John Sayers' Recording Studio Design Forum Archive

Hi there!

I’m Cal, an amateur drum & bass producer from Sydney, Australia. I’ve just moved into a new rental house which has a space that I can use exclusively as a studio (finally my bedroom will be a bedroom again!).

Since I want to do this right, I’ve been trawling this amazing forum for a solid few weeks, searching high and low for information about DIY sound proofing / isolation and sound treatment for the amateur home studio. I’ve learnt so much and I’m so grateful that this resource exists, but I still have many questions about my individual project and so, I was hoping you (all) might be able to help me.

NB: I’ve tried really hard to adhere to the forum rules; but this is my maiden post and my knowledge is still very basic, so I apologise in advance if this post isn’t up to scratch. Also, questions have been clearly marked in the post but grouped in a paragraph near the end… as requested. For example, you will see a "(Question 1)" in the post, but the actual Question 1 is grouped with all the others near the bottom. But please feel free to comment on anything else that sticks out to you along the way as well.

Here goes...

Project status: Research finished. Provisional plan made. Products sourced and quotes taken. Nothing purchased. Hoping to receive feedback from this forum before going any further.

Goals: 1. Construct DIY bass traps 2. Construct DIY acoustic panels 3. Construct a "temporary wall” to fill make the space a room 4. With these things, create a workable studio space suitable for an amateur electronic producer. A room that might not be perfect, but is a marked improvement on a space that was left untreated. 5. Construct DIY speaker stands 6. Achieve optimum room set-up / orientation for this particular space.

Budget: As close to AU$1000 as possible. Cannot go over AU$2000.

Rule 5: "how loud are you? how quiet do you need to be?” I sincerely apologise for lack of detail here but I do not currently have access to a decibel meter. (I intend to get one asap) I have 2 x 5" Focal CMS 50 monitors so I don’t hear a lot of low end but they certainly still pack a punch. I don’t need to be concerned about my neighbours or my housemates because neither will be home during the times I am producing.

Room / space details:

Residence type: rental house
Location of room: second floor (of 3)
Materials: walls = bricks / cement, roof = plasterboard, floor = wooden floor boards + approx. 20cm cement underneath, skirting boards = wooden (apologies for the brevity of info here - I have very limited knowledge of building products)

Room / Space Dimensions: (please see below diagram)
Wall A: Length - 2560mm / Height - 2420mm / Width - 140mm
Wall B: Length - 2880mm / Height - 2420mm / Width - 140mm (assumed)
Wall C: Length - 2560mm / Height - 2420mm / Width - 140mm
Absent Wall D: Length - 2880mm / Height - 2420mm / Width - n/a (150mm proposed)

Railing to Wall E: 1250m
Railing to Wall F: 1120mm
Railing to Wall G: 900mm

Skirting Boards: Width - 20mm / Height - 70mm
Roof Vent: 240mm x 240mm
Wall A to stairs: 700mm
Wall B to stairs: 700m
Linen cupboard: 550mm x 600mm
Bed 1 Built in: 570mm x 1640mm
Bed 2 Built in: 710mm x 1770mm

Room / Space description: the studio space has 3 existing walls (A, B, C). What would be the 4th wall opposite wall B (i.e. “D”) is absent. This means the space is open and one with the stairs space (which leads upstairs to the 3rd floor and downstairs to the kitchen / living area). I know missing walls are bad news (common sense and research have told me this) but apart from that missing wall, and the fact that the proposed space is pretty small, it’s symmetrical (the only symmetrical or appropriate space in the house) and I’m praying that with the construction of a "temporary wall” I could make this work.

Proposals:
- DIY Bass Traps
- Number: 4 in total
- Type: basic rock wool absorber
- Rock wool slab dimensions: 600mm x 1200mm x 50mm
- Rock wool Density: 60Kg/m3 (more dense than I want but this is the lowest my supplier stocks) (Question 1)
- Bass Trap dimensions: 100mm deep x 600mm wide x 2400mm high (i.e. 2 x slabs thick, 2 x slabs high)
- Frame: Pine, 2 x (19mm x 100mm x 2400mm) + 2 x (19mm x 100mm x 600mm) (Question 2)
- Covering: polyester material front and back
- Stand: 4 x L-shaped metal shelf bracket screwed into frame (see diagram) (Question 3)
- Air gap: space between back of trap and corner
- Placement: diagonally across corners
- 2 existing vertical corners, 2 other vertical corners created by proposed temporary wall and existing walls

- DIY Acoustic Panels:
- Number: 6 in total
- Type: basic rock wool absorber
- Rock wool slab dimensions: 600mm x 1200mm x 50mm
- Rock wool Density: 80Kg/m3 (Question 4)
- Acoustic panel dimensions: 50mm deep x 600mm wide x 2400mm high (i.e. 1 x slabs thick, 2 x slabs high) (Question 5)
- Frame: Pine, 2 x (19mm x 50mm x 2400mm) + 2 x (19mm x 50mm x 600mm)
- Covering: polyester material front and back
- Stand: 4 x L-shaped metal shelf bracket screwed into frame (see diagram)
- Air gap: 10-15cm (created by shelf bracket stands) (Question 6)
- Placement: parallel to corresponding wall (Please refer to below diagram)
- 2 on front wall behind speakers
- 2 on back wall aligned with the 2 on the front wall
- 1 on each lateral side’s first reflection point

DIY cloud panel:
- Number: 1
- Type: basic rock wool absorber
- Rock wool slab dimensions: 600mm x 1200mm x 50mm
- Rock wool Density: 80Kg/m3
- Bass Trap dimensions: 50mm deep x 1200mm wide x 1200mm high (i.e. 1 x slabs thick, 2 x slabs wide)
- Frame: Pine, 4 x (19mm x 50mm x 1200mm)
- Covering: polyester material front and back
- Stand: n/a, drill hooks into the roof + drill hooks into the frame and connect them with fishing line so the cloud hangs (Question 7)
- Air gap: 5-10cm
- Placement: roof, directly above the listeners head

DIY Temporary Wall:
- Ok, here I’m really at a loss as to what I should do. This is what I’m thinking:
- Purpose: 1. serve as 4th wall to make the space a room 2. keep as much noise out / keep as much noise in as possible (i.e. isolation)
- Description:
- The temporary wall will be made out of 2 identical parts
- Both parts will meet in the middle to form one temporary wall.
- They will open and shut like double doors (obviously won’t work as well as doors, but it should work…)
- Materials: i.e. what is needed to make 1 of 2 parts, (see complimentary diagrams)
- Frist leaf: 2 x Gyprock layers (10mm x 1420mm x 2400mm each) stuck together with ??? (Question 8.A)
- Frame: Pine, 2 x (1380mm high x 19mm thick x 100mm deep) + 2 x (2400mm high x 19mm thick x 100mm deep) (Question 8.B & Question 8.C)
- Rock wool: 60Kg/m3 x 50mm thick in the space between frame (Question 9)
- Rubber: 2400mm high x 5mm thick x 140mm deep stapled on sides of temporary wall panels to seal the gap between wall and temporary wall panel AND seal the gap in the middle of the temporary wall panels
- Selley’s “No more gaps”: to fill gaps between gyprock sheets
- Metal handle: super-glued onto the front side of the temporary wall panel, towards the middle
- Resilient Sound Isolation Clips (RSICs) + hat channels: to decouple the first leaf and the frame (Question 10.A & Question 10.B)
- Polyester: to cover back of wall (i.e. to leave open, as suggested in my reading of this forum)
- How will they stay standing upright?
- The lateral pressure pushing each part of the wall together should hold them upright (Question 11)
(Question 12.A and 12.B)
- How will I get in and out?
- The idea is that the temporary wall, divided in the middle, will be able to open and close like a double door. I know it won’t be smooth and gracious like an actual door, but it should be functional enough for me to get in and out of the studio when I need to. (Please see diagrams below)

- Other ideas for temporary wall structures: (Question 13)
Sealed, hollow Gyprock wall filled with sand
Loose double brick wall. Floor to ceiling, wall to wall.
Loose cinder block wall. Floor to ceiling, wall to wall.
PVC Pipe pillars, filled with sand. Floor to ceiling, wall to wall.
*** No temporary wall at all *** - this was suggested my production mentor who has over 15 years experience. He said the advantage of leaving it open would be that the space would become less cube-like and there’d be less issues with standing waves between front and back wall. Thoughts?

DIY Monitor Stands:
- 2 x PVC plastic plumbers pipe: 200mm diameter x 1100 high (to make the acoustic axis about 1200mm high)
- 4 x PVC plastic pipe caps: to fit on top of pipe
- dry sand: enough to fill each pipe
- 2x Polyester cloth to cover pipes

For the rest of this post, please assume that the proposed temporary wall is constructed and in place.

Room orientation:
- I’m intending to make wall B the front wall, temporary wall (“D”) the back wall and A + C being the sides. (Question 14)

Monitor Placement:
- Each monitor on it’s own stand, 28% of the length of wall B away from it’s nearest side wall. i.e. approx. 805mm (Question15)

Listener Placement:
- In the middle of the monitors, about the same distance from the front wall as the speakers are apart.

Monitor Angle: 30 degrees turned in towards the listener

Floor coverings:
- Currently wooden floor boards. I was going to put a rug or 2 down but after reading on this forum, it seems that carpet and rugs are a bad idea for studios (Question 16)

Air Flow:
- Will be minimal and the room will get hot and stuffy...I know, but I will have a relatively quiet little fan under my desk to keep me cool. My previous production room was basically a sauna so I’m sure I will cope.

Other:
- There is a small 200m x 200m vent in the roof (Question 17)

(Question 18)

Questions:

- Question 1: From my readings, I know there’s an optimum density but generally speaking, less dense is better for lower frequencies. Will 60Kg/m3 be ok for the bass traps or do I really need a lower density?
- Question 2: Is pine a good wood for the frames? is there a better material to use? is the thickness ok?
- Question 3: Are there any issues with the shelf bracket stands?
- Question 4: From my readings, higher density rock wool is better for mid and higher range frequencies. But 80Kg/m3 costs more than 60Kg/m3. Is it worth buying 80Kg/m3 slabs for the acoustic panels? Is there a better density?
- Question 5: is 50mm thickness for acoustic panels ok? would you recommend any thinner / thicker?
- Question 6: is the 10-15cm air gap for acoustic panels ok? too small? too big?
- Question 7: Do you think this method of hanging the cloud would work? Considering that I am living in a rental house and can’t really make changes to the house (e.g. drill holes) without permission, can you provide any recommendations on other ways I might position the cloud? is a cloud panel even an essential feature in this situation?
- Question 8.A: is it worth forking out the $$$ to use green glue between the 2 gyprock layers? or best to use standard industrial adhesive?
- Question 8.B: please refer to the diagram “Front View (No Gyprock)”. You’ll see that there are 3 air spaces between the vertical parts of the wooden frame. These will be filled with rock wool. The width of the 3 spaces will be 600mm, 140mm and 600m respectively. Wood it be better to make them all more even?
- Question 8.C: I intend to position the horizontal parts of the frame at random heights. Is this OK? Or should they positioned specific heights?
- Question 9: is 60Kg/m3 the correct density to fill the space in a wall? or would 80Kg/m3 be better? Can the rock wool in the wall touch the gyprock or should there be an air gap?
- Question 10.A: can you recommend anywhere that supplies these in Sydney, Australia?
- Question 10.B: is there a specific distance the clips should be spaced from each other?
- Question 11: Would this be enough to keep the wall upright? Or would I need to attach shelf brackets like the bass traps?
- Question 12.A: From my reading of this forum, I’ve learnt that air tight seals are vital for good isolation. So I know that this design for the temporary wall leaves a gap 40mm air gap at the top between the wall and the ceiling, thus compromising the isolation. But will this temporary wall, even with the 40mm gap do a good enough job at turning this space into a room where a lot of the sound is kept in or kept out?
- Question 12.B: Again from reading this forum, I’ve learnt that to achieve decent isolation, you need to address all for walls not just one (the one wall of a fish tank analogy sticks out in my mind). But I was hoping that, because the other walls are cement / brick and should already have decent isolation for my purpose, the only “Wall” requiring attention (or in this case, construction) would be the absent wall “D”?
- Question 13: would any of these alternative ideas work better than the current wall with insulation?
- Question 14: would it be best to face this way or the opposite way? If I had 4 walls made out of the same stuff, I would face either wall A or C because that would make the front - back length longer than the side - side width (which I’ve read is preferable?)
- Question 15: how far away from the front wall should the monitors be? I couldn’t seem to find anything on this in my research.
- Question 16: should I leave the floor as it is without covering because there’s enough absorption on the walls? or would it be better to put a rug down?
- Question 17: will I need to cover this up with something? if so, what would you recommend?
- Question 18: is there anything that I have overlooked and need to consider? (I’m sure there is…)

I know you guys say “the more detail, the better” but I do really think my post might be a bit excessive here. If this, my very first post, is in fact too detailed, or not detailed enough, or if some key information is missing, I once again apologise and thank you for your patience.

I really look forward to hearing from this wonderful community soon. Any help, advice and feedback will be received with great appreciation.

Cheers,
Cal

Hi Cal, and Welcome!

Great first post, by the way! I wish more people would read the rules and post like you did!

this is my maiden post and my knowledge is still very basic, so I apologise in advance if this post isn’t up to scratch.

Youa re doing better than fine.

I do not currently have access to a decibel meter. (I intend to get one asap)

Let us know once you have measured the actual levels.

Location of room: second floor (of 3)

Not so good... if you need lots of isolation. But that doesn't seem to be the case here.

it’s symmetrical

Good!

Cloud ... Placement: roof, directly above the listeners head

It needs to go further forward than that. It should be centered between the speakers and the mix position, more or less over the desk, or even a bit further forward.

DIY Temporary Wall:
- Ok, here I’m really at a loss as to what I should do. This is what I’m thinking:

I'm not convinced that you need that wall. You say you don't have problems with isolation, your levels are acceptable to those around you, etc., and placing that "wall" would make an already very small room even smaller... I'd suggest setting up your gear and basic treatment first, running a few tests to see how you are doing, then taking the decision on that "wall that is not a wall".

- How will they stay standing upright?
- The lateral pressure pushing each part of the wall together should hold them upright

Ummm... I'mnot so sure about that...

- How will I get in and out?
- The idea is that the temporary wall, divided in the middle, will be able to open and close like a double door. I know it won’t be smooth and gracious like an actual door, but it should be functional enough for me to get in and out of the studio when I need to

.... and I'm even less sure about that! Each of those is going to weigh around 100 kg. Are you SURE you can push a very large and very unstable, top-heavy block of mass that weighs 100 kg across your floor? I don't think so...

*** No temporary wall at all *** - this was suggested my production mentor who has over 15 years experience. He said the advantage of leaving it open would be that the space would become less cube-like and there’d be less issues with standing waves between front and back wall. Thoughts?

I'm inclined to agree with your friend (although I don't agree that it will necessarily reduce your modal problems. It MIGHT, but then again, it might not... a lot depends on doing the actual modal analysis, to see which is better. I'm guessing that the "no wall" option would probably be better here, but I'd have to do the math to be sure.

Monitor Placement:

Your diagram shows them in the wrong place. They need to go tight up against the front wall, not close to the desk. Separate them from the wall just enough to get your absorber panels in there. 28% from side walls is about right.

Listener Placement:
- In the middle of the monitors, about the same distance from the front wall as the speakers are apart.

No. Your mix position will need to go about 38% of the distance between the front wall and the back wall, whatever that turns out to be. That's the theoretical best location, although I find that normally there's a better spot a few forward of that position. So set your chair there, for the next part....

Monitor Angle: 30 degrees turned in towards the listener

Not necessarily. That's a theoretical construct, but it's just a starting point, and isn't the best anyway. With your speakers at the 28% position (from side walls) and your imaginary head at 35% from the front wall, angle the speakers inwards until they are both pointing at the same spot, about 30cm behind your head. That should place the acoustic axes of your speakers grazing past your ears, a few cm away. That might or might not end up with your speakers at 30°. Probably not, but don't sweat it: that's the best setup for the widest sweet spot, in most rooms.

Floor coverings:
- Currently wooden floor boards

Perfect! Do nothing. If you find the room to be excessively "bright" once you have done everything else, as a last resort consider putting down a small throw rug under your chair.

Air Flow:
- Will be minimal and the room will get hot and stuffy...I know, but I will have a relatively quiet little fan under my desk to keep me cool. My previous production room was basically a sauna so I’m sure I will cope.

Mmmmmm.... not such a good idea... This is another reason why you might want to forget about the fake wall. Mixing while you are physically uncomfortable is not a good thing.

- There is a small 200m x 200m vent in the roof

Use it!

- Question 1: From my readings, I know there’s an optimum density but generally speaking, less dense is better for lower frequencies. Will 60Kg/m3 be ok for the bass traps or do I really need a lower density?

That's fine. A bit lighter would be better, but you are still OK with that. Another option would be to switch to fiberglass, around 30 kg/m3, or a bit lighter.

- Question 2: Is pine a good wood for the frames? is there a better material to use? is the thickness ok?

The frames are only there to hold the insulation in place, and to look nice. Make them from whatever you want. And cut big holes in them, to increase the area of insulation that is exposed to the room.

- Question 3: Are there any issues with the shelf bracket stands?

Yes: Stability. Those things are not meant for that application. Just hang your panels on the walls.

- Question 4: From my readings, higher density rock wool is better for mid and higher range frequencies. But 80Kg/m3 costs more than 60Kg/m3. Is it worth buying 80Kg/m3 slabs for the acoustic panels?

Believe me, you will NOT need more absorption in the mids and highs! By the time you have enough bass trapping in that room, you'll be begging to get your mids and highs back again, because they will all be GONE! It is often necessary to put pastic in front of your bass traps to prevent them from sucking up too much of the high end.... So the answer is no, it is NOT a good idea to buy heavier insulation.

- Question 5: is 50mm thickness for acoustic panels ok? would you recommend any thinner / thicker?

For your first reflection points, I would go with at least 100mm, and more if you can spare the space.

- Question 6: is the 10-15cm air gap for acoustic panels ok? too small? too big?

It's fine, but once again more is better. The bigger the air gap, the lower down your traps reach (in frequency).

- Question 7: Do you think this method of hanging the cloud would work?

Yes, but use chain, not fishing line. That's a heavy thing, and you do NOT want it falling on your head! Use chain that can handle ten times the weight of the cloud: That's the normal rule of thumb for rigging. Also, use eye-hooks, not open hooks, and use chain links that close completely (either with a clip or a screw thread) to connect your chains to your eye hooks. Never have anything open that can come loose in rigging.

- Question 8.A: is it worth forking out the $$$ to use green glue between the 2 gyprock layers? or best to use standard industrial adhesive?

Green glue is NOT an adhesive. It doe not stick things together, and cannot be used for that. It is a visco-elastic constrained layer damping compound that never hardens. It has very useful acoustic properties, but not is not meant to be used as glue (despite the name). That said, I doubt that you need it. And NEVER glue your layers of drywall together! That makes them act as one single solid block, instead of two individual layers. The only time you want to "glue" layers together, is with Green Glue. It is that, or nothing. There's no other product that does the same and can show it by independent lab tests. Ordinary construction glue is nothing at all like GG, and would make things worse, not better.

- Question 8.B: please refer to the diagram “Front View (No Gyprock)”. You’ll see that there are 3 air spaces between the vertical parts of the wooden frame. These will be filled with rock wool. The width of the 3 spaces will be 600mm, 140mm and 600m respectively. Wood it be better to make them all more even?

Acoustically, very little difference. But structurally, your studs should be spaced either 400mm OC or 600 mm OC.

- Question 8.C: I intend to position the horizontal parts of the frame at random heights. Is this OK? Or should they positioned specific heights?

In Australia, I understand those things are called "noggins"... (No idea why!!!). They normally go at about half the height of the wall, staggered up and down.

- Question 9: is 60Kg/m3 the correct density to fill the space in a wall? or would 80Kg/m3 be better

60 is fine, 80 would be worse, not better.

Can the rock wool in the wall touch the gyprock or should there be an air gap?

It can (and should) touch the drywall. That provides some direct damping of the panel itself, in addition to damping the air cavity.

- Question 10.A: can you recommend anywhere that supplies these in Sydney, Australia?

Any good building supply store or large hardware store. Bunnings, for example. I designed a studio for someone in Lismore, and he's busy building it at present: he frequently sends me links to Bunnings web site with possible materials. Other big hardware stores should have pretty much the same.

- Question 10.B: is there a specific distance the clips should be spaced from each other?

Yes, but ask the specific manufacturer. Each manufacturer has there own specs for the clips that they make. Check their websites as well.

However, I'm not convinced that you'd need clips and hat channel...

- Question 11: Would this be enough to keep the wall upright? Or would I need to attach shelf brackets like the bass traps?

Think of it this way: You have a very large, very unstable, very top-heavy object towering above you, adn it weights about a hundred kilos . . .

You will need something rather more substantial than a shelf bracket!

- Question 12.A: From my reading of this forum, I’ve learnt that air tight seals are vital for good isolation.

Yes. And I don't see how you can achieve that, with your plan...

But will this temporary wall, even with the 40mm gap do a good enough job at turning this space into a room where a lot of the sound is kept in or kept out?

Here's an interesting quote from a well-respected acoustician: "Consider this, a 1/8” opening around all four sides of a door will reduce the effective rating of an STC 52 door down to an STC 21 – guaranteeing very poor acoustical performance". 1/8" is about 3mm. If you lose 90% of your isolation from a 3mm gap, how much do you lose from a 40mm gap?

Here's an interesting graph:
The marked point shows how much isolation you lose from having holes or gaps that total just 0.001% of the wall area. Yes, that's correct one-one thousandth of one percent will lose you a huge chunk of isolation. Your 40mm gaps are more like 0.07%, if my calculations are correct. That's about seventy times as much... The graph stops at 0.01 at the right hand edge... you need to see 0.07 . . . . Extend that graph out about fives times more over to the right, and that's where your case will be....

In other words, your isolation is essentially zero.

- Question 12.B: Again from reading this forum, I’ve learnt that to achieve decent isolation, you need to address all for walls not just one (the one wall of a fish tank analogy sticks out in my mind). But I was hoping that, because the other walls are cement / brick and should already have decent isolation for my purpose, the only “Wall” requiring attention (or in this case, construction) would be the absent wall “D”

Right, but let's take that same fish tank analogy and apply it here: you already have a fish tank with nice thick glass on three sides... and you are proposing to put cardboard with holes in it on the last side...

- Question 13: would any of these alternative ideas work better than the current wall with insulation?

For your wall to work, no matter how you build it, it MUST provide 100% hermetic seal: 0.0000000% open gaps. Anything greater than about 0.0001% is already losing isolation.

I think that graph is a perfect illustration of why seals are so absolutely necessary and critical. Even a tiny gap can trash your isolation.

So, in order to work, you would need a wall that is perfectly sealed, and has enough mass in it to provide the isolation you need. Since it is just a single-leaf wall, it will need a huge amount of mass. The two layers of drywall that you were proposing would provide you with about 30 dB of isolation, assuming that it was perfectly sealed. That's pretty poor. To get the same level as your other three walls, you'd need about ten layers of drywall, perfectly sealed...

- Question 14: would it be best to face this way or the opposite way? If I had 4 walls made out of the same stuff, I would face either wall A or C because that would make the front - back length longer than the side - side width (which I’ve read is preferable?)

If your fourth wall is a perfect wall, then definitely turn to face the short wall. But if you decide to not have a fourth wall, or only have a poor wall, then your current orientation is correct.

- Question 15: how far away from the front wall should the monitors be? I couldn’t seem to find anything on this in my research.

In a small room, as close as possible. The issue is SBIR: unless you can get your monitors more than 2m away from all walls, you will have huge peaks and dips in your low frequency response. The closer you put your monitors to the front wall, the higher up the spectrum those bumps and dips move. When the monitors are right up against the wall, the bumps/dips are up in the mid range, where they are less noticeable and less objectionable. And if the monitors are flush mounted in the wall ("soffit mounted") then those artifacts just go away completely. Which is why I'm such a big fan of soffit mounting!

But anyway, i your case you want them as close as you can get to the front wall, with only the thickness of the front absorbers in between.

- Question 16: should I leave the floor as it is without covering because there’s enough absorption on the walls? or would it be better to put a rug down?

Already answered...

- Question 17: will I need to cover this up with something? if so, what would you recommend?

Cover WHAT up?

- Question 18: is there anything that I have overlooked and need to consider? (I’m sure there is…)

So am I!

I know you guys say “the more detail, the better” but I do really think my post might be a bit excessive here.

Not excessive at all! Just right. You gave absolutely enough detail that I could understand what you are proposing, to arrive at a logical conclusion and answer all your questions. Good job!

Bottom line? I'd re-think your plan for that fourth wall. First, set up without it, as I outlined above, and see how it goes: If your house mates beat you to a pulp, or your neighbors have you arrested for disturbing the peace, then that might be a sign that you should look at another way to make that wall...



- Stuart -

Hi Stuart,

Thanks so much for you prompt reply and the detail of your answer - you really cleared quite a few things up for me, but I have a couple of further questions and again, I'd greatly appreciate your guidance.

"Let us know once you have measured the actual levels."

I sure will!

"Cloud ... Placement:" It needs to go further forward than that. It should be centered between the speakers and the mix position, more or less over the desk, or even a bit further forward.

^^^ Noted.

I'm not convinced that you need that wall...I'd suggest setting up your gear and basic treatment first, running a few tests to see how you are doing, then taking the decision on that "wall that is not a wall".

In light of all the problems you highlighted about the proposed temporary wall, I have decided to abandon that idea for now. I’d like to put up a very light curtain (think mosquito net fabric) where the temporary wall would be. This is for purely aesthetic purposes; just to visually partition the space. I’m hoping that this wouldn’t really affect the sound in anyway? Maybe apart from the super duper high frequencies? If it will affect the sound, I’ll just forget the curtain - it’s a frill.

Monitor Placement:

Thanks for that info - BIG help. I’m assuming that because you didn’t mention anything about the monitor stands, the design was ok?

Will 60Kg/m3 be ok for the bass traps or do I really need a lower density? ...

reply: That's fine. A bit lighter would be better, but you are still OK with that. Another option would be to switch to fiberglass, around 30 kg/m3, or a bit lighter.

- Thanks for the advice. I’ve found another supplier that sells 32Kg/m3 rock wool. Would you advise that I get that density for the bass traps and use 60Kg/m3 for the front, side and cloud panels? Or just use all 32 or all 60? (Sorry to be so picky about the rock wool - I just want to make sure I’m purchasing the most effective stuff because it’s not cheap!)

- Question 3: Are there any issues with the shelf bracket stands? ... Yes: Stability. Those things are not meant for that application. Just hang your panels on the walls.

I hear you loud and clear about the issue of instability. I don’t think I can hang them on the walls because I’m in a rental property. Can you please suggest a way that would allow them to be free-standing?

Thanks again for your help,

Cal

In light of all the problems you highlighted about the proposed temporary wall, I have decided to abandon that idea for now. I’d like to put up a very light curtain (think mosquito net fabric) where the temporary wall would be. This is for purely aesthetic purposes; just to visually partition the space. I’m hoping that this wouldn’t really affect the sound in anyway? Maybe apart from the super duper high frequencies? If it will affect the sound, I’ll just forget the curtain - it’s a frill.

That would be fine. It could be reasonably "not-so-light" as well, if you wanted it to be. Perhaps not as thick and heavy as the curtains at the symphony hall, but it can be thicker than just a then lace curtain. The main reason why the room should be as long as possible is for the modal response, which is all in the low frequency end of the spectrum, and your curtains won't affect that much at all: bass will go right through. You could experiment with different types of cloth until you find one that doesn't kill the highs too much, and still gives you some privacy.

I’m assuming that because you didn’t mention anything about the monitor stands, the design was ok?

Right. That would be fine. Of course, you do have to build them correctly such that the acoustic axis of the speaker ends up 1.2m above the floor (about 47 1/4"). That's the acoustic axis, not the top or bottom of the speaker cabinet, nor the center of the woofer or tweeter, nor even the center of the front face. Your speaker manual likely tells you where that point is located. If not, ask the manufacturer. And if all else fails, we can help you estimate it.

The only thing I'd add to you your speaker stands, is Sorbothane pads between the top surface of the stand and the speaker itself, to provide the final decoupling.

I’ve found another supplier that sells 32Kg/m3 rock wool. Would you advise that I get that density for the bass traps and use 60Kg/m3 for the front, side and cloud panels? Or just use all 32 or all 60? (Sorry to be so picky about the rock wool - I just want to make sure I’m purchasing the most effective stuff because it’s not cheap!)

32 is a bit light, 60 is a bit heavy! Either would work, and close to optimum, so I wouldn't sweat it too much. You could go with just the 60 kg/m3 stuff for the first reflection points, and layer both types for the bass traps. For example, face it with 32 kg/m3, then put 60 kg/m3 at the back.

I don’t think I can hang them on the walls because I’m in a rental property.

Does your contract allow you to hang pictures on the walls? If so, then this is no different. Those panels won't be very heavy, and a couple of screws into the studs at the right height would do the trick. If you can screw eye hooks into the ceiling to hang your cloud, then you should be able to screw into the walls as well, to hang your panels. Your rental contract might say something about having to return the property in the same condition you received it, so worst case you'd just plug the holes and re-paint the wall when you leave. No big deal.

Can you please suggest a way that would allow them to be free-standing?

Instead of shelf brackets, screw a couple of pieces of 1x4 to the bottom, extending out far enough to provide the stability you need.

Your bass traps need to extend from floor to ceiling, and I'd suggest that the best way would be to do the "superchunk" style, of stacked triangles, with a light-weight cloth-colored frame sitting in front of it.


- Stuart -

Thanks again for the quick reply, Stuart. Just a 1 or 2 more questions to clarify and then I'll be on my way.

I’d like to put up a very light curtain (think mosquito net fabric) where the temporary wall would be.

That would be fine. It could be reasonably "not-so-light" as well, if you wanted it to be.... You could experiment with different types of cloth until you find one that doesn't kill the highs too much, and still gives you some privacy.

^^^ Experiment, I shall.

I’m assuming that because you didn’t mention anything about the monitor stands, the design was ok?

That would be fine. Of course, you do have to build them correctly such that the acoustic axis of the speaker ends up 1.2m above the floor (about 47 1/4")...The only thing I'd add to you your speaker stands, is Sorbothane pads between the top surface of the stand and the speaker itself, to provide the final decoupling.

^^^There doesn't seem to be any info in the manual so I have emailed that manufacturer and am awaiting a reply. The monitors are Focal CMS 50's. 5" woofer. 7.7Kg. They each come with a model-specific rubber "decoupling mat", do you think this mat would sufficient or would I still need some sorbothane pads? I've had a bit of a look for sorbothane products on the web and the choices seem to be either flat pads or hemispheres. I'm not sure what the thickness is meant to be, but all products a relatively thin (3-15mm) and diameter is small (30mm max). What should I be looking for?

re: rock wool density...

Either would work, and close to optimum, so I wouldn't sweat it too much.

^^^ Well, I'm very much not a "near enough is good enough" guy, but if either option will be close to optimum, I think I'll stick with the 60Kg/m3 option.

Does your contract allow you to hang pictures on the walls? If so, then this is no different. Those panels won't be very heavy, and a couple of screws into the studs at the right height would do the trick. If you can screw eye hooks into the ceiling to hang your cloud, then you should be able to screw into the walls as well, to hang your panels. Your rental contract might say something about having to return the property in the same condition you received it, so worst case you'd just plug the holes and re-paint the wall when you leave. No big deal.

^^^ Not sure what the contract says, but I'll have a look. If I can hang pictures, I'll take your advice here.

Instead of shelf brackets, screw a couple of pieces of 1x4 to the bottom, extending out far enough to provide the stability you need.

^^^ Thanks, that sounds like a good option.

Your bass traps need to extend from floor to ceiling, and I'd suggest that the best way would be to do the "superchunk" style, of stacked triangles, with a light-weight cloth-colored frame sitting in front of it.

^^^ Yeah I'd prefer this design as well. I know "superchunks" would be more effective but unfortunately I think it would be too expensive for me right now. I'm going to stick with the original, less-effective design (see first post) of a 10mm-thick panel flat across the corners; floor to ceiling. But thanks for the suggestion - I will certainly be making some "superchunks" when I can afford it.

Thanks again for all your help so far, I would have been completely lost without it!

Cheers,
Cal

Hi Stuart,

Just checking in since it has been a week since my last question/post (I'm sure it's been a busy one for you) and also because there has been a speed-bump or two in my project.

Firstly, when you have a chance, please respond to my last post. (Specifically regarding Sorbothane and bass trap design)

Second, my rock wool supplier has fallen through at the last minute. I've found another supplier who can provide me with "Ultratel" (info sheet here: http://bradfordinsulation.com.au/~/medi ... sheet.ashx ). It is 48Kg/m3 which is better than the 60Kg/3 that I was going to purchase previously. I'm just wondering if there is any significant difference between rock wool and this product? Or are they essentially the same thing and will be equally effective?

Looking forward to your reply.

Thanks,
Cal

^^^There doesn't seem to be any info in the manual so I have emailed that manufacturer and am awaiting a reply.

Draw an imaginary line between the center of the woofer and the center of the tweeter. The acoustic axis of the speaker will be a point on that line, and probably about 70% to 80% along that line, close to the tweeter. Pick a point at about 75%, and you won't be very far wrong...

The monitors are Focal CMS 50's. 5" woofer. 7.7Kg. They each come with a model-specific rubber "decoupling mat",

That would probably be fine, if that is what the manufacturer himself supplied. Personally, I still prefer Sorbothane, but that mat is probably good.

I think I'll stick with the 60Kg/m3 option.

That would be fine.

I'm going to stick with the original, less-effective design (see first post) of a 10mm-thick panel flat across the corners; floor to ceiling.

That will work reasonably well, but do try to make it thicker if you can. The thicker the better, but aim for at least 15cm (not mm!!! I think you made a mistake there, in the units... )


- Stuart -

It is 48Kg/m3 which is better than the 60Kg/3 that I was going to purchase previously.

48 is also fine.

I'm just wondering if there is any significant difference between rock wool and this product? Or are they essentially the same thing and will be equally effective?

There are slight differences, yes. One factor is the resin or binding agent that the manufacturer uses, and the method he uses to apply it, plus a few other details. Those all affect the basic properties to a certain extent. That's why it is best to check the actual acoustic specs for each product, to be certain. But to be honest, there isn't a huge amount of difference.

- Stuart -

Kyphosismusic wrote:Hi Stuart,

Just checking in since it has been a week since my last question/post (I'm sure it's been a busy one for you) and also because there has been a speed-bump or two in my project.

Firstly, when you have a chance, please respond to my last post. (Specifically regarding Sorbothane and bass trap design)

Second, my rock wool supplier has fallen through at the last minute. I've found another supplier who can provide me with "Ultratel" (info sheet here: http://bradfordinsulation.com.au/~/medi ... sheet.ashx ). It is 48Kg/m3 which is better than the 60Kg/3 that I was going to purchase previously. I'm just wondering if there is any significant difference between rock wool and this product? Or are they essentially the same thing and will be equally effective?

Looking forward to your reply.

Thanks,
Cal

Another product you can use, and is readily available at Bunnings (and other suppliers) is the Knauf Earthwool product. The R2.7 HD Acoustic Batts (Blue bag) are well priced - shop around though, I found an independent supplier here in Melb. that was significantly cheaper! - it is fiberglass with a density around 27 kg/m^3 (near optimal for fiberglass) and generally nicer to work with than Rockwool. FYI

Cheers,

Scott

Hi Stuart,

Thanks again for your help. The panels are now all built; look and sound great! I'm sure it's far from perfect but it's now probably the best space I've ever had to work in. Will post pictures asap and any feedback on my layout would be more than welcome (if you have time).

Thanks to you, also, rockindad. I ended up purchasing the Ultratel 48Kg/m3 fibreglass before you posted, but I'll certainly keep the Bunnings product in mind when I get around to beefing up my bass traps.

Cheers,
Cal

but it's now probably the best space I've ever had to work in.

Its always gratifying to hear that we have been able to help someone achieve something great! Thanks for mentioning that. Its that type of comment that makes all our efforts as moderators worthwhile.

Will post pictures asap and any feedback on my layout would be more than welcome (if you have time).

Absolutely!!! Please do that. There might be something that can still be improved.

Also, if you feel like it, you could run a REW test in your room and post the results here, so we can analyze them for you.

Looking forward to to seeing the photos!


- Stuart -