John Sayers' Recording Studio Design Forum Archive

I have a 8'8" x 12'4" x 6'8" room.

I have recently made calculations on REW, here are the graphs.

I recognize is the dip at 110HZ could be from SBIR and so I do plan on adjusting my monitors. Currently I have them two feet off the wall with no specific measurements. I have learned that since I have a room on the small side I could put my monitors close to the wall with absorbers right behind since I can't flush mount my speakers.

What I am onto next is constructing panels and bass absorbers (since I am on a slight budget). What I would love to know is how thick I should construct these and where would the ideal place to place them be. I am attempting to create my room as a production/mixing room. I also want to figure out how to set up a mic spot for the best vocal production (I was thinking of being able to move panels if need be to give the vocals more roomier sound)

Would appreciate all the help y'all can offer.

you'll probably want to build about 22 4" thick 2' x 4' absorbers 4 -> span corners. 4 down each side (so of the room. 3 on front wall and 3 on back wall, 3 spaced across ceiling. plus 1 on stand for in-room damping.

What are the boundaries made of..... Concrete.... wood... plasterboard? A light structure will not have strong reflections at LF, which would be great.
Can you post the REW file so we can look at Waterfalls and Topt with our own choice of scales and filters?
I would broadly concur with Glenn but some slight divergence....
I would focus treatment on the Back wall. In many cases it proves best to not treat the Front Wall at all.

DanDan wrote:What are the boundaries made of..... Concrete.... wood... plasterboard? A light structure will not have strong reflections at LF, which would be great.
Can you post the REW file so we can look at Waterfalls and Topt with our own choice of scales and filters?
I would broadly concur with Glenn but some slight divergence....
I would focus treatment on the Back wall. In many cases it proves best to not treat the Front Wall at all.

A little bit of a tangent, but still somewhat related.

I also understood that lightweight structures do not have strong LF reflections, however, I've recently been reading everything I can on anechoic chamber wedges. In all of the papers I have read (some very detailed with complex maths completely over my head) they state, in my own words, that the porous wedges absorb highs and mids, and LF waves are reflected between the wedges, ricocheting back and fourth until the energy is dissipated into nothingness. Of course, it depends on the wavelengths involved and the usual gradual transformation between rays and waves as you go from high to low frequency. The wedges need to be long/deep enough in order to have an effect on the desired LF.

But it is a mechanism of reflection which obliterates the LF energy, not the absorbent properties of the porous fibre. My point is: you can't get much lighter in weight than fibreglass or similar and yet LF energy is reflected off of it according to these papers. The wedge shapes provide a gradual impedance increase which sucks in the ping ponging waves, more and more energy is lost with each bounce. I was surprised to read this, since what does it mean for flat panels and deep whole wall trapping?

From personal experience: My control room in it's current state of progress is simple a timber frame with 1 single layer of 18mm OSB, yet it is clear from the measurements that strong LF reflections exist, the walls are not lossy enough that no strong LF reflections exist.

Therefore, invisible alpha, membranes, lightweight structures and porous absorbent can all be reflective or absorbent in one way or another.

Loose lips sink ships! I am very doubtful that LF waves bounce of the pointy end of those wedges. There are rules of thump else where that suggest that LF waves will not 'see' anything without somewhat comparable dimensions. I don't know what density fibre or foam they use but it seems stiff so let's call it 100KG. We know that absorbs quite well at the thinner end. If any reflection occurs it should theoretically be when the fibre depth has increased. Odd. The LF absorption of Invisible Alfred, plasterboard, ply etc. is surely very LF and quite dependent on the mounting arrangements. Steel studs or even RC could be helpful.


EDIT...... you got my curiosity up Paul! Here the writer chose 90KG fibre because higher values were becoming reflective at LF https://www.diva-portal.org/smash/get/d ... TEXT01.pdf

Hey Dan,

The front wall and the left wall are plaster walls. The back and right wall are painted cinderblock. The floors where tile but I have covered it with a shaggy carpet and carpet padding.

Two walls and a floor solid and a low ceiling..... ouch.
Can you post the .mdat REW file?

DanDan wrote:Loose lips sink ships! I am very doubtful that LF waves bounce of the pointy end of those wedges. There are rules of thump else where that suggest that LF waves will not 'see' anything without somewhat comparable dimensions. I don't know what density fibre or foam they use but it seems stiff so let's call it 100KG. We know that absorbs quite well at the thinner end. If any reflection occurs it should theoretically be when the fibre depth has increased. Odd. The LF absorption of Invisible Alfred, plasterboard, ply etc. is surely very LF and quite dependent on the mounting arrangements. Steel studs or even RC could be helpful.


EDIT...... you got my curiosity up Paul! Here the writer chose 90KG fibre because higher values were becoming reflective at LF https://www.diva-portal.org/smash/get/d ... TEXT01.pdf

In the same document it says:

"In order to reduce the generally reflected sound to a minimum, the surface must be large and the absorption coefficient of the lining must approach the unity.
If the absorption material is well designed, the middle and high frequency sound is absorbed. To ensure the absorption of sound energy also in low frequencies, the absorption material has to be subjected to special geometrical treatment. "

If there was no LF bounce then there would be no need for the special wedge shape.

Yes here is a dropbox link to the .mdat file from my rew calculation
https://www.dropbox.com/s/bbisilbrem73z ... .mdat?dl=0