Originally Posted by Turlen
So is there a simple rule of thumb or an easy to use formula to help you determine what size sub-woofer you need for a given sized room? I find the bigger is always better argument is kind of weak (token: That's not what she said!).
After reading quite a few sticky links I came across this website for speakers and the amount of amplification needed: http://www.crownaudio.com/elect-pwr-req.htm
Is there one like this for subs? Or do I just use the same formula for a sub and spread it across one speaker? I don't need an in-depth PHD level physics discussion, I just want to roughly gauge what I will need for a decent home theater experience.
This post is missing several parameters that relate very strongly to the choice of a subwoofer:
(1) Desired Bass Extension.
(2) Desired SPL
I would break Desired bass Extension down into 3 ranges:
(a) Just want to amplify conventional music - clean response down to 32 Hz is a pretty good solution. Note there are few if any conventional full range speakers that can do this cleanly. A sub is not an option, it is a de facto requirement.
(b) Basically want great sound from both music and drama - clean response down to 20 Hz is "good enough". Note that obtaining sufficient SPL at 20 Hz with 10% or less THD probably exceeds the capabilities of most commerically-available subwoofers.
(3) Wish to create the impression of the earth shifting in its orbit - the sky is the limit - pick a number 10, 6, 3 Hz.
For SPL's you want to be able to go 60 dB or more above the threshold of hearing or ambient noise level in your room at the chosen bass extension frequency. The Fletcher Munsen curve is your friend.
Strictly speaking listening distance not room size dictates the required SPL output of your upper range speakers - LCR and surround.
However, Bass is non directional and te3nds to fill the entire room, so room size matters more.