Questions about an ultra-mini room

Hi! Thanks in advance for any answers you have for me, and thanks for the wealth of knowledge I've been going through for the last few weeks/months. I have a tiny room, and by tiny I mean 1.6m wide x 2.41m high x up to 3.2m long. I say up to because I'm intending to shorten the room to get closer to a better ratio (I believe the ratio I'm hoping to get to is 1:1.5:1.6. The door is likely to be in the centre of the back wall, so I can make a door with diffusion or absorption attached to it as required. I know what you're all thinking at this point, and the good news is, this is not a room that will make me money, and I'm not a professional music maker, I just really want to do the best I can to make the most of a bad situation. As such, I can happily live with "not ideal", I'm really just here hoping to get some feedback before I go down the completely wrong path. Some additional good news is that the only other essential item in this room is my chair; no consoles, desks (sound or office), perhaps just a small place to put a keyboard and mouse. Oh, and a monitor (display) which unfortunately is very large for this room (approximately 70cm across). What I have determined so far is that I'm really keen to try soffit mounting my speakers (and I do mean speakers as opposed to monitors, they are Audioengine A5 powered speakers which do indeed lack a -6db switch, are rear ported, and have an amplifier inside.. yes they are worst case but again, this isn't a room to make money out of). I'll be allowing plenty of air flow as per the designs that float around these and other forums, and may even add some low speed fans to force a little extra air through the channel if cooling is insufficient. The bass boost I hope to deal with via EQ. Soffit mounting suits the visual aesthetic I'm hoping to achieve for the room, sounds like a fun project, and importantly will hopefully resolve some of the issues I was having finding a good placement for the speakers within the room (which I know is more to do with room modes and a lack of treatment at this point). Ok, first question! Because the room is too small to angle the front walls for a RFZ design, I'm intending to place a whole lot of absorption to my left/right. This puts the trapping right against the corner of the soffit baffle, is that a problem? Secondly, the lack of width has me wondering if it would be advantageous to remove a section of drywall to allow me to double the depth of treatment. I realise isolation is going to take a serious hit here, but this room is a fair way away from my (rarely) sleeping baby, and long term I hope to add isolation on the outer side of the wall if noise is an issue. I don't intend to be listening to things amazingly loud anyway. Ideally I would prefer to just use treatment within the area between studs so that the area either side of me is flush with what is the existing wall, otherwise (to remain a neat appearance) I will have to start overlapping the insulation over the soffit. Is that an issue? As I mentioned, I can adjust the length of the room somewhat, by building the front wall out from the wall (giving me space for a soffit cavity and leg room under the centre of the wall (where the monitor will be mounted flush). Is the back half of the room best used with massive angled fibreglass bass traps (like superchunks only not 45 degrees, wide enough for a door way but creating angled walls towards the front of the room) or is it worth trying to mess with the angle of the back walls. I do have a subwoofer that I hope to squeeze in here too... which I realise is probably a bad idea for this size room, but my aim is something of a home theatre room for one in my downtime that I can also use for some music making experimentation, music listening, gaming, etc. A quick question not directly related to room design; I'm hoping to use a 4.1 speaker setup (no centre) with a phantom centre, but using 5.1 sound mixes. Is it a stupid idea to try to get hold of a stereo mixer and a y splitter, and mix the centre channel equally into the left/right channels? Another room design question; can ratios be used in the wrong axis like I'm doing? I'm sure no one ever intends for the shortest dimension in a room to be the width, followed by the height, so do the ratios still apply? I know sound doesn't know about up/down etc (as someone here pointed out recently). One thing I haven't mentioned, I hope to create a cloud of some kind or angle the roof, or both. I'm sure I've left other things out too so feel free to point them out anyway! I hope I'm not out of line asking professionals questions about such a horrible abomination of a project! Thanks for reading! Cheers, Aaron

Hi Aaron, and welcome! :)

I have a tiny room, and by tiny I mean 1.6m wide x 2.41m high x up to 3.2m long. I say up to because I'm intending to shorten the room to get closer to a better ratio (I believe the ratio I'm hoping to get to is 1:1.5:1.6.

You can check your dimensions using both Andy Mel's calculator, and also Bob Golds': http://amroc.andymel.eu/ http://www.bobgolds.com/Mode/RoomModes.htm The dimensions refer to the final hard boundary surface of the room, without treatment or furniture.

The door is likely to be in the centre of the back wall, so I can make a door with diffusion or absorption attached to it as required.

The room is too small to use numeric-based diffusers. I would use only absorption and maybe slot walls for a room that size. Numeric-sequence diffusion is only appropriate for large rooms.

the only other essential item in this room is my chair; no consoles, desks (sound or office), perhaps just a small place to put a keyboard and mouse. Oh, and a monitor (display) which unfortunately is very large for this room (approximately 70cm across).

And maybe some speakers too? :) :shock: :!: :shot:

What I have determined so far is that I'm really keen to try soffit mounting my speakers

Excellent! That's probably the single most important thing you can do to improve the room acoustics. Smart move.

and I do mean speakers as opposed to monitors,

Mmmmm... I don't plan to start a debate on that point, but from my point of view, "speakers" and "monitors" mean pretty much the same thing. The only real difference is the amount of marketing hype... :)

they are Audioengine A5 powered speakers which do indeed lack a -6db switch, are rear ported, and have an amplifier inside.. yes they are worst case but again,

They don't look so terribly bad to me! Frequency response is listed as "50Hz-22kHz ±1.5dB": Pretty respectable if true. OK, so they come as a pair with the electronics all in the left unit, and the right unit is just a satellite basically, but if they are well designed then they should work fine. And if that's what you've got, with no plans to upgrade, then that's what it will have to be! However, you will need a cross-over do the bass roll-off for you. There's large number of units to choose from there, but get a good one, hopefully linear phase, and with a good range of adjustment for cross-over points, levels, and hopefully even delay, in case you add a sub one day and want to fine-tune it.

I'll be allowing plenty of air flow as per the designs that float around these and other forums, and may even add some low speed fans to force a little extra air through the channel if cooling is insufficient.

Convection cooling is normally plenty.

The bass boost I hope to deal with via EQ.

You can't do it with a graphic equalizer: it would have to be a parametric equalizer that has a proper shelving filter for the low end, or better still a cross-over unit, like I mentioned above, with independent level controls and a good range for the cross-over point. If it has adjustable slope too, that's an extra bonus.

Because the room is too small to angle the front walls for a RFZ design, I'm intending to place a whole lot of absorption to my left/right. This puts the trapping right against the corner of the soffit baffle, is that a problem?

That's fine. No problem.

Secondly, the lack of width has me wondering if it would be advantageous to remove a section of drywall to allow me to double the depth of treatment.

You could extend that concept to the entire wall... :) This is commonly done with "inside-out" walls, or with the outer-leaf of an isolation wall. Take off all the drywall on your side of the wall, take out the insulation (if any), then cut strips of 5/8" dryall to fit in between the studs, pushed up tight against the drywall on the other side of the studs, sealed around the edges with caulk, and held in place with cleats. You are adding a lot of mass there, and improving the seal, so you might even get a slight increase in isolation. Then put good suitable insulation in the stud bays, and cover the wall with fabric, instead of drywall. Or do a slotwall... That would gain you many benefits, starting with a room that is about 6 inches wider than it was, better isolated, better damped, etc.

long term I hope to add isolation on the outer side of the wall if noise is an issue.

If you can add another sheet of 5/8" drywall to the far side of that wall at some point, that would increase your isolation by about another 5 or 6 dB. Worth doing.

Is the back half of the room best used with massive angled fibreglass bass traps (like superchunks only not 45 degrees,

Yes!

is it worth trying to mess with the angle of the back walls.

Not really. Just leave it flat, put superchunks in the corners, then cover the rest of the rear wall with 703 or something similar.

I do have a subwoofer that I hope to squeeze in here too... which I realise is probably a bad idea for this size room,

Not a bad idea at all! Subs extend the range of the speakers down lower, which is a good idea, if properly adjusted. Yes, you do run the risk that they might trigger some modal responses that would not have been triggered otherwise, but you also get to hear your entire mix! And if you do the bass trapping right, then the modal response shouldn't be too much of a problem.

A quick question not directly related to room design; I'm hoping to use a 4.1 speaker setup (no centre) with a phantom centre, but using 5.1 sound mixes. Is it a stupid idea to try to get hold of a stereo mixer and a y splitter, and mix the centre channel equally into the left/right channels?

I wouldn't do that, no. The center channel is a separate channel, and there might be phase cancellation issues if you mix it back in with other channels. Is there any reason why you don't want to do a proper 5.1 setup? 4.1 isn't really a valid multi-channel arrangement...

Another room design question; can ratios be used in the wrong axis like I'm doing? I'm sure no one ever intends for the shortest dimension in a room to be the width, followed by the height, so do the ratios still apply?

Sure! As long as you know which way around your room is oriented, that's fine. Ratios only tell you about the modal response of the room, not the orientation. By convention, the initial "1" refers to height, but as long as you are aware that in your case the axes are flipped around, and make the necessary mental adjustments when thinking of where treatment needs to go, then that's fine. Of course, your listening position still needs to be in the correct acoustic location in the room, so you need to take that into account as well. - Stuart -

Thank you so much for the reply! I'm at work at the moment but I wanted to quickly let you know that I appreciate such an excellent response!