Small rooms can be nighmarish. Concrete walls, floor etc. are the worst.
We would need more info to make accurate suggestions but...
Treat all the corners, floor to ceiling. Manufactured Corner Traps are good, Superchunks work really well. (
studiotips - tips on studio design, acoustics, and wiring)
Make a chessboard of 703 slabs on the walls. Opposite walls should have one absorbent, one bare. This will halve your 703 bill! Thicker 703 will reach down into the frequency band and hit the honk. If your walls are Plasterboard/sheetrock, areas of fabric might be enough to remove the Pings and Twangs of flutter echo. Try mounting throws and bedspreads on tall boom stands, clap your hands to test. If the floor is hard, treat the ceiling more. Total 703 covering would be good here. Plywood sheets are very useful for localised treatment. Under a drumkit for that Neil Young barn sound. Angled against a will will remove flutter echo while keeping a woody liveness.
Good luck with it,
Dan FitzGerald AMIOA
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