101FHW

ENCLOSURE RECOMMENDATIONS: 101FHWX4-118
Driver: 101FHWX4-118 (101FHW) — 10" Hi-Fi Subwoofer
Key T/S: Fs=27Hz, Qts=0.3, Vas=54.7L, Sens=87dB 1W/1m
Power: AES 200W / Cont 400W / Peak 800W
Xmax=12.15mm (one-way linear), Xmech=20.15mm, Sd=330.1cm²
Bl=12.7T·m, Re=3.6Ω (4-ohm nominal), Mms=97.8g
Voice Coil: 2" copper on aluminum former (32.3mm winding height)
Magnet: Ferrite (weatherization-coated) | Basket: Aluminum
Cone: Glass fiber loaded paper pulp | Surround: Rubber (single roll)
Spider: Nomex with stitched-in tinsel wires
Volume Displacement (Vd): 401 cc
NOTE: This is a high-excursion 10" hi-fi subwoofer with a very low
Fs (27 Hz) and substantial volume displacement (401 cc). The low
Qts (0.3) and strong motor (Bl=12.7 T·m) combined with the very
low resonant frequency make this driver exceptionally well-suited
to vented enclosures, where it can reach genuine infrasonic
frequencies. Sealed enclosures are viable for more compact builds,
relying on room gain for deep bass extension. The Nomex spider
with stitched-in tinsel wires and weatherization-coated metalwork
ensure long-term reliability under sustained high-excursion use.
  SEALED ENCLOSURES
Sealed enclosures provide the simplest build with smooth, predictable
rolloff. The low Qts (0.3) produces compact sealed enclosures with
moderate-to-high fc values. Room gain (typically +3–6 dB below
50–60 Hz in domestic rooms) significantly extends the effective
in-room bass response.
  a) SEALED — Compact (Qtc ≈ 0.85)
     Net Volume: 8 liters
     System Resonance (fc): 76 Hz
     Qtc: 0.85
     Anechoic -3dB: ~76 Hz
     Estimated in-room -3dB: ~48–55 Hz (with typical room gain)
     Response: Slightly warm with gentle resonance lift
     Notes: Very compact enclosure for a 10" subwoofer. The
     elevated fc (76 Hz) means the anechoic response rolls off
     above typical subwoofer expectations, but room gain in a
     domestic environment effectively extends usable bass into
     the upper 40s Hz. Best suited to smaller listening rooms
     or as a space-efficient sub under a desk or beside furniture.
     The strong motor keeps transient response tight even in
     this compact volume.
  b) SEALED — Butterworth (Qtc ≈ 0.707)
     Net Volume: 12 liters
     System Resonance (fc): 64 Hz
     Qtc: 0.707
     Anechoic -3dB: ~64 Hz
     Estimated in-room -3dB: ~40–46 Hz (with typical room gain)
     Response: Maximally flat sealed amplitude
     Notes: Classic Butterworth alignment providing the flattest
     sealed response. With room gain, in-room response extends
     usably to the low 40s Hz — satisfactory for most music
     and home theater content. A practical balance between
     enclosure size and bass depth for a compact sealed sub.
     *** RECOMMENDED SEALED ALIGNMENT ***
  c) SEALED — Extended (Qtc ≈ 0.6)
     Net Volume: 18 liters
     System Resonance (fc): 54 Hz
     Qtc: 0.60
     Anechoic -3dB: ~54 Hz
     Estimated in-room -3dB: ~34–38 Hz (with typical room gain)
     Response: Overdamped, smooth gradual rolloff
     Notes: Larger sealed enclosure with substantially lower fc.
     The overdamped alignment rolls off gradually, providing
     in-room response well into the 30s Hz. Good for medium
     listening rooms where genuine deep bass from a sealed
     enclosure is desired. The gentle rolloff integrates
     naturally with room acoustics.
  VENTED ENCLOSURES (Bass Reflex)
Vented enclosures are the optimal configuration for this driver's
low Qts and very low Fs. The vented alignments reach genuine
infrasonic frequencies (low 20s Hz) that are simply not achievable
in sealed configurations without heavy EQ. The trade-off is larger
cabinet volumes (50–70L).
PORT RECOMMENDATION: 76mm round port is practical for all alignments
(port lengths 266–343mm, velocities 12–16 m/s). A 100mm round port
reduces velocity further but requires longer port tubes (480–620mm),
which may need to be angled or L-bent inside the cabinet. Flared
port ends are recommended at all diameters for minimum turbulence
noise at high excursion.
  d) VENTED — High Output
     Net Volume: 50 liters
     Tuning (Fb): 29 Hz
     Est. -3dB: 27 Hz
     HP Filter: 19 Hz (24dB/oct recommended)
     Round Port (76mm): 76mm dia × 266mm long
     Round Port (100mm): 100mm dia × 483mm long
     Port Velocity (76mm): 16.1 m/s
     Port Velocity (100mm): 9.3 m/s
     Notes: Moderately compact vented alignment with tuning
     just above Fs. Strong output in the 25–60 Hz region with
     excellent excursion control near tuning. The -3 dB point
     at 27 Hz means genuine deep bass reproduction. 76mm port
     is the most practical option (manageable 266mm length).
     Well-suited to a medium-sized hi-fi subwoofer cabinet.
  e) VENTED — Balanced
     Net Volume: 59 liters
     Tuning (Fb): 25 Hz
     Est. -3dB: 21 Hz
     HP Filter: 15 Hz (24dB/oct or subsonic)
     Round Port (76mm): 76mm dia × 311mm long
     Round Port (100mm): 100mm dia × 562mm long
     Port Velocity (76mm): 13.9 m/s
     Port Velocity (100mm): 8.0 m/s
     Notes: The recommended vented alignment for most hi-fi
     applications. Tuning at 25 Hz provides infrasonic reach
     that covers the deepest musical and home theater content
     (pipe organ pedal notes, film LFE). Port velocities are
     moderate. This alignment reaches frequencies that sealed
     enclosures of any size cannot match without heavy EQ.
     *** RECOMMENDED VENTED ALIGNMENT ***
  f) VENTED — Extended Low Frequency
     Net Volume: 70 liters
     Tuning (Fb): 22 Hz
     Est. -3dB: 19 Hz
     HP Filter: 15 Hz (24dB/oct or subsonic)
     Round Port (76mm): 76mm dia × 343mm long
     Round Port (100mm): 100mm dia × 618mm long
     Port Velocity (76mm): 12.2 m/s
     Port Velocity (100mm): 7.1 m/s
     Notes: Maximum infrasonic extension for dedicated deep-bass
     systems. The -3 dB at 19 Hz covers the entire audible
     spectrum and into tactile/infrasonic territory. Largest
     cabinet but provides the deepest possible response. Best
     for dedicated listening rooms, home theater reference
     systems, and enthusiasts prioritizing absolute low-frequency
     extension. Requires subsonic high-pass protection to manage
     excursion below tuning.
PASSIVE RADIATOR ALTERNATIVE:
A passive radiator (PR) can replace the port in any vented alignment
while eliminating port length constraints and turbulence noise. For
this driver, a PR should have:
  - Sd equal to or greater than the active driver (~330 cm²)
  - Tuning mass selected for the desired Fb (22–29 Hz)
  - Xmax equal to or greater than the active driver (≥12 mm)
  - Compliance equal to or greater than the active driver
A 10" or 12" passive radiator in a 50–70 liter enclosure tuned to
25 Hz provides deep, clean infrasonic reproduction without port noise.
This is the premium implementation for a modern hi-fi subwoofer.
EXCURSION NOTE: The 12.15 mm linear Xmax with 20.15 mm mechanical
clearance provides substantial displacement capability (Vd = 401 cc)
for a 10" driver. This supports high SPL at very low frequencies.
Below vented tuning frequency, excursion rises rapidly — a subsonic
filter is essential in vented configurations.
CONSTRUCTION NOTE: The glass fiber loaded paper cone with Nomex spider
and stitched-in tinsel wires provide the durability required for
sustained high-excursion subwoofer operation. The aluminum former
on the 2" copper voice coil ensures efficient heat dissipation during
continuous high-power use. All metal parts are weatherization-coated
and push terminals are gold plated.