Originally Posted by Alejandro Varela
What do you recommend me?
Maybe adjust the low-end and add reflections treatment to high end?
That's my conclusion, not what it should be...
Getting the low end under control should be the first priority. High frequencies are a cinch to tame/control as they don't carry nearly as much energy. Low frequencies are where the majority of the energy resides (and thus takes the most effort)
Carpet on the walls may be a fire hazard, besides only soaking the highest of frequencies (leaving the mud you're hearing)
There are a variety of methods to tame these frequencies. If you go with porous absorption (THiCK and LOW
density) to get your LF tamed, but you find it is over-dampening the HF-- it's relatively easy to dial back in the highs/mids with some scattering or diffusion while leaving the low end still controlled.
You can always use a combination of devices/methods to attack specific problems. Your panel resonators (assuming built correctly) should do a good job, but you will likely need several of them.
Generally, porous absorption is the first
thing recommended because it doesn't have a big learning curve/trial-n-error for the uninitiated. Get results with little fuss. I'm not an expert, but i usually recommend starting with the porous, and using the other devices to do the finish work if any specific problems remain. YMMV