Lack of bass

[PeterF]

Hi all
Sweden calling.

I have some upcoming mixing jobs and want to be more confident in how my system sounds. At moment i lacks bass (at my position) up to ~140Hz with an extra dip at 115Hz. Both my ears and http://bobgolds.com/Mode/RoomModes.htm (as I read it) tells the same.
My room is an ordinary room with plaster on wooden studs; W3.48 L3.58 H2.31 meter. All parallell. (Attached file is in swedish, but I think you get the layout).
Roof is an "old" paper roof; Craft paper - airgap of 2-4cm - plaster on bearings. Floor is 3cm wooden floor - 2cm spacing - concrete. All four corners are treated with insulation and fabric from floor to roof. Some mid/high absorbing panels and diffusors at side walls and roof for treating early reflections.
Speakers are Focal Twins at 1m from each side walls (spaced ~1.4m) which makes my mixing position pretty much center-center-center of the room. Adjustment of positions is not a problem.

I realize that the room dimensions are not optimal, but the room is great as being in a separate building, and not interfering with family or neighbors.

Will be grateful for any input on improvment.

/Peter

Kontrollrum.pdf

[gullfo]

while the closeness of the length and width are contributing to the issue, the main one if the ceiling mode - consider a nice heavy cloud - 19mm plywood + 19mm MDF glued and screwed together with a 100mm thick cloth covered absorber face. the perforated panel you have is likely not enough in terms of mass or area of coverage. tip down in the front about 300mm above the top of your speakers up to the ceiling just behind your seating position. maybe several cloud units with a slight gap between them and multiple angles. the idea being to break up that mode. obviously - treat first reflection points on the walls, and a deep absorber in front of your desk. treat the back wall for reflections.

[PeterF]

Thanks!

Is membrane absorbers in the ceiling an option to a cloud to break up the mode? I´m thinking (from top):
- ceiling (plaster)
- enclosed air 75mm
- membrane, 12mm plaster (Using the spreadsheet of Jonathan Shaeffer)
- air 2cm
- absorber (insulation) 100mm
- cloth

Is your 19+19+100 cloud construction tuned or "just" heavy? Will I do with -say- 3 layers of 12mm plaster?

Thanks again!
/Peter

[takman]

can you move your listening position out of the null? or least to a slightly better position?

why not run a test tone at your problem frequency, and move around a bit to see if there is a better position nearby.

at least for the time being, since you have jobs coming up soon. Then later address the problem more thoroughly.

just an idea.

[PeterF]

Yes, moving backwards to 3/4 of room length is better, but then the reverberation kicks in - at least that is what it sounds like. I realize I need more absorption with focus on lows.

Thanks
/Peter

[gullfo]

the mass forces a change in the mode behavior currently reinforced by the squareness of the overall space and the low ceiling. you could go w/ the plywood and 2x drywall. the membrane absorber could work but you need it to be large enough to actually work. the heavy cloud does some of that work without being tuned per se.

[PeterF]

Thanks for all input!
Learned some new things about mass by theory and ear!

I´ve been away for a couple of days, so my feedback is delayed.
I had last thursday to make adjustment to my room.
I went for the heavy cloud and went to hardware store before I read your last reply, Glenn.

So - all equipment out. Too small corner traps had to go - front corners.
Built a wooden frame by room width to suspend the cloud and absorption.
Put it halfway up on four pillars.
Mounted the three layers of gypsum plaster board W2.4 x L1.8.
Raised the frame with he cloud. Angled as suggested.
Made angled walls and installed semi heavy (34kg/m3) insulation on all surfaces and in all cavities exept above the cloud.
Cleared the mess.
Friday - put the cloth up and the equipment in.

bild.jpg

bild-1.jpg

Sound?!
It made the difference!
Not superflat, but engaging and dry bass. Actually the hole spectrum straightened up with - for example - less harshness in hi-mids.
The bass indepth is slightly dampened up to ~90Hz, and a slight dip at ~125Hz.
But I gained the confidence in my system and are eager for the upcoming jobs!

Really grateful for your advice, and satisfied with the result.
Thanks!

[gullfo]

glad its working. you could also add some light insulation above the cloud to add some more aabsorption there if necessary.