101FHW

ENCLOSURE RECOMMENDATIONS: 101FHWX8-118D
Driver: 101FHWX8-118D (101FHW) — 10" hi-fi subwoofer, 8 ohm
Key T/S: Fs=25.0Hz, Qts=0.34, Vas=73.3L, Sens=87.0dB
Power: AES 200W / Cont 400W / Peak 800W
Xmax=12.15mm, Xmech=20.15mm, Sd=363.0cm², Bl=14.6T·m
Le=0.63mH | Two aluminum demodulation rings

NOTE: This is the 8-ohm variant (Re=5.8Ω) of the 101FHW series.
The equivalent 4-ohm version is 101FHWX4-118.

RECOMMENDED ENCLOSURE TYPES:
  PRIMARY:   Bass Reflex (Vented) — Qts=0.34 is in the classic vented
             alignment range; excellent motor control, deep extension
  SECONDARY: Sealed (Acoustic Suspension) — for DSP/active systems
             with Linkwitz Transform bass correction
VENTED ALIGNMENTS (Primary)
Port: 75mm diameter round, flared both ends (Hi-fi preferred)
Vd = 363 cm² × 12.15mm = 441.1 cm³

IMPORTANT NOTE ON TUNING: The very low Fs (25 Hz) combined with
compact box volumes produces long port tube lengths in alignment (a).
A passive radiator is strongly recommended as an alternative to a port
for alignment (a), and is a viable option for alignments (b) and (c).

  a) Deep Extension
     Net Volume: 30 liters
     Tuning (Fb): 30 Hz
     Est. -3dB: ~30 Hz
     HP Filter: 25 Hz (24dB/oct recommended)
     Port: 75mm dia × 487mm long [!]
     Passive Radiator (recommended): Sd ≥ 363cm², mmd ≈ 120g
       tuned to 30 Hz (add mass to PR if required)
     Port Velocity: 18.8 m/s ✓
     Notes: Compact hi-fi sub with very deep extension approaching
            infrasonic range. Long port makes passive radiator the
            preferred solution. Room gain (+3–6dB below 50Hz) provides
            additional effective bass extension.

  b) Balanced Response
     Net Volume: 50 liters
     Tuning (Fb): 26 Hz
     Est. -3dB: ~26 Hz
     HP Filter: 22 Hz (24dB/oct recommended)
     Port: 75mm dia × 389mm long
     Port Velocity: 16.3 m/s ✓
     Notes: Best balance of low-frequency extension and cabinet size.
            General-purpose hi-fi, home theater, and studio subwoofer.
            Port length is practical.

  c) Extended Deep Bass
     Net Volume: 70 liters
     Tuning (Fb): 22 Hz
     Est. -3dB: ~22 Hz
     HP Filter: 18 Hz (24dB/oct recommended)
     Port: 75mm dia × 388mm long
     Port Velocity: 13.8 m/s ✓
     Notes: Reference-grade extension well below 30 Hz. Large cabinet
            suitable for floorstanding integration or under-room
            installations. Room modes engaged below 20 Hz — appropriate
            for critical listening environments with DSP room correction.
SEALED ALIGNMENTS (Secondary — DSP/Active Systems)
Sealed enclosures offer superior transient response and smoother
rolloff (12dB/oct) ideal for active systems with DSP crossover and
bass management. With 12.15mm Xmax and a Linkwitz Transform, the
system can be corrected to flat response down to ~25 Hz.

  d) Compact Monitor (10 liters)
     Qtc: 0.98
     fc: 72 Hz
     Est. -3dB (passive): ~57 Hz
     Est. -3dB (with Linkwitz Transform to 0.707/25Hz): ~25 Hz
     Notes: Small footprint for desktop or surround subwoofer use.
            Requires DSP bass correction for hi-fi application.
            Xmax headroom accommodates the boost required.

  e) Balanced Sealed (14 liters)
     Qtc: 0.85
     fc: 62 Hz
     Est. -3dB (passive): ~54 Hz
     Est. -3dB (with Linkwitz Transform to 0.707/25Hz): ~25 Hz
     Notes: More relaxed sealed alignment, reduced excursion vs (d).
            Good platform for sealed/sub integration in 2.1 systems
            with DSP high-pass to satellite speakers.

  f) Butterworth Sealed (22 liters)
     Qtc: 0.707
     fc: 52 Hz
     Est. -3dB (passive): ~52 Hz
     Est. -3dB (with Linkwitz Transform to 0.707/25Hz): ~25 Hz
     Notes: Maximally flat sealed alignment. Can be used passively
            in 2-way systems crossed below 100Hz; with DSP correction
            provides the best combination of linearity and extension.

ROOM GAIN NOTE:
In typical domestic rooms, low-frequency room gain of +3–6 dB below
50–60 Hz effectively extends apparent bass response by approximately
one octave. In-room performance of vented alignment (b) or sealed
alignment (f) is therefore equivalent to a flat anechoic response
extending to ~15–20 Hz before room correction.
APPLICATION SUMMARY
  - Hi-fi 2.1, 2.2, or multi-channel home theater subwoofers
  - Studio reference monitors with sub integration
  - Compact audiophile subwoofer enclosures
  - DSP-managed active subwoofer systems (sealed preferred)
  - 8-ohm impedance suits bridged amplifier configurations or series
    wiring of two drivers per channel (8+8=16 ohm)