10NPM

LOUDSPEAKER ENCLOSURE DESIGN REPORT
Driver: 10NPMX8-319
Generated: 2026-04-12
Application: Professional 2-way PA systems, touring and installation
DRIVER SPECIFICATIONS
Code             : 10NPMX8-319
Description      : 10" Neodymium Pro Mid-Woofer — Carbon Fiber Paper Cone
Nominal Impedance: 8 Ω
AES Power        : 200 W
Continuous Power : 400 W
Peak Power       : 800 W

Fs               : 58 Hz
Re               : 6.5 Ω
Qes              : 0.36
Qms              : 4.68
Qts              : 0.33
Vas              : 29.3 L
Sd               : 363.1 cm²
Sensitivity      : 95.07 dB (1 W / 1 m)
Mms              : 47 g
Rms              : 3.66 kg/s
Cms              : 0.16 mm/N
Bl               : 17.9 T·m
Le               : 0.79 mH
Xmax             : 6.35 mm (one-way, peak)
Xmech            : 16.85 mm

Voice Coil       : 3" (76.2 mm), CCAW, Glass Fiber former
Cone             : Carbon fiber paper (Paper CF)
Surround         : Fabric (double-roll, constant geometry)
Spider           : Nomex
Basket           : Aluminum
Magnet           : Neodymium (inside slug design)
DERIVED PARAMETERS
Volume displacement
  Vd = Sd × Xmax = 363.1 cm² × 0.635 cm = 230.6 cm³

Inductance rolloff onset
  f_Le = Re / (2π × Le) = 6.5 / (2π × 0.00079) ≈ 1,309 Hz

Cone beaming onset
  r_cone = √(Sd / π) = √(363.1 / 3.14159) = 10.75 cm
  f_beam = c / (π × r_cone) = 34,400 / (3.14159 × 10.75) ≈ 1,018 Hz

Working band        : ~65 Hz – 1,000 Hz
Crossover to horn   : 800 Hz – 1.5 kHz (f_beam at 1,018 Hz is the
                      practical upper limit; Le onset at 1,309 Hz provides
                      additional natural rolloff above crossover)

Maximum SPL (anechoic, 1 m)
  At 200 W AES   : 95.07 + 10·log₁₀(200) = 95.07 + 23.0 = 118.1 dB
  At 400 W cont  : 95.07 + 10·log₁₀(400) = 95.07 + 26.0 = 121.1 dB

Note on motor design: Inside-slug neodymium magnetic circuit provides
a consistent, high-integrity flux gap with minimized flux modulation.
The CCAW voice coil on a glass fiber former reduces moving mass and
improves high-frequency motor response compared to copper-wound designs.
ENCLOSURE RECOMMENDATION
Qts = 0.33 → Vented (bass reflex) is the required alignment.
Sealed enclosures are not recommended for this driver.

PORT SIZE WARNING: Vd = 230.6 cm³ is large for a 10" driver.
  A 75 mm round port produces port velocities ≥ 22 m/s at the
  tighter tuning frequencies — exceeding the PA/touring limit.
  Minimum port: 100 mm round (Ap = 78.54 cm²).
  Do not specify a 75 mm or smaller round port for this driver.
VENTED ENCLOSURE ALIGNMENTS
Port: 100 mm round (Ap = 78.54 cm²)  ← minimum acceptable size
  Port velocity limit: ≤ 17 m/s (hi-fi / install) / ≤ 22 m/s (PA)

Leff = (Ap × c²) / (4π² × Fb² × Vb)
  c = 34,400 cm/s ; c² = 1,183,360,000 cm²/s² ; 4π² = 39.478

Port velocity: v_peak = Vd × 2π × Fb / Ap
  Vd = 230.6 cm³ = 2.306 × 10⁻⁴ m³ ; Ap = 7.854 × 10⁻³ m²

┌──────────────────────────────────────────────────────────────────────┐
│ Alignment │ Vb (net) │  Fb   │ 100mm Port Length│ Port Velocity     │
├───────────┼──────────┼───────┼──────────────────┼───────────────────┤
│     A     │   20 L   │ 68 Hz │      255 mm      │  12.6 m/s  ✓     │
│     B     │   28 L   │ 60 Hz │      234 mm      │  11.1 m/s  ✓     │
│     C     │   38 L   │ 52 Hz │      229 mm      │   9.6 m/s  ✓     │
└──────────────────────────────────────────────────────────────────────┘

Port length calculations (100 mm round port):
  Alignment A: Leff = (78.54 × 1,183,360,000) / (39.478 × 4624 × 20,000)
                    = 9.298×10¹⁰ / 3.652×10⁹ = 255 mm
  Alignment B: Leff = (78.54 × 1,183,360,000) / (39.478 × 3600 × 28,000)
                    = 9.298×10¹⁰ / 3.979×10⁹ = 234 mm
  Alignment C: Leff = (78.54 × 1,183,360,000) / (39.478 × 2704 × 38,000)
                    = 9.298×10¹⁰ / 4.058×10⁹ = 229 mm

Port engineering note: All three alignments produce near-identical
effective port lengths (229–255 mm). This is the characteristic
near-constant port behaviour of low-Qts drivers: larger Vb and lower
Fb compensate each other in the Helmholtz equation. Physical tube
length (Leff minus end corrections of ~75 mm) is approximately
154–180 mm — manageable within a standard 10" pro cabinet.

--- Vented Alignment A — 20 L / Fb = 68 Hz ---
  Compact high-SPL cabinet, tuned slightly above Fs for maximum
  mid-bass punch and strongest mechanical excursion protection.
  Suited to compact portable touring 2-way cabinets and stage monitors
  where cabinet volume is at a premium.

--- Vented Alignment B — 28 L / Fb = 60 Hz ---
  Balanced PA cabinet tuned near Fs. Good balance of output,
  low-frequency extension, and enclosure size. The recommended
  general-purpose alignment for 2-way touring and installation
  PA enclosures.

--- Vented Alignment C — 38 L / Fb = 52 Hz ---
  Extended low-frequency response to approximately 49 Hz (4th-order
  rolloff below Fb). Suited to larger installed 2-way enclosures
  and medium-throw installation systems where modest sub-60 Hz
  coverage is needed without a dedicated subwoofer.
  Mandatory high-pass filter at 40–45 Hz to protect driver below
  port tuning.
CROSSOVER AND SYSTEM INTEGRATION
Crossover to compression driver on horn (acoustic): 800 Hz – 1.5 kHz
  f_beam = 1,018 Hz (cone directivity increases rapidly above this)
  f_Le   = 1,309 Hz (inductive rolloff onset)

  Recommended crossover frequency: 1.0 kHz; third or fourth-order
  acoustic slope to suppress cone beaming above f_beam.
  The Le onset at 1,309 Hz provides additional natural attenuation
  above the crossover point, aiding horn loading.

Zobel network (passive crossover impedance compensation):
  R_z = 6.5 Ω (use 6.8 Ω nearest standard)
  C_z = Le / Re² = 0.79e-3 / 42.25 = 18.7 μF → use 18 or 22 μF, 100 V non-polar