"Movable" front wall for RFZ (instead of framing)

[Beak]

Hi, this is my first post on this forum, so please forgive me if I accidentally break a rule (yes I did read the rules )

This will be my third project studio build. I've relocated to Italy and am building in a farmhouse (think old, thick stone walls). Due to the joys of Italian bureaucracy and new building codes, I'm quite hamstrung on my ability to frame out a front wall to create an RFZ.

So my thought was to create a set of reinforced frames with a (semi) reflective front. Imagine a box but with only one heavy, hard side and the rest of its is open framing filled with fiber (open, not closed, to prevent box resonance).

I would place these along the front wall to create the desired angles, and flush my JBL6332s within the wall by using one "box" as a plinth on which to set the speaker and another as a cap to cover the space above the speaker. The frames would be filled with mineral fiber or similar to serve as trapping for the area between the actual stone wall and the "fake" front wall to reduce resonance and trap bass in the corners. I would presumably also weight the frames to avoid resonance, buzzing, etc.

The benefits for me are - (1) no permitting at all, because it's all just furniture, and (2) it's all adjustable, so if I don't like the way things are going, I could change angles, add or remove trapping, etc.

My question for the forum is: has anyone tried something like this who could offer advice on whether this is even a feasible strategy? And if so, are there lessons learned that I could use?

Thanks in advance and I apologize if I've accidentally gotten off to a bad start here.

[gullfo]

something like this?

[Beak]

Hi Glenn, sorry for the late reply.

Yes, I was thinking something more or less like that, only more modular and with more framing in the back to offer more support.

Is this the solution you built? What materials did you use for the front panel, and how do you feel like it performs?

[gullfo]

it's an example. generally speaking you'd want to add the necessary supports - which could be as simple as a sheet of plywood on the floor and ceiling you could move the assembly (note "assembly") forward and back and then secure. otherwise i tend to design these specifically for a given space including all the other critical parts of the room.

[Beak]

I plan on making the front-facing panel as massive / damped as practical to prevent resonance. Do you have a recommendation? I planned on using HDF or MDF which would then be covered in FR fabric and then slatted. This would give the panels high mass and a little diffusion/diffraction. I'm open to your suggestions. Thanks for your replies!

[gullfo]

25mm-30mm of MDF on the front soffit will be massive enough unles you have much older speakers which don't have any damping (most modern ones do). you could add a layer of veneer, cloth, finished plywood, paint, etc as desired. given the baffle plates support the LF rather tah MF and HF, slats / scattering features in close proximity to the speaker won't do much, if anything.
the theory is infinite baffle for the LF until the cut off (-20db @ 30hz for e.g.) and of course there are limits... so the lower part of the assembly has the bottom extension with a 300mm opening on the bottom (wrap for absorption and vent ducts) and similar up top. the bottom is inset with absorption for desk reflections, and the middle and sides should wrap as cleanly as possible into the walls or side absorption units (in my example slats). in an ideal world you would have the speakers on 30° each, then the adjoining walls another splay on 30°, and then on side treatments often with 12-15° or so so create the smoothest transition. in rooms with 6m width this is easier than smaller room widths.

[Beak]

Hi all - this is a first-pass layout of my proposed control room setup. Note this is my first attempt using Sketchup (web version) so please go easy on me

The room is, as you can see, somewhat trapezoidal - squashed over to the right. I have to make use of the walls that I have, and can't add framing. I know this is not optimal so don't bother to tell me not to do this etc. because it's the room I have to work with, perfect is the enemy of good, etc. etc. My job is to do the best with what I have.

The side walls are close-to-parallel (they splay out by 25cm from front to back) and the front and back walls are parallel. I've laid out the front wall along the true center line between the side walls which produces the shape that you see in the drawing, so it's symmetrical L-R and skewed F-R. This should give me good MF/HF imaging and room for bass trapping in the front wall corners if desired.

the only glass between me and the tracking room is a 1.1m glass door to the side that gives a reasonable angle into the tracking room. The large door on the south will be closed up. The door on the southwest side will have an absorber similar to the opposing wall.

Ceiling height is 2.7m, flat. My intent is to drop panels 20cm from the ceiling, the panels can contain as little or much absorption as needed.

The front panels are absorbers top and bottom with a 3cm MDF reflective baffle. The speaker box is 1.5cmMDF and I can reinforce it as much as needed. Speakers are JBL LSR6332s driven by a pair of Adcom 565s. I've placed ducts and returns on the top and bottom of two of the front panels.

I have 50cm of space in the back of the room which will let me hang bass hangers. My layout calls for 12 hangers, 40cm x 250cm using 9mm OSB and 10cm of lightweight (25kg/m2) craft-backed rockwool which should be easy to mount to the OSB.

Not sure what additional info might be helpful at this stage, any feedback would be helpful.

Thanks in advance.

[Beak]

For what it's worth here is the REW room simulation of my room using average measurements for the length and width and some rough guess numbers for absorption coefficients. I know these numbers are more or less meaningless in the context of my wonky room.

My plan for setting up the room is this: I'll build the front all sections and set them up along the center axis. I have a leftover ceiling cloud I can temporarily throw up over the mix position, and set of decent broadband bass traps I can put in the back wall corners, and some mid/high absorbers I can temporarily set up in the first reflection zones on the side walls. I can then analyze the room with REW and get a sense of what the room is going to do, and adjust the sides/rear accordingly.

[gullfo]

sounds like a good plan!

[Beak]

Source of the post sounds like a good plan!

:sigh:

Glenn, you're doing it wrong. This must be your first week on the internet.

This is the part where you tell me that I'm an idiot, that the plan will never work, and suggest that I exit the field of pro audio and take up ditch digging or perhaps animal husbandry.

(seriously) Thanks for the feedback

[gullfo]

oh. i didn't say you were going to be successful! LOL. no plan survives first contact...