Small mixing room - good advice needed

[Jukka]

Hi,

this is my first post, although I've read the forum for some time now.

Recently I moved in to a new place. Here I have a small room (old workshop) next to the carage, that I'm
transforming into a mixing room.

Room dimensions are: Length 4,55m; widht 3,24m; height 2,25m.
The carage/workshop building is basicly timber structured. Inner surfaces are made of gypsum board.
Floor structure is as follows:concrete slab, 2"x4" framing with 4" rockwool, planking.
Ceiling is interesting: Sparse planking with silverpaper and wool above it. The actual roof is slanted and it's basicly
a meter above the inner ceiling. There are two small windows on the right side of the room.

I've already made some movable absorption panels, 125mm rockwool in wooden frame and covered with cotton, placed
at first reflection points. The front wall is covered with 125mm rockwool and carpeted with reflective cloth.
I moved my speakers and computer in and made some measurements with REW and a measurement mic.

measurement_04_11_2012.jpg

impulse.jpg

rt60.jpg

waterfall.jpg

EDIT: At this point I'm mostly interested in the room bass responce. That's why the freq. measurement is below 500Hz only.

mic position is about 38% from the front wall, good starting point at least. Speaker placement is based on the flattest low bass responce I could find. I'm a bit puzzled about the mid and high bass dip. Any ideas on improving this?

[Soundman2020]

Hi Jukka, and Welcome!

There doesn't seem to be any major modal activity visible in that graph, or at least not in the section you are showing, so I'm guessing that the dips you are seeing around 80 and 160 Hz. are probably due to phase cancellation (SBIR) or reflections from somewhere.

Please post some photos of the room, showing the existing treatment and the positions of the speakers and measurement mic.

Also, what speakers are you using?


- Stuart -

[Jukka]

Thanks Stuart for taking the time to comment.

The speakers are RCF Ayra Eights. http://www.rcf.it/products/recording/ayra/ayra-8

Some photos of the room:
Behind the black cloth there is 125mm rockwool.

DSC_4885.jpg

[RJHollins]

Just an observation ...

In your 'Freq Response' chart, you have "1/6 octave smoothing is on".

Lots of details are hidden due to that. You should post charts with NO smoothing.

[Soundman2020]

There doesn't seem to be much treatment at all on the rear wall: I would suggest putting two large superchunks in the two rear vertical corners, as well as treating more of the rear wall, then measure the room again.

Also, those bags of insulation in the two front corners are in the wrong place to get the most effective result: Right now they are in the middle of the walls, with a gap underneath and a gap above. The tri-corners are the most effective place for treatment, so they should go all the way from the ceiling to the floor.

In your 'Freq Response' chart, you have "1/6 octave smoothing is on".
Lots of details are hidden due to that. You should post charts with NO smoothing.

Yup! Very true!


- Stuart -

[Jukka]

There doesn't seem to be much treatment at all on the rear wall: I would suggest putting two large superchunks in the two rear vertical corners, as well as treating more of the rear wall, then measure the room again.

Okay, I will do that as soon as possible.

Also, those bags of insulation in the two front corners are in the wrong place to get the most effective result: Right now they are in the middle of the walls, with a gap underneath and a gap above. The tri-corners are the most effective place for treatment, so they should go all the way from the ceiling to the floor.

Yes, I know. I just quickly put them in the corners to give some extra absorption. I haven't build any superchunks in the front corners yet, because I haven't excluded suffit mounting the speakers. Would you recommend on doing that?

In your 'Freq Response' chart, you have "1/6 octave smoothing is on".
Lots of details are hidden due to that. You should post charts with NO smoothing.

I have to be more specific in the future, thanks!

[Soundman2020]

I haven't excluded suffit mounting the speakers. Would you recommend on doing that?

Absolutely! The benefits from soffit mounting are excellent, and it looks like you have enough space to do it right. You also need lots of bass trapping in that room, so I would suggest using John's design, which has bass trapping built into the lower section.

I have to be more specific in the future, thanks!

If you turn of the "smoothing" function in REW then re-post the graph, that will reveal a lot more details of the acoustic response.


- Stuart -

[Jukka]

I finally had the time to treat the back wall and corners with rockwool.
Here are the new measurements. No major changes. Any comments or suggestions?

meas_11_24.jpg

[Soundman2020]

No major changes. Any comments or suggestions?

It is impossible to say if there have been any changes or not, since you didn't post the graphs that would tell is if there have been changes! You only posted the frequency response curves.

It also looks like you did the test at a lower level this time: apparently the level was about 5 dB lower than last time. Also, you switched off the smoothing, so we are looking at different curves! You can't compare graphs that were created in different ways, based on different parameters.

Please post the actual REW data file, with all the readings from both "before" and "after".

Also please post photos of the what you changed in the room.

- Stuart -

[Jukka]

Thank's for your patience. This measurement stuff is quite new to me.
I'm sorry but I think I have not saved the 'before' data, 'cos can't find it anywhere.
The 'after' file can be downloaded here: https://www.box.com/s/om53ylvp006sw0qg2fe4
I'll post some pictures soon too.