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PostPosted: Mon Nov 16, 2020 9:38 am 
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Location: Puglia, Italy
Hi everyone, first of all I have to thank you all for this great forum and for keeping sharing your knowledge here, It’s an invaluable resource. Thank you all!

With this post I hope to get some advice on my tiny home studio. I started this build way back in 2008, but I ended up moving to a new country and left it unfinished. Now I’ve been back for a while and would like to give this project the love it deserves.

I will go straight to the point: I use this room for music mixing and voiceover editing. I’m not concerned with soundproofing, as I have no neighbours to worry about, but rather I’d like to get it to sound as good as it can without going all out on budget because in a few years’ time the room will be tore down. Talking of budget: €400/500 is what I’m willing to invest and I will do all the labour myself.

Here’s a SketchUp drawing of the room with current treatment + photos below
Click here to download the drawing

Attachment:
Sketchup Top.jpg

Attachment:
Sketchup Side.jpg

Attachment:
Front Wall and ceiling.jpeg

Attachment:
Left Corner.jpeg

Attachment:
Back Wall.jpeg



ROOM ANATOMY:
Length: 2.57m
Width: 2.18m
Height: 3.05m
All parallel surfaces
Volume 17.09m3
Surface area: 40.18m2

Front wall: 10cm single layer gypsum partition with metal frame, with no absorption in the cavities, hard concrete pillar on the right-hand side corner.
LHS wall: 20 cm hard brick wall plastered with a cast iron radiator at the back corner.
RHS wall: 19cm single layer gypsum partition with double metal frame, double layer of absorption and 2cm air gap in the middle. There’s a wooden door opens towards the outside.
Back wall: 20cm hard brick wall plastered. There’s a wooden door that goes to a toilet and it needs to be accessible.
Floor: Tiled + a double layer of 2mm polyethylene foam pad and laminate flooring on top.
Ceiling: hard concrete plastered.


EXISTING TREATMENT:
For the existing treatment I used the same product everywhere, including in the right-hand side wall. This material is:

ISOVER fiberglass PAR 0.6m roll panel
Density: 13Kg/m3
Thickness: 45mm
Gas resistivity flow: 7kPa s/m2
Backing: fiberglass foil on one side

Front wall:
Corners below speakers: 70% filled with fiberglass, 30% air and a layer of cotton cloth on the front.
Wall between the speakers: the depth of this cavity is 18cm, but only filled with a double layer (9cm) of 60cm wide fiberglass hanging from a wire at the top of the wooden frame. One layer of cotton cloth on the front.

False Ceiling:
Made of a slanted wooden frame, one half of it only has one layer of cotton cloth. The back part has 6mm chipboard panelling that can be removed. The white board in the middle is made out of laminate flooring leftovers and hosts the lighting.
Above the false ceiling there are 6 hangers of varying height, equally spaced (about 35-40cm spacing between each hanger), made out of heavy 18mm melamine chipboard panels with a couple of layers of fiberglass all around and wrapped in cotton cloth. Here they are:
Attachment:
Hangers detail 2.jpeg


Side walls: only two freestanding self-made panels 90x8.5x202cm constructed as follow:
• Quite heavy and tightly woven cloth.
• One layer of 2mm polyethylene foam pad (same used for the flooring, most likely closed cell).
• Three layers of absorption materials slightly compressed to make them fit in the box.
• One layer of 4mm plywood as backing.

Back wall:
Nothing apart from one freestanding panel like the ones above, placed upright and centred along the wall.


SPEAKERS AND MEASUREMENTS:
My main speakers are a pair of Neumann KH120A (52Hz to 21KHz), no subwoofer. Speakers are placed on the front corner shelves as it seems to be the place with the most even low-end response. I have tried moving them forward into the room, but they sounded worse, (measurements confirmed that too).
Currently the main speakers are spaced 135cm apart and my listening position is at the same distance from the speakers. Listening levels vary from roughly 60 to 95dBspl, but mostly 70-75dBspl.


I took a set of measurements following the invaluable tutorial by Soundman2020. (unfortunately, the only SLM at my disposal for calibration was a radioshack one and I also had to lower the level of the speakers to about 77dBspl as the L+R sweep clipped the input. Please forgive me Sir).

Link to REW measurements
Attachment:
All SPL.jpg

Attachment:
Impulse L.jpg


Attachment:
T30 L.jpg

Attachment:
T30 R.jpg

Attachment:
Waterfall L.jpg

Attachment:
Waterfall R.jpg


ISSUES:
Although the stereo image is fairly broad, I feel localization of elements is somewhat blurred, it may be the low end masking the upper range, in fact there’s too much of it, as well as being uneven and messy. The area between 400Hz - 900Hz is often a struggle and I can’t quite understand what the issue is there as sometimes I end up with too much of it, other times the opposite.

ACTION PLAN:
After much reading around in the forum I put together a list of treatments from which we could start a conversation.
One thing where I still have some confusion on is what density and thickness of absorption would work best in the different areas. And here is where I could do with some help, especially if someone here knows what’s available here in Italy.
What I can get from my local dealer is:
5cm Rockwool acoustic 225 Plus panel 70Kg/m3
They also have some lower density alternatives at 40Kg/m3, but they couldn’t tell me the name of the product.

Anyhow, here’s what I would do to the room:

• Back wall:
I believe the most critical area to treat is the back wall, so I’d like to leave it for last and focus on everything else first. Once all the other treatment will be placed, I will take measurements and decide what to do with the back wall then.
One thing I would do right away is placing a cubic chunky bass trap in the back-left corner above the radiator. Dimensions: 38x38x100h cm
Attachment:
Bass Trap back left corner.jpg

• Ceiling:
I’m not convinced all that space above the false ceiling is used to its maximum potential as I believe the way I built those hangers and the spacing between them is not making them effective at all.
Since this is the largest area where I could put bass trapping in, I would start by building a chunky bass trap all along the top back corner with the following dimensions: 50x50x218cm (for the whole width of the room).
Then I could put in new hangers properly built and properly spaced as described in this tread.
Would you put treatment on the walls and ceiling above the false ceiling or only one layer laid on the false ceiling is enough?
Another thing that came to mind is a slot resonator, what are your thoughts on this? Doable?
Attachment:
Ceiling trap and hangers.jpg


• Side Walls:
I’m thinking to build two shorter (not floor to ceiling) but larger acoustic panels to replace the ones I’m using now. Dimensions:
RHS 100x120cm (LxH)
LHS 140x120cm (LxH)

• Entrance door on the RHS wall:
Absorption panel attached to the door. Dimensions: 70x194cm (LxH)
Here the depth of the panel could be up to 25cm if needed.

• Front wall:
In the area between the speakers, I will replace the fiberglass with larger panels of rockwool. (Here the usable depth is 18cm).
I will add absorption behind and all around the speakers.
The shelves above the speakers are currently used as bookshelves and I really like that, so I will leave the books there, but add a layer of absorption on the walls.
Regarding the bass traps in the lower corners, what do you think of the type and amount of fiberglass that’s in them?
Attachment:
FL Treatment.jpg

Attachment:
FR Treatment.jpg

Well, I think there’s a lot of information here and thank you if you got this far. I will welcome all your thoughts, suggestions and also insults for such a long post :)
I thank everyone who will chime in with constructive comments!
Cheers,
Antonio


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PostPosted: Mon Dec 14, 2020 11:48 am 
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the overall response in the space looks decent given the size... so adding some more density to the absorption will be helpful but if you're getting consistently the same set of problem frequencies, you might do some EQ to tweak it - it's a small space so you don't have a lot of listening positions and thus tailoring the response to your desk is fully legitimate...

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PostPosted: Mon Dec 21, 2020 9:23 am 
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Location: Puglia, Italy
gullfo wrote:
the overall response in the space looks decent given the size... so adding some more density to the absorption will be helpful but if you're getting consistently the same set of problem frequencies, you might do some EQ to tweak it - it's a small space so you don't have a lot of listening positions and thus tailoring the response to your desk is fully legitimate...


Thanks for your reply Gullfo, I have seen it only now. Actually I have made progress and I will share the details soon.


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PostPosted: Mon Dec 21, 2020 7:16 pm 
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Location: Puglia, Italy
Hi everyone, I’m back with an update on the progress of my re-build.

I have re-done everything above the false ceiling:
- Built two massive bass traps along the top front and back corners.
- Filled the centre part with a hybrid of hangers/waveguides.
- Closed everything off with a 12cm layer of rockwool.
- Put some spare fiberglass in the gap between the aforementioned layer and the front bass trap.
I filled the front wall between the speakers with a 16cm layer of rockwool.
I filled the front lower corner bass traps with cut-to-size layers of fiberglass top to bottom.
Placed a 6cm layer of rockwool in the corners where speakers and books are.
Then I have built new RFZ side panel made out of a 12cm layer of rockwool.

I have done nothing to the back wall as of yet, but I’m currently using two free standing old side panels to absorb some reflections.

Here are a couple of sketchup screenshots that show the progress.
Attachment:
sketchup1.jpg

Attachment:
Sketchup2.jpg


The rockwool I used is 40Kg/m3, here in Italy is called Pannello 211, made by Rockwool.
The fiberglass is the same stuff described in my first post: 13Kg/m3, 7kPa s/m2

Below are some photos taken while the works were in progress up until how it looks now.
I’ll post measurements shortly.

Cheers
Antonio

Attachment:
IMG_6199.JPG

Attachment:
IMG_6206.JPG

Attachment:
IMG_6205.JPG

Attachment:
IMG_6227.JPG

Attachment:
IMG_6248.JPG

Attachment:
IMG_6286.JPG


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PostPosted: Tue Dec 22, 2020 1:49 am 
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looking good! i like the bookshelves with the bookshelf monitors

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PostPosted: Tue Dec 22, 2020 3:21 am 
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Looks warm! A couple of points, for the future. I believe Polyester insulation is becoming common in italy. A nice alternative to fabric and RW.
In deep traps, say over 200mm, very low density/GFR fibre is best.
Almost anechoic spaces like this, and most CRs, do not add room tone. So we hear the speakers directly, without this 6 -9 dB LF boosting tilt.
This leads to a very bright unnatural response, flat, like Audiometric Headphones.
I have repeated success using the Bruel and Kjaer Target Curve.
I have more or less abandoned multiple speakers in the CR. The anechoic thing makes them all sound wrong the same way! Now I feed the Mix or Master to different systems in different rooms.
I would focus on the Neumenn and make MDF Baffles for them. Ethan Winer has shown elsewhere that the Back Wall is a high priority. Modes take our attention but Back Wall BIR is hugely destructive, especially in such small rooms. Given your dimensions, I recommend thinking about some sort of membrane or panel trapping on the whole wall. An array of V fronts inspired by John's designs here?

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http://www.irishacoustics.com
http://www.soundsound.ie


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PostPosted: Tue Dec 22, 2020 4:00 am 
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gullfo wrote:
looking good! i like the bookshelves with the bookshelf monitors

Thank you Glenn, glad you like it.

DanDan wrote:
Looks warm! A couple of points, for the future. I believe Polyester insulation is becoming common in italy. A nice alternative to fabric and RW.
In deep traps, say over 200mm, very low density/GFR fibre is best.

Hi DanDan thanks for your answer, what a honour, I have read a lot of your great posts here.
I have tried getting some lower density material, but the 40Kg/m3 was the lowest density i could find, so I had to go with that.

DanDan wrote:
Almost anechoic spaces like this, and most CRs, do not add room tone. So we hear the speakers directly, without this 6 -9 dB LF boosting tilt.
This leads to a very bright unnatural response, flat, like Audiometric Headphones.
I have repeated success using the Bruel and Kjaer Target Curve.

I never heard of this LF boosting tilt, would you be so kind to elaborate this please?

DanDan wrote:

I would focus on the Neumenn and make an MDF Baffle for them.

By MDF baffle, do you mean a "wall mounted speakers design"?


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PostPosted: Tue Dec 22, 2020 4:11 am 
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So, following the works described earlier today, I have to say that I’m very happy on the improvement to the sound in the room. It was totally worth it!
To be more precise:
[*]Low end is way more even and punchier.
[*]The perception of depth, reverb and space in general has improved greatly.
[*]Same for stereo localisation.
[*]Now I can hear a greater amount of details across the whole spectrum.
[*]Midrange is more defined and lower midrange is punchier.
[*]I also feel the low end now extends a little further and with some tracks I now feel a thump on my chest, which I previously couldn’t feel.

I have already worked on a project and I was able to eq and set reverbs way more effortlessly than I used to.

I can still hear some issues in the form of nulls and with the help of an oscillator I can locate them at around 70hz, 120hz, 165hz and 400hz.

But now on to the measurements:
Here is a link to the REW file
I think the overall improvement is obvious but would appreciate if anyone could help me translate these into possible additional treatment for the next step.

Looking at the SPL graphs, especially the separate L and R, I see some nulls have become “deeper”. Why has that happened?
Attachment:
L SPL.jpg

Attachment:
R SPL.jpg

Attachment:
L+R SPL.jpg

Regarding the ETC curve, I have some confusion which arose when I compared the after measurements with a set taken halfway through, when the ceiling was pretty much untreated, with only one and half of the two ceiling bass traps present. To me the ETC curve of those measurements looks better than the last ones. This really puzzles me as I expected to see a decrease in reflections once the ceiling was completed and absorption behind speakers placed. Any idea why this happened? Could the fabric or the books causing those reflections?

In the graphs below I have highlighted the area -20dB/20ms which ideally should be free of any reflections, right?
Attachment:
L ETC.jpg

Attachment:
R ETC.jpg

Attachment:
L+R ETC.jpg

Attachment:
L T30.jpg

Attachment:
R T30.jpg


With the LEFT waterfall graph something similar to the ETC curve has happened. If you look at the 120hz and 300-400hz, on the “after” graph a resonances appeared that weren’t there on the “halfway” measurements.
Attachment:
L Waterfall.jpg

Attachment:
R Waterfall.jpg

Attachment:
L+R Waterfall.jpg

Attachment:
L+R Spectrogram.jpg


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Last edited by Antonio on Wed Dec 23, 2020 9:12 am, edited 1 time in total.

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PostPosted: Wed Dec 23, 2020 3:04 am 
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Well done Antonio. Medium Density Fibreboard...... engineered wood. Heavy plywood would be fine too.
If you suppress the reflection between the back of your speaker and the Front wall you might lose that SBIR dip in your bass response.
You will also probably add a few useful dB of LF, saving stress on the little Neumann. And you will lower the cut off frequency.
Soffit or Flush Mounting creates a hard baffle extension of your speaker.

A typical domestic room with half decent speakers has a frequency response tilted about 6dB The Bruel and Kjaer curve, measured in actual rooms, is about +3dB at 100Hz and -3dB at 10KHz. Good Monitor headphones have this curve built in. in an anechoic room we need to adjust the LF/HF balance at the speaker crossover, amps, or apply an external Target Curve. Harman, Sonarworks, and many others measure the domestic response now and then. It seems remarkably consistent. 1dB per Octave or about 6dB Tilt 100/10K https://forums.audioholics.com/forums/t ... ary-for-a-“perceived”-flat-response.109946/

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http://www.irishacoustics.com
http://www.soundsound.ie


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PostPosted: Sun Jan 10, 2021 5:01 am 
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Happy New Year everybody!
DanDan wrote:
Well done Antonio. Medium Density Fibreboard...... engineered wood. Heavy plywood would be fine too.
If you suppress the reflection between the back of your speaker and the Front wall you might lose that SBIR dip in your bass response.
You will also probably add a few useful dB of LF, saving stress on the little Neumann. And you will lower the cut off frequency.
Soffit or Flush Mounting creates a hard baffle extension of your speaker./


Oh, I know what MDF is :) what I wasn't sure about was what you meant by "making a baffle" for the speakers, but it's fully clear now. Unfortunately that's not a viable option as on one of the corners there's an electrical switchbox which can't be closed off by a baffle. :cry:

DanDan wrote:
A typical domestic room with half decent speakers has a frequency response tilted about 6dB The Bruel and Kjaer curve, measured in actual rooms, is about +3dB at 100Hz and -3dB at 10KHz. Good Monitor headphones have this curve built in. in an anechoic room we need to adjust the LF/HF balance at the speaker crossover, amps, or apply an external Target Curve. Harman, Sonarworks, and many others measure the domestic response now and then. It seems remarkably consistent. 1dB per Octave or about 6dB Tilt 100/10K https://forums.audioholics.com/forums/t ... ary-for-a-“perceived”-flat-response.109946/


Interesting, I never thought what the response of a speaker would be in a semi-anechoic space, but it makes sense.
I am experimenting with a Sonarwoks demo, as well as generating EQ curves with REW and applying them manually on my DAW output. I agree with those who say that flat doesn't sound pleasant at all, but flattening out the response and applying a tilted house curve seems to bring some improvement. I'll keep messing around..
Regarding Sonarwoks I'm not sure I like what it does though. It takes all the punch out of the low end, may it be bad phase on the EQ side? I listened to all the filter types and none sound good to my ears. Or it may also be the limited control one has over the house curve..are there any alternatives that allow more control?

P.S. the link to the audioholics forum is broken but managed to find it and here it is


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