4FR

4FR Mid-woofer was designed with outdoor applications in mind. All speaker parts are coated to provide good protection against weather elements. The surround, cone and dust cap are produced with UV stabilizers. Our state of the art glue application and glue selection ensures the glue joints are waterproof.
Magnet circuit is designed around sizable ferrite magnet. Consistent and wide Bl field add to the well balanced performance of this driver.
Polypropylene cone and dustcap are lightweight solution and deliver the highest levels of performance. Large surround roll extends the peak to peak cone displacement and greatly improves the LF performance.
The best application is in 2-way or multi-way speaker systems that can be designed for indoor or outdoor usage in Hi-Fi or professional products.

The 4FRX4-385 is a 4-inch, outdoor-rated mid-woofer / full-range driver featuring
a ferrite magnetic circuit with a consistent wide Bl field, a steel basket with all
components coated for weather resistance, a polypropylene (PP) cone and PP dustcap
with UV stabilizers, a wide-roll NBR rubber surround, Nomex spider, and a 25.4mm
copper voice coil on an aluminum former. The PP cone and dustcap are injection-moulded
for dimensional consistency and do not absorb moisture; waterproof adhesive throughout
ensures the glue joints remain intact under prolonged humidity and temperature cycling.
The aluminum former provides efficient thermal conduction from the voice coil. The wide
mounting flange (OD = 116 mm, baffle cutout 94.5 mm) provides a large gasket sealing
surface suited to outdoor cabinet construction. The manufacturer specifies this driver
for 2-way or multi-way systems in indoor or outdoor, Hi-Fi or professional applications.

Enclosure alignments:
- Sealed (primary):
2.13 L / Qtc = 0.707 / f-3dB = 111 Hz (Butterworth - flattest)
1.10 L / Qtc = 0.85 / f-3dB = 115 Hz (recommended - balanced size and bass)
0.69 L / Qtc = 1.00 / f-3dB = 123 Hz (compact)
0.43 L / Qtc = 1.20 / f-3dB = 139 Hz (very compact; suited for column bays)
Note: The excursion-limited Vd (1.76 cm3) means acoustic output below ~200 Hz
will be modest regardless of alignment; a subwoofer is required for extended bass.
- Vented (secondary) - 30 mm port:
1.5 L / Fb = 75 Hz / ~229 mm physical port / 1.17 m/s peak port velocity
2.0 L / Fb = 70 Hz / ~194 mm physical port / 1.10 m/s peak port velocity
3.0 L / Fb = 65 Hz / ~145 mm physical port / 1.02 m/s peak port velocity
Port velocities are negligible (Vd-limited, not port-limited); sealed preferred
for construction simplicity and equivalent acoustic output.

The 4FRX4-385 is suited for outdoor and all-weather loudspeaker systems where a
weather-resistant 4-inch mid-woofer is required and environmental durability takes
priority over bass excursion - including outdoor column speakers, installed sound
systems in humid or exposed environments, and PA enclosures subject to rain or UV
exposure; 2-way and multi-way active or passive loudspeaker systems crossing this
driver above 100-150 Hz (subwoofer) and below 1,500-2,000 Hz (tweeter) where the
PP cone construction and waterproof adhesive are the primary selection criteria over
the paper-cone alternatives in the family; compact sealed column driver bays (0.43 L
at Qtc=1.20) in multi-element outdoor column systems; and applications where the
widest mounting flange (116 mm OD) provides the largest gasket sealing area for
weather exclusion at the driver/baffle interface.