8FHW

ENCLOSURE RECOMMENDATIONS: 8FHWX4-088
Driver: 8FHWX4-088 (8FHW) — 8" Hi-Fi Subwoofer
Key T/S: Fs=41Hz, Qts=0.6, Vas=19.6L, Sens=84.4dB 1W/1m
Power: AES 200W / Cont 400W / Peak 800W
Xmax=8.7mm (one-way linear), Xmech=16.7mm, Sd=202.3cm²
Bl=7.88T·m, Re=4Ω (4-ohm nominal), Mms=45.9g
Voice Coil: 1.4" copper on aluminum former (25.4mm winding height)
Magnet: Ferrite (flux-modulation optimized) | Cone: Paper
Surround: Rubber (single roll, long-excursion) | Spider: Conex
NOTE: With Qts=0.6, high Xmax (8.7mm linear / 16.7mm mechanical),
and Fs=41Hz, this driver is best suited to SEALED hi-fi subwoofer
enclosures. The compliant suspension and moderate Qts produce
well-controlled sealed alignments in practical cabinet volumes.
Vented designs are possible but require very long ports (>500mm) at
these tuning frequencies and cabinet sizes — a passive radiator
alternative is noted below.
  PRIMARY — Sealed Enclosures
Sealed enclosures are the recommended configuration for this driver
in hi-fi subwoofer applications. The smooth, predictable roll-off
below resonance integrates well with room gain (typically +3–6 dB
below 50–60 Hz in domestic rooms), which effectively extends the
in-room response below the anechoic -3dB point.
  a) SEALED — Compact (Qtc ≈ 1.0)
     Net Volume: 11 liters
     System Resonance (fc): 68 Hz
     Qtc: 1.0
     Anechoic -3dB: ~68 Hz
     Estimated in-room -3dB: ~45–50 Hz (with typical room gain)
     Response: Broad lift near resonance (~+3dB peak at fc),
     punchy character with strong upper-bass impact
     Notes: Most compact practical enclosure. The elevated Qtc
     produces a broad resonance peak that adds warmth and punch
     in the 60–80 Hz region. Combined with typical domestic room
     gain, usable in-room response extends well below 50 Hz.
     Well-suited to smaller listening rooms or where cabinet size
     is the primary constraint. Can be EQ'd flat with modest DSP.
  b) SEALED — Balanced/Musical (Qtc ≈ 0.85)
     Net Volume: 20 liters
     System Resonance (fc): 58 Hz
     Qtc: 0.85
     Anechoic -3dB: ~58 Hz
     Estimated in-room -3dB: ~38–42 Hz (with typical room gain)
     Response: Slightly warm, smooth rolloff with gentle lift near fc
     Notes: Excellent all-round hi-fi alignment. The gentle warmth
     near resonance sounds natural and musical, integrating smoothly
     with room acoustics. In-room, this alignment typically delivers
     the most satisfying subjective bass quality without EQ. This is
     the recommended starting point for most hi-fi applications.
     *** RECOMMENDED FOR MOST HI-FI APPLICATIONS ***
  c) SEALED — Extended (Qtc ≈ 0.80)
     Net Volume: 25 liters
     System Resonance (fc): 55 Hz
     Qtc: 0.80
     Anechoic -3dB: ~55 Hz
     Estimated in-room -3dB: ~35–40 Hz (with typical room gain)
     Response: Near-flat amplitude, smooth extended rolloff
     Notes: Larger enclosure with extended low-frequency response.
     The near-Butterworth alignment produces a smooth, accurate
     response with minimal resonance peak. Best for larger listening
     rooms, critical listening applications, or when accurate tonal
     balance is prioritized over maximum output. Pairs well with
     room correction systems (Dirac, Audyssey, etc.).
ROOM GAIN NOTE: In typical domestic rooms (15–40 m²), boundary
reinforcement provides +3–6 dB of gain below 50–60 Hz. Corner
placement adds further gain. This means the effective in-room
-3dB point is significantly lower than the anechoic figure.
Sealed alignments with Qtc 0.8–0.9 typically sound best in-room
because room gain compensates for the gentle rolloff, producing
a naturally flat in-room response.
  SECONDARY — Bass Reflex (Vented) / Passive Radiator
Vented enclosures extend the low-frequency response below what sealed
can achieve in the same volume, but the long port lengths required
(>500mm for a 65mm port) make conventional round ports impractical
for these cabinet sizes. Two practical options are noted below.
OPTION 1: VENTED WITH FOLDED SLOT PORT
  d) VENTED — High Output
     Net Volume: 8 liters
     Tuning (Fb): 47 Hz
     Est. -3dB: 43 Hz
     HP Filter: 37 Hz (24dB/oct recommended)
     Round Port: 65mm dia × 512mm long (impractical — use slot)
     Slot Port: 161mm W × 40mm H × 750mm L (folded internally)
     Port Velocity: 15.7 m/s
     Notes: Compact vented alignment. The slot port must be folded
     inside the cabinet (L-shaped or U-shaped path). Provides
     strong output in the 40–80 Hz region with good excursion
     control near tuning.
  e) VENTED — Balanced
     Net Volume: 9 liters
     Tuning (Fb): 43 Hz
     Est. -3dB: 40 Hz
     HP Filter: 33 Hz (24dB/oct recommended)
     Round Port: 65mm dia × 547mm long (impractical — use slot)
     Slot Port: 161mm W × 40mm H × 800mm L (folded internally)
     Port Velocity: 14.3 m/s
     Notes: Good balance between extension and cabinet size.
     Slot port must be folded. Reaches usably into the low 30s Hz
     in-room with room gain.
  f) VENTED — Extended Low Frequency
     Net Volume: 11 liters
     Tuning (Fb): 39 Hz
     Est. -3dB: 33 Hz
     HP Filter: 29 Hz (24dB/oct recommended)
     Round Port: 65mm dia × 544mm long (impractical — use slot)
     Slot Port: 161mm W × 40mm H × 790mm L (folded internally)
     Port Velocity: 13.0 m/s
     Notes: Maximum extension, reaching into the low 30s Hz
     anechoic and below 30 Hz in-room. Larger cabinet but still
     practical for an 8" hi-fi subwoofer. Requires high-pass
     protection below tuning.
PORT NOTE: All vented alignments require port lengths exceeding
500mm, which is impractical for straight round ports in cabinets
of this size. Folded slot ports (L-shaped or U-shaped internal
ducting) are the practical solution. Ensure the slot port has a
minimum height of 40mm to avoid whistling artifacts.
OPTION 2: PASSIVE RADIATOR (Recommended Alternative to Vented)
A passive radiator (PR) eliminates the long port entirely and
provides the same acoustic loading in a compact, sealed-looking
enclosure. The PR should have:
  - Sd approximately equal to the active driver (~200 cm²)
  - Tuning mass selected to achieve the desired Fb (39–47 Hz)
  - Compliance similar to or higher than the active driver
  - Xmax equal to or greater than the active driver (≥8.7mm)
A passive radiator configuration in 8–11 liters tuned to 40–45 Hz
provides deep, clean bass extension without the port noise and
length constraints of a vented design. This is the preferred
approach for modern compact hi-fi subwoofers.
EXCURSION NOTE: The 8FHW has substantial linear excursion (8.7mm)
with further mechanical clearance to 16.7mm. This provides significant
displacement capability (Vd = 176 cc) for an 8" driver, supporting
meaningful output to low frequencies. However, below the tuning
frequency in vented/PR configurations, excursion rises rapidly —
a subsonic high-pass filter is essential.
The 8FHWX4-088 is an 8-inch ferrite woofer designed for hi-fi subwoofer and home audio applications requiring deep bass extension, high excursion linearity, and low harmonic distortion. It features a 1.4-inch copper voice coil on an aluminum former with 25.4 mm winding height, a lightweight paper cone with a long-excursion single-roll rubber surround, and a ferrite motor circuit optimized for minimum flux modulation and low distortion. With 8.7 mm of linear excursion (16.7 mm mechanical), 200 W AES / 400 W continuous power handling, and a 4-ohm nominal impedance, the driver provides substantial low-frequency displacement capability for its size class.
In sealed enclosures, the driver's Qts of 0.6 produces well-controlled alignments in net internal volumes of 11 to 25 liters. A compact 11-liter sealed enclosure (Qtc 1.0, fc 68 Hz) provides a punchy, space-efficient design that relies on room gain for in-room extension below 50 Hz. A 20-liter sealed enclosure (Qtc 0.85, fc 58 Hz) is the recommended starting point for most hi-fi applications, producing a warm, musical response with estimated in-room extension to 38–42 Hz in typical domestic listening rooms. A 25-liter enclosure (Qtc 0.80, fc 55 Hz) extends the anechoic response further and provides near-flat amplitude for critical listening applications. In all sealed alignments, typical domestic room gain (+3–6 dB below 50–60 Hz) significantly extends the effective in-room bass response below the anechoic -3 dB point.
For applications requiring deeper anechoic extension, vented or passive radiator configurations in 8 to 11 liters tuned between 39 and 47 Hz extend the -3 dB point to approximately 33–43 Hz. Port lengths exceed 500 mm at these tuning frequencies, making folded slot ports or passive radiators the practical implementation choices. A passive radiator of similar Sd and excursion capability, tuned to 40–45 Hz, provides clean bass extension without port noise artifacts and is the recommended alternative to vented loading for compact hi-fi subwoofer enclosures.