I remember installing my acoustic panels, during early covid days.Right after I did first reflection part on walls and ceiling and the bass traps, I put my gear back, what the difference that was, the treated part of the room no echo clap, the untreated part big echo clap.But, when I finished off the whole room, the sound became different.Of course, I was skeptical at first, those panels and bass traps are not cheap, but it was worthed and it's done once and for all.My room treatment was done Vicoustic from Portugal.I sent them all room measurements and pictures, few days later, I have received blue print.They recommended to keep walls treatment as symmetrical as possible, for example, if one wall has door, leave the gap on the opposite wall.Keeping the ceiling symmetrical to walls wasn't that important, but it's good to keep it close, especially first reflection.The blue print is still in my gallery, if enyone wants to see it.Three years ago, I paid 50 euro for my project request, three years later and it's 130 euro.
