good material for studios, and I use it a lot in my designs.

I will also add reclaimed laminate to add mass and change material density which I hope will help.

What is "reclaimed laminate"? Do you have a link to that?

You do not need to have materials of different densities in your wall: That's a myth. Yes, it does help slightly with impedance mismatch at the interface, but what you gain there, you lose from the lower mass of one of the panels! Just use two layers of MDF, if you need that much isolation.

b) I intend to use short supply chain recycled fabric batting instead of rockwool.

Do you know the Gas Flow Resistivity numbers for the specific product you plan to use? You can't just substitute anything! You need to use damping that has the correct characteristics. You need something with around 15,000 rayls.

anyone see any problems?

I would need to see the acoustic lab test reports for that product, in order to say if it is good or not for this application.

So far I have just planned to use the same as the wall structure – one ceiling on the inner walls, and another ceiling on the outer walls –

I'm not sure I understand: you already HAVE your outer leaf! It is the concrete ceiling (floor) above you: You only need to build your inner-leaf ceiling below that, and the inner leaf ceiling must rest only on the inner leaf walls, not touching the outer-leaf walls or ceiling at all.

The total height of the keller is 2480mm and I'm 198cm tall so really trying to save headroom here! Build your ceiling "inside-out", and make it very massive.

4) Floor
As this will be concrete below, what structure should I put on it?

Nothing! Concrete is about the best possible floor you can have in a studio.

I had thought of using U-boats, beams and OSB plates on top. Would this be a good idea?

It would be a terrible idea! A waste of time, money and headroom. You do NOT need to float your floor: that is another common myth. Here is why:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

I suspect floating on a basement slab is a waste of time and money!

Right!

If you don't like the look of the concrete, then just put some laminate flooring on top of it, on top of s suitable underlay. That will take up less than one cm of height, and give you a great floor.

Any comments on the structure? I guess the walls should also sit on a rubber base?

Why? Same reason as in the thread I linked to above for the floor. Yet another myth.

6) Ventilation
So far I have planned to use PVC flexi tubing (with wire in), 10cm. I have yet to find a really good thread on simple ventilation (lots on HVAC).

You won't find any threads on "really simple ventilation" for home studios, because there is no such thing! It does not exist. You DO need a good HVAC system. It does not need to be overly complex, but it does need to do the job.

As it is in the keller the temperature is quite constant so I'm not too worried about adding heat/cold

Your room will be extremely well insulated, thermally, and it will be extremely well sealed, hermetically. No air can get in or out. No heat can get in or out. But YOU will be inside, generating heat and humidity with your body, using up the oxygen in there, and generating CO2 plus many other gasses. See if you can imagine what will happen in there... Your equipment, instruments, computers, lighting and everything else in there will be generating heat too. The human body generates anywhere between about 100 watts and about 1000 watts, depending on how hard you are working.

In other words, there WILL be heat sources inside the room, and no way for the heat to get out... so you DO need cooling. You will also be producing humidity, so you do need dehumidification. And you will also be depleting the oxygen and increasing the O2. So you do need ventilation. You have no choice: if you build a well isolated studio, you DO, absolutely, and without any doubt, need HVAC.

Some people think "Well, I'll just open the door then, when I'm not mixing". Nope. That won't work either. Air needs a reason to move (difference in pressure), and a path to move. Opening the door does neither of those. You would have to put two fans in the doorway, one pointing in the, other pointing out, to make air circulate.

What I still struggle is with how to silence this hole.

You build silencer boxes, of the correct internal dimensions. Like these:

http://www.johnlsayers.com/phpBB2/viewt ... 0&start=45
http://www.johnlsayers.com/phpBB2/viewt ... 9&start=74
http://www.johnlsayers.com/phpBB2/viewt ... 25&start=2
http://www.johnlsayers.com/phpBB2/viewt ... 42&start=5
http://www.johnlsayers.com/phpBB2/viewt ... 61&start=0
http://www.johnlsayers.com/phpBB2/viewt ... 5&start=98
http://www.johnlsayers.com/phpBB2/viewt ... &start=157
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=13821
http://www.johnlsayers.com/phpBB2/viewt ... 8&start=44
http://www.johnlsayers.com/phpBB2/viewt ... 2&start=16

My plan was to have 2 x 10cm holes in the ceiling, back and front for in and out. Then 3m of tubing, wrapped in insulation. Then the fans.

Nope. Bad idea.... You MUST do it right... assuming that you like to breath and stay alive inside your room! And also stay comfortable. And also have good isolation.

The space is around 20 cubic meters with a 'working' space around 17 I guess. The fan is 90 cubic meters per hour and 38db.

The recommended exhcange rate is at least 6 room changes per hour, preferably 8. So you would need at least 120 m3/hr, and preferably 160 m3/Hr.
HOWEVER! The nominal fan capacity is for free field capacity, meaning with no ducts attached. It will move a lot LESS air than that in a real situation, because of the resistance imposed by the ducts, the silencers, and the room itself. This is called "static pressure". The documentation for the fan should show how much air it can move for each static pressure: You will have to calculate the static pressure for your system, then find a fan that can produce the correct amount of airflow at the correct speed for that static pressure.

BUT!.... consider that trying to push 120 m3/Hr through a duct that has a cross sectional area of 0.03 m2, means that the air will be flowing at a speed of 4,000 m/hr, which is 1.1 m/s. That is higher than the ideal rate of 0.5 m/s, so you will need larger registers, and expansion adapters.

Any suggestions or comments?

All of the above, to start with. Those are the big issues. There are several other less important issues that we can deal with as your design progresses.

- Stuart -

[timo6600]

Hi Tim, and welcome!

I can't count the number of posts I've read from you and I've learned so much from your posts - great that you've joined here – thanks so much!

First thing I noticed is that "possible future wall - not in out control". If you have no control over whether or not that wall will appear, then you have a problem. If you build a 2-leaf wall just short of that location, and somebody then build another wall, you will have a 3-leaf or 4-leaf system, potentially reducing your isolation. (Yes, reducing: acoustics is not intuitive in many aspects, and this is one of them.

To compensate for that possible future situation, you will need to make your outer-leaf wall across that area very massive (very heavy), and leave a slightly larger air gap.

So does this mean only reinforcing this wall with extra layers/more mass? And is this something I could do later when/if this occurs (as it seems unlikely to be for a long time yet).

The trapdoor is also going to be a problem. That will be very hard to isolate. Can you block that off completely, and seal it up? It is also in the exact place where you are going to need bass trapping...

Unfortunately that is where the stairs will go to access it from the apartment. I should say, my main aim here is to isolated the sound within the control room, not in the keller. There are so many areas which noise could leak out into the surrounds, hence my two leaf system, hoping to keep as much isolated within the built structure. For example:

The windows to street level (there is a grill above a void) is exposed to weather and near impossible to isolate without modifying the outer building (which I am not allowed to do – it's an old apartment block).

The current bordering wall to the 'north' (upper) is built from wooden slats and goes through to one of the neighbouring kellers. Their space is also very not-air-tight! I had planned to build a thin dividing wall over thee slats there to stop dust etc coming from their side.

The door to the keller hallway will also be hard to isolate – and I'm not sure I see the point there as it just goes to other keller areas that are surrounded by supporting walls. I will likely just put a chunk of wood over it and a medieval style wooden bar over it

There are several problems with that layout, and they are mostly related to the geometry of the speakers and listening position. You need to get that correct first.

Totally, this is where I'm having difficulty.

To start with, you are showing your mix position exactly in the middle of the room, 50% of the distance between the front wall and back wall. That is the worst possible position in the room! It is precisely where all the modal peaks and nulls will be at their maximum values. The correct location is about 33% to 38% of the distance from the front wall to the back wall.

Ah yes, forgot that slightly basic and fundamental rule -- but when I was designing, not sure what to change to affect them. For example, the normal listening triangle should be equilateral, right?

So either I end up with something like this which has no space to soffit mount my speakers:

alt1.jpg

Or I throw away the equilateral triangle and end up with something like this:

alt2_not30.jpg

Both of these options use a lot more space and have their downsides in terms of speaker geometry, no?

You also show that the dimensions of the finished room make it square, and perhaps even a perfect cube! That is the worst possible shape for a room. With a cube, all of the modes in all three axial directions will line up perfectly, multiplying each other, and creating large gaps between each other in the modal spread. You should set the dimensions to be close to one of the known good ratios, or at least to be inside the Bolt area, in order to have reasonable modal response.

I'm also aware of this and know the Bolt system too. I managed to get it just on the edge of the bolt zone with one of my designs – I was loosely basing this design around this image:

Control Rool.gif

which I think was from SAE manual (Sayers)??? Could be wrong. But used this as a guide as I can see no other way except to have an (almost) square room. If I had more space to play with then yes, but I need to maximize space which leads to this annoying cube thing! The 33-38% rule you mentioned – how does this work here? Is that because it's the REAR 33-38%? And if so, my original design also conforms to that:

studio_original-no-nearfields.jpg

Also, you have your door in the corner of the room, which is a really bad place to put it, as that is where your bass traps need to go. Rather, put the door in the middle of the back wall.

Of course! Great idea! (slaps head)

You also seem to be creating some 3-leaf and maybe 4-leaf situations yourself, plus you are not making the most of the outer leaf that is already in place.

As mentioned the space may change a little, but until it does, the rest of the space will be used for storage of the normal type that people use kellers for . So again, I'm trying to keep that room just a room instead of an extensive part of the treatment.

Your design can be improved, and maybe simplified a bit, but with studio building, there is no such things as "easy / cheap / fast" and also "good". You can choose only ONE of those...

Hahah I've seen you write that so many times – still makes me chuckle I don't know why I even tried it

However, the soffit does have to be designed correctly for the room (yours isn't)...

so what would you suggest?

The room must be symmetrical, so the soffits must be the same distance to the left and right of the center line that runs down the middle of the room. The soffits must be deep enough to fit your speakers in, and must be angled correctly to create the right geometry for the listening position, and they must be positioned correctly to minimize unwanted artifacts and to produce the cleanest sweet spot.

Right I get all that – but I'm struggling to make the soffit corner angles and the depth, whilst giving the optimal listening position. Stupid cube!

You can still have a window in the middle, if you want, in between the soffits. Many studios do that.

sure, assuming the soffits don't take up all that space.

The density of drywall (gypsum board) is around 680 kg/m3. The density of MDF is around 750 kg/m3. So there is no problem with substituting MDF for drywall. It is harder to cut, of course, and more problematic to build with, but it's a good material for studios, and I use it a lot in my designs.

actually OSB is more like chip board – like this: http://bit.ly/1Jr8IkE

What is "reclaimed laminate"? Do you have a link to that?

just means synthetic laminate pull up from someone's house – pretty heavy stuff tho!

You do not need to have materials of different densities in your wall: That's a myth. Yes, it does help slightly with impedance mismatch at the interface, but what you gain there, you lose from the lower mass of one of the panels! Just use two layers of MDF, if you need that much isolation.

yeh I think the point was to use as much post-consumer / postbuilding site materials as possible, rather than new ones for everything (obviously the inner layers of the outer leaves would be new – I don't want it to be a crazy bricolage with loads of gaps etc).

b) I intend to use short supply chain recycled fabric batting instead of rockwool.

Do you know the Gas Flow Resistivity numbers for the specific product you plan to use? You can't just substitute anything! You need to use damping that has the correct characteristics. You need something with around 15,000 rayls.

This I'm not sure about – I have asked the manufacturer about this - will get back to you.

So far I have just planned to use the same as the wall structure – one ceiling on the inner walls, and another ceiling on the outer walls –

I'm not sure I understand: you already HAVE your outer leaf! It is the concrete ceiling (floor) above you: You only need to build your inner-leaf ceiling below that, and the inner leaf ceiling must rest only on the inner leaf walls, not touching the outer-leaf walls or ceiling at all.

The total height of the keller is 2480mm and I'm 198cm tall so really trying to save headroom here! Build your ceiling "inside-out", and make it very massive. [/quote]

So you mean one single leaf (perhaps 2 layers OSB/GIPS with wooden beams then insulated?). Like this?:

ceiling layers.jpg

In other words, there WILL be heat sources inside the room, and no way for the heat to get out... so you DO need cooling. You will also be producing humidity, so you do need dehumidification. And you will also be depleting the oxygen and increasing the O2. So you do need ventilation. You have no choice: if you build a well isolated studio, you DO, absolutely, and without any doubt, need HVAC.

I think the point there is that I wanted to draw the air from the main keller space into the studio itself. The main keller space is ventilated just thruough it's not-airtight nature and is always relatively cool and dry… would that not be the best analogue HVAC you could use if you could draw that air into the control room?

You build silencer boxes, of the correct internal dimensions. Like these:

great thanks for the links – sometimes the search function is pretty hard in this forum when people just mention something in passing...

You MUST do it right... assuming that you like to breath and stay alive inside your room! And also stay comfortable. And also have good isolation.

OK definitely more research needed here on my part!

Stuart, thanks so much! This has given me a lot more to think about – I think my main issue is the geometry! I can't get my head around it – your feedback is invaluable, thanks again! In the end, if there is absolutely know way around it, will have to eat into the stairwell zone a little - but not much room to play there. I'm wondering how modifications to the various leaves might affect the shape..

Tim

[timo6600]

Just thought I would add this image showing the actual usable area.

usablearea.jpg

I'm kind of digesting the feedback and realising the whole multileaf problem here - but having a lot of trouble identifing how to deal with it. For example the 'south' bottom wall here can act as the second leaf as it is so close. The other walls are so far away, I don't really understand how they react - should I just build a three sided 'outer' leaf, that attaches to the massive south wall? This very loose sketch shows the 30cm perimeter where the double wall would go.

The other three walls are not really airtight, and are far away so I'm really wondering how to deal with this :/

Oh and then of course there's the geometry

I decided to extend it into the stairwell zone by 30cm. That puts my in the 1:1.34:1.54 ratio (just about almost close to Bolt )

I think my eyeballs are going to fall out after all that reading...

- edit -

I'm editing this as I think I read somewhere that adding posts puts you further down the list and it's been kind of lonely around here

Anyway I've modified the design (obviously some bits missing like insulation in parts etc, just want to get the geomatery and leafing right)

- removal of one leaf at the bottom of the picture
- soffit cavity one leaf removed (needs insulation/timber detailing)
- 38% triangulation on both monitors (I read that 38% to rear wall is ok too...)
- room dimensions changed to be in Bolt area
- Slot resonator insulation (this doesn't count as a leaf right? Because it's not airtight?)
- Door in middle of design (Thanks Stuart!)

studio5edit.jpg

- 2nd edit -

So now I'm just having a look at the side view and the relationship of the leaves with ceiling and speakers

sidewsoffit.JPG

Shown here is the ceiling of the inner leaf, a gap and then the insulated original ceiling of the space. My question here is pretty short. If the Soffits are in between the inner and second leaf, how does this get isolated? I mean the rest of the room inside has two leaves between it an the outside world. The speakers kind of sit in the middle of those leaves... or is it the case that because the speakers are part of the first leaf with a thick shell that joins the first leaf, then insulated heavily behind (not pictured here), it is considered 'inside' this inner leaf? What about the gap for heating issues recommended in most soffit design? Doesn't that then leak sound into the middle cavity?

Does this structure look right so far?

And please! some feedback about the multileaf situation with the outside room as outlined above would be invaluable!!!

Thankyou!

[timo6600]

Sorry for the bump but going to start building 1st March and want to sort out as much as possible!

[Soundman2020]

I can't count the number of posts I've read from you and I've learned so much from your posts - great that you've joined here – thanks so much!

Sorry to be a bit slow on replying to yours, but times are busy right now! Got quite a few projects on the go...

So does this mean only reinforcing this wall with extra layers/more mass? And is this something I could do later when/if this occurs (as it seems unlikely to be for a long time yet).

It works like this: low frequency isolation (and therefore the overal isolation of the wall for the entire spectrum) depends mainly on something called MSM resonance. That stands for Mass-Sprin-Mass, where the two "masses" are the leaves on either side of the central "spring", which is the air trapped between them. That is a resonant system, and it isolates terribly at the resonant frequency. It can, in fact, amplify tones around that frequency, passing them through even stronger than no wall at all! But above 1.4 times that frequency, an amazing thing happens: you get BETTER isolation than can be obtained in any other way. So this is the ideal type of wall to have for a studio, provided that you can get the MSM resonant frequency down low enough, below the audible range, such that the wall isolates for the entire spectrum. You "tune" the resonant frequency of a wall by adjusting the mass on each leaf (how heavy it is) and the depth of the air gap between the leaves. More mass = lower frequency = better isolation. Bigger gap = lower frequency = better isolation.

That much is easy to grasp. But problems can arise if you add another leaf close by, with an additional air gap. That is an "MSMSM" system: two air gaps and three masses. The math is rather more complex, but it turns out that such a wall will have a HIGHER resonant frequency than the equivalent 2-leaf wall. Not intuitive, but resonance is a strange thing... it can tear bridges apart, and it can trash your isolation too. In fact, there are multiple resonances going in in 3-leaf wall, but even the lowest one is still higher than it would have been for the equivalent 2-leaf system.

So that's the issue here: if someone comes along after the fact, and builds another wall next to your beautiful 2-leaf isolation wall, they could potentially harm the isolation of your wall, making it worse. to remedy that, you would need to add mass to your wall, a I already mentioned: The problem is that you need to add it to the MIDDLE leaf for it to have the most effect. And of course, if somebody builds a wall there, you won't have any access to that middle leaf any more! You can add mass to your third leaf as well, but it isn't as effective: you need more mass than you would have needed on the middle leaf. However, in order to add mass to your third leaf (which is the interior wall of your studio!), you would have to take apart your entire room... You would also be making the room smaller than it was (by the thickness of whatever mass you need to add), which might potentially have other repercussions, such as altering the modal response of your room, changing first reflection locations, etc.

So that's the issue. If there's a real possibility that the "unknown" wall will appear, then it would pay you to just add the extra mass on your outer leaf now, even though you don't need it. That outer leaf would then become the "middle" leaf, if the person does build that wall, and you won't need to do anything. For the cost of a few sheets of drywall, I think that is very cheap insurance!

my main aim here is to isolated the sound within the control room, not in the keller.

OK, that makes sense.

Ah yes, forgot that slightly basic and fundamental rule -- but when I was designing, not sure what to change to affect them. For example, the normal listening triangle should be equilateral, right?

Wwwwellll..... Yes... sort of... It needs to be a triangle, of course, and it needs to be symmetric, but in reality the "equilateral" part isn't so necessary: Most studio designers that I know change that as needed, adapting it to the room conditions, and also to a simple fact: Our ears are on the SIDES or our heads, not on the front! Most diagrams you see for the "equilateral triangle" thing, show the apex of the triangle in the middle of the mix engineer's head... which would work great, if his ears were located where his eyes are! But in reality, our ears are off to the side, so the triangle needs to be broader, and the apex of the triangle needs to be behind your head, not in the middle of your head. In addition to that, you can make the sweet spot wider and smoother by moving the speaker axes even further out, a few cm away from the ears: that allows you to move your head from side to side without losing good balance, and without losing the stereo image. And finally, many mix engineers prefer to have there heads a bit forward of where theory says it should be, because they say it sounds better there (probably because of the above reasons...). So in general, the tendency in modern studios is to widen the triangle a bit, with slightly smaller angles (it does not have to be 30°!).

So either I end up with something like this which has no space to soffit mount my speakers:

Actually, there IS space to soffit-mount there! You only need to adjust the geometry correctly...

I'm also aware of this and know the Bolt system too. I managed to get it just on the edge of the bolt zone with one of my designs

Excellent! That is good news.

I was loosely basing this design around this image: ... which I think was from SAE manual (Sayers)??? Could be wrong. The 33-38% rule you mentioned – how does this work here? Is that because it's the REAR 33-38%?

Yes, that is one of John's designs... but no it is not in the rear 38! Take a careful look, and you will see that he is doing exactly what I said above: the acoustic axes of the speakers meet in the middle of the room, yes... but that is many cm behind the engineer's head! The "head" is about where it should be, at about 38% of the room depth (front 38%)... (don't forget that the speaker soffits change the average depth of the room... ) So that's exactly what I'm talking about: designers tend to do that today, because it works better than the "theory" of the equilateral triangle with the apex at your head.

so what would you suggest?

Use John's basic design for soffits, and adapt it as necessary to fit your room. You might need to adjust the angles and locations go get it right, but that's what studio design is all about: compromise. You'll often have to change one thing to make another thing better, so it's a matter of deciding on priorities, and choosing which things are most important, then modifying other things to optimize those.

Right I get all that – but I'm struggling to make the soffit corner angles and the depth, whilst giving the optimal listening position.

Yep! That's what studio designers do! We struggle to make things fit, tweaking and adjusting dozens of times, .... Welcome to the club!

sure, assuming the soffits don't take up all that space.

There are ways of dealing with soffits to make that happen.... the front edge of the soffit does not necessarily need to go all the way to the front wall: you can chop it off a bit, if you need to, so you can get a reasonable size window in there...

actually OSB is more like chip board – like this

Yes, that is OSB, and the density is lower than both: it is more like 610 kg/m3, so you will need to make it thicker to get the same mass.

So you mean one single leaf (perhaps 2 layers OSB/GIPS with wooden beams then insulated?). Like this?:

Yes! That's correct. The name for those beams is "joists", and they must rest ONLY on your new inner-leaf walls: they do not touch the existing walls or ceiling at any point. You will also need to select the correct size for those, as the will be supporting the load of the drywall (which is heavy). They need to be bigger than the studs that you use to make the walls frames. There are tables for figuring out how big they need to be.

I think the point there is that I wanted to draw the air from the main keller space into the studio itself. The main keller space is ventilated just thruough it's not-airtight nature and is always relatively cool and dry… would that not be the best analogue HVAC you could use if you could draw that air into the control room?

As long as the keller is not a "living space" where people are present all the time, then that might be OK. But you still need some place to send your exhaust air: you can't send it back to the kellar! It needs to go outside the building...

Just thought I would add this image showing the actual usable area.

I think you can move the front wall closer to the windows. There's no need for such a big gap there. You can gain several cm of space like that for inside the control room.

For example the 'south' bottom wall here can act as the second leaf as it is so close. The other walls are so far away, I don't really understand how they react - should I just build a three sided 'outer' leaf, that attaches to the massive south wall? This very loose sketch shows the 30cm perimeter where the double wall would go.

For that wall, you don't need to add anything at all! That wall IS your outer leaf, for that side of the studio. The other three sides of your outer leaf will connect to that, and you do not need to add a forth wall there on the outer leaf. As long as you prepare that surface properly, that will make an excellent "fourth wall". And it saves you money, because you don't have to buy the materials to build that wall...

Anyway I've modified the design (obviously some bits missing like insulation in parts etc, just want to get the geomatery and leafing right)

You are on the right track, yes. That's much better! And you have fitted in your soffits, too!

Wellllll, you have almost fitted them in: you do need to enclose the other two sides of the triangular area behind them, in order to complete the inner-leaf. But apart from that, you are doing well with the soffits.

However, there's an issue with your geometry, and with your speaker choices. which are your main monitors, that you use for all of your mixing? The Tannoys, or the Genelecs? If it is the Tannoys, then they need to be the ones that are aiming at the mix position, with the Genelecs sett off to one side or the other, on stands. But if the mains are your Genelecs, then they should be soffit mounted, and the Tannoys should be on stands!

Either way, the most important speakers, the ones that you use all the time for all your critical mixing, are the ones that must be in the soffits. The secondary speakers, that you just use occasionally for "checking the mix" can go anywhere, really. Just set them up on stands in such a way that they don't interfere with mains.

So once you decide on which ones are your mains, in the soffits, set up the geometry so that they are aiming at the phantom point about 20 to 30 cm behind your head. Adjust the angle of the soffit face, and the position of the speakers in the face, to make that work.

The speakers should NOT be in the exact middle of the soffit, as that tends to create "beaming" and "lobing". Offset the speakers to one side or other of the center of the soffit. Make sure that there is a different distance to from the acoustic center of the speaker to each of the four edges of the soffit front panel ("baffle"). A good location is to center the speaker about 3/5 of the width of the soffit, roughly.

And the speakers need to be aimed for the FRONT 38%, not the rear one.

do yourself a favor, and create a sphere to represent your head, in your model. Put that at the mix position, at about 35% of the room depth (roughly!) and aim your speakers so that the axis lines go past the outside of your ears, missing your ears by a few cm, and aiming for that imaginary point about 20-30cm behind your ears. Adjust the speaker angles to make that happen. The speakers should be about 28% of the room width away from the side walls, roughly. Play around with all of those parameters until you make it work, then post the result here so I can take a look at it.

I would also suggest modifying your side slot walls: create a short more steeply angled solid section at the front, where it meets the soffit, and angel that so that all the reflections from BOTH speakers, are sent past your head, well away from it. Then make the rest of that into a slot wall, starting roughly at the mix position.

If the Soffits are in between the inner and second leaf, how does this get isolated?

By completing the other two sides around the back of the speaker!

- Stuart -

[timo6600]

Hi Stuart, Thanks so much for catalysing my ideas - incubation lab full steam!

Took me a while to digest this and then redesign but great food for thought so thanks!

So that's the issue. If there's a real possibility that the "unknown" wall will appear, then it would pay you to just add the extra mass on your outer leaf now, even though you don't need it. That outer leaf would then become the "middle" leaf, if the person does build that wall, and you won't need to do anything. For the cost of a few sheets of drywall, I think that is very cheap insurance!

Right! Understood - this is good advice, and for sure I will take it!

Wellllll, you have almost fitted them in: you do need to enclose the other two sides of the triangular area behind them, in order to complete the inner-leaf. But apart from that, you are doing well with the soffits.

However, there's an issue with your geometry, and with your speaker choices. which are your main monitors, that you use for all of your mixing? The Tannoys, or the Genelecs? If it is the Tannoys, then they need to be the ones that are aiming at the mix position, with the Genelecs sett off to one side or the other, on stands. But if the mains are your Genelecs, then they should be soffit mounted, and the Tannoys should be on stands!

I've decided to use the Tannoy's as mains for now. They may get changed in the future. But the Genelecs are a little underpowered and (to be honest) a bit abused. I swear I didn't doit

So here is a new design:

2 variants.jpg

Obviously this is asymmetric - I am providing two alternatives for design to show two possible variations (I'll call them 'upper' and 'lower'). Thing is, I'm really confused by the angled wall before slots you suggested - doesn't this create a three leaf scenario? Or should this angle merge with the soffit wall? Or should there be a dividing wall?!?!

And if the slots start at the mix position then they end up small, unless i lower the angle of the wall (on the upper example) to extend it further. Either way, these slots would have a not very large depth cavity behind so doesn't this defeat the point?

And why should the front section of this wall (before mix position) be solid, instead of slots? Is that because slots also diffuse so could cause early reflections?

BTW I am unable to gain extra space towards the windows as I need to access these windows. I need to clean them out - they have grills that go onto the street. When we were clearing out the space they looked like this:

windowtrash.jpg

Now they look like this:

windowclean.jpg

Fortunately, this is a long time of neglect - I found a newspaper about 3/4 down the trash from 1993!

But yes I still need to clean them out occasionally hence the gap!



Thanks!
Tim

[timo6600]

OK so here is an update - I had to change the room dimensions (smaller- grrr - I won't go into why).

So how does this look?

6.1skp.jpg

6.1.jpg

Please say it's great.

So I if this is looking ok would like to start filling in some details in particular starting with the things mentioned in the last post (where is the divider between soffit/solid angle bit/ 3 leaf system and how they interact)

Any clues?

Thankyou!
Tim

[Soundman2020]

I had to change the room dimensions (smaller- grrr - I won't go into why).

That's a pity! But it can still work...

So how does this look?

Much, much better! I think you can still save a bit more space on the side walls by not taking them so far back in the room, and also by increasing the angle of the small angled divider wall, as well as moving it out a bit (a bit too close to the speaker), but apart from that, it's looking good!

(where is the divider between soffit/solid angle bit/ 3 leaf system and how they interact)

Yup!

Think of this: You need to maximize room volume now, so anything you can do to your side walls / angled divider walls to achieve that, would be good. You could maybe even completely get rid of the side sections, and leave on the divider section, made as small as possible, and angled more, and move further out along the soffit face...

You are definitely on the right track now, and advancing in the right direction.

- Stuart -

[timo6600]

Hey Stuart,

Much, much better! I think you can still save a bit more space on the side walls by not taking them so far back in the room, and also by increasing the angle of the small angled divider wall, as well as moving it out a bit (a bit too close to the speaker), but apart from that, it's looking good!

Yay thanks! So how's this:

studio7.jpg

studio7ray.jpg

(where is the divider between soffit/solid angle bit/ 3 leaf system and how they interact)

So what I actually meant here was questions about this:

soffit details.jpg

1) Should the soffit wall continue to the inner leaf wall or should that cavity be part of the solid wall section?
2) Doesn't the solid wall section create a 3 leaf?
3) Should there be a wall between the solid section and the slots? So the solid section is a cavity filled with insulation?
4) Is it not a problem that the walls toward the rear of the studio are parallel?
5) Should these walls be treated somehow or just raw chipboard (painted obvs.)?
6) In the ray trace diagram you can see I've removed the basstrap lines - I'm assuming they will absorb reflections, so I don't have to worry about reflections back towards the mix position, right?

Think of this: You need to maximize room volume now, so anything you can do to your side walls / angled divider walls to achieve that, would be good. You could maybe even completely get rid of the side sections, and leave on the divider section, made as small as possible, and angled more, and move further out along the soffit face...

Definitely a good idea to move those angles!

Thanks again, so great to have your input!
Tim

[Soundman2020]

1) Should the soffit wall continue to the inner leaf wall or should that cavity be part of the solid wall section?

A better way to do it:

soffit details-2b.jpg

2) Doesn't the solid wall section create a 3 leaf?

To a certain extent, yes, but it is nothing to worry about, if you do it correctly.

4) Is it not a problem that the walls toward the rear of the studio are parallel?

No, not at all. That's a myth. Parallel walls can potentially produce flutter echo, but that is easy to treat. Parallel walls can produce modal standing waves, but you'd get those anyway, unless you steeply angle the walls. So just leave the, parallel (maximizing room volume), then treat as needed for whatever problem happens to arise.

5) Should these walls be treated somehow or just raw chipboard (painted obvs.)?

You can do whatever you want to the front surface. Many people use good quality wood with nice grain for the final, surface. Some use concrete, stone, or even glass. That's more of an aesthetic call than an acoustic call.

However, you will need your front panel to be much thicker than that. They need to be substantially massive. At the very least, two layers of 5/8" MDF.

- Stuart -

[timo6600]

A better way to do it:

wow that's much more simple. I like that! Thanks!

2) Doesn't the solid wall section create a 3 leaf?

To a certain extent, yes, but it is nothing to worry about, if you do it correctly.

oh good to know.... wait a minute! 'do it correctly'?? Exactly what do you mean by that?

Parallel walls can potentially produce flutter echo, but that is easy to treat. Parallel walls can produce modal standing waves, but you'd get those anyway, unless you steeply angle the walls. So just leave the, parallel (maximizing room volume), then treat as needed for whatever problem happens to arise.

so is the best way to proceed to build the main structures as in my previous designs and measure it - then decide what to do with the parallel walls?

However, you will need your front panel to be much thicker than that. They need to be substantially massive. At the very least, two layers of 5/8" MDF.

OK great, have modified! So now here's a few options for the soffit build - which is better?

soffitreara.jpg

or

soffitrearb.jpg

Of course all sections will be insulated, just so you can see it.

Which variation is best in this case? I'm guessing the first one so that the bass trap section is discrete (as the solid section should remain solid?)

And another question (braces self for barrage of 'you can't do that')

In order to fit in the soffit mounted speakers, I want to (ahem) gently modify the tannoys. Here is their structure:

tannoy3d.jpg

So the question is, I want to chop the back of the speaker off up to where the amplification section wall is, thus creating this:

tannoy3dmod.jpg

Now I know that is a bit naughty and could change the speaker dynamics, but the tannoys have a lot of dip switches for correcting frequencies, and also the soffits change the dynamics anyway right? Is what I'm doing a disaster or will I get away with it?

I would have to remove the amplification section anyway for external control in the main room...

Here is the Tannoy options:

tannoydips.jpg

Thanks again Stuart, your input is invaluable!

[Soundman2020]

so is the best way to proceed to build the main structures as in my previous designs and measure it - then decide what to do with the parallel walls?

Yep. That's always the best plan: as soon as the room shell itself is complete (walls, floor, ceiling, doors, windows, HVAC, electrical, etc.) but BEFORE any treatment goes in, do a complete test with REW. That's your baseline acoustic data. You compare all future tests against that, to see how well each device is working, what isn't working, and what still needs to be done at each stage.

OK great, have modified! So now here's a few options for the soffit build - which is better?

Either of those is fine, but the first one is better structurally, and easier to build. You also need to consider your framing, though. And the front baffle probably needs to be built up from at least two layers of MDF.

And another question (braces self for barrage of 'you can't do that')

"you can't do that"!

I want to (ahem) gently modify the tannoys.

Ummmm... that's just a little more than a "gentle modification"! That's a major ripping destruction and rabid mangle!

In other words, I would mildly suggest that you probably should refrain from proceeding in that direction.

That would completely re-tune your speakers, and cause who-knows-what artifacts. The drivers, amps and cross-overs are all carefully designed to work against the original interior pressures and resonances inside the box. By doing such a major change, you would be causing a situation that the designer never foresaw, and the results would be unforseen too. The ONLY mod you could safely do is to remove the amp section from the back, and add wiring extensions so you can position it outside the soffit for easy adjustment, but even then you'd need to fill the cavity where the amp was with insulation, and put a new blank panel on, to replace the rear panel you removed.

But you cannot cut down the box, or change the interior cavity volume or dimensions.

The other thing you will need to do, is to put some low density insulation in the reflex port. We'll get to that when the time comes...

Now I know that is a bit naughty

You seem to be a Master of the Understatement!

and could change the speaker dynamics, but the tannoys have a lot of dip switches for correcting frequencies,

My car engine has a lot of controls for adjusting its performance, but I think if I replaced the transmission in my car with the gearbox from a Mack truck, and used rocket fuel instead of gasoline, they perhaps might not be quite enough to compensate ....

and also the soffits change the dynamics anyway right?

... and THAT is what the controls are for! The manufacturer figured you might want to place the speaker in any of several acoustic environments, so he provided controls for adapting to that, but he never figured you'd want to rip the guts out of your speaker, shred the body, then use chewing gum and paper clips to hold the remaining bits together!

All of the controls are for compensating for acoustic situations OUTSIDE the box. None of them are useful for compensating for munging and mangling the innards.

I would have to remove the amplification section anyway for external control in the main room...

... Which is why the manufacturer made his speakers in such a way that you can do that, without destroying the properties of the entire speaker....

Here is the Tannoy options:

Which one of those controls do you think will change the Thiele-Small parameters of the drivers to compensate for the different acoustic loading of your butchered, mutilated and lacerated cabinet? ...

http://www.eminence.com/support/underst ... aker-data/

- Stuart -

[timo6600]

Hi Stuart,

Yep. That's always the best plan: as soon as the room shell itself is complete (walls, floor, ceiling, doors, windows, HVAC, electrical, etc.) but BEFORE any treatment goes in, do a complete test with REW. That's your baseline acoustic data. You compare all future tests against that, to see how well each device is working, what isn't working, and what still needs to be done at each stage.

OK well time to start building then! (after I've levelled the floor with self levelling concrete)

Ummmm... that's just a little more than a "gentle modification"! That's a major ripping destruction and rabid mangle!

In other words, I would mildly suggest that you probably should refrain from proceeding in that direction.

I will consider taking your subtle hints on board. (you can't do that #2)

But you cannot cut down the box, or change the interior cavity volume or dimensions.

(you can't do that #3)

The other thing you will need to do, is to put some low density insulation in the reflex port. We'll get to that when the time comes...

ooh! (scribbles in notebook) thanks!

My car engine has a lot of controls for adjusting its performance, but I think if I replaced the transmission in my car with the gearbox from a Mack truck, and used rocket fuel instead of gasoline, they perhaps might not be quite enough to compensate ....

Ever seen Mad Max? Hm. OK maybe not the best outcomes involved for everyone, point taken (obtuse you can't do that number... oh hell with it..)

... and THAT is what the controls are for! The manufacturer figured you might want to place the speaker in any of several acoustic environments, so he provided controls for adapting to that, but he never figured you'd want to rip the guts out of your speaker, shred the body, then use chewing gum and paper clips to hold the remaining bits together!

hey hey! easy now!

All of the controls are for compensating for acoustic situations OUTSIDE the box. None of them are useful for compensating for munging and mangling the innards.

ooh! that hurt!

Which one of those controls do you think will change the Thiele-Small parameters of the drivers to compensate for the different acoustic loading of your butchered, mutilated and lacerated cabinet? ...

OK ok i get it! I can't seem to find the butchered mutilated lacerated munging mangling of innards shredded disembowled chewing gum paper clip DIP switch. So my next question, why didn't they include that?

Phewph. Now that I've weathered that barrage, I'll just humbly add that 8.5cm back into the design and take it back to the drawing board (puts me out of the sweet spot into almost 50% crossover zone ;(...)

But wait! I think now I have some pretty good templates, and rather firm instructions on how to not disrespect my (ahem) beautiful Tannoy's. Not to mention a MUCH better understanding of the design thanks to you!! So I will just get on with it and build the two walls, HVAC and Window and see the actual as built dimensions.... and measure the room to offer it like a bleeting baby goat to sacrifice to the gods of the audio forum

Well y'know, at the end of the day, I thought I probably wouldn't get away with that one. But I just had to check, y'know? Would have made the design much nicer! But probably the audio awful, so thanks again for your firm guiding words

Great stuff

Thanks again!!!

[timo6600]

Just as a side note, as this will be in build mode, should I start on the Construction forum or just continue my design questions here?

Thanks!