John Sayers' Recording Studio Design Forum Archive

Hi Stuart,

I have just discovered the ModeCalc program Graphical Mode Calculator from http://www.realtraps.com (Ethan Winer)

The recommended Ratios it suggests are:

Ratio (HWL):

1 : 1.14 : 1.39
1 : 1.26 : 1.59
1 : 1.28 : 1.54
1 : 1.30 : 1.90
1 : 1.40 : 1.90
1 : 1.50 : 2.10
1 : 1.50 : 2.50
1 : 1.60 : 2.33

Does this sound accurate to you ?

I am playing around with numbers keeping in mind the reduced size of the De-coupled Double Stud Wall and air cavity of about 50mm

Aslong as the completed walls and ceiling hit any of these ratios I should be ok ? or is there more to it than that ?

Here is a number I have come up with so far:

Ratio (HWL) 1 : 1.40 : 1.90

= 2.47m H x 3.47m W x 4.7m L

or

Ratio (HWL) 1 : 1.50 : 2.10

= 2.47m H x 3.7m W x 5.19m L

or

Ratio (HWL) 1 : 1.50 : 2.10

= 2.38m H x 3.58m W x 5m L

or

Ratio (HWL) 1 : 1.50 : 2.10

= 2.57m H x 3.86m W 5.4m L


How do these ratios / dimensions sound ? Am I on the right track ?

Ideally I do not want to have to go higher than 3m for ceiling , hence why I am trying to calculate with the Height at 2.47m keeping 53cm spare to play with for the decoupled double beam ceiling and air cavity.

Thanks

Hi Stuart,

So this kind of leads me into a few basic questions about air cavities in the decoupled walls and ceiling.

(Q1) What is the standard or recommended size for the air cavity ?
(Q2) Are there any issues with having large air cavities ?
(Q3) Are there any issues with have different sized air cavities between the side walls, front and back walls and ceiling ? I presume that these acoustic ratios will offset the sizes of the air cavities between the front and back and side walls and ceiling.
(Q4) Is the myth about larger air cavities are better "bigger is better" true ?

I have read around some builds and recommendations of air cavity size of 25mm which is smaller than I originally expected.

I will report back all of the details, sizes and specifications of materials on tuesday.

Once I figure out the beam and stud sizes and how much Width, Length and Height a typical decoupled double stud wall and ceiling will remove from the dimensions , I can then start to calculate some ratios on the ModeCalculator.
I may be able resize the dimensions to the ratios above a little bit larger, although I am liking the looks of Ratio (HWL) 1 : 1.50 : 2.10 = 2.47m H x 3.7m W x 5.19m L

Thanks

Hi Stuart,

I understand that you are probably taking a break from the forum over the weekend.

However I just want to notify you that I really don't have the luxury available of hiring a studio / acoustic designer, its all about resources, and they are hard to find in rural Australia. Its all about who you know and how big your wallet is.

While I appreciate your free professional input on my studio, I just simply won't be able to provide you with accurate SPL readings, I can not guarantee of the monitor make and model in the future as it is subject to change.
I probably couldn't really afford to contract a studio designer anyway.

Maybe a waste of money to some, but Basically I am just happy that I am going to get new clean space to work in, yes the construction and plans might be flawed and not scientifically accurate. All I have to work with is these acoustic room ratios I have discovered and to just pick one ratio and stick with it.

If I was so worried about acoustics etc etc I would never get any music finished, im a musician at heart.

I would really love to be able to contract someone like yourself to design something professionally over 6 months or whatever , but its not really a viable option.

Im not sure if I can stop construction, the builder seemed pretty pissed when I mentioned it. Stopping the construction would be fucking around with too many peoples weekly pay.

Anyways, I know that this isn't the best information for a forum like this, but just wanted to say I appreciate the help.

Thanks

Hi Stuart,

I just made a $20 donation for your help.

I ended up choosing the ratio of 1 : 1.50 : 2.10

2.53m H x 5.3m L x 3.79m W , this will be the final dimensions internally with dry wall.

Construction starts tomorrow, sooner than I expected, oh well ill work with what ive got.

I will try and do some basic tests once its completed to see the rooms response with pink noise etc.

Thanks for all your help, sorry I could not stop construction and work with you more.

I have just discovered the ModeCalc program Graphical Mode Calculator from realtraps(Ethan Winer)

That's not a good one to use. IT only takes into account the axial modes, and completely ignores the tangentials and obliques. Better use these two:

http://www.bobgolds.com/Mode/RoomModes.htm

http://amroc.andymel.eu/

They give you the complete picture, plus a boatload of other extremely useful info.

(Q1) What is the standard or recommended size for the air cavity ?

How much isolation do you need, and what frequency do you need it at? An MSM wall is a tuned system. You tune it by varying the cavity depth, and the mass of the two leaves.

That said, you should never really go much less than about 4" depth, or you start needing huge amounts of mass on the leaves.

(Q2) Are there any issues with having large air cavities ?

Nope! The larger the better. Larger cavity = lower resonant frequency = good.

(Q3) Are there any issues with have different sized air cavities between the side walls, front and back walls and ceiling ?

As long as you adjust the mass on the leaves to compensate, there's no problem. Smaller gap, you need more mass.

(Q4) Is the myth about larger air cavities are better "bigger is better" true ?

It's not a myth: in this case the rumors are true: Size matters. Of course, there's a point where making the gap any bigger doesn't really help much more (diminishing returns), so a wall with a gap 20" wide would not perform a whole lot better than one with a 15" gap, but overall bigger gaps = better isolation. As long as you get the resonant frequency one octave lower than the lowest note you need to isolate, then making your gap much bigger probably isn't necessary.

I have read around some builds and recommendations of air cavity size of 25mm which is smaller than I originally expected.

That's only 1"!!!! Nope. Just nope. Uh huh. Way too small. Unless maybe you wanted to put an inch of lead sheeting on each side...

However, don't confuse the depth of the cavity with the gap between frames in a pair of stud framed leaves... it's not the same thing. Having a one inch gap (25mm) between two conventionally built 2x4 framed leaves, gives you a cavity depth ("air gap") of 8" (200mm)

Once I figure out the beam and stud sizes and how much Width, Length and Height a typical decoupled double stud wall ...

Careful with terminology! There are no beams in walls.... Beams run under walls, or under ceilings, but the are not arts of walls. Walls have sole plates, top plates, and studs. The studs are usually king studs, but if you have doors and windows then you also have jack studs and cripple studs, and headers. Ceilings don't have beams either: there might be beams that support the ceiling, but the ceiling itself has joists.

I understand that you are probably taking a break from the forum over the weekend.

I wish! Just snowed under with projects right now....

I really don't have the luxury available of hiring a studio / acoustic designer,

How do you know? Have you asked one to quote you?

they are hard to find in rural Australia.

You don't need a designer from rural Australia. You just need a designer. He can be located physically pretty much any place in the world. I have designed a few studios for customers in Australia, but I haven't been back there in nearly 40 years! (even though I was born there.....) I very rarely get to visit the studios I design, and very rarely get to meet the people I design them for. That's the same for most studio designers, these days. With modern technology, it isn't necessary.

I just simply won't be able to provide you with accurate SPL readings,

The there's not much that anyone can do to design your place, including yourself! Trying to design a studio without know how much isolation you need, is sort of like trying to go on vacation without having a destination, or any way of getting there....

I probably couldn't really afford to contract a studio designer anyway.

How do you know? Did you ask a designer to quote? One important point: You will likely save money by hiring a designer. He will probably save you the cost of the mistakes you will make if you try to do it yourself unprepared, many times over...

If I was so worried about acoustics etc etc I would never get any music finished, im a musician at heart.

Let me flip that around and send it back at you, so you can see the flaw in your reasoning: "If I was so worried about music and instruments etc etc I would never get any studios designed! I'm an acoustician at heart."... Not sure if you see the silliness in that. As a studio designer, the most basic thing I am concerned about is NOT studio design, but rather music any instruments. That is the very reason I do what I do. If my most basic concern was not music and instruments, I wouldn't be much of a studio designer! Ditto for a musician who is not concerned about the acoustics of the rooms he plays in, and mixes in... Acoustics is the underlying principle of what music is all about.

I would really love to be able to contract someone like yourself to design something professionally over 6 months or whatever , but its not really a viable option.

How do you know? Did you ask a designer to quote?

- Stuart -

Hi guys,

Thanks again for the abundance of information, appreciate it.

I will try to keep this short and sweet.

So my budget came from inheritance from the passing of my Grandmother, so my parents allowed for $20,000 AUD for the studio.
Unfortunately on my behalf my parents had rushed into the situation without doing much of their own research on material costs etc etc, and I would get very old school responses like "ah it won't cost very much more" etc.

So to my surprise one of the most expensive things has been the cost of the 2 builders over a period of 2 weeks. We had just suffered one of the lergest floods in our region since the 1970's and we had alot of rainy days to deal with. Rainy days where I would of preferred the builders to stay home they still came to work just to make some wages (thats just what its like in Australia, work is hard to come by and theres no luxury for most of us to put things on hold because we are living week to week, suicide is one of Australias leading causes of death FYI.)

In regards to the build these were the materials used:

- 40mm NRG Green Board Foam , which comes in available sizes 20mm, 40mm, 60mm, 75mm, 100mm
http://www.nrggreenboard.com/
http://www.nrggreenboard.com/thermal/rating
http://www.nrggreenboard.com/sites/defa ... w%2047.pdf
http://www.nrggreenboard.com/sites/defa ... 2060mm.pdf

Had I known more about this material I would of opted for the 60mm as its a fairly in-expensive product, but we have already broken the budget so I can't complain, this was the choice of the Builder made for me.

- Weather Resistant House Wrap
- First Layer of Insulation - 88mm CSR Bradford Soundscreen
In regards to insulation there are basically 2 main providers in Australia, CSR and Pink Batts (which is a registered trademark of Owens Corning)
I ended up going with the CSR Bradford Soundscreen because it had better acoustic information in its stat sheets and was a little bit cheaper and more closely available to me.
http://www.bradfordinsulation.com.au/ho ... oundscreen
http://www.bradfordinsulation.com.au/~/ ... asheet.pdf

- Plastic Packing Wrap with staple gun to hold insulation in place.
- 200mm Air Cavity
- 2nd layer of insulation
- Wall Studs and suspended ceiling joists (not sure if thats right word) both spaced at 430mm
- Ended up using a single layer of 13mm Gyprock with some adhesive on the frame. A 2nd layer of gyprock with greenglue compound was going to be too expensive in comparison, even with 10mm gyprock, like a extra couple of thousand dollars.

We didn't know how to decouple the walls and suspended ceiling any better at the time, we had to secure one side of the wall to every 2nd roof rafter, we wedged some AbleFlex expanding joint foam material wherever possible to help provide some kind of decoupling. Then the suspended ceiling was attached to every other 2nd roof rafter.

Not exactly sure how it will turn out, but I don't really care at this point as I can't complain about anything considering all the circumstances. If the room is no good at isolating sound then atleast the double stud wall and double layer of insulation should help with better thermal properties for the room and air conditioning lol.

Ended up just using a bead of Green Glue underneath the floor beams to help seal air gaps and possibly provide a little additional decoupling as it stays a little rubbery and flexible once it sets.

I had some difficulties with the workers throughout the construction, none of them wanted to use the green glue sealant, I think I missed some opportunities to use some sealant behind the corner plywood bracings etc, and I also didn't get to check over the insulation installation behind the bracings either but oh well. The builders did a fairly poor job installing the insulation aswell as they scrunched it up in alot of places and I had to re-do quite a bit, they just want to build the wood stuff and go home. By that point I was fairly hands on and on-site most of the day keeping a eye on these builders and trying to make sure communication was clear etc.

Yes I tried using your 2x provided calculators plus the Ethan Winer calculator. I ended up choosing the internal room dimension of 3790mm W x 5290mm L x 2520mm H

There was 3 main reasons I decided to go with this dimension:

1) I ran out of time to decide lol
2) The width and Length air cavities were symmetrical being 200mm
3) I started to notice I couldn't find many more room dimension sweet spots without making the roof excessively high.

A little later on I came to realise that my ears would be sitting fairly closely to the halfway point between wall and ceiling which I read is un-desirable in most cases, but maybe a little angle up or down with the monitor placement might help.
The room might sound like crap until I make some diffusers etc im not sure we will soon find out.

The calculators was showing some issues around 140Hz 150Hz , I don't know how to interpret much of the other information from the calculators, might be more issues than one would hope for, but in the end I can't complain.

Thanks for all the help

P.S. I should have mentioned that I ended up going with a flat ceiling instead of a angled ceiling because I ran out of time to design and quote the studio construction and it would of complicated the build too much at the time and cut into the builders wages.

The main roof rafters have a 5 degree pitch down angle. They are pitching down across the width and not the length, so I presume if I wanted a 5 degree angle pitch in the inner ceiling I probably would of had to of made the outside walls and main roof rafters a little bit higher as the rafters currently come close to the suspended ceilings bottom roof chord which allowed for roughly 8cm height adjustment before hitting the rafters, which I don't think is enough room for inner ceiling 5 degree pitch.

The parents have been annoying to deal with throughout the construction, they want it to look "aesthetically" pleasing and would of liked to of had glass windows and doors and all sorts, basically a "hybrid bedroom". Its hard for them to understand and they always have some kind of annoying input even though its my studio, but its not really my money so yeah, the whole process has been a bit painful between dealing with parents and builders.
But if you have enough spare time available to do the building yourself and 1 friend to help out for cheap I think its possible to make a pretty killer studio for pretty cheap.

Im not sure how much information I will be able to provide about the rooms response as I don't own a measurement microphone and it will take me a little while to test different speaker placements in the room until I find somewhere I like.
What kind of tests would be good to do ? run some pink noise and sine sweeps and see what the frequency analyzers show ?

Electricals getting installed this week, then carpet, then custom built desk, then making acoustic panels, then get back to producing.

For the carpet im thinking of doing a 3mm Underlay with 7mm latex backed carpet. I probably could of made the ceiling 5mm - 10mm higher to compensate for the carpet which I didn't consider at the time.

Carpet - http://www.autex.com.au/carpets/images/
http://www.nolanuda.com.au/products/autex-images/
http://www.nolanuda.com.au/wp-content/u ... asheet.pdf

Heres some pictures, I had to resize and re-crop them to fit 500kb file size.

Things I would have done differently if I had the chance:

1) Choose 60mm NRG Green Board instead of 40mm
2) Have a 5 degree angle pitched internal ceiling
3) Put a little more time into studying room ratios
4) Think more about extra support beams for electricals, acoustic panels and screen mounting. (You can see in the pic I could of put another support noggin for the electrical power points on the other side of the wall studs. Potential more support noggins for diffusers etc , but with the wall studs being space 420mm apart it shouldn't be too big of a deal.) little details like this.

Also I thought the builders did a pretty poor job with the maxi bond adhesive on the NRG Green Board in some areas, so I re-beaded some areas.

Lastly, one of the weakest spots in the build is the door jam as it is not the full width of the double walls, it has 2x solid wood doors but we had hit the budget by this time and the builder had already made a piss poor thin door jam and my dad didn't show any interesting in spending more money to make a new one. So we just ended up covering the remaining wall with blue board and green glue sealant.

Waiting to finish things up and move in....
Ive got a Virus TI2, Waldorf Blofeld, some Controllers and other bits and pieces, my room has turned into a mess
Been building up my collection since 2003, life time investment..... when you need to buy new clothes, buy more synths, when you need to buy food, buy more synths. Keep the dream alive.

some more pics. Im happy with the way things are turning out considering all the circumstances.