Absence basse fréquences dans mon home studio

Regardes comme même ... Au cas où ..

Firstly, the good news is that your DIY panels have done a pretty efficient job of reducing the decay time across most of the range. There are one of two areas though which really do need addressing –

a) Reflection Points – Your first reflection points are your windows and possibly the door. I would seriously consider doing something about these areas. Your IR Filter suggest multiple and large reflections in these areas. I would also look at treating the ceiling. You may want to consider some freestanding panels for the side. Your current set up is going to affect your stereo imaging as there are a lot of reflections in this area
b) Low end. You are right, there is more needed to be done in this area. One possibility is to use your own panels off the back wall for the first reflection points and then use 3 X 6A alpha panels in their place. I would also consider extending your superchunks to reach the ceiling and placing 2 X tri Traps across the wall at the back where the wall meets the ceiling. Finally, as there is limited space in their room. I would also consider replacing the foam at the forint with 4A Alpha panels and again consider the tri trap option.

Perso je suis tout de même assez surpris par la pente d'atténuation en bas du spectre.

Un HP monté dans une enceinte close se comporte comme un filtre passe-haut du 2nd ordre avec une pente à 12 dB / octave (ou 20dB/décade) ; une enceinte avec un bass-reflex (ce qui correspond à ta config) se comporte comme un filtre d'ordre 4 avec une pente de 24 dB/octave (ou 40dB/decade).

Là j'ai l'impression que l'on n'y est pas. Je regarderai d'un peu plus près quand j'aurai un moment.

Tes mesures micro sont calibrées ? Plutôt qu'un filtre supplémentaire sur tes enceintes, à partir de 50 Hz on doit avoir la pente d'atténuation du micro qui s'ajoute.