I have a pair of Focal Supra N2 in my 15 X 13 X 9 feet dedicated 2-channel listening room. The speaker is rated 34Hz +/- 3dB and 28Hz -6dB. In my room, when measured using the RadioShack SPL (slow, C-weighted) at my listening position, the frequency response is pretty flat from 40-200 Hz, +/- 1dB, then 31.5Hz -4dB, 25Hz -10dB, 20Hz -18dB. I listen to all kinds of music, solo voice, solo instruments (listen to many piano and violin), chamber, full scale orchestra, jazz, pop, etc, exceptions such as hard rock or heavy metal. Do I need a subwoofer? If yes, one or two sub? One example of a sub spec, sealed acoustic suspension, 20-200Hz, adjustable low pass filter 40-150Hz, a fixed 24dB/octave crossover, and 1200 watts amp. Thanks in advance.
Recommend reading Floyd Toole’s book “Sound Reproduction”. It will explain why it takes 3 or 4 subs to get proper bass in a residential setting. It has to due with how bass waves propagate in a ‘small’ room.
I have (3) 10" inexpensive subs, 2 professional ported that each connect my DSJ to JBL 708P monitors, the 3rd is a nice sealed unit that is located 2/3rds the way back along the left wall. The professional subs are located near front left corner and 4ft from front right corner along side wall. This dispersed bass source is the key for flat. response across the room.