6NPM

ENCLOSURE RECOMMENDATIONS: 6NPMX8-164
Driver: 6NPMX8-164 (6NPM) — 6.5" Midrange
Key T/S: Fs=150Hz, Qts=0.35, Vas=2.9L, Sens=96.8dB 1W/1m
Power: AES 180W / Cont 360W / Peak 720W
Xmax=0.4mm, Sd=143.1cm², Bl=13.7T·m, Re=6.9Ω
Voice Coil: 1.75" aluminum edge-wound on glass fiber former
Magnet: Neodymium | Cone: Paper pulp | Surround: Fabric
RECOMMENDED ENCLOSURE TYPE: Sealed
NOTE: This is a high-efficiency midrange driver with Fs=150Hz and
very low Vas (2.9L). Small sealed enclosures raise the system
resonance well above the intended crossover point (typically 300–500Hz)
and provide controlled acoustic loading for maximum SPL in the
midrange passband. The low Qts (0.35) allows very compact sealed
volumes without excessive peaking.
SEALED ALIGNMENTS:
  a) High SPL (Qtc ≈ 1.0)
     Net Volume: 0.4 liters
     System Resonance (fc): 429 Hz
     Qtc: 1.0
     Response: Slight broad peak near fc, maximum output in passband
     Crossover HP: 400–500 Hz (24dB/oct LR recommended)
     Notes: Maximum acoustic output in midrange passband; the elevated
     Qtc provides a gentle lift near system resonance that can be EQ'd
     flat or used as a passband boost. Ideal for high-SPL touring
     applications where maximum output per driver is required.
  b) Balanced (Qtc ≈ 0.85)
     Net Volume: 0.6 liters
     System Resonance (fc): 364 Hz
     Qtc: 0.85
     Response: Slightly warm, smooth transition through resonance
     Crossover HP: 300–400 Hz (24dB/oct LR recommended)
     Notes: Good compromise between SPL output and response flatness.
     Suitable for most professional midrange applications including
     line arrays, point-source cabinets, and stage monitors.
  c) Extended / Butterworth (Qtc ≈ 0.707)
     Net Volume: 1.0 liters
     System Resonance (fc): 303 Hz
     Qtc: 0.707
     Response: Maximally flat amplitude, textbook Butterworth alignment
     Crossover HP: 250–350 Hz (24dB/oct LR recommended)
     Notes: Flattest possible sealed response. Lower system resonance
     allows a lower crossover point. Best for applications prioritizing
     accuracy and smooth crossover integration over maximum SPL.
THERMAL NOTE: The neodymium motor assembly is in direct thermal contact
with the CNC-machined aluminum basket section. For sustained high-power
operation in small sealed volumes (especially ≤0.6L), the optional
bolt-on aluminum heatsink is recommended to manage voice coil temperature.
--- AI SUMMARY (copy/paste ready) ---
The 6NPMX8-164 is a 6.5-inch high-efficiency neodymium midrange driver designed for professional sound reinforcement systems requiring high sensitivity (97 dB 1W/1m) and controlled, low-distortion reproduction in the 300–5000 Hz range. It features a lightweight paper pulp cone on a fabric surround, driven by a 1.75-inch edge-wound aluminum voice coil on a glass fiber former. The motor and suspension are optimized to maintain consistent performance at high drive levels, with controlled excursion and reduced thermal compression during long-term operation.
In sealed enclosures, the driver is intended for very compact net internal volumes of 0.4 to 1.0 liters, producing system resonances between 300 and 430 Hz. Smaller volumes (0.4–0.6 liters, Qtc 0.85–1.0) maximize acoustic output in the midrange passband, providing a broad sensitivity lift that can be used directly for high-SPL applications or equalized flat via DSP. Larger volumes approaching 1.0 liters yield a Butterworth-class response (Qtc 0.707) with maximally flat amplitude, better suited to applications where accuracy and smooth crossover integration are priorities. The very low Vas (2.9 liters) and moderate Qts (0.35) make this driver particularly well-suited to the small sealed chambers found in professional line array modules, compact coaxial cabinets, and horn-loaded midrange systems.
The driver is rated for approximately 180 W AES / 360 W continuous power handling and requires active DSP crossover management. A high-pass filter in the range of 300–500 Hz (24 dB/octave Linkwitz-Riley recommended) should be set according to the chosen enclosure volume and system architecture. The neodymium motor provides direct thermal coupling to the aluminum basket, and an optional bolt-on aluminum heatsink is available for sustained high-power operation in sealed low-volume enclosures where thermal management is critical.