Studio Acoustic Treatment - Help needed :-)

Hi Team hows it going? Milla here from Sydney, Im looking for some help with setting up my control room I'v spent some time looking around this forum and its fantastic, love it! I run small rehearsal studio with 3 rehearsal studios, I'v decided to step into recording, so off the side of one of my rehearsal rooms iv built a control room. I have a background in construction so the build was quite simple for me. I am however a little stumped with how to attack the acoustic treatment within the room. Iv read through the tutorials on this site but Im still having some trouble grasping it. How to approach setting up with helmholtz resonators and such, how to configure the right balance Control room The room i have is 3.87m wide x 4.23m long and 2.38m high (I have taken some photo's to help, the baffles in the shots are from when i was about to use it as a rehearsal room but than changed my mind and decided to turn it into a control room). All walls have 3 layers of firecheck gyprock and the ceiling has 2 layers.The floor has carpet (Im going to put in a square section of timber flooring under the mixing console chair area. I also have a pleather (fake leather) couch at the back wall 2m wide by 80cm high. In the centre of one wall which is to you left when you walk in the room (wall 3.89m wide) i have put in a window that is 1.30m wide by 1m high which is at an angle of 5 degrees pointing down. The bottom of the window is 98cm of the floor. In front of the window is my Soundcraft Mixing console 2.2m long x 80cm wide, my computer will be on a small desk on wheels Here's where its a little tricky... (I think) The door to the room is 82cm wide and (facing the window) is on the left side of the room, looking from the inside of the room the door is only 32cm back from the wall with the window. So when you open the door from outside your looking directly inline with the console. Not perfect i know but this is what the building had for me to work with. I feel this restricts me from having the walls fanning out from behind the console like in many of your studio designs on this forum. The room is obviously quite small so Im hoping i can work within the wall i already have standing as space is an issue. Here's some shots and a floor plan i drew up.... forgive my architectural skills are lacking somewhat :-) I also have a bunch of Polymax Acoustic insulation made by Martini CSR Australia left over, enough to cover all the walls 150mm deep (If it were needed). I have MBA 32kg per/m3 sheets at 100mm thick and 50mm thick http://www.polymaxinsulation.com.au/dow ... _Sheet.pdf http://www.polymaxinsulation.com.au/dow ... _Guide.pdf I also would like to ask a few things about my live room acoustics but one thing at a time i guess :-) If your able to give me some direction I would so so happy as Im feeling a little lost at the moment. My budget is only 1- 2k But bare in mind i already have a bunch of timber and insulation. I'd love some advice on how to go about laying this room out acoustically for a great mixing environment if possible? I hope I have included enough information, please tell me if you need more All the very best! Milla

Hey guys hows it going? Milla here again So i'm about to start fitting out my room within the week as i have set myself a deadline to have it finished by the 1st of September. From what I have picked up Im thinking of building pannels on my walls on the left and right side of my console where my line of sight (while using a small mirror) reflects back to my monitor speaker cone, and having the pannels angled by at least 12 degrees towards the back of my room. Using the products i have mentioned above in my previous post I plan on lining the walls with the insulation to deaden the room and also to have corner bass traps like in my photo's in above post. Im still a little unsure of some asspects of weather/ how to build the right diffuser for my back wall and weather or not i need to include resonator's.. I'd love a little advise if anyone can help :-) Thanks a bunch in advance, hope everyones feeling great! Milla

Hi Milla, and Welcome! :)

The room i have is 3.87m wide x 4.23m long and 2.38m high

A reasonable size, and the ratio is OK too. There shouldn't be anything out of the ordinary with modal response there.

All walls have 3 layers of firecheck gyprock and the ceiling has 2 layers.

On the inner leaf, or the outer leaf? Or on both leaves?

The floor has carpet (Im going to put in a square section of timber flooring under the mixing console chair area.

Actually, it should really be the other way around! There should be no carpet on the floor (since large areas of carpet do nasty things to acoustic response, and also psycho-acoustic perception), with just a small section of carpet under the mix position, if needed.

i have put in a window that is 1.30m wide by 1m high which is at an angle of 5 degrees pointing down.

The angle isn't necessary for any acoustic reasons, and in fact could damage the room isolation (because the MSM gap is now smaller at the bottom of the window than at the top, and the smallest distance for cavity depth is what defines isolation). But if you already have it in, and you are getting enough isolation, then that's fine.

my computer will be on a small desk on wheels

Are you SURE you want to do that? Changing the position of furniture can change the acoustic response of the room. You'd be hearing different things with the desk in different positions... It would be better to have it fixed in only one position.

I feel this restricts me from having the walls fanning out from behind the console like in many of your studio designs on this forum.

Those are only really needed if you are going to do a proper RFZ design for the room, and it seems you are not doing that, because the room is already finished. That door does, indeed, limit your options. If you did want to do an RFZ room, then the options open to you are to either move the door (which is probably not as big a job as you might imagine), or to flip the room 180° so it is facing the other wall. That would allow you to do it, but of course then you'd have your back to the window, and no place to put your rear wall treatment, which is critical for control rooms. So I'd suggest moving the door, if you want an RFZ design. If that's the case, I'd also suggest soffit-mounting your speakers, which is a big part of a successful RFZ design in any case! If you don't want (or can't) get an RFZ design, then just go with a plain rectangular room, which can also work very well provided that you do the correct acoustic treatment for that.

I also have a bunch of Polymax Acoustic insulation made by Martini CSR Australia left over, enough to cover all the walls 150mm deep (If it were needed). I have MBA 32kg per/m3 sheets at 100mm thick and 50mm thick

That could be useful for your first reflection points, but not much use for your rear wall or superchunk bass traps. The low frequency characteristics just aren't that good. You will need something like OC-703 for that. To give you an example, 75mm of OC-703 has a coefficient of absorption of 0.53 at 125 Hz, compared to 0.4 for your stuff, and 1.19 at 250 Hz, compared to 0.85. (I'm assming ASTM-A mounting in both cases, even though the Polymax specs don't say. If it was E-405 mount, then the OC-703 specs are even more impressive, with 0.66 at 125 Hz.) So you'll need to get some better stuff for your bass trapping and rear wall.

I'd love some advice on how to go about laying this room out acoustically for a great mixing environment if possible?

On a tight budget, I would keep it rectangular, keep the speakers on stands (they must be very massive! Extremely heavy), and set them up as follows: 114 cm from the side walls, which implies they will be 161cm apart (I am talking about the acoustic axis of the speaker, of course: not the edges of the box). Adjust each stand stand so that the acoustic axis is about 1.2m above the floor, rotate the speakers about 28° inwards, and set up your chair so that your ears will be about 172 cm from the front wall when you are mixing. Adjust the speaker stands so that the rear edge of the speaker cabinet is about 10cm from the front wall (which leaves just enough space to put in some good absorption behind it, to help a bit with SBIR control). That geometry will set the intersect point for the speaker axes about 30cm behind your head., and places your ears at about 142 cm from the speakers. An easy way to get the speaker toe-in angle correct is to set up a mic stand with the arm vertical, so that it is 172 cm form the front wall, exactly on the mid-line of the room. Set up a laser pointer on top of each speaker, exactly above the acoustic axis, and exactly perpendicular to the front baffle (if you don't know where the acoustic axis is on your speakers, ask the manufacturer, or just assume that it is about 90% of the distance between the center of the woofer and the center of the tweeter: That's not precise, but close enough). Now turn each speaker so that it is pointing at the mic stand, and the laser hits the middle of the mic stand arm, while at the same time the acoustic axis of the speaker is the correct distance from the side walls. When the lasers on both speakers are hitting the same spot on the mic stand, then you have the angles correct. That's not ideal (the sweet spot will be a bit narrow), but it's about the best compromise I could come up with for that shape and size of room. It's pretty darn good, though! With the speakers set up like that, try tweaking things just a a little each way while you play music that you know really well, to see if you can get a noticeable improvement. For example, move the speakers a couple of cm further apart or closer together, and/or change the toe-in angle by one or two degrees. You might get a useful change, but I'm betting there won't be much difference. When you have them in the best position, confirm once again that they are both at identical distances form the side walls and front wall, and they are both aimed at exactly the same point, about 30 cm behind your head. Now that you have your geometry correct, put the desk, console and other furniture in the room such that it is all comfortable for you, without moving the chair at the mix position! In other words, move the console, rack gear and computer desk until you can operate them comfortably with the chair in the correct position. Now do a measurement of the room response using the REW acoustic software (which is free!) and a good measurement mic (should cost around US$ 100). Do make sure you fully calibrate REW before you test! You'll need a quality sound level meter to do that (also around US$ 100: avoid the Chinese toy junk ones that go for under US$ 50): Post the MDAT file from REW some place where we can download it to do the analysis, then we can suggest what treatment you will need. Do the first test with no treatment at all in the room: that's your "baseline" test, and it reveals all of the "ugliness" of the room's acoustic response, which is what we need to see in order to figure out your treatment. When you measure, set up your mic exactly where the middle of your head will be while seated at the mix position. Make sure you are not in the room while the test runs (use the "delay" feature to give you enough time to get out, close the door, and a few extra seconds for things to settle down after you leave).

From what I have picked up Im thinking of building pannels on my walls on the left and right side of my console where my line of sight (while using a small mirror) reflects back to my monitor speaker cone,

Yes, you will definitely need those. Those are your "first reflection points". You could use the Polymax XHD stuff for that, 100mm thick. Make the panels big: at least 1.5m high and at least 60cm wide. If you can spare the room, then space them away from the wall by another 10 cm, or more of you can. And don't forget the first reflection point on the ceiling! That's a big one, and VERY important. I would probably hang hard-backed cloud up there, in your case. Make it wide and deep, and put at least 15 cm of XHD in there, then another 10cm at least on top of the hard back.

and having the pannels angled by at least 12 degrees towards the back of my room.

Not necessary. That would just take up extra space in the room, and it is already narrow. Just leave them flat against the wall, or angle them a bit if you want, but it won't make a huge difference. 12° is the angle for splayed walls to get rid of flutter echo, but you don't¿t have the space (or the budget) for that, and absorption panels do the same job.

I plan on lining the walls with the insulation to deaden the room

:shock: :!: Not a good idea!!!! A dead room sounds terrible! The concept of control room treatment is to make it neutral, not dead. You want the frequency response and decay response to be as smooth and neutral as possible, with the overall decay time in keeping with the room volume. There are equations for calculating all that, but with a room that size I'd shoot for an overall decay time of around 200ms, or as close as you can get to that (it will probably end up less than that, unfortunately, but we can try to improve it). So do not cover your walls with that stuff! The correct approach to control rooms like this where there are so many unknown factors, is to start with the baseline test, then do a series of measure - treat - measure - treat - measure - treat until one of three things happens: 1) you get perfect response, totally flat in both frequency and time domain, except for a 20 ms ITDG, followed by smooth and even decay across the entire spectrum. (This is the least likely of all outcomes, but it is the goal you are shooting for). 2) You run out of money. 3) You run out of patience. Number two is the most likely outcome... :)

also to have corner bass traps like in my photo's in above post.

Definitely! You will most certainly need those, and probably more besides in the other room corners. It's a small room, so it will need heaps of bass trapping. But don't use the Polymax stuff for those: wrong characteristics. See if you can find proper Owens Corning OC-703. That's what you need for those things.

Im still a little unsure of some asspects of weather/ how to build the right diffuser for my back wall

No. Your room is not big enough to be able to have diffusers on the rear wall. Or at least, not tuned diffusers (such as Schroeders, skyline, QRD, binary, etc). You need at least 3m between your ears and the diffusers for that to be possible, and you won't be able to get more than about 2m or so. Maybe 2.4, best case, but still not usable. Your best bet for rear wall treatment, is just 15 to 20 cm of OC-703, or something similar. You could do that just for the top section of the wall (1m above the floor, upwards to the ceiling) if you wanted, but doing the entire wall would be better.

and weather or not i need to include resonator's

Perhaps... but only REW will reveal that! :) - Stuart -

Stuart, your an absolute legend, thank you so much for all this info!!!! Still quite amazed at the detail and help that is provided through this site, i will be making a tasty donation for sure!! At this point unfortunitly I am unable to move the door posintioning due to costs and deadlines, but by the sounds of it i will be able to use some of the polymax at a few points so its looking like (hopefully) i will only need to purchase some extra foam 703 or similar (not sure if its sold in oz). I'll keep the room rectangular as a pose to the RFZ design due to cost and deadline ....... and the door position The walls have 3 layers of gyprock on the inside of the room which are stuck to concrete walls, except for the wall the joins with the live room which is a double stud timber framed wall. I will put some timber flooring in also as suggested, the computer desk is on wheels for maintenance and to make accessability to the back of the console easy. It will be kept in the same position while working. I did at one point think about having the computer monitor on a wall mount which i could move around depending on if I'm tracking or or not and have it placed behind the console where the window is, (like this type- http://www.amazon.com/Cotytech-Apple-Mo ... B007F1QEUW ). The idea was that i could move it lower or to the side so i can see into the live room while tracking and then just position it to a better viewing position when mixing..... what are your thoughts on that idea? It would make for more space in the control room. I have downloaded the REW software and ill get the new flooring in, set up and run the test. As for a measurement mic would a neumann TLM 102 work fore this or are there some spercific mics you would recomend? Ill get to work on getting the room ready to run the tests, would love to know your thoughts on the computer monitor positioning too? Once again thanks so much for everything so far, so amazing! All the best! Milla

At this point unfortunitly I am unable to move the door posintioning due to costs and deadlines, but by the sounds of it i will be able to use some of the polymax at a few points so its looking like (hopefully) i will only need to purchase some extra foam 703 or similar (not sure if its sold in oz). I'll keep the room rectangular as a pose to the RFZ design due to cost and deadline ....... and the door position

Sounds like a solid plan.

The walls have 3 layers of gyprock on the inside of the room which are stuck to concrete walls,

:shock: Whoa!!! If I'm understanding you correctly, you attached drywall directly to existing concrete walls? Is that correct? If so, then the question is: "WHY?" What's the reason for that? There's no acoustic reason to do that. The density of concrete is around 2200 kg/m3, and I'm guessing that the the walls are probably 15cm (6") thick, so you have a surface density of around 330 kg/m3. The density of drywall is about 650 kg/m3, and each sheet is normally 16mm thick, so the surface density of that would be around 10 kg/m2. So all three layers of drywall together don't even add 10% to the total mass of the wall. The surface density would go up from 330kg/m2, to maybe 360 kg/m3, which would have no noticeable effect at all on isolation of the room. You would have to double the surface density to have any usable effect, and that would require that you add thirty three layers of drywall... a total of over half a meter thick! So basically, three layers of drywall attached to concrete does nothing at all. It does not change the isolation, and has very little effect on room acoustics too. You also said that the drywall will be "stuck" to the concrete: That implies you plan to use glue to attach the drywall to the concrete? Not only is that not safe, it is probably also not legal! I doubt that your building code will allow you to do that. Drywall is basically just hardened gypsum wrapped in thin cardboard. If the cardboard delaminates from the gypsum then the gypsum will fall off. It is heavy, and can cause serious damage, injury, possibly death. It has happened before, which is why it isn't permitted in most places. Drywall must be attached with suitable fasteners that penetrate through the sheet and into the substrate. Normally, that is nails or screws. So even if it was worthwhile attaching drywall to concrete, you would not be able to do it with glue. You'd need to drill dozens ( hundreds of hole in the concrete, insert plastic or wood anchors, then screw into those. But maybe I'm just not understanding correctly what you said about "three layers of gyprock stuck to concrete walls". IF that's the problem, then maybe you could explain the plan in more detail? If you already have that situation I'd strongly suggest that you should either take off the drywall and just stay with bare concrete as your walls (and gain some extra room volume), or drill holes and use suitable screws to make sure that the drywall is held in place safely.

I will put some timber flooring in . . .

I'd suggest laminate flooring as being your best option. It looks just like real wood. It also installs much faster, wears much better, is great acoustically, and probably cheaper. This is the stuff I had in mind: http://www.bunnings.com.au/search/produ ... ctFrom=Any https://www.masters.com.au/flooring-til ... e-flooring

The idea was that i could move it lower or to the side so i can see into the live room while tracking and then just position it to a better viewing position when mixing..... what are your thoughts on that idea? It would make for more space in the control room.

You could do that, as long as you are aware that moving it will change what you are hearing, and probably more than you expect because it is right in front of you, close to your ears. A few years back I designed a control room for a studio in Belgium where they had a similar request. I used a larger flat screen (44 inch, IIRC) up against the front window, mounted on a motorized lifter mechanism that raised it out of the line of sight, above the window, but still visible, for tracking sessions, then lowered down in front of the window again for mixing sessions. That placed the moving surface much further away from the ears of the engineer, and very close to the front wall surface, where it did not interfere with the direct sound from the speakers, and had little overall effect on the overall room acoustics. You could do something similar.

As for a measurement mic would a neumann TLM 102 work

Nope, unfortunately not. That's a great mic, but not for acoustic measurement. It is cardioid and has deliberately non-flat response, since it is meant to be a vocal mic. For acoustic measurement, it has to be an omni mic with perfectly flat response down to very low frequencies. I normally use a Presonus PRM1, but I also have a Behringer ECM8000. DBX and others also have good measurement mics that are not too expensive (around US$ 100, +/-). It also works very well as an instrument mic for many situations, so it's not wasted money; you can add it to your collection of mics, and I bet you find more than just a few uses for it. - Stuart -

Yep i made a mistake with all the extra gyrock, i should have left it with one layer on the walls simply to give them a nice finish. Wasted a couple of bucks there. Structurally they are sound, they were screwed and glued on with a massive amount of fix points. Yes the laminate timber flooring is also the type i was thinking too I have a Rode K2 large diaphragm condencer with has omni directional settings, that would be my next best option. If thats not worthy ill go buy something? cheers Milla

I have bought the personus prm1 mic, ill get set up and run the test asap :D

Hi Stuart, Iv run the text, whats the best way to share the results with you, shall i place the saved measurements folder in dropbox and add you? What works best for you? YEWW! Im excited!

Upload it to DropBox (or any other file-sharing service) and post the link here. - Stuart -

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

Well this is cool! Seldom do I see such a perfect match between prediction and reality! Here are two graphs about your room. The top one shows the predicted modal response, and the bottom one shows the actual modal response that you measured: Textbook perfect! Your axials are crystal clear, your first few tangentials are fairly well defined, and there's even a good hint of a couple of obliques. It's not often that you get such a close match. Congratulations! It means you measure the dimensions of the room accurately, and you also ran the REW test very carefully. OK, but the obvious conclusion is that the room sounds like crap right now! (Pardon my French...) Those are some pretty big modal issues. You can see the decays better on the waterfall plot: And also on the RT60 graph: Not a pretty sight! The good news is that since your problems are so clearly defined and so predictable, they are also relatively easy to treat. First order of business is to define the target RT60, and I'd suggest about 200 ms for this room, give or take a bit. That should be doable. Second order of business is bass traps. Big ones. But there's a big question here, too: What treatment did you have in the room when you did this test? Your photos show superchunks in the corners, absorption on the rear wall, and a small cloud on the ceiling, but those are not very evident in the REW graphs at all! So I'm guessing that either you took them out for the test, which is great, or if that's not the case, then they are not working. If the treatment really was in the room when you tested, then please describe exactly how each device was built (what materials and dimensions), so I can figure out why it isn't working. On the other hand, if it was NOT in the room for the REW test, then please put it back in now, and do another REW test. - Stuart -

Haha, wow thats awesome! and i loved the way all your comment's were uplifting and then the french phrasing of reality set in :-) perfectly placed! Cool, so yes i took all of those bass traps, panels and all acoustic treatment out so we could start off with a true test of the room. All i had in there was the console, monitors, computer desk with computer and the couch at the back of the room. I ran the test twice with the computer desk in 2 different spots, i was wondering if there was any difference between them. The first test the computer was in my most committable position where if i turn to my right from the sweet spot i can reach it easily, the other spot was pushed over to the wall on my right hand side.... do you have an opinion on this? Anywhoo, ill set up and run a couple of tests ill do one with the bass traps in just the corners Then with some panels added to the room this is awesome!!

Cool, so yes i took all of those bass traps, panels and all acoustic treatment out so we could start off with a true test of the room.

Excellent! I figured that was it, because there's no sign of any useful treatment in there. OK, so we have a great baseline acoustic profile of the room. Time to put things back in, bit by bit, and run another test each time, with the mic in the exact same location! That is critical. If the mic is not in the identical location for each test, then we can't validly compare them.

I ran the test twice with the computer desk in 2 different spots, i was wondering if there was any difference between them.

Oh yeah! There are noticeable differences. Take a look: The purple line is the first test, and the light blue line is the second test. I did 1/24th octave smoothing on both of those curves, to make things a bit more clear. You can see the difference for yourself. Below 80 Hz, there's practically no difference (expected), but there are many differences across the entire mid range, up to about 2 kHz, with minor differences above that up to 12 kHz, then bigger differences there again. In some places the differences are as big as 5 or 6 dB, although most of them are around 2 or 3 dB. This is what I was talking about when I said there would be differences if you had a mobile desk that you moved around.

The first test the computer was in my most committable position where if i turn to my right from the sweet spot i can reach it easily, the other spot was pushed over to the wall on my right hand side.... do you have an opinion on this?

From the point of view of frequency response, neither one of those two is amazingly better or worse than the other, so you could go with whichever you prefer. But from the point of view of reflections, the second position introduces a very strong reflection at about 24 ms, so from that point of view, I'd go with the first position. And in the time domain, the second position does quite a bit of not-so-good stuff, it seems, so here too, I'd go with the first position. HOWEVER! We are only looking at a test with BOTH speakers on! That tells you a lot about the room as a whole, but we also need individual tests with just the left speaker, and just the right speaker (before you put the treatment back in the room!!!!), with the desk in both positions, to see how it is affecting the stereo imaging and sound stage. So please do another test with just your L speaker on, then one with just your R speaker on, and finally with both speakers on again, just as a confirmation. Then move the desk and repeat all three of those tests (L only, R only, both). Then start putting the treatment in bit by bit, and do the set of three tests (L, R, both) at each stage. The more tests you do, the more data we'll have for comparing, to see just how well the treatment is working. Oh, and please label each test in REW! There's a small field at the top left of each measurement where you can do that, and a larger space underneath each test where you can add more extensive notes if you feel like, such as which pieces of treatment you had in place, and the location of the desk. - Stuart -

Hey champ, Iv just run a few tests and uploaded the new results to the dropbox for you to check out. I did a couple of different set ups and have added notes to each one describing the set up. YEW! :yahoo:

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!

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

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 -

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

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 -

Soundman2020 wrote:

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.

Soundman2020 wrote:

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.....

Soundman2020 wrote:

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...?

Soundman2020 wrote:

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.

Soundman2020 wrote:

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....

Soundman2020 wrote:

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.

Soundman2020 wrote:

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 :-)

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

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 -

Milla83 wrote:

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/LiteratureRetrieve.aspx?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..

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 -