Really? So its ok to use slats on first reflection broadband panels/clouds/rear-wall panels in MLS sequence??

Yes, especially in smaller rooms, where you lose too much of room liveliness, after you finally solve low frequency issues, both resonant and non-resonant. "Dead" rooms aren't good for mix translation and cause more (faster) fatigue as short term consequence, and less working motivation, long term...

40mm wide 3mm thick slats are ok ?
I guess thicker slats will work at a lower frequency though..

I use 30-50mm wide and 10+mm thick... if you use 3mm thick, try not to only touch the absorber surface with slats, make some gap 3-5mm between surface and slat or glue slat directly to surface, I had some bad experiences and I fear that they will be able to generate audible noise because LF vibrations, if they only touch the surface.

So the slats have to either be a wee bit away from the fabric or glued to it as a whole.. This applies only to thin slats (around 3mm or so) or even for the 10mm thick ones u use?
What is the advantage of using thicker slats in an MLS sequence vs thinner ones?

yes, only for thin
can be standard wooden product (even construction wood ~5x3cm), can mechanically protect fabric covered contents behind... etc

Im sorry I dint understand this part..
I was wanting to know the advantage of using thicker slats (10mm or more) vs thinner ones (around 3mm)...

I don't know what you don't understand, can you be more specific?
I already noted two of them (as I remember)... And yes, my reasons aren't directly related to acoustic performance.

EDIT: two reasons:
1. I can use relatively cheap construction wood which is thicker (spruce, 5x3cm or similar), for the slats.
2. I can protect soft absorptive content (covered by fabric) of bass trap from mechanical damage, with thicker slats.

That makes it clear. So there is essentially no benefit acoustically whether u use thinner or thicker slats..

there are acoustical differences for sure, but from my perspective, reasons I contributed are more important than acoustical differences. also, room liveliness introduced with random slats is much more important than anything, whatever slat thickness you use... slight differences because thickness are irrelevant, from this view.

Great. Thanks for the Info..

So according to these pics I can assume that it is okey to use (over the absorption) 1d air transparent diffusers on some points of the walls (probably at 1st reflection points) and slats on a pseudo-random sequence everywhere else. Is that correct?

Also is there a problem if the diffusers are not flush mount to the surround absorption?
I am planning to attach each diffuser's slat directly on the absorption's frame (A) and not make a frame to hold everything together (B). I made a quick drawing to help you understand.

No. Binary diffuser is always a compromise.
I will recommend amplitude grating binary diffusers only in the room corner areas, if you want a full effect of a strong diffusion in the room.
That may be ok.

Why only in the room corners? I can see you are using slats on every wall except floor in your designs..

My original concept was to bring the hf energy of the room back using slats in MLS sequence everywhere, as you do. But then I read the myroom acoustic white paper.


So if I understand, you say I have 2 options:
a) use slats in MLS sequence everywhere
or
b) use 1D air transparent diffusion on 1st reflections, front-back walls and MLS sequence slats only on corners

IF you must combine amplitude grating diffusers with air transparent phase grating diffusers, then placing slats only in the corners is my recommendation
Ok, but "slats concept" isn't "MyRoom Design"... They are only a great compromise, while sharing a basic principle, but when it is no budget for phase grating diffusers... diffusion field is much less pronounced with slats.
Actually three.
MyRoom Design is basicaly:
c) using air-transparent phase grating transparent diffusion everywhere

but if you need to spare some money, you can exchange phase grating diffusers with slats (amplitude grating), in the corner regions.

Okey everything is really clear now! Thank you very much for your time and for your precious help.
I admire all the work you have done and how you acoustically transform rooms.

Do you remember, from your experience, the approximate weight for each 60x60 diffuser cell?

I will use mdf though, but just to get an idea..

I need to know what to build, how much weight will the frame be capable to hold, especially the ceiling frame.

Sorry, I'm really not that smart to remember everything...

try this approximate formula m=D*a*b*rho/4 I just made for you, instead... and add some "headroom" (25%?), then you will get some sense of the weight.

Ah, I almost forgot description.... "m" ia mass, "D" is depth of largest well (whole diffuser), "a" and "b" is width and height of diffuser element/panel, "rho" is density of your material (MDF, plywood, particle board, OSB). heh

REMARK: If you exclude "a" and "b" from formula, you will get surface density information of diffuser layer and not mass of one single element, and that may be more interesting for frame bearing calculation.

That will help a lot , thank you very much for all your help

So, I made some calculations. Posting here for anyone interested.

For 60x60cm air transparent phase grating diffuser 16cm deep
made from mdf with normal dencity around 700kg/m3,
the weight should be around 13.5Kg.

i used pine! and its work fine!

I think spruce may be even better.

Last weekend I finally took the chance to team up with Boggy in Belgrade (50min flight from Vienna) and visit RES Media Studios as well as some other studios he had designed.

At the RES Media Studios Control Room we set up a near-field listening chain with Notebook > RME Babyface > BOZO (Boggy & Zorica) Hypex Amp > Yamaha NS10s (sitting just above the console) and I had enough time to listen to my files being curious about how the well documented specs of this room would translate to my personal listening experience!? In short I liked it a lot and I want to give Boggy credit for this room ...

Back in Austria this comes to my mind:

• overall the room is tight/controlled sounding and not at all "dead" or "overdamped"
• acoustically comfortable to talk/listen/work there
• easy to hear "through" the speakers, to "forget" them
• extended listening "sweet spot" -- the qualities of a mix stay very much the same for different mix positions
• (left-right) center is just spot-on, "razor-sharp"
• revealing imaging -- panning of instruments and the stereo-width of a mix is immediately apparent
• differentiated depth (both position and size)
• defined, strong bass, no "dead notes", walking around the room the bass response stays quite consistent (we checked this with full range speakers as well)
• very nice listening experience at the client position in the back, totally workable

I couldn't find any downside apart from the fact that the looks of room are "small", nevertheless one engineer and two clients (plus desk space for paperwork etc.) can easily be accommodated. For sure not the common listening experience but an exceptionally good mixing environment (with a lot of first grade outboard available there as well).

Big up for Boggys MyRoom Acoustics room design at RES Media Studios and many thanks for the hospitality wherever we showed up in Serbia!

I'm looking forward to trying this phase/ amplitude grating approach. It may be that I go for all vertical slats, 8ft tall. Do you think that having everything in that vertical plane would compromise the listener experience too far?

No (EDIT: Not much). My new MyRoom Acoustic Design Mk2, simple variant, will have 1D front, sides and back walls vertical diffuser slats, and ceiling will be "horizontal" ... (just connecting left and right side slats).

More complicated variant with vertical axis diffusion component on walls, will be provided by 2D version of new design principle

Ok thanks. All-vertical slats seems (to the amateur construction engineer in me) simpler and probably cheaper...

From my understanding of the MyRoom design so far, it seems like the ceiling height of the shell would usually become the limiting factor for the diffusion cut-off frequency. Say you want to stand up and remain in the diffusion field, at a 6' ear height plus 3.3' for 1kHz diffusion plus 2' for the wells and absorption, you are at 11' already.

Do you end up compromising the absorption above the ceiling wells? The white paper has Pressed Lizard listed with less than 9' of ceiling height.

Thanks.

-Jim

Hello Jim, sorry for delayed answer...

Well, for small residential type of rooms where ceiling is no more than 9' you can't have normal diffusion field when you standing, and also, you won't have sweet spot from speakers, while standing.. they are already adjusted to ear height while you sitting on the chair at main listening position.

When I have chance to "adjust" ceiling heights for control rooms before treatment and in "concrete phase", I newer recommend less than 13'.
Well, curious thing in small rooms is that their modes are higher in frequency than in bigger rooms... so we usually don't have anything to worrying about below 40-50Hz, and with new modifications of MyRoom design, I can reach this range with serious absorption, with no more than 1' or 1.5' ceiling treatment thickness (diffusers included)

And yes, Pressed Lizard Studio had compromises, but not conceptual... Following same basic way of thinking, we can design better control room in that small space using MyRoom Design principle with additional R&D done in the meantime.


hope I answer your question.

-BP

No worries!

That validates my thinking; I had come up with 14' after some sketching.

That makes a lot of sense and is something that never occured to me.

1. That's remarkable.

2. Does it follow that a taller ceiling, with lower modes, would need porportionally more space allocated to trapping?

2b. Do you mantain that 1.5' treatment depth on the walls? Or do those typically larger room dimensions dictate deeper trapping?

I've been fascinated by the idea of mixing in a massively diffuse room ever since the first pictures of Blackbird Studio C came out. It just seems like an elegant solution to surround monitoring.

Wonderfully, thanks.
-Jim

Thank you.
Hmm... Proportionally? I'm not sure...
It is about design... And particular room...
At least... I never spend more than 2.5' thickness of treatment, diffusers including... But I didn't do large rooms
It really depends.... bigger rooms really may have deeper trapping useful, but there may be also other ways to... skin the cat...
Yes, Blackbird Studio C treatment is first real surround acoustical design principle, logical and honest before everything... No compromises where they don't need to be.