hi guys am a newbie and dont have much technical knowledge. i had a few technical queries i hope u'll cld help me with :
1) i'm planning to buy a sub and hv been told that bigger is better but i was wondering that if one calibrates the sub to ones fronts properly so that they blend together and are seamless then wont the extra capacity be wasted. for eg., if in calibration my bookshelves matches a 12" sub at its, say, 40% volume level then isnt the remaining 60% of the sub amp going wasted whereas if i went for the 8" or 10" sub where they were matched at the 60-75% level i'd theoretically get the same spl output. is this correct?
2)if i crossover to my subs at say 80hz then what is the use of a bigger bookshelf or a floorstander that goes down to 35-45 hz as from 80hz and below all the work will anyways be done by the sub. why waste the money on larger speakers if they are anyways going to do the work of a satellite ?
3)if my a/v reciever has a fixed crossover i've read that its better to use the subs high level connections and connect my fronts to the subs high level output. but in this case i'm using the sub's amp to drive my fronts and cldnt this sound possibly be inferior to my main a/v reciever?
1) you first question... i think your asking, why not use smaller drivers at a little higher wattage to get the same spl output. well first as you know the larger drivers will move more air per push-pull and at higher pressure. and the more air moved the louder the sound. you could theoretically move the same amount of air with a bank of 5, 3in woofers (with the same extention [xmax]) running them though a higher power amp and using an EQ to tune them, as a 15in woofer. but the distortion of the bank of 3in woofers would be much higher and you would have to constantly change the EQ to compensate for the ups and downs in the response curve of them whereas the 15in woofer has a constant response curve. i some cases you definitly right, a bank of 8 or 10 15in subs at a rock concert is more logical than a single 120 or 150 in sub. it all depends on the soundstage too...
2) the main reason of a crossover'd sub is to separate the sound spectrum and let the satelite speakers do what they do best instead of trying to reproduce the lows of a drum kick while also trying to reproduce the mids and highs of a guitar (hence more distortion). And then theres also in home theater setups, to use LFE (sometimes down to 15-17hz) the woofer must reproduce frequencies so low that the listener never hears the sound but feels the room shake to add to the experience.
3) it all depends on the a/v reciever. if your reciever has a dedicated (low level) sub-out then always use it (if you want to use DTS, like before, it separates the sound spectrum) also, if it does have a fixed crossover and you run your fronts off the sub off the front left and right out, it may mean you are only getting the fixed crossover levels (prob 70-80hz and up) to both your sub and fronts... this could be horrible for the final sound. also using high level inputs and outputs doesn't mean you use the subs amp to drive the fronts, it means your a/v reciever is running your front throught the sub, without the sub degrading the signal at all.
hope this helped a bit... and anyone feel free to correct me if im wrong in any of this