- Good low frequency response
- Lightweight surround, stiff paper cone
- Affordable woofer
- The 81FHW woofer was designed with smaller hi-fi subwoofers in mind. The woofer works well in vented enclosures or combined with a passive radiator.
- Optimized magnetic structure delivers good level of performance and balancing well performance vs cost. We have chosen lightweight foam surround in this design.
- Our extensive development and testing of this material yielded in custom formulation of the raw material we use for the surround and guaranties its long lasting performance.
General specs Nominal Diameter: 8 in. Rated Impedance: 4 Ohm Power handling AES Power: 100 Watts Program Power: 200 Watts Voice Coil Diameter: 1.4 in. Winding wire: Copper Former: Aluminum Winding height: 18.2 mm T/S Parameters Resonant frequency: 39 Hz Re: 3.6 ohm Qes: 0.58 Qms: 5.4 Qts: 0.52 Vas: 21.5 liters Sd: 201.1 cm2 Mms: 44 grams Bl: 8.25 Le: 1.12 mH Sensitivity: 85.94 dB Design details Surround Material: Foam Cone material: Paper Spider: Nomex Plate thickness: 6 mm Peak to peak linear cone Displacement 19 mm Overall diameter: 209 mm Bolt circle diameter: 197 mm Baffle cutout dia.: 180 mm Number of mounting holes: 8 Depth (flange to rear): 95 mm Net weight: 1.7 kg Ordering codes: 4 ohm version: 81FHWX4-289 Recone kits: Download: Spec download 2D drawing 3D model
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PRODUCT CODE: 81FHWX4-289
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--- ENCLOSURE RECOMMENDATIONS ---
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ENCLOSURE RECOMMENDATIONS: 81FHWX4-289
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Driver: 81FHWX4-289 (81FHW) — 8" Sub-woofer
Key T/S: Fs=39.0Hz, Qts=0.52, Vas=21.5L, Sens=85.94dB
Power: AES 100W / Cont 200W / Peak 400W
Xmax=6.1mm, Sd=201.1cm², Bl=8.25T·m
RECOMMENDED ENCLOSURE TYPE: Bass Reflex (Vented)
PORT RECOMMENDATION: Round port (65mm diameter) — adequate for compact enclosures with lower air volume velocity
a) High SPL
Net Volume: 10 liters
Tuning (Fb): 45 Hz
Est. -3dB: 41 Hz
HP Filter: 37 Hz (24dB/oct recommended)
Round Port: 65mm dia × 405mm long
Slot Port: 144mm W × 40mm H × 722mm L
Port Velocity: 10.4 m/s
Notes: Strong mid-bass impact, reduced cone excursion, maximum output
b) Balanced Response
Net Volume: 12 liters
Tuning (Fb): 41 Hz
Est. -3dB: 38 Hz
HP Filter: 31 Hz (24dB/oct recommended)
Round Port: 65mm dia × 413mm long
Slot Port: 144mm W × 40mm H × 738mm L
Port Velocity: 9.5 m/s
Notes: General-purpose PA/subwoofer, even response, good transient behavior
c) Extended Low Frequency
Net Volume: 16 liters
Tuning (Fb): 37 Hz
Est. -3dB: 31 Hz
HP Filter: 25 Hz (24dB/oct recommended)
Round Port: 65mm dia × 430mm long
Slot Port: 144mm W × 40mm H × 766mm L
Port Velocity: 8.6 m/s
Notes: Deep bass extension, requires proper system protection below tuning
--- SUMMARY ---
The 81FHWX4-289 is an 8-inch sub-woofer driver designed for compact hi-fi subwoofer systems, home audio, and cost-effective installation applications. It operates at 85.9 dB sensitivity (1W/1m) and features a compliant suspension design suited to moderate-volume vented or passive-radiator enclosures with extended low-frequency response.
In bass reflex enclosures, the driver performs best in net internal volumes of 10 to 16 liters, tuned between 37 and 45 Hz. This alignment provides a balanced combination of low-frequency extension, cone control around resonance, and efficient port loading. Lower tuning improves deep bass extension but increases excursion below tuning, requiring appropriate high-pass filtering. Higher tuning increases output in the upper bass region while improving mechanical control. Note: the 65mm round port at these tuning frequencies requires a length of approximately 405–430 mm and will need to be folded within the enclosure; a slot port may offer a more practical alternative.
The driver is intended for use with moderate amplification (approx. 100 W AES / 200 W continuous) and DSP control. A high-pass filter in the range of 25–37 Hz is recommended depending on enclosure tuning, along with appropriate limiting to manage excursion below tuning. Typical operating bandwidth is 31–100 Hz, suitable for integration with a mid-bass or full-range driver in a two-way system.
This design is well suited for single-driver compact bass reflex or passive-radiator enclosures in hi-fi, home theater, and cost-conscious installation applications, where a balance of low-frequency extension, compactness, and value are the primary priorities.
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