Can I trap Horizontally?

#1

Hi there. First post. I have a weird room.

I'm looking for some advice on treating this room. To cut a long story short, it was initially just meant for making noise without disturbing upstairs, but I'd like to mix in there.

Dimensions of main rectangle are H2600 W3200 L6000.

The wall on the left of the chair is a 1 foot thick stone wall..
The wall on the right of the chair is cinderblock (beser brick) rendered both sides and hung with 2 layers of 16mm Fyrecheck drywall on acoustic hangers with tontine insulation hung 2cm off of the concrete floor.

The wall in front of the chair is 1 foot concrete wall then earth. Also hung with fyrecheck with tontine insulation.

The ceiling is 150mm suspended concrete slab with tontine insulation and 1 layer of 16mm Fyrecheck hanging on Rondo acoustic clips.

The wall behind is 200mm thick concrete blocks (200mm x 200mm x 50mm pavers used as bricks) with 3 windows in it. >AND ONLY 2000mm TALL..<

All doors are timber with double glaze 2 x 12mm laminated sheets.

All windows are Jarra framed and double glaze with 2 x 12 mm laminated glass. All joints are filled with acoustic sealant.

It's basically a room within a room (almost just trying to resolve the back wall).

The back wall leads outside into a valley and I think I'll just put double glazing or 2 sliding doors on the perimeter. That'll probably do for isolation.

I realise the corner doors are in a poor position for trapping, I also see the 2 windows either side of the chair are RFZ nightmares, but I think I can fix that with Autex panels.

My real question is bass trapping. Basically I thought I should flush/soffit mount my Neumann 310's and trap behind them and make the front wall soft., but is that even possible with flush mounting? I have access to acoustic materials. I have made the front wall a 700mm thick absorber with 2700 pa.s Pink insulation. It looked good in the calculator for that thickness..It has greatly smoothed the room and reduced the horrible dip at 68hz, but it still exists. I thought perhaps the KH750 with DSP would help.

I'm wondering if I can flush mount, and will the 700mm of insulation still be of any value if the bezels are solid? Or do I keep the centre section soft?

The rear wall...Is it possible to mount trapping horizontally above the rear wall and out, overhead, into the anti chamber? (all concrete)..It would be 600mm H and about 1800mm deep along the ceiling out over the antechamber.

I know thats not all I need, I'll be treating all surfaces as well. I just need to get this fundamental aspect understood before I throw money down the drain.

Thanks for any advice. Cheers!

#2

looks like isolation is well in hand :-)

you can place absorption horizontally. i typically use soffits on the wall-ceiling join to support my HVAC circulation, conduits, and absorption. add a front wall which has the baffle sized for the LF drivers and leave the rest open for absorption there. add some side wall absorbers to control the side reflections as well as a ceiling cloud between the soffits.

#3

as a note, you can add angled interior windows to match the side wall absorption if you are not planning on closing the windows off - and possibly some heavy draps when you need more attenuation of the solid surface reflections.

#4

Thanks Glenn,
Great info there, I think I will run some air and conduit through there like you do.
I have a question if I may? My KH310's have an 8" driver, so a baffle will need to be 2000mm per side I think? with a 1/4 length wave length at 68hz? I don't think it'll fit?
Have I got this wrong? Would you mind looking at the dimensions again? I've been through Stuarts' flush mount guide and I think I thought I have that right. I would love to flush mount these and if I can utilise the 700mm of insulation on that wall at the same time that would be great.
Cheers, and thanks for your help
Steve
Edit: I see Stuarts rule:
8 ) Make the front baffle of your soffit as wide and tall as you can, within reason. The width should be at least three times the diameter of your low frequency driver. In other words, if you have a speaker with an 8" woofer, then you want the soffit baffle to be at least 24" (60cm) wide. Wider is better.
I can get mine to 1000mm wide and 1200 Tall based on the structure I've made to house the insulation. It's also super rigid so I can hang the baffles off of it.. That will leave room for the damping behind it to do something I believe.

#5

This shows the insulation structure in progress. I can add baffles to this at the appropriate angle.

#6

given the LF is 8.25" you really only need 16.5" on each side - so 42" wide - but - remember you have side and center panels to extend the baffle plates... so really vertically, if you have your speakers centered on a 48" high plate, you'll be fine. to improve things a bit - you can add behind the lower cloth section (absorb console reflections) a 3/4" plywood backing to extend the baffle. you could do the same above. but i would add a duct board venting path so leave about 12" top and bottom to incorporate that.

#7

Hi Glenn,
Cheers, those drawings are super helpful, but I have an issue. Can I run my woofers on the outside to get them further from the 45° line from of the corner of the room and the tweeters closer to the equilateral triangle of the LP? I don’t think I’ve got the room to come inside the 45° of the room corners. Or do I pull the frame out and make it narrower and shallower to get the baffles more in the middle and closer to 30°? At the moment the tweeters are about 9 inches to wide per side, but they look like they’re pointing at the LP from the chair,,,,( i Still have the 45° of the room issue.) Then add wings like your drawing? Its made with screws so not impossible, just a bit of a PITA. If you’re wondering about the layout here, theres a 1 foot h x 2 foot deep concrete footing that has dictated the build a bit. Should i make the whole thing shallower and lose the attenuation back there? The REW was much better with it there without the flush mount.
I appreciate your input. I’ve confused myself a bit.
Cheers
Steve
PS, I'll just point out- in the photo, where it says "1600' in the woofer, is the optimal place for the tweeter for the LP triangle. Have I answered my own question?

The edge of the speaker box itself has landed in the centre of the baffle that is just over 3 foot (960mm).
I can add another layer of glass or perspex/acrylic to keep the wall acting as the outside baffle if neccassary.

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