Cube : Soffit Angles / Speaker Converge Point

So my studio is comming together with the inner cavity wall nearly completed, and now is the time when I need to start considering the acoustics of the room. Room Size: Width: ~3.06 Meters Length: ~3.14 Meters Height: ~2.6 Meters Obviously this is bad bad bad, but its what I've got. Plans are to soffit mount the speakers (Event 20/20 bas V2's); Slat absorbers for the first 2/3 of the room, then absorbsion at the back. The rough design shows approximately how this is going to look. Before I can really consider the sizes of everything else in the room I need to find where the best place for the speakers is. As you can see by my sketch 45 Degree angles seem to give the best options as the speakers will converge nearer the monitoring position. My main question for this post is whether I should stick to the standard 30 Degree angles and have the speakers converge well into the room, or to use 45 Degree angles to allow the speakers to converge closer to the mix position? Also, would it be best to use "Superchunk" style trapping at the bottom half of the soffit or Hangers? Once I've decided on the soffit wall I'll be able to go into more detail about the rest of the room treatment. Thanks, Gareth. p.s, the sketchup file is included if anyone wants a play with it. [Edit:] Just a point to say I want the window in the room, so building a wall across it won't be an option. Thanks again, Gareth

looks good to me. the sidewall resonators all look correctly placed, very nice work.

Ahh I must admit a lot of that is courtesy of John. My first design was a little more basic:P Glad it looks "in order", been reading quite a lot of relevent threads and just using ideas to fit my needs. Any comments on where I should make the speakers converge? Further back in the room at 60 Degrees or closer to the mix position at 45? Thanks for the comments, Gareth

i think the soffit view if correct - position the convergence point about a foot (30cm) behind your seated position. if 60 degrees does that, then fine, if its 45, thats also fine. the next step is to determine what kind of reflections you might have with either position and treat accordingly.

Thanks for that! Thats cleared things up. Once I design the soffits then I'll be able to design the acoustic treatment to exact measurements, but as the picture shows, I'm pretty sure what I want to do with that. I just used Real Traps' Mode Calc to get some calculations for my room and came up with the following graphs. Im not quite sure how to interpret them. I've also added a calculation with the "ideal" room ratios, and my response doesnt seem to differ a huge amount, in that at least the graph has a similar shape? In the frequency table, are all the numbers places where modes will be excited? Given the results of the calculation, what would you reccomend for treatment? The slat resonators can get tuned to some of the frequencies, but obviously there's a lot there! I'm assuming it would be best to tackle the ones where there are several modes bunched together, for example 270 - 280 ish? I know due to the room size and shape I won't be able to make it perfect, but I may aswell do the best I can. Tomorrow I'll try to give the "are my speakers in a null" post a read and do the calculations on there. So basically the question is: What frequencies should I try to centre the slat absorbers at, and where can I expect problems around the listening position? Thanks for the input, Gareth

one thing - small volume - small dimensions mean room modes will be spaced apart or grouped rather than evenly (or better) distributed. and because the width and length are close, the modes will be close. in your chart, 55, 112, and 168 should be targets - keeping in mind you want to use broadband initially and then after you construct the room and do the basic treatment, measure and then do final treatments on any remaining problem frequencies.

Ahh right yeah I'm with you now. Thanks for that:) Yeah, I'll be measuring the room once its built so that I can get some exact measurements using RoomEQ Wizard. The broadband traps will be the first in after the soffits, followed by the slats which I'll then try to tune near the problem frequencies. On the rear wall I'm considering using a membrane absorber as shown in Sound on Sound. Would this be preferable to just rockwool? (The trap would be 1200mm x 1200mm x 200mm), and the bottom half of the wall will be a gobo on wheels, so it can be used while tracking and put back while mixing. Thanks again, Gareth

On the window wall, below the window I have allowed 200mm for another limp mass absorber as shown in my previous post. Would it be better to use the space to push the mixer closer to the window so that I could get a bit further from the mid point of the room? Just wondering what would have a better effect on the sound: Another bass trap, or more "room" around the mix position? Thanks, Gareth

One problem with a 45-degree angle in a nearly-cube room is that the ideal listening position will then be almost exactly in the center of the cube/room. This is not the best place, it will almost certainly exhibit a null or a peak. Remember the 38% rule.... I'd put the listening position there, and angle the speakers accordingly. In that small of a room, I'd probably go 38% out from the rear wall.

Yeah, I've taken the 38% from the front though, because 38% from the rear wall would just leave too much unused space at the front of the room. Not ideal perhaps, but I need to make a compromise between space and sound too. Unless you mean make the speakers converge at 38% from the rear of the room and sit in the position shown on my diagram (38% from the front)? Thanks, Gareth

just to follow up with previous questions you've asked in other threads - the slat resonators will be (slightly) diffusive as well as absorptive. the angled versions John drew for you will be broadband in nature and if you look at the wall unit designs, you'll get a sense of the range for them - which should mostly address the modes in your room. generally speaking, the angle of the soffits will depend on your monitors, space, desk, etc - but ultiimately you want a balanced equilateral triangle. the SOS absorber was geared toward a vocal booth more than a larger room - it might work but i'm not certain its effectiveness in louder volume or lower frequency situations - as compared to hanger traps or slat resonators, or superchunks.

the slat resonators will be (slightly) diffusive as well as absorptive. the angled versions John drew for you will be broadband in nature and if you look at the wall unit designs, you'll get a sense of the range for them - which should mostly address the modes in your room.

Thats good. Should be able to get more accurate measurements using roomEQ once its built, so I can try to tune the slats to any problem frequencies.

generally speaking, the angle of the soffits will depend on your monitors, space, desk, etc - but ultiimately you want a balanced equilateral triangle.

Yeah, I think its going to have to be a bit of a compromise really, but I can get a *good* spot (on paper!) with 45 Degree angles, so thats probably going to have to do it.

the SOS absorber was geared toward a vocal booth more than a larger room - it might work but i'm not certain its effectiveness in louder volume or lower frequency situations - as compared to hanger traps or slat resonators, or superchunks.

Okay, I'll check that out over on the SOS forums. To be honest, I might use it anyway, as its probably a little more effective than just rockwool on its own (unless you suggest otherwise?), and I don't really want slats there as it would look odd. I could cover them, but I'm not sure it would really be worth the effort because the space available isn't really very big, so probably won't be able to tune the slats to a low enough frequency. I'll do some checking up and calculating on that. Thanks for your help. I'll design some soffits in the next week and post them up for review. Gareth