Small control room (33 m3), KH 120 II – independent diagnosis welcome (REW .mdat included)

Hello everyone,

I am treating a small home studio control room (mixing all genres, mainly rap / hip-hop, plus vocal recording) and I would like an independent reading of my measurements before I build anything.

Everything is in one pack: a PDF with the room dimensions and construction, the existing treatment with lab data, speaker and mic positions, the measurement setup (REW 5.31.3, Sonarworks mic with the 30° file, 256k sweeps, one speaker at a time), plans, 3D views and plots, plus the five .mdat files (20 to 24 October). Main reference: "L 30 P0 REF 24.10" and "R 30 P0 REF 24.10" in TEST 24.10.26.mdat.

Link: https://www.icloud.com/iclouddrive/067vJTJwcPrKMV_0JEJfJ3jEg

I have my own hypotheses, but I am deliberately not sharing them, so as not to steer you. My questions:

1. What do you see in the measurements, and what do you think causes it?

2. What would you treat first at the listening position?

3. Section 9 of the PDF lists the ideas I am considering (front corner traps, flush-mounted speakers in a false wall, membrane absorbers, etc.). Are they good ideas?
Thanks a lot for your time.

Hello and welcome @Iamrealnino, My first thoughts after looking over your room information is that you have used way too much thin foam absorbers which would over absorb high frequencies and deaden the liveliness of the room... I think your priorities are to remove at least half of the thin foam absorbers... Next steps would be to make or buy some thick bass absorbers for the front wall corners, floor to ceiling... Add some broad band absorbers at what might be the left and right speaker reflection points... Deal with the window with heavy curtains or your false wall idea... Rear wall corners could use the same thick bass absorbers as the front wall... My rule of thumb is 1/4 to 1/3 of all surfaces need broad band absorbers... Bass absorbers should use a strike plate to reflect high and some mid frequencies...

It seems that you are doing some tracking/recording as well as mixing/mastering... For tracking/recording you want a more lively room and for mixing/mastering you want a touch less lively... A few portable/freestanding absorbers could be moved/removed for each specific use case...
Decay times under 200 ms can feel overly dead... Decay times over 500 ms in small rooms cause frequency masking and smeared transients...

I'll spend a bit more time on this over the next few days...

Thanks a lot for taking the time, ddude003, very helpful.

Where I am now:

- MA 1 room alignment done (26.10): the peaks are tamed, but the 76-79 Hz dip (reflection from the opposite side wall, confirmed by a position test) and the ~1.5 s decay at 33 Hz (most likely the first length mode) remain.

- You're right about the room being too dry: RT is 0.05-0.09 s from 500 Hz to 8 kHz (target 0.17-0.2 s). Removing thin foam is in the plan, after the bass traps.

- Front right corner trap is designed and ready to build: floor to ceiling, 20 cm of mineral wool with an air gap behind, to be measured before/after. A slatted front (our version of a strike plate) is ready as an option, decided by the measurement.

- First reflections: ETC shows them at least 13 dB below the direct sound; a test with a thick absorber at the left reflection point removed the reflection but did not change the response above 1 kHz.

- Movable panels for tracking: planned.

Three questions, if you have time:

1. Which thin foam would you remove first: the panels away from the first reflection points, or would you replace them with thicker broadband panels?

2. Strike plate: slats (~30-40% open) or a thin membrane (kraft / FRK facing)?

3. Any experience with a 33 Hz mode and a ~1.5 s decay in a room this size (33 m³), short of an active trap?

Thanks again!