RCF LF21N551

Woofer

21″ / 533 mm
Nominal diameter
35 Hz
Resonance
0.33
Q factor
95 dB
Sensitivity
± 15 mm
Linear excursion
4000 W
Program Power
Discontinued
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
Discard
Apply
Sensitivity (1W, 1m, infinite baffle)
SPL1W
95.3
dB
Frequency response
30 - 1000
Hz

Thiele & Small parameters

Resonance frequency (free air)
fS
35.0
Hz
Mechanical quality factor
QMS
6.20
Electrical quality factor
QES
0.35
Total quality factor
QTS
0.33

Large signal parameters

Maximum linear excursion
xmax
15.0
mm
Maximum excursion before damage
xlim
36.0
mm
Air volume displaced at xmax
VD
2550
cm³
Power handling
P
2000
W
Program power
Pmax
4000
W

Voice Coil

Nominal impedance
Z
8
Ω
DC resistance
RE
5.2
Ω
Inductance (1kHz)
LE
3.2
mH
VC Diameter
135
mm
Winding height
HVC
39
mm
Winding material
Copper

Magnet

Force factor
Bl
39.0
N/A
Motor constant
Bl/√RE
17.1
N/√W
Material
Neodymium

Diaphragm

Effective diameter
470
mm
Effective area
SD
1700
cm²
Moving mass
MMS
434
g
Moving mass (without air load)
MMD
385.1
g

Suspensions

Stiffness
KMS
20.41
N/mm
Compliance
CMS
49
µm/N
Equivalent volume to the compliance
VAS
200
L
Mechanical resistance
RMS
15.39
N·s/m
Surround material
Polycotton

Dimensions

Nominal diameter
21
533
mm
Overall diameter
547
mm
Baffle cutout diameter
512
mm
Overall depth
260
mm
Flange thickness
18
mm
Mounting depth
242
mm
Volume occupied by the driver
7.2
L
Net weight
14.0
kg
RCF LF21N551 Impedance
RCF LF21N551 SPL

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