Help with 'live end' of one room studio

[hazza26]

Hi there

I've lived with my studio half finished for a while, now it's time to do the last bits of treatment and put fabric over the rockwool!

Currently my 'recording end' is pretty much sorted (I think) with massive superchunks (120cm front, pink fluffy), SL920 (45kg/m3) 10cm thick at the sides of the listening position, and a 10cm thick hanging cloud of SL920. Wall beneath front window currently untreated.

At the 'live' end I currently just have SL920 10cm thick across the back wall (10cm gap behind). My plan is to do smaller superchunks (~90cm fronts) in front of the SL920 (hoping I can find something low density in stackable slab format?), then 5cm thick SL920 ceiling clouds (height isn't great), and 10cm SL920 panels along the walls. There's a sofa below the 3 shorter panels, and a piano next to the 2 full length ones.

My questions:
- given the dimensions, am I right to go for 100% absorption across the entire space, or is there room for any kind of diffusion? If so what and where?
- the door into my office at the live end opens inwards to the studio, what should I do to treat it?
- is the untreated ceiling across the middle going to contribute reflections to what I record in the live end?
- have I missed any potential improvements at the control room end?

That's it - many thanks!

Harry

studio overhead3.jpg

studio underneath3.jpg

[hazza26]

The other thing I would really like to know is how people fabricate thin frames to wrap fabric across. I was wondering if I could put my picture frame joining tool to some use with some 45º corners. Won't work on the cross-supports though. Or just use flat joining plates?

Was thinking of using L-brackets and velcro to attach fabric frames to inside of panel absorber frames.

Any tips much appreciated

[Gregwor]

- given the dimensions, am I right to go for 100% absorption across the entire space, or is there room for any kind of diffusion? If so what and where?

Your best best is to use polys as you won't experience lobing with them.

Regarding your 100% absorption, I doubt you want that. You usually can aim for ~50%, not 100%. The best thing for you to do is take acoustic measurements. With REW data, you/we can totally see how your room is performing and adjust the treatment as necessary.

- the door into my office at the live end opens inwards to the studio, what should I do to treat it?

Depending on the REW data, you could either put a shallow poly on it or a thinner layer of insulation. You don't want to have treatment prevent it from opening fully if possible. But as you know, it is possible that leaving it as a hard flat surface could cause unwanted reflections.

- is the untreated ceiling across the middle going to contribute reflections to what I record in the live end?

Possibly. Take REW measurements.

- have I missed any potential improvements at the control room end?

You possibly have too much absorption. We need to see your RT60 data.

Greg

[hazza26]

Hi Greg

Thanks so much for the reply, I didn't get a notification so apologies for the silence.

Yes, I was suspecting a REW measurement might be essential to make progress! Attached are SPL & RT60 (full range) and waterfall (20-400Hz), all taken at mix position. In case I messed up the ranges the .mdat is here: https://www.dropbox.com/s/3d3g83175n8gl ... .mdat?dl=0

To clarify - this is all the front end absorption and just 100mm RWA45 + 50mm gap across back wall (apart from door).

I must admit I hadn't considered polys, I thought I read they were inferior to QRDs? So far I have been looking into QRDs and BAD panels, but admit I am struggling to properly understand the sonic implications of each.

That 30Hz resonance looks troublesome. Also unsure whether the skinny rear door is acting as a hard boundary or allowing bass through into the untreated back office. Should also mention there's a crawl space directly underneath the speakers.

Many thanks for pointing me in the right direction

Harry

REW SPL.jpeg

REW RT60.jpeg

REW waterfall 20-400hz.jpeg

[Gregwor]

3 things:

1. Your SPL for your measurement is too low. Check the REW instructions on the forum again and get them up to 80 for each speaker.
2. You need more bass trapping.
3. You will benefit from some polys and or slats to increase your RT60 in the mid and high frequencies.

Greg

[hazza26]

Hi Greg

Thanks so much. I've followed the REW instructions and done some fresh measurements inc soundcard calibration and SPL correction. Download here: https://www.dropbox.com/s/wehj2mrlk9ccj ... .mdat?dl=0

Also suddenly aware that my crawl space and back office could be contributing to bass problems, so attached is a plan of the room.

So my immediate questions are:
- do you think the crawlspace or back office are a problem? If so would you suggest bass trapping in either? Would a heavier door into the office help? I had originally planned to knock down the partition but decided against.
- what additional bass trapping would you suggest in the main room? I'm guessing rear 1m-front superchunks aren't going to cut the mustard?!
- where would you advise to place polys or slats? Is QRD / BAD treatment unsuitable for this room?
- in an ideal world what would the waterfall graph (realistically) look like?

Incredibly grateful for your advice, please let me know a suitable donation for your time

Best
Harry

EDIT: after some more research it looks like bass trapping all the ceiling-wall corners is the next port of call. Is Rockwool panels at 45º with air gap behind the way to go? What is the best material/thickness/gap for this?
Also: would beefing up my proposed rear superchunks to 120cm fronts be a sensible move? My front superchunks are very low density (10kg/m3), is it good to stick with that? I read a comment from John that a 50mm layer of Rockwool on the front improves the performance, but strangely plugging the numbers into the multi-layer absorber calculator suggests the opposite.. Is it even possible to tame 29Hz at these trap depths?!
Also: now understand that the long axial mode is responsible for the 29Hz resonance, hence whole back wall is a hotspot. Does treatment across the entire wall also need to be thicker / bigger air gap?

studio bare dimensions.jpeg

[hazza26]

Ok so after more research this is my plan of action:

- strip out rear wall RWA45
- install 80cm deep rear superchunks using Knauf Eco Roll (10kg/m3)
- build 40cm deep rear wall using similar low density insulation (does anyone make this stuff in slabs rather than rolls?)
- construct additional rear wall inner 'door' absorber - open-fronted frame with built in insulation cavity (same depth/density as wall)
- install 200x200mm soffits (RWA45) on side and front ceiling-wall joins (any bigger and my ceiling & wall panels will have to be rebuilt!). Are these big enough to make a difference?
- add extra layer of RWA45 to first reflection areas (to make 150mm insulation + 50mm gap, bringing in line with 200mm soffits)
- experiment with thick bass trapping in crawl space beneath speakers (really not sure if this is likely to help, any input much appreciated)

Diffusion: there’s really very little info I can find about polys. I assume they would need to be orientated for horizontal scattering? But how big? All the same size or make an array of varying sizes? Still struggling to understand the relative merits of poly vs QRD vs BAD - from what I can gather they each have an ‘acoustic footprint’, although I have not found anything online that articulates the difference. But I understand lobing is a factor, am I right in saying that QRDs are not applicable for my ‘live end’ since I will be recording in close proximity? I’m trying my best to employ my ‘running shoe’ purchasing methodology - ignore aesthetics and base entirely on function!

Also unclear as to whether rear side (and possible ceiling) absorbers should partially scatter towards rear wall. Slats perhaps? Slightly angled?

REW readings still available from previous post, and request for donation guidance still stands! I really want to get this right and am delighted for pay for expert guidance.

[Gregwor]

Sorry about the late reply my dude! I've been swamped.

credibly grateful for your advice, please let me know a suitable donation for your time

John pays out of his own pocket to keep this forum running so feel free to use the donate button at the top of the page

The other thing I'd ask is for you to not give up on your build and please post finished pictures and measurements! Thank you!

- build 40cm deep rear wall using similar low density insulation (does anyone make this stuff in slabs rather than rolls?)

I can't say for sure that the stuff is available where you live but yes, there SHOULD be low density insulation that come in batts.

- install 200x200mm soffits (RWA45) on side and front ceiling-wall joins (any bigger and my ceiling & wall panels will have to be rebuilt!). Are these big enough to make a difference?

Anything is better than nothing. Heck, in one of my temporary control rooms I have right now, I threw an old dog bed in the corner and REW shows an improvement in the sound!

Diffusion: there’s really very little info I can find about polys. I assume they would need to be orientated for horizontal scattering? But how big? All the same size or make an array of varying sizes? Still struggling to understand the relative merits of poly vs QRD vs BAD - from what I can gather they each have an ‘acoustic footprint’, although I have not found anything online that articulates the difference. But I understand lobing is a factor, am I right in saying that QRDs are not applicable for my ‘live end’ since I will be recording in close proximity? I’m trying my best to employ my ‘running shoe’ purchasing methodology - ignore aesthetics and base entirely on function!

There is a decent section in this book:

http://www.roletech.net/books/HandbookAcoustics.pdf

And

Volkman on Polycylindrical Diffusers-1.pdf

And

AcousticAbsorbers & Diffusers.10.4.Polycylinders..pdf

Also unclear as to whether rear side (and possible ceiling) absorbers should partially scatter towards rear wall. Slats perhaps? Slightly angled?

A hard surface like slats need to be carefully placed to prevent any first reflections. Pure insulation doesn't need to be worried about in terms of angles.

REW readings still available from previous post

Your low frequency time domain needs addressing -- bass trapping should take care of this! Your mid and high frequencies seem to be dying too quickly so polys and things like adding slats or film to the face of your bass traps could help this.

There are certainly first reflection issues. Panels at your first reflection points should help this.

Your room doesn't look horrible though! You're off to a great start!

and request for donation guidance still stands! I really want to get this right and am delighted for pay for expert guidance.

If you ever want parts of your room designed by a pro, I would contact John directly. From what I know he is very affordable and of course the best in the biz!

Greg

[hazza26]

Thanks for the continued support Greg.

I feel like I'm going round in circles trying to arrive at the 'perfect' solution... it's time to start getting on with it! I am going to do all the new absorption treatment and will report back with fresh REW measurements before moving onto diffusion & fabric.

Donation made

[Gregwor]

Amazing! Thank you!

Greg