Small or large sub for music

Room size and low frequency extension desired determines how large a sub need be. In general you need a larger sub with a larger bass driver or possibly somewhat smaller if multiple drivers or passive radiators are used if your room is larger and you want bass to extend all the way down to 20 hz or so which is typically about as low as any music like low pipe organ notes might go.

So basically size does matter when it comes to extended bass.  

For example I use a 8" sub with dual pasive radiators that can go down to almost 30 hz or so in a modest sized room.   I use these with small monitors somewhat similar in size to kef ls50  that do little below 60hz or so.    I don't know of any any single driver 8" sub that can do that.    

If your mains are larger and more full range you will likely have to go with a larger 12" or even larger sub iin order to cover the lowest frequencies not covered otherwise by the mains.  

Hello mapman,

     Sorry, I'm a bit confused by your last post. 
     As I understand it and in other words, you're stating that deep bass extension down to about 20 Hz can be achieved in most larger rooms through either a single large sub with a large driver or through multiple subs each with smaller drivers.possibly also incorporating passive radiators.  And you add that you're unaware of any single 8" driver sub that can reproduce deep bass down to the typical audible limit of 20  Hz.
     If the above accurately reflects your thoughts, I agree with you.

     But then you go on to state: 
" If your mains are larger and more full range you will likely have to go with a larger 12" or even larger sub in order to cover the lowest frequencies not covered otherwise by the mains."

      I think I clearly understand your statement but disagree with it. 
      I believe, in your quoted example above, that excellent in-room bass response down to 20 Hz +/- 3 dB can be achieved  in virtually any sized room through the use of 4 smaller subs with 10" drivers if configured as a distributed bass array system.  
     I believe this because my mains are larger and are run full range but only extend down to about 34 Hz.  I utilize a db, consisting of 4 smaller subs with 10" drivers, in my medium sized? (23 x 16 foot) room to provide excellent in-room bass response from 20-40 Hz  +/- 3 dB that integrate seamlessly with my large Magnepan panel mains for both music and ht.
     I understand you don't currently require this degree of bass extension in your own system but thought you'd like to know this type of bass extension is possible in virtually any sized room without the need for subs with 12" or larger drivers .

Tim        

TBC, having the space and money to have 4 subs is not the normal music lover's situation. 

@mapman  was talking to that. He was not discrediting the use of 4 subs. 

I too will never be able to have more than 1 sub in my listening area so to me, the 4 sub array point is moot.

That doesn't mean I don't see the merits. From a cost/performance space situation, the bass traps + eq are the far better and cheaper option, but hey, I make my own loudspeakers so the measurement and calibration is waaay easier for me than the average music lover. 

noble yes for 20 hz in large room you need at least 1 larger sub up to teh task (check specs) or multiple subs or drivers. Distributed multiple subs or sub array allows more  for smoother bass response throughout a room than extending low end frequency response..

Ideally I would want  2-4 larger quality subs distributed around a room but practically I do not want to have to deal with all that so I go with just a single smaller sub that is easier to manage.   This is in a second system.  My main system has full range speakers so no subs needed.