103FIND

LOUDSPEAKER ENCLOSURE DESIGN REPORT
Driver: 103FINDX8-583B
Generated: 2026-04-12
Application: Professional 2-way PA systems, touring and installation
DRIVER SPECIFICATIONS
Code             : 103FINDX8-583B
Description      : 10" Ferrite Pro Mid-Woofer — Carbon Fiber Paper Cone
Nominal Impedance: 8 Ω
AES Power        : 250 W
Continuous Power : 500 W
Peak Power       : 1,000 W

Fs               : 56.2 Hz
Re               : 7.2 Ω
Qes              : 0.32
Qms              : 3.66
Qts              : 0.29
Vas              : 32.75 L
Sd               : 349 cm²
Sensitivity      : 95.0 dB (1 W / 1 m)
Mms              : 42.38 g
Rms              : 4.09 kg/s
Cms              : 0.19 mm/N
Bl               : 18.2 T·m
Le               : 0.70 mH
Xmax             : 4.05 mm (one-way, peak)
Xmech            : 12.05 mm

Voice Coil       : 63.5 mm (2.5"), Copper, TIL former
Cone             : Carbon fiber paper (Paper CF)
Surround         : Fabric
Spider           : Nomex
Basket           : Steel
Magnet           : Ferrite
DERIVED PARAMETERS
Volume displacement
  Vd = Sd × Xmax = 349 cm² × 0.405 cm = 141.3 cm³

Inductance rolloff onset
  f_Le = Re / (2π × Le) = 7.2 / (2π × 0.00070) ≈ 1,637 Hz

Cone beaming onset
  r_cone = √(Sd / π) = √(349 / 3.14159) = 10.54 cm
  f_beam = c / (π × r_cone) = 34,400 / (3.14159 × 10.54) ≈ 1,039 Hz

Working band        : ~65 Hz – 1,000 Hz
Crossover to horn   : 800 Hz – 1.5 kHz (f_beam at 1,039 Hz defines the
                      upper usable limit; Le onset at 1,637 Hz provides
                      additional natural rolloff above crossover)

Maximum SPL (anechoic, 1 m)
  At 250 W AES   : 95.0 + 10·log₁₀(250) = 95.0 + 24.0 = 119.0 dB
  At 500 W cont  : 95.0 + 10·log₁₀(500) = 95.0 + 27.0 = 122.0 dB
ENCLOSURE RECOMMENDATION
Qts = 0.29 → Vented (bass reflex) is the required alignment.
Sealed enclosures are not recommended for this driver; the low Qts
produces a severely underdamped response in any practical sealed volume.
VENTED ENCLOSURE ALIGNMENTS
Primary port: 75 mm round (Ap = 44.18 cm²)
  Provides manageable physical tube lengths for compact 10" PA cabinets.
  Port velocity limit: ≤ 17 m/s (hi-fi / install) / ≤ 22 m/s (PA)

Alternative port: 100 mm round (Ap = 78.54 cm²)
  Lower velocity at cost of longer physical tube; suited to larger
  installation cabinets where port length is not space-constrained.

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 = 141.3 cm³ = 1.413 × 10⁻⁴ m³

┌──────────────────────────────────────────────────────────────────────────────────┐
│ Alignment │ Vb (net) │  Fb   │ 75mm Port Length │ Port Velocity │              │
├───────────┼──────────┼───────┼──────────────────┼───────────────┤              │
│     A     │   15 L   │ 70 Hz │      180 mm      │  14.1 m/s ✓  │              │
│     B     │   20 L   │ 62 Hz │      172 mm      │  12.5 m/s ✓  │              │
│     C     │   28 L   │ 55 Hz │      156 mm      │  11.1 m/s ✓  │              │
└──────────────────────────────────────────────────────────────────────────────────┘

Port length calculations (75 mm round port):
  Alignment A: Leff = (44.18 × 1,183,360,000) / (39.478 × 4900 × 15,000)
                    = 5.228×10¹⁰ / 2.902×10⁹ = 180 mm
  Alignment B: Leff = (44.18 × 1,183,360,000) / (39.478 × 3844 × 20,000)
                    = 5.228×10¹⁰ / 3.036×10⁹ = 172 mm
  Alignment C: Leff = (44.18 × 1,183,360,000) / (39.478 × 3025 × 28,000)
                    = 5.228×10¹⁰ / 3.343×10⁹ = 156 mm

Alternative 100 mm port lengths (lower velocity, longer tube):
┌──────────────────────────────────────────────────────────────────────────────────┐
│ Alignment │ Vb (net) │  Fb   │ 100mm Port Length│ Port Velocity │              │
├───────────┼──────────┼───────┼──────────────────┼───────────────┤              │
│     A     │   15 L   │ 70 Hz │      320 mm      │   7.9 m/s ✓  │              │
│     B     │   20 L   │ 62 Hz │      306 mm      │   7.0 m/s ✓  │              │
│     C     │   28 L   │ 55 Hz │      278 mm      │   6.2 m/s ✓  │              │
└──────────────────────────────────────────────────────────────────────────────────┘

Note: 100mm tube lengths (278–320mm) exceed the internal depth of compact
10" cabinets (~200–260mm). Specify a folded or bent port tube if the
100mm option is used in Alignments A or B.

--- Vented Alignment A — 15 L / Fb = 70 Hz ---
  High-SPL compact cabinet. Tuning above Fs provides strong mechanical
  protection against cone over-excursion above the port frequency.
  Maximum mid-bass punch with the smallest practical enclosure volume.
  Suited to compact portable touring 2-way cabinets and stage monitors.

--- Vented Alignment B — 20 L / Fb = 62 Hz ---
  Balanced PA cabinet. Near-Fs tuning; good output balance between
  mid-bass punch and lower-frequency extension to ~60 Hz.
  The recommended general-purpose alignment for 2-way touring
  and installation PA enclosures where both output and extension matter.

--- Vented Alignment C — 28 L / Fb = 55 Hz ---
  Extended LF response. Below-Fs tuning provides coverage to
  approximately 52 Hz (4th-order rolloff below Fb), reducing the
  need for a subwoofer in applications requiring modest low-frequency
  coverage. Suited to larger installed 2-way enclosures and
  medium-throw installation speakers in venues with limited sub support.
  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 = 1,039 Hz (cone directivity increases rapidly above this)
  f_Le   = 1,637 Hz (inductive rolloff onset)

  Recommended crossover frequency: 1.0 kHz for most 2-way PA designs;
  1.5 kHz is achievable if off-axis coverage above 1.0 kHz is not
  critical. Third or fourth-order acoustic slope recommended to
  suppress cone beaming above the crossover point.

Zobel network (passive crossover impedance compensation):
  R_z = 7.2 Ω (use 6.8 Ω nearest standard)
  C_z = Le / Re² = 0.70e-3 / 51.84 = 13.5 μF → use 15 μF, 100 V non-polar