I have an 01 BMW X5. I am using the stock head unit (non-DSP) and replaced all the factory speakers with component Focal 165 KFs (80W nominal power) in the front doors and coaxial Focal 165 CV1 (70W nominal power) in the rear doors. An Alpine PDX 4.100 amp is powering the front speakers. The system sounds great now but lacks the depth that only a true sub can bring.
I am trying to decide between subs to fit in the hidden right rear pocket.
The space is tight around .3 - .6 c.ft.
The mono sub amp will depend on the sub I use. I plan on using either an Alpine M450 (220W) or Alpine M650 (400W).
Here are the options I have narrowed it down to: 2 of which are pre-built and 2 require a custom built box:
1. Bavarian Sound Works sub box is pre built for the X5 and uses an 8" Alumipro Alusonic EX 8" sub (150W/250W).
$650 with Alpine M450 (220W) amp
Xmax: 10 mm
2. JL Stealthbox is a prebuilt box for the X5 and uses the 10" 10W1v2 sub (150W)
I believe they squeezed .6 c.ft out of the area.
$600 with Alpine M450 (220W) amp
Fs: 25.24 Hz
Vas: 1.783 cu. ft. / 50.46 liters
Xmax: 0.375 in. / 9.5 mm
Efficiency (1W/1m): 84.53 dB SPL
OR one of these subwoofer options that require a custom box to be built:
3. Focal 21 V2 8" (250W/500W max)
$250 for this sub + the Alpine M650 (400W) amp ($230) + the cost of a custom box
(.35 minimum sealed enclosure for tight punchy bass- .42 c.ft recommended for more dynamic bass)
I prefer this option as it keeps the Focal speakers consistent and can take more power than the other options.
Vas: 15.27 liters 0.54 cu.ft.
Xmax: 9mm 3/8"
Sensitivity (2.83V/1m): 85dB
4. RE Audio RE 8" D4 (175W)
$100 for this sub+ the Alpine M450 (220W) amp ($150) + the cost of a custom box
(.3 c.ft minimum - .35 c.ft optimum sealed enclosure)
This option is very appealing since it is the least expensive.
Fs: 22.8 Hz
Vas: 27.1 liters
Xmax: 12 mm
Efficiency -SPL (1W/1m): 81.2 dB SPL
How do I compare these numbers and does anyone have any listening time/experiences with these options? Thanks in advance.