Is there something wrong with carpeting the lower half of my theater walls? I was thinking of placing panels with linacoustic behind them, but also though the carpet would absorb sound pretty good as well. Any opinions?

I did that and it removed all the slap echo from my room, so in my case it appeared to do a good job. I say appeared, because it was a totally unscientific approach and I have no measurements to see what frequencies it may be absorbing unnecessarily, or which ones it should be absorbing but isn't. I also carpeted the entire screen wall in black.

It was cheap foam backed carpet that I glued to the walls using thick wallpaper paste. I coated the walls first and let it soak in over night, and the next day I applied the carpet with a good coating of paste on the foam back. I've not had any problems with it coming away in over 6 years so it seems to have stuck well. If it needs to be removed, it can be done using a steamer, just like with wallpaper (though it will be harder I would think). It has the advantage of being less destructing than contact adhesive on the surface it is sticking too (such as Sheetrock).

I would think those with a good knowledge of acoustics and the properties of various products wouldn't consider carpet due to its unknown properties, but if you're on a budget it may work for you in a similar fashion.

Gary

Floor materials 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz
carpet 0.01 0.02 0.06 0.15 0.25 0.45

Carpet over pad is a very poor acoustic material because it absorbs differently across the spectrum. Proper acoustic materials have even absorption from about 500hz and up. Then you tackle the 50-500hz range with bass traps, resonators, panel absorbers, etc.

Carpet on walls is also against code in most areas.