actually you can do this....
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but before i get a flame war started here...lemme be absolutely clear .. that is not aurelex (
www.auralex.com )
it is not studio foam ... its family dollar foam padding ... 2 layers .. it DOES NOT MAKE THE ROOM SOUND PROOF ...
the only way to have a COMPELETE sound proof room is loads of $$$ depending on the room you may not need a sound proofing treatment .. i mixdown in this room and the foam helped with bass reflection and high frequency dispersion but you can still feel the bottom end throughout the house ... but in the room the sound is really flat because it has no hard surface to reflect off of ... if you are attempting to put lyrics down .. a closet with the same inexpensive treatment or some old shag carpet will do the trick nicely ...
i think alot of us are confused with
SOUNDPROOF and a
SOUND TREATMENT soundproof leads one to believe you could have a semi concert in your studio and no1 could hear it but you...this is a very daunting task even in multi million dollar studios..
a sound treatment helps a room to sound better and can be accomplished with inexpensive materials and a little experimenting... the cardboard treatment..i wouldn't recommend it simply because there no absorbment properties in cardboard ....now if you can get some cardboard..and possibly mount some foam to it this will work loads better then str8 cardboard...
of course this is my humble opinion..i dont know how big your space is or how small but i would say if you can find some old carpet like at a second hand store .. or some of the foam as i have used you will get a much better result than the cardboard