I have a small room that is used for mainly mixing with some vocal tracking and the occasional guitar tracking. Unfortunately this small apartment is rented and I cannot make any significant changes to the dwelling. I’ve spent a fair bit of time experimenting with commercial traps and panels and have done some simple DIY treatment with Rockwool. I feel that I’ve done about as much improvement as possible with what I have and given the restrictions of the room and the fact that it’s my living room too.
So far I’ve made some OK progress using the basics as discussed here on the GS forums – so thanks to everyone for sharing their valuable knowledge. I’m now trying to come up with some ideas and options to improve the room to take it to the next level. I’ve attached some results that I got with REW. The frequency responses are for left and right monitors measured separately. The waterfall and spectrogram are for both monitors at once. There are also some Sketchup models of the room layout. I’ve also attached some screenshots of the RealTraps mode calculator and the REW measurement file zip is also attached.
First some details….. Room Info
Width: 11’8” (355cm), Depth: 15’5” (480cm), Height: 8’6” (260cm)
Volume: 44.3 cubic metres (1564 cubic feet)
Measurement Microphone: Audix TM1 Omni
Studio Monitors: Barefoot MM35
- No holes in the ceiling or walls
- Hallway doorway at left of front wall
- Glass balcony door with Venetian blinds at rear of the room on the right wall.
- Bedroom folding door at front of the room on the right wall near first reflection point.
- Not obstructing water views from the back window – OK to pull the curtains and close the Venetians when mixing as this has some improvement on the room response.
- Monitor placement is somewhat limited although the desk is on wheels and I’ve been able to move it away from the front wall to reduce SBIR.
- Aesthetics – this is my living room too! Right wall has some artwork hanging and I’d really like to avoid taking this down to add more traps/treatment.
Current Acoustic Treatment:
- Panels at the front of the room are 4’x2’x3.25” RealTraps Mini-traps on stands. The 2’x2’ x3.25” centre trap is a HF trap as is the right reflection point trap. Panels are 8” from front wall.
- Front corner traps are RealTraps corner 4’x4’9”x4.25” Mondo traps on stands.
- Left wall panels are 4’x2’x2” Primacoustic broadband panels. Panels are 1” from wall.
- Adjustable modular ceiling cloud uses three 4’x2’x2” Primacoustic broadband panels with two 4’x2’x3” ones fitted above the monitors giving 5” in total. The cloud is angled to reduce high frequency reflection to listening position.
- 2” Primacoustic corner traps fitted to front corners.
- Rear wall corner panels are 4’x2’x3” Primacoustic broadband panels. These are the ones sitting in front of the curtains.
- Lower rear wall (and corners) also treated with Ikea book cases that are filled with 18” deep Rockwool which extends 3” out the back. I have read in another post that the lower frequency response (<100Hz) can be improved by removing the shelves or drilling (rather large) holes in them and the side walls of the bookcases. I plan on doing this – at least to the shelves which won’t be visible.
- Left over Rockwool fitted behind the rear sofa.
Test position for the data shown was optimised with Pink Noise and RTA in REW. Interestingly the flattest response is very close to the centre of the room approximately 45% from the front wall when the monitors are moved around 2’ from the front wall. I found that when the desk was closer to the front wall and the test done at 38%, the 38Hz mode was only slightly higher, but there was a substantially wide and deep dip between the 38Hz and 125Hz modes which produced an audible absence of low end. The 1/3 octave averaged response is around +/-5dB while the 1/24th averaged response is more like +/-10dB due to a few dips and peaks.
I’m not sure which figure is how I would rate my room – is it a +/-5dB result (Level 3) as in the post by Hannes_F? (See Acoustics/Treatment Reference Guide sticky). If I’m still at +/-10dB then there’s a long way to go!
The room sounds much better compared to before the recent addition of the rear traps and ceiling cloud. I’ve found that the sweet spot and translation have significantly improved. Overall, it’s good but I want better.
Now I’m looking to lower the peak(s) around 125Hz, remove the dips at 150Hz, 170Hz, & and others around 500Hz. Finally there is the prominent 38Hz mode. If I can moderately address these issues then I’d be content as this is probably all that I could hope to achieve for my room given its dual purpose and the fact that I cannot make constructional changes to the room itself. I could live with the way the room sounds right now for mixing, but I’d really like to lower the impact of the remaining problems if it doesn’t cost a fortune. What Next?
How can I get to the next level? Some things I’m considering which are:
- I need to address the dips around 500Hz - could this be SBIR or LBIR? I’ve see similar issues on responses posted by other members – does anyone know what dips in this range are typically caused by? Maybe I can investigate this with a directional microphone and RTA, or alternatively test with some sine waves. I assume the nulls around 150Hz and 170Hz are modal.
- Apply Helmholtz or additional bass trapping between the floor and front wall to lower room mode around 38Hz. There have been some very informative GS posts on the Helmholtz designs lately, but I’m not sure if there is enough space for this type of treatment to make a difference. One option is to re-deploy the front panels to the walls and look at fitting some kind of modular wall design with slats and/or membranes for the front wall. This might me expensive but this is the only wall where I can claim most of it for treatment. If I go this way then I would probably get an expert involved.
- Apply Rockwool behind and under sofas to improve room modes. If there’s space and it’s not visible then I figure why not if it’s cheap and out of sight.
- Beef up the left and right first reflection points by using thicker traps so they treat lower frequencies over a larger area? The peak at around 125Hz appears to be a combination of close modes. When I added the ceiling cloud the peak was lowered but also got narrower which I assume indicates that the height contribution was significantly reduced leaving reflection from the side walls – mainly the left wall as the right wall has a doorway.
Aside from any comments on my initial ideas to improve the response, I would be thankful if anyone has some alternative ideas. I’m not very experienced in this area so there may be ways I could improve the room by re-arranging what I already have or some other ways I’m not aware of.