John Sayers' Recording Studio Design Forum Archive

Hi all,
This is a continuation of a thread that started as "choosing a mixing room" in the Acoustics forum.

The goal is an accurate, articulate, and inspiring mixing environment, to professional expectations, that uses materials that can be reused in another future space. Eventually I would like to have this type of space on my property but it is not in the cards right now. The goal is not a commercial space but to be as accurate as one.

I am renting a materially asymetrical, rectangular 8000 - 10000 cu ft space and building a room in a room within it for mixing purposes. There are currently drop ceilings at apporx 12-13 ft. I'm not sure what's above them.

The idea is to build frames - essentially theater set flats, not a permanent install - 4 ft by 8ft - filled with 4 inch 4 pound rockwool and covered in fabric, and use those to build a room within the larger space, that measures approx 8 ft high, 10 ft wide, and 12 ft long

This is just for me, and the primary goal is mixing, soundproofing is not a consideration.

I have a few big questions
1. Should my initial plans include an absorptive ceiling, or will proportionately greater distance and prior considerations render that unimportant once the walls are built?
2. I speculate that this wll end up sounding "too dead" - what would be the best way to bring back a realistic liviliness to the room?
3. What should I do with the back wall? I'd rather not hang doors or anything so that i can keep to lightweight and cheap materials. Should I build that wall long and create portals on the sides for people to walk in, or build it short so there are two symettrical "doors" to walk in through? Should this back wall be all diffusion or diffusion + absorption?

I'm not building a forever studio, or commercial studio, or studio for rent here, I am trying to build an accurate space to work as quickly an affordably as possible, and reuse the absorbtive and diffusive components in a future space.

The idea of such a cave is to block and diminish the reverb of the larger room. Perhaps build the walls first, if there is too much reverb, add the ceiling. I would leave the back open until last.

I can source this mineralwool locally in 4" 8pcf. Thermafiber Industrial Board 80.

Would this be an appropriate material for treatment in this manner?

Would it translate to more traditional treatment in a smaller room down the line?


Thank you.

I wonder about those pcf numbers, 705 is usually the highest density we see used, 96KG 6 pcf. But The absorption data look good.

DanDan wrote:I wonder about those pcf numbers, 705 is usually the highest density we see used, 96KG 6 pcf. But The absorption data look good.

Actually, I think this looks quite a bit better, eh? (more info here: https://www.jm.com/en/building-insulati ... wool-safb/)

125 - 0.97
250 - 1.28
500 - 1.25
1K -- 1.10
2K -- 1.10
4K -- 1.09
8K -- 1.20

I did my first quick measurements in the untreated room today and my first guess of a mix position, and there is plenty of room for improvement in the low-end phase and decay time

Much better. But I wonder if that stuff is rigid enough to push fit into your cave frame.

DanDan wrote:Much better. But I wonder if that stuff is rigid enough to push fit into your cave frame.

It does say that it is made to friction-fit into building framing, so I think it looks promising. I described the project to the guy on the phone and he seemed to think it would work.

It's in 16" width, so I think my plan is to build 4Lx8H frames with horizontals on 16" centers so the batts are laying on their long side with their shortest side on the vertical. I think this will give the least sag. I am hoping that by stapling burlap every 16" I can avoid adhesive and salvage the batts for the next room after this phase has run its course.

I got the speakers and interface and a desk and chair in mix position (just a guess, based on 37% and recommended speaker distance from the manufacturer) today for some testing. There are a few nodes that stand out but the biggest issue is reverb.

The nice (I think?) thing about the larger room is you can walk around and really get a sense for where the nodes and antinodes are in the room.

I'm hoping that I can strategically place the absorptive walls in the high energy areas (for example, 80 HZ has an axial peak a few feet behind the speakers) and knock down some of the nodes while simultaneously knocking back RT.

Should have the batts tomorrow. I'll get some lumber in soon to follow and start building!

Great, vaya con dios. I recommend forgetting about 37% and even the speaker manufacturers thoughts. None of that applies here. REW or other software will get you to the sweet spots for listener and speakers with certainty.

DanDan wrote:Great, vaya con dios. I recommend forgetting about 37% and even the speaker manufacturers thoughts. None of that applies here. REW or other software will get you to the sweet spots for listener and speakers with certainty.

Totally. I really appreciate your insight. This was just a starting point to get some soundwaves in the room. I have REW and SMAART at my disposal. I may be off-base here from a purely tech perspective but I've been learning a lot about the space just sending test signal and walking around the room slowly with tape and a sharpie.

Batts came today, they ended up about $1/cuft

I've attached an MDAT file from my "first guess" build.

To paint a picture, this is a 12x15 foot space framed by absorption and built from JM SFAB 4" walls that are 8ft tall.
2.1 system, measurements are L+Sub. Mic at the listening position.