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PostPosted: Tue Jun 30, 2020 1:35 pm 
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Location: New York USA
First post- Hopefully I got everything right and won't be banned forever.

Just moved into a new mix room and need some help tuning it up.

Here's some basics:

- Room is 26'6" x16'6" with a 9'x9' extension in the rear left.
- Existing space, room is 2nd floor over hallway and between two 2-story warehouses (fun)
- Left wall is brick/concrete block, front wall is brick, all other walls are insulated metal stud with 5/8" sheetrock
- Floor (front half) is 2 layers of 3/8" sheetrock sandwiched between 3/4" plywood. 2x8 joist with sheetrock ceiling below. Area under desk/rug is ~9'x12' 8mm rubber flooring
- Floor (back half of room) is 5/8" diamond plate steel covered by 8mm rubber flooring
- Ceiling is concrete, 11’ high with two 9'x6'x3’extensions (removed skylights), 2x8 joist and plywood to roof. These extensions are 14’ high inside.
- All beams and columns are concrete.
- Double doors are (semi) permanently closed, covered by 10’ curtain, room is accessed by 30' door only.

Existing treatment:

Right Wall:
10- 2'x4'x2" panels

Left Wall:
12- 2'x4'x2" panels
12'x20"x18" roxul stuffed soffit (floor/wall corner)

Front wall corners:
2'x8' floor to ceiling roxul stuffed corners

Rear Wall:
4- 2'x4'x2" panels
Rear Left Corner 8'x4" corner trap

Rear Right:
8'x4" corner trap
10' curtains

Floor:
2- 5'x7' shag rugs
1- 8'x11' Shag rug
1- 8'x11' Area Rug

Ceiling:
Untreated except for 8'x6' cloud over mix position, 7'6" from floor at 5 degrees

I've added all relevant drawings, photos, REW data in my Dropbox

I probably have whatever information you need, and am just forgetting to post it here.

Notes: I'd like whatever I do to be able to be moved when I leave this space, as I won't be here forever and I don't own the building.
Ideally I won't drill into the ceiling anymore than I already have. Also need to work around sprinklers
Isolation? Doesn't matter. I can make as much noise as I want, and don't have to worry about much noise from outside the room. Hint: I'm not all that loud anyway.

Here's my current goal- Knock down the resonance at ~48Hz and ~68Hz. Whatever other improvements can be made are also appreciated. I'm considering GIK's scopus tuned bass traps, as (most of) the open spaces between panels are hot at 50Hz and 70Hz, but I'd like to hear about other (better?) options. Budget- $5k?

EDIT: Should I add some diffusion?

What would you do?

Thank you!


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PostPosted: Thu Jul 16, 2020 8:14 am 
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Location: New York USA
Well, I've ordered some scopus tuned traps, will keep this updated as I continue to build incase anyone is at all interested


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PostPosted: Fri Jul 17, 2020 12:12 am 
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Location: Cork Ireland
Fabulous big space. Lucky you. Some detail of the testing plse, is that just a sub? Could you post the .mdat file and make it clear what we are looking at.
I think you can could keep enough liveness in the room by using distributed absorption only.
I would go for minimum early reflections at the mix position though.... Much more cloud. More area and thicker.
Suspended ceilings using completely absorbent tiles or 705 batts ( I think RealTraps sell these) work really well.
You can beef up the vertical mode suppression by adding pink fluffy cheap fibre over the tiles.

DD

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PostPosted: Fri Jul 17, 2020 12:47 am 
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Location: New York USA
Thank you Dan

I can't add a ceiling grid unfortunately, but I could add more cloud behind the desk/over the monitors. Suggested size/thickness/ height above floor?
I feel that the early reflections are pretty well tamed, and the biggest issue I'm looking to hit next is the low end decay times. The room is pretty dead, or at least seems that way due to the distance of the walls from the listening position...

The screenshot is just the sub, which was just to add context to my main area of concern, and there's more photos including the mdat (too large to post here) in my Dropbox
I'm adding a screenshot of the Left speaker waterfall and RT60 to show the full spectrum.


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PostPosted: Mon Aug 03, 2020 2:34 am 
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Not much love on this one. Any takers?


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PostPosted: Thu Aug 27, 2020 8:00 am 
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Location: Lincolnshire, UK
Hi Joefis,

I echoe what DanDan said about your cloud/ceiling. You need more absorption up there.

Your low end problems appear to be linked to your width and height modes.

I would first place super chunks across the wall-ceiling corners front to back off the room. This would reduce the ringing causes by your width and height modes together.

If you can't make permanent alterations, get some insulation netting and staple it across the corners to hold it in place.

You need a lot more ceiling treatment though. Ideally over the whole ceiling if you can, but definitely the corners.

If you're worried about killing the high end, you can add thin plastic/wooden strips across the absorption to reflect some HF energy back into the room.

After absorption, if there is still ringing at the low end you can use some BBC A10 style low frequency membrane absorbers (3mm hardboard membrane over a 180mm deep box made of 9mm plywood, fully filled with fluffy loft insulation). These have a strong absorptive effect for frequencies right where your issues are, and don't absorb at all above 100Hz.

Dan

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PostPosted: Fri Aug 28, 2020 1:26 am 
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Location: Cork Ireland
The simplest temporary bass trap I know is just plastic wrapped rolls of Attic Insulation stacked up in corners.

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PostPosted: Thu Sep 17, 2020 2:47 am 
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DanDan wrote:
The simplest temporary bass trap I know is just plastic wrapped rolls of Attic Insulation stacked up in corners.


I don't need temporary in that sense, just not going to make alterations like a drop ceiling to to a building that isn't mine, or at least would like to take as much with me when I inevitably move from this space.


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PostPosted: Thu Sep 17, 2020 2:52 am 
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Joefis809 wrote:
DanDan wrote:
The simplest temporary bass trap I know is just plastic wrapped rolls of Attic Insulation stacked up in corners.


I don't need temporary in that sense, just not going to make alterations like a drop ceiling to to a building that isn't mine, or at least would like to take as much with me when I inevitably move from this space.


What Dan is alluding to is a simple way to quickly build some traps without making permanent changes to the space. You can cover these piled up rolls with fabric stretched over a free standing timber frame (imagine a corner bookshelf with open sides).

Paul

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PostPosted: Thu Sep 17, 2020 2:53 am 
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Waka wrote:
Hi Joefis,

I echoe what DanDan said about your cloud/ceiling. You need more absorption up there.

Your low end problems appear to be linked to your width and height modes.

After absorption, if there is still ringing at the low end you can use some BBC A10 style low frequency membrane absorbers (3mm hardboard membrane over a 180mm deep box made of 9mm plywood, fully filled with fluffy loft insulation). These have a strong absorptive effect for frequencies right where your issues are, and don't absorb at all above 100Hz.

Dan


Thank you for that! I've searched around here for info on A10 absorbers, but didn't find much. I did manage to find the BBC papers and those definitely look promising. What I'm wondering is if there are alternate dimensions I could build them and still get similar results? I've found membrane absorber "calculators" online, but I can't seem to get them to even calculate the A10 given specs correctly, so I'm hesitant to try to modify the dimensions. Any insight or resources on that end?


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PostPosted: Thu Sep 17, 2020 2:57 am 
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Location: New York USA
[/quote]

What Dan is alluding to is a simple way to quickly build some traps without making permanent changes to the space. You can cover these piled up rolls with fabric stretched over a free standing timber frame (imagine a corner bookshelf with open sides).

Paul[/quote]

Ah- Thank you. That's essentially what I've done in the front corners, and the soffit along the left wall/floor corner. The other wall corners are 4" deep open back panels bridging the wall/wall corners.

My next move, as suggested here is to build more clouds as the ceiling is still very exposed


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PostPosted: Thu Sep 17, 2020 6:01 am 
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Location: Cork Ireland
Clouds bring deep joy.
Quote:
What I'm wondering is if there are alternate dimensions I could build them and still get similar results?


Absolutely, but I wouldn't go smaller. The BBC designs are very very practical. Local materials, cheap, easy to construct, hard to get wrong, a reasonable size choice.

Elsewhere, a friend Acoustician Jeff Hedback, added simple pegboard to big 'Soffit' traps. LF absorption was significantly increased.

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PostPosted: Thu Sep 17, 2020 6:12 am 
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Location: New York USA
DanDan wrote:
Clouds bring deep joy.
Quote:
What I'm wondering is if there are alternate dimensions I could build them and still get similar results?


Absolutely, but I wouldn't go smaller. The BBC designs are very very practical. Local materials, cheap, easy to construct, hard to get wrong, a reasonable size choice.

Elsewhere, a friend Acoustician Jeff Hedback, added simple pegboard to big 'Soffit' traps. LF absorption was significantly increased.


Will look into pegboard results as a possible mod.

As for the A10- I was sure they could be built in various dimensions, but more curious if/how the absorption characteristics would change if I built them closer to 600/1200mm, and how I might compensate to retain the ~63Hz peak. I haven't been able to find a calculator to model this, and I'm certainly no physics/math pro. From what I've seen, the resonant frequency seems to be a result of the panel thickness/density and the depth behind it. The length and width are less of a factor?


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PostPosted: Wed Dec 16, 2020 4:20 pm 
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Joined: Wed Nov 04, 2015 9:26 am
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Location: Valencia, California
Curious to see what your solution was, I'm in the process of building my studio and my graph is looking similar. Looking at bass treatment options and will probably go with the A10's.
Did you build the A10's and if so did they work well?


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PostPosted: Mon May 03, 2021 11:55 am 
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mattsal wrote:
Curious to see what your solution was, I'm in the process of building my studio and my graph is looking similar. Looking at bass treatment options and will probably go with the A10's.
Did you build the A10's and if so did they work well?


I've been away from here for a bit, and am probably due to post an update. I've added the Scopus boxes from GIK, as well as curve diffusors/absorbers from Acoustic geometry. But I can tell you that I had the best results with building resonant panel absorbers as outlined in the book Master Handbook Of Acoustics- https://www.amazon.com/Master-Handbook-Acoustics-Sixth-Everest/dp/0071841040 in the wall/ceiling corners, tuned to the specific frequencies I was measuring there. Essentialy A10's built into the corner. I will likely build more, and probably A10 box absorbers, but wanted to see my results before committing to the project, which I see now is worthwhile


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