Well I do car audio,and placement is everything!
We also have to display stuff in a room,and the best place I have found is closer to a corner of a room..try closer to one side of the corner(within 1'),then about 1.5-2.5 from the other wall..As with anything else,you must experiment,but i usually find thats a good start..
a couple things,i am assuming they fire down,and have a crossover built into them..
now again,in car audio,i usually cross them @ about 80 or so,then start the mids off @ 120+-(front) then 150+-(rear)..there is usually a resonance between those points in a car..the fronts being lower to 'stage' the sound farther forward..these are freqs we tend to associate with the placement of drums for instance..below the 80 mark,bass is very non-directional..the striking of the skin is where our mind(notice choice of word) places the drum,or the pluck of the string,etc..
now,do you even have the option of a high pass crossover?
depending on your other speakers,they could be doing major stuff to what you eventually hear..
just for s's&*'s,try positioning yourself in different parts of the room.. see what kind of differences you hear..I cant exactly tell you what to do without some report on this,but more for your info about what positioning can do to sound..
now,you have probably made sure they are in phase(with each other,as opposed to the rest of the system..)in other words,the '+' is that on both(again an assumption on my part;stereo inputs)..
and also double check the other speakers..
now try putting the '+''s in the'-''s spot(on BOTH inputs)
this SHOULD change the sound dramatically..which way do you think is better?
accuracy isnt necessarily the point,your PERCEPTION is what is important here..which one makes you happy?
now,i made a few points to ponder..i would suggest positioning as the first step,like i said try a corner,but move it,then move yourself back to where you listen to it,NOT next to the sub..do a couple quick attempts to move it,and listen..very rough,just close to the corner,and try some audio..
then try changing the phase(again BOTH the +'s,and BOTH -'s,not just one input,the idea is to change the way the sub 'relates' to the rest of the system,sometimes reversing them helps alot,sometimes it doesn't do much,and sometimes it hurts..but they must always be in phase with each other..I was just thinking POSSIBLY the rattling you hear is the sub reaching their physical limits..i would think most people would understand there is something major wrong,but if the inputs are out of phase,and you have a stereo amp in it,the subs may be exactly 180 out of phase,and they are exactly canceling each other,so you turn it up,and hear something,but you quickly reach the limits,which is easy in a combined box,because they help each other move the other way....
i would doubt it is stereo,but i wanted to make you aware of the possibility..
i realize this is a long post,but i like to ensure you understand what i am saying,and why i say it!
The most important thing i can say(relating to the options i discussed) is to try all of them(check their phase to each other once,from there you keep up with it,because after that,they are BOTH changed together from then on..)
i dont want to get into simultaneous stereo/mono amps,they could really screw stuff up! in the home forum,i am completely unsure who has what type,but just check you manuals to see if it says something about a mono sub,with stereo speakers..this would change the situation alot,because they shift the phase of certain freq's...
enough,try the stuff above first,but check the manual to see..(of the amp driving the speakers)..
i want to keep explaining this,and it almost hurts not too..
but anyway,enough babbling,post your test's outcomes..
i think thats enough info to either make you happy,or make you want to get rid of it!(i doubt this,after trying stuff,but..)
