Large open mixing space

[simman]

Long time reader; first time poster. I’ve read the Before You Post Read This tread and I’m hopeful I’ve hit most of the applicable requirements. Not sure about posting the picture (size) but I did try and save it as 750 X 700 pixels.

I live in New Jersey and I am currently in the research/design process of this project. My goal is to be able to have a space in my unfinished basement for mixing only. I have no need for tracking so isolation is not really a major concern for me – I also don’t plan on having to mix at 3am without waking the wife. Measured ambient noise in the basement during the day is ~65 – 70dB depending on what’s going on upstairs. While I haven’t measured this throughout the entire house yet (but have listened), with ~80dB of music playing in the mix position in basement, the volume throughout the house is not a concern. I can measure and provide details if necessary.

Ok, some room dimensions. The overall size of the basement is approximately 43ft long x 24ft 9in. wide and 7ft 9.5 inches high (measured slab to 1st floor subfloor). The house is a single story ranch with a full basement – all floors are plywood with all red oak hardwood throughout the house (except kitchen & bathroom – plywood with ceramic tile). The basement is completely dry, doesn’t leak, exterior walls are cinder block, and exterior walls have been sealed/painted with dry lock. The ceiling is completely open i.e., exposed joists (standard 2x10) with no insulation. My going in plan is to use the northwest corner of the basement as this location is farthest for the bedroom(s) and directly under a low traffic room. I have attached the basic initial layout.

Plan.jpg

As depicted in the layout the monitors are JBL LSR-305 (rear ported) on stands 48" high and sit 2 feet from the front wall and ~33" from the side wall.

I have spent time searching and reading threads on this site as well as many internet searches; however, most everything I’ve seen relates to the acoustic issues with small(er) rooms. Since my initial thought was to not enclose the space or build any walls, most issues normally found in smaller spaces would be minimized. I have found a lot of information about treating smaller rooms but very little on the topic of large open rooms.

So, I could really use a sanity check and welcome any help and or recommendations with the following:
1.) Are my initial thoughts of not enclosing the space sound (no pun intended)?
2.) As depicted in the initial layout, could use your thoughts & recommendations on the initial layout & acoustic treatment. Given the openness and size of the room, will treating just the front wall with a few 2” think (703) absorption panels, a ~7ft corner bass trap in the near corner, and treating first reflection points on the near side wall (and potentially a cloud) be adequate? I get that more bass trapping and treatment in small rooms the better but I’m not sure that applies here?????
3.) Could use any thoughts on treating any other walls especially far side wall and ceiling?
4.) Is there any benefit to enclosing the space that might justify the cost?

I am still formulating a total budget for this project but a lot of it will be driven by how far off my going in thought process is ( and I’m sure there’s a high probability I’m way off ). I have been using 5K as a place holder; however, I have no delusions that this will be enough if I need to enclose the space. I already have the wall treatments depicted in the layout left over from another studio project so I’m able to save those costs at least.

Any insight or direction the forum can provide is greatly appreciated.

Thanks, Bill.

[Soundman2020]

Hi Bill, and Welcome!!

I’ve read the Before You Post Read This tread and I’m hopeful I’ve hit most of the applicable requirements.

Measured ambient noise in the basement during the day is ~65 – 70dB depending on what’s going on upstairs.

That's pretty loud for a basement. I guess that was measured with "C" weighting, and "slow" response?

Why is your basement so noisy? What is causing that noise? Some type of fan, furnace, pump, or something like that? I think you'll find it not so easy to mix in an environment where the background noise is louder than some of the sounds you are working with.

The overall size of the basement is approximately 43ft long x 24ft 9in. wide and 7ft 9.5 inches high (measured slab to 1st floor subfloor).

Reasonably big in "X", decent in "Y", but rather small in "Z"! Not a happy situation.

The basement is completely dry, doesn’t leak, exterior walls are cinder block, and exterior walls have been sealed/painted with dry lock.

Excellent! That's very good, all around. Is the basement completely below ground, or only partially so?

as this location is farthest for the bedroom(s) and directly under a low traffic room. I have attached the basic initial layout.

... and is also right next to the furnace!!!

As depicted in the layout the monitors are JBL LSR-305 (rear ported) on stands 48" high

That's too high. That places the acoustic axis about 67" or 57" above the floor, which is not good. The acoustic axis of the speakers should be around 47-1/4", or maybe a bit more. You will need to adjust your stands lower, cut them down, or make new ones.

Also, what are those stands made of? Are they heavy or light-weight?

and sit 2 feet from the front wall

Why? That will create a rather large SBIR dip in the frequency response at roughly 141 Hz... Why did you choose that distance, when you have 43 feet of room length to play with?

however, most everything I’ve seen relates to the acoustic issues with small(er) rooms. Since my initial thought was to not enclose the space or build any walls, most issues normally found in smaller spaces would be minimized.

Your room is small. Small-room acoustics still apply. If you said you were taking over a old symphony hall, movie theater, airplane hanger, warehouse, church, or other really large space, then we could talk about large room acoustics. But a room with a ceiling less than 8' high is small, acoustically. The same rules apply to your space as to all other small rooms.

I have found a lot of information about treating smaller rooms but very little on the topic of large open rooms.

Your room is not large, acoustically, so there's no need to carry on looking for that. An acoustically large room is one where all of the dimensions are comparable to the wavelengths of the lowest frequencies of interest. A bass guitar, for example, goes down to nearly 30 Hz, so any room where all of the dimensions are less than about 37 feet, is acoustically small.

1.) Are my initial thoughts of not enclosing the space sound (no pun intended)?

Not really, for several reasons:

1. You have a very high ambient noise level, in the region of NC-60 or so, on this chart:

NC-CURVES.jpg

The general recommendation for studios is NC-15, or maybe NC-20. Even most home studios are still around NC-25. Yours is way, way too loud. As I mentioned above, you wont be able to mix well in there, when most of the sounds you are dealing with are quieter than the ambient level. You need to isolate. You need about 40 dB of isolation, +/-.

2. You have no symmetry! Symmetry is absolutely critical for mixing. Without that, you have no accurate stereo imaging, no sound-stage, no balance, uneven frequency response, etc. Your right ear is 3 feet from the right wall, your left ear is 21 feet from the left wall. That's HUGE difference! Your ears will be hearing very, very different things, your mixes will not be balanced, and they won't translate.

3. Your "room" would be e-x-t-r-e-m-e-l-y long and very thin! Take a look at "room ratios" and "modal spread" to see why that is a bad idea.

Given the openness and size of the room, will treating just the front wall with a few 2” think (703) absorption panels, a ~7ft corner bass trap in the near corner, and treating first reflection points on the near side wall (and potentially a cloud) be adequate

Nope!

I get that more bass trapping and treatment in small rooms the better but I’m not sure that applies here?????

It's a small room: it needs bass trapping.

3.) Could use any thoughts on treating any other walls especially far side wall and ceiling?

Treat them by moving them closer!

4.) Is there any benefit to enclosing the space that might justify the cost?

Yes. All of the above.

Any insight or direction the forum can provide is greatly appreciated.

I would suggest enclosing the other two sides of that area, placing your new walls at locations that allow you to make the room as big as possible while still having a usable ratio, within the Bolt area at least. Then set up your gear symmetrically, with the correct geometry and layout for that size space, then put bass traps in as usual, and first-reflection point treatment as usual. Then run a test with REW to see how things are going, and if anything else needs doing. Actually, run an initial test with REW as soon as you have your walls in place, with the room totally untreated, so that you have a baseline acoustic signature against which you can compare all future measurements.

- Stuart -

[simman]

Stuart, thank you for the quick response! I greatly appreciate your expertise and will now rethink this a bit more. I've tried to provide some answers to your questions below.

Hi Bill, and Welcome!!

Measured ambient noise in the basement during the day is ~65 – 70dB depending on what’s going on upstairs.

That's pretty loud for a basement. I guess that was measured with "C" weighting, and "slow" response?
Why is your basement so noisy? What is causing that noise? Some type of fan, furnace, pump, or something like that? I think you'll find it not so easy to mix in an environment where the background noise is louder than some of the sounds you are working with.

Well I don't know what I was thinking when I took this measurement but yes, measured C weighting & slow response. I had that ah ha moment after reading your comment - the noise was/is the furnace. Remeasured (c weighting & slow response) at same position with the furnace off and the level is approximate 40 - 43dB.

The overall size of the basement is approximately 43ft long x 24ft 9in. wide and 7ft 9.5 inches high (measured slab to 1st floor subfloor).

Reasonably big in "X", decent in "Y", but rather small in "Z"! Not a happy situation.

Yeah the ceiling height is not optimal but I'm stuck with it.

The basement is completely dry, doesn’t leak, exterior walls are cinder block, and exterior walls have been sealed/painted with dry lock.

Excellent! That's very good, all around. Is the basement completely below ground, or only partially so?

Yeah being dry is a rarity especially since I'm down at the Jersey shore. The basement is mostly underground with only about 2ft above grade.

as this location is farthest for the bedroom(s) and directly under a low traffic room. I have attached the basic initial layout.

... and is also right next to the furnace!!!

Very well thought out don't ya think I'm rethinking this now. Looking at the southeast corner - further away from the noise maker.

As depicted in the layout the monitors are JBL LSR-305 (rear ported) on stands 48" high

That's too high. That places the acoustic axis about 67" or 57" above the floor, which is not good. The acoustic axis of the speakers should be around 47-1/4", or maybe a bit more. You will need to adjust your stands lower, cut them down, or make new ones.

Sorry I should have been more clear - I should have said that the acoustic axis is 48" off the floor.

Also, what are those stands made of? Are they heavy or light-weight?

Stands are light-weight - which I know is not good.

and sit 2 feet from the front wall

Why? That will create a rather large SBIR dip in the frequency response at roughly 141 Hz

Not sure how you came up with this? I need to go back and check again with Barefoot's wall bounce calculator - most likely I missed something


Ok given all the above Stuart, I think I get where you're coming and want to thank you again for your time and help! I will do more research and see if I can't apply one of the many control room designs on this site to my space.

Bill

[simman]

Stuart, I have a follow-up question if you don't mind.

I was looking at John's "Small Studio in 3D" design thread, I noticed most of the walls in his design are basically insulation covered in fabric. Flipping my space to the opposite corner of the basement away from the furnace and building enclosing walls.
my question is; would it be better to apply something similar to John's design and make all walls 3" Roxul covered in fabric, Super chunk bass traps in corners, treat ceiling and leave the floor reflective? Or, simply use sheet rock and treat the space by hanging traps & absorption?

Thanks,
Bill

[Soundman2020]

I was looking at John's "Small Studio in 3D" design thread, I noticed most of the walls in his design are basically insulation covered in fabric.

Not really! That's John's "inside out" wall design. There is still substantial mass on those walls, just a with any other isolation wall. The only difference is that the mass (layers of drywall) faces into the wall cavity, not into the room. In other words, with a conventional wall, the studs face the cavity, but with John's inside out wall, the studs face the room. That leaves the space between the studs available for treatment. In many cases, it can indeed be left as insulation covered with fabric, but that depends on what treatment the room needs.

- Stuart -

[simman]

I was looking at John's "Small Studio in 3D" design thread, I noticed most of the walls in his design are basically insulation covered in fabric.

Not really! That's John's "inside out" wall design. There is still substantial mass on those walls, just a with any other isolation wall. The only difference is that the mass (layers of drywall) faces into the wall cavity, not into the room. In other words, with a conventional wall, the studs face the cavity, but with John's inside out wall, the studs face the room. That leaves the space between the studs available for treatment. In many cases, it can indeed be left as insulation covered with fabric, but that depends on what treatment the room needs.

- Stuart -

Thanks Stuart