4645C
Single 460 mm (18 in) Subwoofer System
SPECSHEET
Key Features:
• 650 W (72 Vrms) power handling (100-hour AES rating), 800 W (80 Vrms) power handling
(2-hour AES rating)
• Usable response to 22 Hz (-10 dB) with no EQ; flat to 22 Hz (-3 dB) with external EQ
• 2242H SVG™ (Super Vented Gap) driver provides long peak-to-peak excursion, high
sensitivity and high maximum SPL capability
• SFG™ (Symmetrical Field Geometry) magnet structure for extremely low 2nd and 3rd
harmonic distortion
• Approved by Lucasfilm, Ltd. for THX® installations
Description:
The JBL 4645C is a high-quality subwoofer system, featuring a technologically advanced 460 mm (18 in) low frequency transducer mounted in a direct
radiator, bass-reflex enclosure for smooth response to the lowest audible frequencies. The 4645C is ideal for low frequency augmentation of either
analog or digital soundtracks in motion picture theaters and for general sound reinforcement applications. The 2242H transducer utilizes the patented
Vented Gap Cooling (VGC) process*, which pumps air through the magnetic gap and directly over and around the voice coil, providing immediate heat
transfer and a reduction in operating temperature. This increases power handling while reducing power compression.
The 2242H utilizes a rugged 100 mm (4 in) diameter voice coil and incorporates a large motor structure with a pole piece that extends both above and
below the top plate to improve gap flux symmetry and increase thermal conductivity. This magnet structure and the use of a voice coil with one-third
more exposed area than in former designs, provides the 2242H with very effective heat sinking, enabling the system to carry an 800 watt continuous
AES pink noise power rating.
Specifications:
Component Electronics – Model 2242H
Low Frequency Transducer 1 x 2242H, 460 mm (18 in)
Rated Impedance 8 ohms
Minimum Impedance 7.2 ohms
Power Handling Capability
Input Power Handling
(AES 100-Hour Rating)
Input Power Handling
(AES 2-Hour Rating)
650 W (72 Vrms), pink/IEC
800 W (80 Vrms), pink/IEC
Output Capability
1
Sensitivity
Max Continuous SPL @ 1
2
meter
Max Peak SPL @ 1 meter2132 dB 138 dB 143 dB 147 dB
Frequency Response
3
40 Hz – 100 Hz, 97 dB, 1 W @ 1m; reference 2.83 V
Single
Module
126 dB 132 dB 137 dB 141 dB
Lower Frequency Limits (no EQ):
-10 dB: 22 Hz
-3 dB: 35 Hz
Lower Frequency Limits (with EQ):
-10 dB: 20 Hz
-3 dB: 22 Hz
Two
Modules
Four
Modules
Eight
Modules
Other
Recommended Crossover
Frequencies
System Polarity EIA Standard. Positive voltage to RED terminal
Input Connectors Color-coded push terminals
Net Weight 63 kg (138 lb)
Shipping Weight 69 kg (151 lb)
High-pass: 20 Hz, 12 dB/octave or greater
Low-pass: 80 Hz to 150 Hz, 12 dB/octave or greater
produces forward cone motion.
Enclosure
Materials and Finish 19 mm (0.75 in) particle board with 25 mm (1 in)
Enclosure Tuning Frequency 25 Hz
Net Internal Volume 225 liters (8 cubic ft)
Dimensions (H x W x D) 1010 mm x 674 mm x 450 mm
1
Averaged half-space (2pi). Quarter-space (1pi, wall/floor junction placement) is 6 dB
higher.
2
Per industry practice, maximum long-term SPL is a calculation that references half-
space 1W/1m sensitivity, scaled by the long-term continuous power rating.
3
Based upon specified sensitivity, 40 Hz to 100 Hz.
JBL continually engages in research related to product improvement. Some materials,
production methods and design refinements are introduced into existing products
without notice as a routine expression of that philosophy. For this reason, any current
JBL product may differ in some respect from its published description, but will always
equal or exceed the original design specifications unless otherwise stated.
baffle and back panel; extensive bracing on all panels
(39.75 in x 26.50 in x 17.75 in)
THX is a trademark of THX Ltd. which may be registered
in some jurisdictions. All rights reserved.
*U.S. Patent #5,042,072. Foreign Patents Pending.
Note: specifications are subject to change without notice.
12/2018. © 2018 Harman International. www.jblpro.com
4645C
Single 460 mm (18 in) Subwoofer System
SPECSHEET
Dimensions: Graphs:
Frequency Response
Note: Drawing not to scale. All dimensions are for reference only.
The magnet structure and compliance allow for long peak-to-
peak excursions without damage to the speaker. The pole piece
incorporates a shorted copper ring while functioning as a shorted
secondary turn, with the voice coil acting as the primary winding.
The benefits are a reduction of third harmonic distortion from
magnetic flux modulation and a reduced inductive component
of the voice coil impedance, for improved transient response.
Symmetrical Field Geometry (SFG) minimizes second harmonic
distortion.
Enclosure: The enclosure is constructed of dense stock and is
extensively braced on all panels. It has a net internal volume of
225 liters (8 cu. ft.) and is tuned to 25 Hz with a very large port
to minimize port compression and to reduce distortion due to
turbulent air flow.
1 watt at 1 meter, with 150 Hz Linkwitz-Riley 4th order low-pass filter
and 2nd order high-pass filter at 25 Hz with Q=2. 1pi (upper curve)
and 2pi (lower curve) conditions.
Frequency Response: The 4645C is intended for use as a
subwoofer with a low-pass filter and appropriate high-pass
filtering for protection and equalization.
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