This is really a good post. What I am looking for is a bit more intensity and not really loudness. I just always thought loudness and intensity was the same.
I really like when I can feel the sound a bit, not just hear it if you understand what I mean.
Would adding another subwoofer be more beneficial? I have one Klipsch R-115SW
Very hard to tell what "intensity" means to different people.
To some people it is that thump in the chest of a kick drum (which typically requires substantial output from the woofer in the mid bass zone - not very deep, but you need to be able to produce decent SPL's at that frequency.... I remember in the 1980's Boston Audio A400's used to achieve it easily with twin 8" woofers...)
To others it is the dynamic swing, the ability to instantly go from quiet to a very loud peak, without compression...
Yeah compression - a nasty word that one - and one that you seldom see measured or mentioned by manufacturers.... Electrostatic speakers are an example of speakers that do dynamics absolutely wonderfully - they can take it from soft to loud.... BUT - they are very limited at the LOUD end... and they will compress when they approach their loudness limits.... so no 110db headbanging, but marvelously intense dynamics....
Pretty much all speakers compress the sound as they approach their loudness limits (note: loudness limits, not power rating limits.... !!)
And finally some people consider intensity to = loudness - in which case the key thing is max SPL's (hearing damage be damned!)
As to what you need and how to calculate it.....
Well, the first step is to measure a setup you like, and see what the SPL's at the listening spot are.
Personally I like to listen at around 72db (average) - people who like it loud may run at 85db (average)
The "theatre" standard sets reference at 85db (average/continuous), with the requirement for 20db headroom (which means a need for 85+20=105db peak... NOT CONTINUOUS).
Basically the theatre reference standard is based on liking things LOUD (the levels involved WILL damage hearing if listened to for extended periods of time!)
Once you know what your average/continuous level is - then you have a basis with which to calculate what any combination of speaker/amp can achieve....
the Average level at the listening point should be based on at least stereo ... so 2 speakers - that means double the output, or, an additional 3db.
Distance from the speaker - the level halves (drops 3db) for every doubling of the distance - so if you listen at 2m (6ft) from the speakers, the level will be 3db down on base spec. (you can find calculators for distances that don't divide neatly!)
Increasing the level by 3db, requires doubling the power input
So here is your starting point:
1) Speaker sensitivity SPL = 90db (for 1W input @ speaker nominal impedance)
2) Stereo speakers +3db = 93db
3) Listening distance 2m = -3db = 90db
So looking at power requirements:
90db = 1W
93db = 2W
96db = 4W
99db = 8W
102db = 16W
105db = 32W
110db = 64W
As you can see, assuming a 90db SPL/wm speaker, you don't need massive power to go very very seriously loud!
Assuming a continuous/average SPL when listening at 85db, with peak requirements of 105db - then you only need the amp to be capable of around 1W continuous (!!) and 32W Peak (based on that imaginary 90db SPL/wm set of speakers, listened to at 2m)
If your speaker is less efficient then you may need a heck of a lot more power.... an 87db/wm speaker would require twice as much power, an 84db/wm speaker would require 4x as much power.
So go forth, measure YOUR preferred listening level - and then calculate what is needed for any specific set of speakers.
This is the "easy" stuff.... the "hard" stuff is where you need to go looking for detailed reviews of the speakers of interest, and try to work out at what level (SPL @ 1m) the speakers start to compress (keep in mind that this level will differ at different frequencies) - in a perfect world, you would want that compression to be beyond your Average+20db peak reference level.... in the real world, that may not be possible, and a compromise may be needed. (very few recordings get near the 20db dynamic headroom - some very dynamic recordings in the pop/rock genre, only get dynamic differences of less than 15db.... classical music tends to have a much wider dynamic range)
hope that helps
