John Sayers' Recording Studio Design Forum Archive

I was wondering, as the roof is inevitably the weak point in my build, would it be worth forking out for a higher density 100kg/m3 or 140kg/m3 for the roof section? Would that make a discernible difference, or will I be wasting cash unnecessarily?

Yes it would make a discernible difference: it would significantly REDUCE your low frequency isolation, since higher density insulation is worse at absorbing low frequencies. 60 kg/m3 is OK for mineral wool. 50 kg/m3 is optimal, but 60 is also fine: very little difference. Or if you prefer to use fiberglass insulation, then it should be about 30 kg/m3.

- Stuart -

And that is why this forum is amazing...... Thanks Stuart!

So, a bit of an update as this design thread turns into a build thread! (does this topic need moving now?)

First point is stating the obvious to anyone who has done construction before, everything takes WAAAAAY longer than I thought!! Instead of the end of summer, my new still-optimistic deadline is by Christmas.....

I have attached some pictures of the stages so far including:

*painting brick to seal them

* I have added two layers of 0SB3 board to the roof between the joists, both sealed with acoustic caulk. This was a total pain in the neck...and back...and shoulder blades....

* The framing is up, barring a gap at the garage door end for access with large materials. This will be closed up at a later date.

****MAJOR FRAMING DISCLAIMER**** I had a near miss at this stage with my handy man insisting the walls were screwed to the existing joists...after a sleepless night trawling this forum I found the solution I was after, and I'm glad i did at this stage. I will be adding new joists on top of the framed walls, and when this is done I will remove the screws to fully decouple the inner room from the outer. The black stuff you can see around the top frame is a strip of neoprene, which is acting as a spacer and will also be removed when the new joists are up.

* I have fitted my ventilation inlet and outlet vents and put pipes through the wall for those

* The outer layer (brick walls and roof) now has a full covering of 100mm Earthwool RS60 panels, I decided to make a frame to hold this up and use wire to hold it in place

* Some of the internal frames have been wired and insulated also

Doesn't seem a lot written down, but it certainly seems to have been a lot of work for, on the most part, one person!

So my next main steps are to sort out the ventilation system (connect pipes, mount inline fan, build silencer boxes to fit in roof cavity), and putting up the new internal joists.

I have a few little questions at this point:

- I currently plan to have a small air gap between my two walls (between the Earthwool filled frames). What I have read on here recently suggests that it would be better to fill that small gap with fluffy insulation, is that so?
- If that is the case, would it be possible to use the offcuts from my rs60 panels and tear them up to reduce density and put them in the gap?

- Insulation related question 2: When I have my new joists up, do I need to avoid having my Earthwool rs60 panels touching both the original joists and the new ones? Would it have enough density to create a flanking path?

- Now a ventilation related question, is it better to have the inline fan pushing air into the room, or extracting it out? I seem to be reading conflicting advice about this.

- finally does anyone know anywhere in the UK that can supply duct liner??

Any help/suggestions are much appreciated!

Thanks,

Adam

Unfortunately, there was a glitch with the forum server yesterday, and your photos seem to have disappeared into the mysterious nether regions of cyberspace, with no trace! Please could you re-post the photos.

When you have them in place again, I'll take another look at your post so I can respond intelligently, after seeing the things you are talking about, instead of just pretending I saw them!

- Stuart -

Hi Stuart,

thanks for the reply. I can still see the pictures on the post, has the issue been resolved or are they in my cache? I'll reattach them just in case.

Looking forward to your response!

Thanks

Adam, did you have any luck finding duct liner? I am currently on the same search.

Hi,

I've literally just pressed the order button on some liner. After a whole week of failed attempts and no call backs from a few companies, I came across this site and their foam liner:

https://www.efoam.co.uk/fireseal-class- ... c-foam.php

I gave up trying to get hold of the lined mineral wool type, even though the performance seems slightly better. It seems to hard to get hold of in the UK, and any companies that advertise it make it from scratch, so my order was too small to be worth their while apparently, at least that's what I read into their constant lack of call backs!

Hopefully this stuff will do the trick.

URGENT ADVICE NEEDED!!

I've been pressing on and things are starting to take shape, but have come across an issue I am unsure about:

I have acoustic flex duct for my ventilation system in the roof space, as you can see in the picture the duct is currently lying on both my original joists and my new internal shell joists (the thicker ones in the picture). Is this contact enough to create a transmission path between the inner and outer shell?

Look forward to your advice!

Thanks

No, that is flex duct, so it won't create flanking paths. But do be careful when you install flex duct to make sure that it is not kinked or even indented slightly from sitting on top of narrow joists: those slight kinks can cause a large increase in turbulence, air noise, back pressure, lost speed, etc. Also, make sure you stretch it out to its full length: don't just stretch it a bit.

- Stuart -

Thanks again Stuart.

I now have insulation and vapour barrier installed, so next stop is the plasterboard-a-thon, whoop whoop!

Hi again folks,

WOW, trying to build a home studio room whilst working and having a family REALLY takes a long time! I may have underestimated that this time last year

The good news is, I pretty much have a sealed room now, just need to get my door on and we're sealed. So on to the next phase, the treatment!

I have a question about my back wall treatment, which I'd appreciate some thoughts on. I know I will have some hefty bass issues in this room, the dimensions aren't ideal (W 2.96m x L 5.07m x H 2.7m) but my plan was to maximise the volume I could get from a single garage and then treat treat treat. I plan to have 60cm superchunk treatment in the front corners, but there is still a question mark over my rear wall.

I have planned to have a large corner trap of some description in one rear corner, as I am limited by the door entrance in the other corner. My question is, which type of bass treatment would be most effective use of this space? Would it be just to have a very large superchunk (cutting my 120 x 60cm earthwool slabs diagonally and stacking them) or would putting a few hangers in there be more effective?
I have a quick question about the front wall also, I plan to have a reclaimed pallet wood wall between my two front superchunks, would this be best directly applied to the plasterboard or could I build a frame leaving room for 100mm mineral wool behind? Would I be stepping into dangerous "untuned slot resonator" territory if I did this??

I know some elements of the treatment can't be defined until I test the room, which I will do as soon as the door is on, but as I know there will be 200hz downwards issues I want to get cracking with my low end treatment.

Thanks again!

WOW, trying to build a home studio room whilst working and having a family REALLY takes a long time! I may have underestimated that this time last year

That makes you a normal, typical., fully-qualified studio builder! It always takes longer, is more complex, and costs more than you ever imagined when you first started...

I have a question about my back wall treatment, which I'd appreciate some thoughts on. I know I will have some hefty bass issues in this room,

The very best thing you can do is to measure the acoustic response of your empty room BEFORE you put any treatment at all in it. You do that using the REW software package, which is free. That will tell you exactly what the issues are with your room, and based on that you'll be able to design the correct treatment.

I plan to have 60cm superchunk treatment in the front corners,

Is there any reason why you didn't want to flush-mount ("soffit-mount") your speakers? That would do several things for you, among them saving space in the room, but most importantly eliminating many of the problems, issues, and artifacts that come from having speakers in the room.

My question is, which type of bass treatment would be most effective use of this space? Would it be just to have a very large superchunk (cutting my 120 x 60cm earthwool slabs diagonally and stacking them) or would putting a few hangers in there be more effective?

Both would work fine, but you'll very likely need more than just that back there.

I plan to have a reclaimed pallet wood wall between my two front superchunks,

why? What acoustic purpose does that serve?

Would I be stepping into dangerous "untuned slot resonator" territory if I did this??

It would not be a slot resonator unless you sealed it air-tight, and even then it would likely not be tuned usefully (if at all): more likely it would be an unpredictable diffuser/reflector with unknown properties...

but as I know there will be 200hz downwards issues I want to get cracking with my low end treatment.

That's sort of like saying "I know I'll get sick at some point in my life, so I'll take a whole bunch of drugs now, randomly, in advance, and hope one of them works....

First, get the tests done to find out what "illness" your room really has, then treat only that. There's no point treating "illnesses" that it does not have, and in fact the treatment could make it even more "sick", in other ways...

- Stuart -

The very best thing you can do is to measure the acoustic response of your empty room BEFORE you put any treatment at all in it. You do that using the REW software package, which is free. That will tell you exactly what the issues are with your room, and based on that you'll be able to design the correct treatment.

Once again you speak the wisest of words, I am in a battle between my impatience to get it finished and the desire to do it right I will be getting a rig in there to do a REW test as soon as I can get the room dust free, and look forward to your help decoding the results!

Is there any reason why you didn't want to flush-mount ("soffit-mount") your speakers? That would do several things for you, among them saving space in the room, but most importantly eliminating many of the problems, issues, and artifacts that come from having speakers in the room.

I have being swaying between soffit mounts and not, and the main thing that has kept me from doing it at this stage is that as soon as I have paid of some construction costs my next big upgrade will be monitors. So I'd rather not create custom soffits for my currrent Mackie's when I know an upgrade is imminent. Secondly, I am currently eyeing up the Focal Twins, which is understand aren't ideal for soffit mount?

why? What acoustic purpose does that serve?

The pallet wall is purely a cosmetic idea, with perhaps some bonus minuscule diffusion due to irregularities???

I have a big and fairly pressing question at my current stage; my clouds are nearly complete (pics soon) and I am looking into the hard backing. I initially planned to use 18mm OSB, but the sheer weight of the stuff is scaring me, seen as these things will be above my head! Would 9mm OSB be suitable, or is that not massive enough to break any waves?

Thanks again Stuart, you are truly an Acoustic Buddha!

I will be getting a rig in there to do a REW test as soon as I can get the room dust free, and look forward to your help decoding the results!

Set it up with the configuration being as close as possible to the way it will actually be once every last piece is finished. Speakers at the exact location, height, and angle, mic set up exactly where your mix position will be, in the middle of your future head. Then mark and measure those positions with great accuracy, so you can always get everything back to the same point. That's the only way to ensure that you can validly compare data later, after you start installing treatment. Particularly the mic: it is very important that you always get it back to that exact same spot for all future measurements, so measure carefully to points that wont be covered up and inaccessible later!

Then calibrate REW carefully, following the instructions and using a good quality hand-held sound level meter to do the calibration. (not an iPhone app, nor a cheap Chinese "toy" meter!)

as soon as I have paid of some construction costs my next big upgrade will be monitors. So I'd rather not create custom soffits for my currrent Mackie's when I know an upgrade is imminent.

You don't have to custom fit them! You can have a soffit that allows for easy replacement of the speakers at any time in the future.

Take a look at this thread: www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=20471

When I originally designed that room three years ago, the customer warned me that he would probably change his speakers later, but he didn't know what he would get. So I designed the soffits with slide-in "trays" that hold the monitor, and I made the tray bigger than the largest monitor he might want to use. Fast forward to early this year: he had to change his monitors as one of the old ones was getting "crackly". So he got the new monitors, which are very different from the old ones, slid out the old tray+monitor assembly, slid in the new ones, and we re-tuned the room to take care of the differences in response. Simple!

I am currently eyeing up the Focal Twins, which is understand aren't ideal for soffit mount?

You mean the 6Be model? No problem. They are front ported, and have the necessary rear panel controls for rolling off the low end. They can be soffit mounted. In fact, I've changed my views over the years: I use to think that most speakers could not be soffit mounted, with only some being suitable. Now I know better: pretty much any speaker can be soffit mounted, unless it has drivers on the sides, top or back, or has a very strange physical shape that would be too hard to fit into a baffle. Most speakers can be soffit mounted: In that room that I linked above, for example, the speakers are Eve SC-407's, which are in fact rear ported! Conventional wisdom says you can't soffit mount a rear-ported speaker. I spoke to the chief engineer at Eve (a very helpful guy), and he said there would be no problem doing that, and gave me some tips on things I should take into account. That speaker is also normally meant to be used horizontally, but I felt it would work better vertically in that room. We discussed that too, and he agreed. So I broke all the rules with that mount (with the manufacturers blessing), and it works fantastically, even though it is rear ported and mounted vertically.

So long story short: Design your soffits with removable trays for your speakers, and mount your mackies in there now, then your Focal Twins later when you get them (or any other speaker that you might decide to get in the meant time...)

my clouds are nearly complete (pics soon)

B...B...B...But you can't mount them yet! You first have to run REW on the empty room!

Priorities....

I initially planned to use 18mm OSB, but the sheer weight of the stuff is scaring me, seen as these things will be above my head!

So wear a crash helmet while you mix! Sheesh! What's the problem???
Don't worry: just kidding...

Would 9mm OSB be suitable, or is that not massive enough to break any waves?

Correct.... there's also the issue of flexibility: 9mm OSB is fairly flexible, and might have strange resonances...

To mount your cloud, use chains, not wire or rope, and use proper rigging hardware to hang them: no S-hooks, for example: only links that lock. Use eye-bolts (not hooks) screwed into the joists, and use enough of them to spread the weight safely. All your hardware should be rated for ten times the weight of the cloud, for safety. So if for example your cloud weighs 30 kg, your hardware should be able to support 300 kg. Use at least six chains at different points on the cloud.

Another point: you might not need to cover the entire cloud back with thick OSB. In that same room above, part of the cloud is hard-backed and part is not. You can see that it is in several sections, all hung independently, and there are two different angles involved there. You might want to do something similar, and split your cloud into two or more smaller sections, with hard backing only on the ones that need it. It also means that each individual section is lighter in weight, so it won't crack your skull so seriously if it falls! (Just kidding, again - I have a weird sens of humor... )

Thanks again Stuart, you are truly an Acoustic Buddha!

I don't think I've ever been called a "buddha" before! That's a first! And I'm still not all that much of an expert anyway. Acoustics is one of those things where the more you learn, you realize the more there is that you don't know! It's like one of those nightmares where you are running for the door to escape the monster, but the more you run, the further away the door recedes...


- Stuart -