8″ / 203 mm
Nominal diameter
40 Hz
Resonance
0.76
Q factor
84 dB
Sensitivity
± 7 mm
Linear excursion
300 W
Program Power
Driver
Port
Combined
Frequency response
Hz
Impedance
Ω
Impedance Phase
°
Excursion
mm
Velocity
m/s
SPL
dB
Acoustical Phase
°
Group Delay
ms
Transient response
ms
Sensitivity (1w, 1m, infinite baffle)
SPL1W
84.1
dB
Thiele & Small parameters
Resonance frequency (free air)
fS
40.0
Hz
Mechanical quality factor
QMS
9.85
Electrical quality factor
QES
0.83
Total quality factor
QTS
0.76
Large signal parameters
Maximum linear excursion
xmax
7.0
mm
Air volume displaced at xmax
VD
194
cm³
Power handling
P
150
W
Program power
Pmax
300
W
Voice Coil
Nominal impedance
Z
2 x 2
Ω
DC resistance (in series)
RE
3.1
Ω
Inductance (1kHz, in series)
LE
1.61
mH
VC Diameter
38
mm
Magnet
Force factor (in series)
Bl
9.5
N/A
Motor constant
Bl/√RE
5.4
N/√W
Weight
0.5
kg
Diaphragm
Effective diameter
188
mm
Effective area
SD
277
cm²
Moving mass
MMS
96.5
g
Moving mass (without air load)
MMD
93.6
g
Suspensions
Stiffness
KMS
6.1
N/mm
Compliance
CMS
164
µm/N
Equivalent volume to the compliance
VAS
17.9
L
Mechanical resistance
RMS
2.46
N·s/m
Dimensions
Nominal diameter
8
″
203
mm
Baffle cutout diameter
177
mm
Mounting depth
92
mm
Volume occupied by the driver
1.42
L
Similar subwoofers to Rockford Fosgate RM18D2
8″Subwoofer
fS
42 Hz
SD
277 cm²
QTS
0.81
xmax
7.0 mm
SPL1W
85 dB
Bl/√RE
4.98
Pmax
300 W
12″Subwoofer
fS
40 Hz
SD
471 cm²
30 - 300 Hz
QTS
0.65
xmax
23.5 mm
SPL1W
84 dB
Bl/√RE
9.29
Pmax
2500 W
10″Subwoofer
fS
41 Hz
SD
346 cm²
QTS
0.64
xmax
17.5 mm
SPL1W
86 dB
Bl/√RE
6.96
Pmax
800 W