Smalish bedroom studio acoustic treatment

[musictracer]

Hello everyone,
First of all, I know it's been a while now, but I would like to express my deep condolences to - the great master of acoustics - John Sayers' relatives and friends. It was of great sadness to learn about his passing. I pray he rests in peace and will always be remembered as the great generous acoustics engineer and consultant that helped so many of us reach our dreams through his forum completely free of charge.

Now this topic will practically be the continuation of this topic https://www.digistar.cl/Forum/viewtopic.php?t=208 which derailed from it's initial title after the title request was resolved. Through a couple of recent replies I understood that this was confusing people, so I thought it would be best to start from where it got as a new topic that is focusing an the new target and not what the previous title was reading.

So, I have a bedroom which is currently the only room I can use for mixing. The rough dimensions are 3,26m x 2,5m(due to furniture) x 2.76m. With Stuart's useful advice in the initial topic I was able to build 3 big corner absorbers along with the 3 First Reflection panels I had already, as well as a ceiling cloud that is omitted in the sketchup snapshots for practical viewing reasons. My monitoring setup consists of a pair of hs5's paired with an adam sub7 , a pair of APS klasiks2020 as mains and a 2.1 desktop system. In my current setup my mains don't perform as they are meant to and fixing this will practically be the goal of this very topic.

As previously mentioned I have created a sketch of the room layout which gives a good representation of what my room looks like (it is always more beneficial to have a sketch rather than trying to describe a room's layout ) The layout was different initially , but following Stuart's advice I managed to get the desk across the balcony door which provided a definitely noticeable lower end improvement compared to the previous setup.

There are quite a few issues that I hope that can be fixed in there , but one that I am consistently struggling with is the missing of issues around the 740hz when mixing with my mains, (curiously something I am not having with my hs5's ) and that is frustrating because klassiks2020 are meant to be quite flat, so hopefully it has to be a room issue and not a speaker one.

I upload a few measurements done in the past along with the REW mdat file and of course snapshots that hopefully will help get a better view of what is going on in there.

Please note that these are slightly different measurements than the ones posted in the latest posts of the initial topic. Over time I have taken plenty of measurements, but the main difference between these and the initial topic ones is that the Klasiks are on the outside, while the hs5's are on the inside in the current setup. Regardless these are just for a preview of the room behavior as I hope that by getting some help on this topic , more measurements will be needed to be taken for sure

Bedroom studio 2022 - across balcony door - E..jpg (43.59 KiB) Viewed 12889 times

Bedroom studio 2022 - across balcony door - E..jpg (43.59 KiB) Viewed 12889 times

Bedroom studio 2022 - across balcony door - S..jpg (43.85 KiB) Viewed 12889 times

Bedroom studio 2022 - across balcony door - S..jpg (43.85 KiB) Viewed 12889 times

Thanks a lot in advance!
Stay safe, God bless!

[gullfo]

based on your diagrams, you have significant disparity in the symmetry of treatments, so i'd work on making either side of your desk much more symmetrical...

[musictracer]

Source of the post based on your diagrams, you have significant disparity in the symmetry of treatments, so i'd work on making either side of your desk much more symmetrical...

Hey gullfo, thanks for your advice!
You are right in that I am having a symmetry issue in there which has an impact in stereo representation, phantom center, etc. The problem is that nothing you see in the sketch (furniture) can be moved outside the room. It all has to be in there, creating this intensive lack of space. Imagine that I had a different lay out initially with the desk across the left (long) wall. It was more convenient in terms of space management, but quite worse in terms of acoustics.
Following Stuart's advice I managed to get it along the balcony door, as it is now. This for example made it hard to reach the drawers on the right whenever I need to , but definitely improved acoustics both stereo and spectrum wise, so I stayed with that with no second thought .
Regardless, the biggest issue I am facing right now is the extensive dip around the 700hz area shown in my main monitors. Probably the 180hz and the 90hz as well, which seem to have an harmonic relation, but I don't know what might be causing it. Probably an SBIR issue, dunno. I'll need advice on this.

[musictracer]

Hello everyone!
Just came back with an update as I decided to add another absorption panel across the balcony door, right behind and above the pc monitor. The panel is of same length (1.2m) and width (0.6m) as the side panels, but it is 50% deeper (0.15m).
I am not sure how obvious this may seem in the measurements, but it definitely helped get a clearer sonic view, both clarity and stereo wise. Comb filtering was diminished to some point for sure as with careful listening I get to easier distinguish resonances I was missing previously around the 700hz area. It's far from perfect yet, but the improvement is obvious and that is really encouraging.

I also replaced half of the insulation of the 2 side panels with a lighter yet still effective synthetic product called izifon. It is the same I used for the most part of the cloud panel. This could probably have played a part in the improvement as well, though I can't be sure, as I only measured after both the insulation replacement and the addition of the balcony door panel.
As before, I have attached the new REW mdat file for anyone interested in further investigation.
Any recommendation on improving acoustics in my room is desired and appreciated!

[musictracer]

Hello again,
so I am back after about a year of not having any reply to my latest post. Regardless I will lay down a few thoughts on how I am planning to move on and hopefully get some opinions on that.

So while trying to find out what would be best for improving the frequency response of the room I ended up leaning towards the helmholtz slat resonator. My aim is to decrease the response graph roughy between 150 - 570 hz so that it is closer to flat. Now, while trying to estimate the construction dimensions and shape I found out that it would be quite hard to cover all that frequency range with a single unit , so I thought of splitting it into two parts. The first part will be roughly 320-570 hz and for this I have already made a sketch which I upload here.

[Please keep in mind that the dimensions of the "box" don't include the timbre dimensions, because I don't know them yet (haven't chosen the timbre that 'll be used), so consider these dimensions as the inner cavity dimensions.]

But I have a few things that I haven't cleared up yet in my mind. In this calculator the picture shows (and takes in account) the distance from the wall. http://www.mh-audio.nl/Acoustics/SlotAbsorber.html

1. One thing that confuses me though is whether the construction (resonator) includes the space between the "timber frame" and the "wall", or is this space just empty space, and not part of the airtight cavity of the resonator? In an older Stuart's post in legendary John Sayer's forum he had mentioned that the resonator could be angled to the wall, so that leads me to conclude that the space behind the timbre is not supposed to be part of the construction, but then again I am concerned as to why is the construction supposed to be airtight , if the space outside it ( behind it ) is influencing its performance.

2. How much insulation should I use? Some use 2/3 of the cavity, others like in the picture of the link above use much less. I know the more is used the more broadened the range of affection will be, but I have calculated the dimensions of the box so that it will strictly affect only the swelling between 320- 570 hz. If the effect is broadened , it will go beyond these boundaries and this, of course is not desirable.
And my the way, is the insulation supposed to be appended on the back of the front "face" as in the upper link sketch, or could it be anywhere in the airtight cavity?

3. Correct me if I am wrong, but from what I have understood , the device primarily relies on friction at the opening areas to attenuate the desired frequencies' amplitude, so practically I could build the construction without any insulation at all, right? Or maybe with just a little on back the "face" (front) side, as shown on the upper link (calculator).

4. How am I supposed to fit the insulation behind the "face" (front) and keep it in place, inside the cavity? The timbre slats will be placed lastly, at the end of the construction, so where and how is the insulation supposed to be "stuck" on them, since it should be placed prior to the slats. Please forgive me because English is not my main speaking language, but I hope I am making my thoughts clear here

5. Should I begin with a slot or a slat at the edges of the front face, or does it not matter that much?

6. I am thinking of making the front face able to be easily taken apart and put back together , so that I could edit the construction with relative ease if necessary (trial and error process). This way I could e.g. add or remove insulation if desired. Probably with rubbers (to keep it airtight). Do you think this is a good idea?

7. Do you think that the dimensions of the construction are sufficient for the size of the room and the problem I am trying to fix?

There are also a few more things I am considering about for the room acoustics enhancement:

8.One is to use plastic stripes over the existing insulation (e.g. at the corners) as reflecting points of higher frequencies , to keep them "alive" in the room. I remember Stuart mentioning that a few times, but the problem is I don't know what thickness and density they should be , and how these relate to the targeted frequencies. Any idea on that?

9. I am very much intrigued by the thought of building a 1 dimension QRD diffuser on the back wall. Now I know that there is a certain distance needed between the wall and the sweet spot (Stuart mentioned 6 meters in an old post in John Sayer's forum, but hopefully he was targeting really low frequencies). AFAIK there should be at least 2 full cycles of the lowest targeted frequency between the device and the sweet spot for the lobbing to smooth out, so maybe if I built QRD tuned from e.g. 550hz and above I should be ok, right?
Generally is it a good idea to go with diffusion on the back wall of such a small place or should I stick to absorption and HH resonators?
And by the way, is there any performance difference between 1d and 2d diffusers?

10. As I have mentioned before the room includes a ceiling cloud with 30cm of insulation. I remember once Stuart adviced me to make it hard back and angle it so that it would redirect the sound towards the back wall. I am considering doing so for the half of the cloud (at the points where first reflections hit from the speakers) and keeping the rest as it is with insulation. Stuart, if you ever happen to read this I would much like your opinion as to how dense and thick the timbre used should be. Could I maybe use plastic instead? And what about the rear wall? Should I use absorption, diffusion , or maybe a HH resonator?

So that's it for now,
Thanks in advance for any help!
God bless everyone!