Hi everyone !
Although I have been following this very valuable forum for some time and greatly benefited from its content, this is my first post here. Being French, I apologize in advance for some potential awkwardness in my writing. Furthermore, I hope my post follows the forum rules and is complete enough for your needs.
My situation overview
I am a young musician / music producer, I just finished my musicology curriculum and recently moved to a rented 54 sqm apartment, second floor, with three rooms (living room, bathroom, bedroom, hallway). I am mostly specialised in pop, rock and metal genre and my goal, like most small home studios, is to be able to record monophonic, moderatly loud instruments at home (vocals, guitars etc.) and to do critical listening/mixing.
My workspace is in my living room, which I will more precisely describe below. Most of my furniture and equipment is already in place and I am now planning the DIY acoustic treatment, taking into acount the fact that I cannot deteriorate the room in any way more than some holes in the walls, and that it has to remain a reasonable place to live in everyday.
I am looking for some opinions, advice on the configuration of the furniture/equipment and the design of the acoustic treatment.
The room
The room is L shaped with approximately 27 sqm of total area and 66 cubic meters of volume. The larger portion is where my studio is set up, while the smaller portion is the kitchen. A 2.5m double door/window bay opens up to a large balcony. One door leads to the corridor. The ceiling is 2.42m high.
Larger portion (LWH) : 5.2m*4.36m*2.42m
Smaller portion (LWH) : 2m*2.3m*2.42m
As far as sound isolation is concerned, the building is modern (2009), and noise should not be too much of an issue with neighbors, especially since I do not listen at very high volume, and do not intend to record live instruments or vocalists too late. I could not really do anything about isolation anyway.
The front wall of my listening position is heavy concrete. When hit by hand it does not resonate. Since that wall is adjacent to another apartment, it is probably purpose built for isolation. Ceiling is also concrete. All the other walls are drywalls. The floor is laminate artificial wood.
Current furniture and equipment configuration
I will not linger too much on the kitchen part. It is equipped with a fridge, a cooker, a washing machine and storage furniture. In the main portion of the room there is a couch at the rear wall, a small glass table in front of the couch, a bookcase hiding the fridge, my desk and the speakers.
The speakers are Eve Audio SC3010 with cheap but massive DIY concrete stands (62kg each). There is a 1.5cm sheet of anti-vibration material between the concrete and the speaker. It is not purpose built for that application though, it is for washing machines. But it was cheap and will at least prevent concrete from scraching the speakers.
The desk is this one
Thanks to the angled 19" racks, it seems to prevent most of the reflections there would be with an horizontal surface.
Following online advice, the speakers are placed in the symmetrical part of the room, shooting along the longest dimension (5.2m). They are also placed very close to the front wall (6cm at the closest), to avoid SBIR at untreatable low frequencies.
Low end boost due to wall proximity is taken care of with a -3.5db low shelf. Acoustical centers of the speakers are 195 cm appart, 119 cm high and 122 cm from the side walls (0.28 of room width). Speaker to listener distance is about 187cm. Listening position is currently 214 cm from the front wall (0.41 or 7/17 of room lengh). I started at 0.38 but found 0.41 was a bit better. It may change with further acoustic treatments. Speakers are angled so that the apex of the listening triangle is about 35cm behind my head.
I have also placed a few full band absorbent panels that I had built for my previous room. They are 135*60*10cm, with rockwool in the 15000 to 20000 rayls/m range. Two of them are at the lateral first reflection points. Two are against the front wall, right next to but not behind the speakers (the reflection should passe through them though). And there is the equivalent of 5 of these panels piled up behind the couch (30cm depth of material at the most).
Sorry for the bad quality pictures. The sketchup drawing is not perfectly accurate nor complete but gives a rough idea.
I have made some REW measurements with that configuration. Microphone is a Behringer ECM8000. It was placed at the listening spot (214cm from the front wall, 119cm height, middle widthwise). Since I don't own a soundmeter, sound level was set up so that it was rather loud but far from extreme.
Here is the link for the mdat file
In its current state, the room doesn't sound bad but of course I expect much better, notably in the bass department.
Acoustic treatment design
While trying to keep the room sufficently practical for everyday life, I intend on doing a rather large amount of treatment to bring bass under control. Do justice to the Eve.
First point reflection treatment (side walls and ceiling) would be achieved with my already made full range acoustic panels.
As far as bass management is concerned, my plan is to place, wherever is practical enough, large blocs of low density fiber glass (Isover IBR, 4000 rayls/m), wrapped in multiple layers of plastic sheets to avoid excessive absorption of higher frequencies. Some of these chunks would be placed directly on the floor while other would be hanged in the ceiling to wall junctions, thanks to rails fixed to the ceiling and multiple nylon straps wrapped around them. The bottom layer of the hanging chunk would be made of more rigid 10cm thick fiberglass panels (15000 rayls/m) in order to maintain a correct shape.
I have made a sketchup model with rather precise scaling, showing what I would do.
Chunks in red are the low density fiber glass wrapped in plastic.
Panels in blue are the full range absorbers.
Here is the link for the Sketchup file
Total absorbent volume would be around 7 to 8 m^3 according to my calculation.
Questions
Now that I have, hopefully, properly exposed my situation and plan, I would be very grateful if you could advise me on the following points :
1 - Is the listening position globally correct ? According to what I have already read on this forum and others I would be inclined to think it is, but the opinion of more experienced people is always welcome.
2 - It is often recommended to place speakers away from the front wall, especially rear ported ones (which the SC3010 are). While I am fully aware of the SBIR problems and the low end boost (which I easily tamed with speaker low shelf in my case), are there some specific deteriorations due to rear port proximity to the wall ? I haven't noticed anything special with my current speaker configuration but I would be curious to know.
3 - Always concerning the speakers, it is recommended, when they are close to the wall, to place some absorption behind them to prevent SBIR. In my case, instead of behind, I intend on filling the space between the two speakers with a 40 cm deep absorbent chunk which should be in the path of the reflecting waves. Would this still work the same ?
4 - Being unable to invert the door opening side, I cannot place more than 10cm of absorbtion depth here. Should I rather place the absorption on the door or on the portion of the front wall behind the opened door ?
5 - Front wall corners cannot be totally symmetrical, especially since the left corner would much more treated than the right one. Is this going to be a problem ?
6 - In order to take care of the ceiling SBIR and room height modal issues at the listening position, I plan to place 10cm deep full range absorption 50cm below the celing, and fill the space above with 40cm of low density absorption. The resulting block would be 140*190*50 (LWD), and would cover the space from above the front of the speakers to the front of my desk (about 2m from the front wall). Is that a good idea or not ?
7 - In order to prevent destructive phase issues with the floor, I intend on placing two small bloc (40*50*30 LWH) of wrapped fiberglass under my desk on the reflection's path. Is that a good idea or not ?
8 - Is the low density fiber glass I plan to use adequate for 60cm depth or more ? Isover IBR 4000 rayls/m, 12 kg/m^3
9 - What is your opinion on the use of large 3 way speakers such as mine at rather close listening distance (185-190cm in my case). According to Eve Audio manual, ideal distance for the SC3010 is between 1.5 to 4m. I was under the idea that what really matters is to have enough distance for the proper blending of the midrange driver with the tweeter at the crossover frequency (which is 1800hz on the SC3010). Since the distance between the tweeter and the midrange woofer is not much higher than on a 2 way speaker, minimal listening distance should not be much higher either. Is this reasoning correct ?
My excuses for such a lengthy post and thanks in advance for the advice you can give me !
Acoustic treatment design for L shaped 27sqm room
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Scholl
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