Post by redrum on Mar 26, 2017 21:57:21 GMT
Howdy!
I'm midway into redoing acoustic treatment of a studio, and I have some issues / questions.
LAYOUT / ROOM INFO:
The layout of the room and existing treatment can be seen here: LINK 1
Non-panorama pics (to get a better feeling of the room):
1. Left wall and ceiling - LINK 2 (At the base there are "ISO boxes" which I'm not allowed to move. Bare wall inside - I could do a layer of fiberglass - not sure if it would make sense.
2. Front wall - LINK 3 (Pretty much bare - just 5 cm of rigid fiberglass)
What's not visible on these pics is the Right Wall - huge windows top to bottom, which are pretty much 100% absorptive below 100 Hz I believe, extremely thin and do nothing in terms of soundproofing. I think I'll leave them like this - I can live with the neighborhood noise, not residential. They are covered with a 10 cm of porous absorbent, to kill high freq. reflections. Below them, until the floor - 1m high, 30 cm thick fluffy. Also the superchunks are HUGE, approximately 1m x 1m x 1,5m -> 4m high.
The room is 4m high, 8 meters wide, 5,3 meters "long". I write "long" in quotation marks, as the Front Wall has slanted edges, as can be seen in this wonderful top view drawing - LINK 4
Here's the REW FR plot (LINK 5), and waterfall (LINK 6). I think it's quite OK, sub is a bit too loud maybe (can be modified easily), problems between 150Hz and 300Hz are mainly a combination of SBIR (speaker driver at 40cm from FW), and an empty console desk in front of the speakers. Suggestions on how to fix it are welcome, but not the reason why i write this post. I was planning on tackling these later anyway.
The real problem I am trying to solve now is longer decay at sub and low frequencies. REW "decay" plots show this - for example: Decay after 100ms (LINK 7), and decay after 400 ms (LINK 8). If I'm reading these graphs correctly, the area around 35 Hz falls for only 5 dB in the first 100ms. After 400 ms, the level is 40 dB below original. Also, the area just above 100 Hz is a bit slow also... I've been informed that AES/EBU finds 400 ms RT60 acceptable at low frequencies - mine is probably a bit slower than that.
The source(s) of this problem (I presume) might be these factors:
1. Not enough porous absorbent. I'm thinking about treating also the ceiling above the front part of the room with a thick layer of "pink fluffy". This ceiling is slanted downwards, using wooden boards. Maybe remove some boards and fill the whole space with "pink fluffy"?
2. Resonating front wall. The area just below the separating glass resonates at around 32 Hz (aerated concrete). Can be heard while thumping it (AUDIO REC). I temporarily dampened it with a wooden board and the audible resonance was almost completely gone (LINK 9 - WALL DAMPENING), but the decay measurements remained unchanged - even though this is where the decay plots show the biggest issue -> maybe I haven't dampened it enough/properly. Maybe it could actually be helping - if I "really" dampen it properly - effectively turning it into an absorber?
3. "Bad" speaker. But I would rule that out because the measurement is the same with both my Adams S2A + sub, and the Genelecs 1031A only.
It would be helpful if someone with more experience than me would point me in the right direction. Pretty please
RECAP - My questions are:
1. What is the ballpark of "what to aim for" for the low end decay - considering room volume and current conditions. 400 ms RT 60 for the sub-low-end?
2. What could be the cause of my slower low end decay ? I listed my assumptions -> any ideas/guesses?
3. 150 - 300 Hz FR problems, how to fix them? Maybe put some fiberglass around the speakers for the 200 Hz SBIR dip? How about the console midrange dip - will it be better or just different after the desk is filled up with equipment?
THANK YOU!!!
P.S. - Full .MDAT file -> MDAT
I'm midway into redoing acoustic treatment of a studio, and I have some issues / questions.
LAYOUT / ROOM INFO:
The layout of the room and existing treatment can be seen here: LINK 1
Non-panorama pics (to get a better feeling of the room):
1. Left wall and ceiling - LINK 2 (At the base there are "ISO boxes" which I'm not allowed to move. Bare wall inside - I could do a layer of fiberglass - not sure if it would make sense.
2. Front wall - LINK 3 (Pretty much bare - just 5 cm of rigid fiberglass)
What's not visible on these pics is the Right Wall - huge windows top to bottom, which are pretty much 100% absorptive below 100 Hz I believe, extremely thin and do nothing in terms of soundproofing. I think I'll leave them like this - I can live with the neighborhood noise, not residential. They are covered with a 10 cm of porous absorbent, to kill high freq. reflections. Below them, until the floor - 1m high, 30 cm thick fluffy. Also the superchunks are HUGE, approximately 1m x 1m x 1,5m -> 4m high.
The room is 4m high, 8 meters wide, 5,3 meters "long". I write "long" in quotation marks, as the Front Wall has slanted edges, as can be seen in this wonderful top view drawing - LINK 4
Here's the REW FR plot (LINK 5), and waterfall (LINK 6). I think it's quite OK, sub is a bit too loud maybe (can be modified easily), problems between 150Hz and 300Hz are mainly a combination of SBIR (speaker driver at 40cm from FW), and an empty console desk in front of the speakers. Suggestions on how to fix it are welcome, but not the reason why i write this post. I was planning on tackling these later anyway.
The real problem I am trying to solve now is longer decay at sub and low frequencies. REW "decay" plots show this - for example: Decay after 100ms (LINK 7), and decay after 400 ms (LINK 8). If I'm reading these graphs correctly, the area around 35 Hz falls for only 5 dB in the first 100ms. After 400 ms, the level is 40 dB below original. Also, the area just above 100 Hz is a bit slow also... I've been informed that AES/EBU finds 400 ms RT60 acceptable at low frequencies - mine is probably a bit slower than that.
The source(s) of this problem (I presume) might be these factors:
1. Not enough porous absorbent. I'm thinking about treating also the ceiling above the front part of the room with a thick layer of "pink fluffy". This ceiling is slanted downwards, using wooden boards. Maybe remove some boards and fill the whole space with "pink fluffy"?
2. Resonating front wall. The area just below the separating glass resonates at around 32 Hz (aerated concrete). Can be heard while thumping it (AUDIO REC). I temporarily dampened it with a wooden board and the audible resonance was almost completely gone (LINK 9 - WALL DAMPENING), but the decay measurements remained unchanged - even though this is where the decay plots show the biggest issue -> maybe I haven't dampened it enough/properly. Maybe it could actually be helping - if I "really" dampen it properly - effectively turning it into an absorber?
3. "Bad" speaker. But I would rule that out because the measurement is the same with both my Adams S2A + sub, and the Genelecs 1031A only.
It would be helpful if someone with more experience than me would point me in the right direction. Pretty please
RECAP - My questions are:
1. What is the ballpark of "what to aim for" for the low end decay - considering room volume and current conditions. 400 ms RT 60 for the sub-low-end?
2. What could be the cause of my slower low end decay ? I listed my assumptions -> any ideas/guesses?
3. 150 - 300 Hz FR problems, how to fix them? Maybe put some fiberglass around the speakers for the 200 Hz SBIR dip? How about the console midrange dip - will it be better or just different after the desk is filled up with equipment?
THANK YOU!!!
P.S. - Full .MDAT file -> MDAT
). 
