Studio Acoustic Treatment - Help needed :-)

[Milla83]

Man i only just saw your last reply..... so sorry. I have already gone and run a bunch of tests with different amounts of treatment in the room. I have had the computer desk all the way over to the wall on the left hand side of the room for all the test.... sorry i jumped the gun a bit there, my bad!

I do think that this is really the best spot for the desk though, let me know what you'd like me to do next?

Sorry!

[Milla83]

Ok, so I'm going to empty the room tomorrow morning and re run the tests starting from an empty room. Left, right and middle, ill then add the bass traps and acoustic panels i already have with the Polymax XHD and pop it all in the dropbox with notes attached. Do you want Left, right and middle tests done at each stage of adding treatment also?
Hope you've had a great weekend!


cheers, Milla

[Soundman2020]

Ok, so I'm going to empty the room tomorrow morning and re run the tests starting from an empty room.

Great!

Left, right and middle,

Left, right and BOTH!. Will you be using a subwoofer in this room, in addition to the mains? If so, then we need that one as well. If that's the case, the each test would be: A) Sub only, B) Left only, C) Right only, D) Both L and R without sub, E) All three together. If there is no sub, then the sequence will be: A) Left only, B) Right only, C) Both L and R together. Do not change any calibration or settings on your console, interface, speakers or within REW! All tests must be done with the exact same settings, and of course with the mic in the exact same position.

Do you want Left, right and middle tests done at each stage of adding treatment also?

Yes please! It's best to have an abundance of data, then remove the bits that aren't so important later.

- Stuart -

[Milla83]

Hey champ,

Iv re tested the room with Left, Right and both speakers. I'm not running a sub.

Here's the link, iv added info in each of the descriptions. I have tested the room empty, then with corner bass traps and then also with acoustic absorption panels on the sides and back walls. i have left the ceiling free for the moment.
Let me know what you think and what the next move is.... Im guessing perhaps pick up some other acoustic insulation batts?

cheers n beers brotha!

https://www.dropbox.com/sh/tshyqq4p091u ... wm-wa?dl=0

[Soundman2020]

You want the good news first, or the not so good news, or the bad news?

Well, whatever, let's just blurt it all out!

You have several problems.

First is a symmetry problem, and it's a humdinger.... There's some pretty significant differences between what your Left speaker does to the room, and what your Right speaker does. We need to fix that before doing anything else, as you'll never get a reliable stereo image the way it is right now.

First, is there anything in the front half of the room that is obviously asymmetrical? Some item of equipment or furniture on the left side that isn't matched by a similar item on the right side?

Next, tell me about that door: what is made of? Solid-core or hollow core? Good seals around the perimeter? Was it closed for all of the tests?

And finally: how are your speakers set up? Are they arranged perfectly symmetrically around the center line of the room? Exact same distance from each speaker to the wall next to it? Exact same distance from each speaker to the front wall? Exact same height? Exact same toe-in angle? Are the controls set up identically? Are the stands both very heavy, rigid, and solid, and identical?

Any other reason you can think of why the room or the speakers are not symmetrical?

Next issue: the decay rate seems to be showing two different environments: It starts off decaying fast for the first 100 to 150 milliseconds or so, then from there it goes to a slower decay. That usually means that there is a larger room adjacent to this room that is acoustically coupled to it in some manner. Is that the case? That "other" room seems to be about twice the size of this one, or maybe less.

Next problem: Your bass trapping isn't deep enough, and your rear wall panels aren't doing enough. Sad to say, that PolyMax stuff just isn't cutting it. Are you SURE that what you have is their "Absorb-HD" product? It certainly isn't acting like it is supposed to, according to their data.

Also, how are your panels built (the ones on the rear wall)?

What other insulation products can you get where you live? Best of all would be Owens Corning OC-703, so look around to see if you can find that. If not, second best would be any other type of semi-rigid fiberglass panel that has a density of around 30 kg/m3 or a bit less, and/or gas flow resistivity of about 10,000 rayls, give or take a few thousand. Third best would be ordinary "pink fluffy" fiberglass with a density of around 20 to 30 kg/m3, and fourth best would be mineral wool with a density of around 50 kg/m3 or a bit less. See what you can find in your local hardware stores and building supply stores.

Let me know what you think and what the next move is.... Im guessing perhaps pick up some other acoustic insulation batts?

Yep! Good guess!!!! ...


- Stuart -

[Milla83]

First, is there anything in the front half of the room that is obviously asymmetrical? Some item of equipment or furniture on the left side that isn't matched by a similar item on the right side?

The only thing that is unmatched left to right side of the room is the computer desk set up with is what I'm assuming is the problem there..... ill attach a photo.

Next, tell me about that door: what is made of? Solid-core or hollow core? Good seals around the perimeter? Was it closed for all of the tests?

There are 2 solid core doors 45mm thick with good seals around on them, perhaps i have closed the outside one to quickly on one occassion and it has pushed the inside one open a little, the door does sit 30mm recessed from the wall so its not flush with the wall.....

And finally: how are your speakers set up? Are they arranged perfectly symmetrically around the center line of the room? Exact same distance from each speaker to the wall next to it? Exact same distance from each speaker to the front wall? Exact same height? Exact same toe-in angle? Are the controls set up identically? Are the stands both very heavy, rigid, and solid, and identical?

i Just double checked and the left speaker was out by 23mm and the right speaker was pointing lower by a very small margin (2mm) which i have now fixed. I will admit the stands could maybe be a little more solid...?

Any other reason you can think of why the room or the speakers are not symmetrical?

Next issue: the decay rate seems to be showing two different environments: It starts off decaying fast for the first 100 to 150 milliseconds or so, then from there it goes to a slower decay. That usually means that there is a larger room adjacent to this room that is acoustically coupled to it in some manner. Is that the case? That "other" room seems to be about twice the size of this one, or maybe less.

Yes i do have a room next to the control room, if you check my orriginal photo's you'll see there is a live room which is right next to this control room. The live room and control room both come out to a main foyer area. There is a double wall between the control room and the live room, timber frames, gyprock and insluated. Between the main foyer area and the studio rooms there is only one wall which is made of Bessa block, unfortuniatly i was unable to have a completely isolated frame due to space issues.

Next problem: Your bass trapping isn't deep enough, and your rear wall panels aren't doing enough. Sad to say, that PolyMax stuff just isn't cutting it. Are you SURE that what you have is their "Absorb-HD" product? It certainly isn't acting like it is supposed to, according to their data.

Thats what they have sold it to me as, so by the specs they have on it should it be doing a better job? I'f this is the case i will have to get in contact with them about it as i have spent a lot of money with them when setting up my rehearsal spaces....

Also, how are your panels built (the ones on the rear wall)?

Its a square box 140mm x 18mm pine with no backing in it the polymax has been placed in it with some light breathable polyester covering it. They were made to go in a rehearsal room originally, ill add a photo.

What other insulation products can you get where you live? Best of all would be Owens Corning OC-703, so look around to see if you can find that. If not, second best would be any other type of semi-rigid fiberglass panel that has a density of around 30 kg/m3 or a bit less, and/or gas flow resistivity of about 10,000 rayls, give or take a few thousand. Third best would be ordinary "pink fluffy" fiberglass with a density of around 20 to 30 kg/m3, and fourth best would be mineral wool with a density of around 50 kg/m3 or a bit less. See what you can find in your local hardware stores and building supply stores.

I'll start looking into how to get ahold of 703, how much would i be needing as an estimate? Im guessing that its definitely needed for the bass traps but how much more would you expect i need?
Im guessing its best to get ahold of the 703 or equivilent asap to continue test, but then again we still have the issue of the symmetry .....?

Hmmm a few thing to address huh, tell me my next move and I'm on it! I know its not a perfect structure to start with but I'm happy to spend the time it needs to get it as good as possible.


And once again thank you so much, its incredibale the help your providing!

- Milla

[Milla83]

Hi Stuart,

Just thought I'd touch base with you, haven't heard back from you in a little while. Is there something else i'v missed that i should have included posting up?

Hope all is well!

Ryan

[Soundman2020]

i Just double checked and the left speaker was out by 23mm and the right speaker was pointing lower by a very small margin (2mm) which i have now fixed.

Hmmm... I doubt that was it. Some small effect, but not very important.

I'm wondering if the symmetry problem might be the speakers themselves: try swapping them: Put the left one where the right one is and vice versa, then test again.

Yes i do have a room next to the control room, if you check my orriginal photo's you'll see there is a live room which is right next to this control room. The live room and control room both come out to a main foyer area. There is a double wall between the control room and the live room, timber frames, gyprock and insluated. Between the main foyer area and the studio rooms there is only one wall which is made of Bessa block, unfortuniatly i was unable to have a completely isolated frame due to space issues.

It could be that, but it seems to be bigger than what I'd expect from things like that. How about the ceiling? What's up there?

so by the specs they have on it should it be doing a better job?

Can you get plain old Owens Corning OC-703 where you live? If so, get a few panels and put them across the corners and on the back wall, just like they come, straight out of the packaging, then re-test to see how big the change is. If that works as expected, then buy more and put it in place properly. Re-build your superchunks using that stuff, and I would expect to see a large difference.

- Stuart -

[tez]

Can you get plain old Owens Corning OC-703 where you live? I

No OC Downunder, but a close relative is Fletcher FI 32 (as in 32kg/m3)
They also do 48/96 options.
The Tech Sheet below doesn't have all the data that is required these days for Acoustics.
It comes in semi-rigid sheets.
I think I've also seen KNAUF with similar specs, but may only have been on rolls.

http://www.insulation.com.au/Literature ... x?ID=38636
They sell via retailers, and have a location search page.

Last I looked the Polymax site may be dormant, as the Web Enquiry Form failed. Their phone also appeared to be disconnected. An email also bounced back, unknown user..

[Soundman2020]

The Tech Sheet below doesn't have all the data that is required these days for Acoustics

It's not very detailed, but it looks like the 75mm or 100mm stuff would be good. Either faced or unfaced. The 75mm AcoustiFORT faced stuff has a slight advantage, but if there is a big price difference, then the unfaced stuff should work fine too.


- Stuart -