The quest for a better mixing environment continues.....

Hi.




Background:

I have been in and out of a couple of small home studios over the past five years and when I have time I try to improve my understanding of acoustics as well as improve my mixing environment.



I moved into a new place about a year and a half ago.



I made my own bass traps and I bought the rest of my acoustic treatment from a small independent eBay business. I followed the room set up guides, correct listening position and so on. However as this location is only temporary I wasn't willing to go the whole way and create the acoustic excellence Ethan so carefully describes. I will definitely do this when I get my own place. I needed something portable, storable and relatively quick to put together as time is very limited. However I also need it to work. SO I went OTT and thought I could refine afterwards. This leads me to where I am now.



Room:


My room dimensions are: 5.5 meters long, 3 meters wide and 2.4 meters high.





My bass traps & other panels:



I went for an adaptation of Ethan's more simple 'fill each corner' technique because as I said, I needed something that I could store and reuse.



So I have 14 large bass traps: 1200x600x255mm (2 stacked on top of each other, floor to ceiling, in each corner in front of my listening position (behind the speakers) and then I literally created a wall at the back of the room leaving an air gap behind of 200mm, again stacks of two on top of each other (floor to ceiling) The only issue is I have to get in and out of this wall so there is an opening with a heavy curtain to the left hand side which leads to the door.
There was no way around this.



My design for the bass traps was a 25x35mm wooden shell filled with 3x900mm Knauf Earthwool Flexible Slab (density of 33kg/m3) Unfortunately this is all I could get my hands on as I live in the wilderness of Scotland and I couldn't get anyone to deliver Rockwool (we can't get Owens Corning over here). They are covered in a very thin transparent fabric.



For the acoustic absorption coefficients I can only get access to 400mm and 1000mm info (not my 900mm) both of which are measured against a "solid backing" - I was advised that this could be plasterboard/typical indoor wall. I presume this is why Ethan emphasises that traps are securely placed against walls if not sealed to create an air lock....



Anyway, these are the coefficients for Knauf RS33 (Flexible Slab)



Thickness 125Hz 250Hz 500Hz 1000Hz 2000Hz 4000Hz NRC



400mm     0.19   0.46   0.79    0.92     1.00     1.00     0.80



1000mm   0.57   1.00   1.00    1.00     1.00     1.00     1.20



So one would presume my 900mm would be close to the 1000mm



My traps use three = 2700mm and the majority are in a snug position but not exactly sealed.





Moving on:



I also have sixteen large panels: 1240x640x50mm



9 on the ceiling 



7 on the walls 



Wrapped in an acoustically transparent fabric covering a sound insulating slab (Rockwool - I don't have the exact model at hand so I can't tell you the coefficients), which absorbs low, mid and high-end frequencies. Open back design with a fabric rather than a wooden panel to maximize sound absorption
,






My experience with this setup:

Generally this is probably the best set up I have had however there is something wrong with my lower frequencies and how I hear them. I have a feeling I have removed too much bass now (I wonder why...) So after making some measurements I decided to put in a graphic eq (Yamaha 2031B) just to see if it could make any difference to my listening position. This takes me to where I am now and my decision to start this thread as I know Ethan is the man to ask and I hope it will help others.





Acoustic measurements:



I am measuring each speaker (Yamaha NS10M & Sub SW10) from my listening position using the USB UMIK-1 microphone, my studio audio interface and REW 5.20 Beta 5.



Running my speaker output at 33dB setting REW to a scale of 50-110dB from 40Hz-20kHz with 1/12 octave smoothing.





My latest results are as follows:





LEFT & RIGHT WITH GRAPHIC OFF:









LEFT & RIGHT WITH GRAPHIC ON








LEFT WITH GRAPHIC ON & OFF:






RIGHT WITH GRAPHIC ON & OFF:









DEQ2496 RESULTS:





LEFT & RIGHT






LEFT, RIGHT & LEFT+RIGHT MONO (Green)









Here are a couple of pictures to give you a better idea:







BOTTOM:






Conclusion:



Generally I would be extremely grateful if you could help me establish the best course of action to fix my lower frequency issue and perhaps create a flatter response from 1kHz to 2kHz (I am considering getting a parametric for this).


Many thanks.



M.