18SOUND 8NCX750
18SOUND (Eighteen Sound) 8NCX750 — 8" / 8 inch Coaxial Driver · Coax / Coaxial Driver · Neodymium
3"/2.4" voice coils · 8 Ω
Part no.: 42A-CHS-KO-18S-0003
Documents
18SOUND 8NCX750 — 8" · Coaxial Driver
300 W AES · 98 dB Sensitivity · Frequency range 90 Hz – 1600 Hz
Technical data
- Diameter: 8 "
- Voice coil: 3 "
- Power handling: 300 W AES
- Sensitivity: 98 dB
- Impedance: 8 Ω
- Magnet: Neodymium
- Weight: 3.95 kg
- Mounting depth: 132 mm
- Frequency range: 90 – 1600 Hz
- Cone material: Titanium
- Coverage angle: 80 °
- Rec. crossover: 1.2 kHz
Datasheet (PDF) · Manufacturer page
Series: NCX · Part no.: 42A-CHS-KO-18S-0003
18Sound 8NCX750: 8" coaxial midrange with 98 dB, 90–1600 Hz and 3"/2.4" voice coils
The 8NCX750 is not a small full-range coax but a mid-high coaxial for 3-way systems. 18Sound specifies the cone section from 90 Hz to 1600 Hz, the resonance frequency is 111 Hz and Vas is only 5.2 l. Reading those values, it is obvious: this is about high-efficiency midrange reproduction, not bass. A neodymium motor, a 3" voice coil in the cone and a 2.4" voice coil in the tweeter deliver 300 W AES and 98 dB sensitivity.
The motor figures are remarkable for an 8": BL 20 Tm with 29 g of moving mass and Qts 0.26. Such a tight motor is exactly what a midrange needs: fast decay, low compression at level and transient behaviour of the kind sought in point-source designs with large woofers below. The titanium-diaphragm tweeter radiates through an 80° cone and sits, as in every coax, on the axis of the cone.
Use and enclosure
The 8NCX750 belongs in a sealed midrange chamber, not a reflex box. The computed guideline for a Butterworth alignment is 0.8 l; in practice the chamber will be larger simply because of the driver's own volume, which lowers Qtc slightly and is harmless for a midrange. What matters is a well-damped, rigid chamber without standing waves behind the cone. The 132 mm mounting depth keeps the chamber compact, and at 3.95 kg the driver barely loads even a stacked mid-high cabinet.
The lower crossover to the woofer should sit well above the 111 Hz resonance, with steep filters and a high-pass that protects the 4 mm Xmax. Upward, the crossover to the tweeter is recommended at 1.2 kHz, which the 2.4" HF coil is designed for. The result is a 3-way system in which the entire speech and presence range comes from a single axis. Typical targets are compact main monitors in the studio, point-source tops for rental and home-theatre centre speakers with high dynamics.
What to look out for
- Midrange, not full-range: 90–1600 Hz for the cone section, Fs 111 Hz
- Sealed midrange chamber, guideline 0.8 l: build it damped and rigid
- 98 dB at 8 Ω, Re 5.4 Ω: 300 W AES as the power reference
- Xmax 4 mm: a steep high-pass below the crossover is mandatory
- 132 mm mounting depth and 3.95 kg: compact and light thanks to neodymium
Frequently asked questions
Can I use the 8NCX750 as a full-range coax in a small box?
No, it is not designed for that. With Fs 111 Hz, Vas 5.2 l and Xmax 4 mm it lacks low end. It is meant as a mid-high unit for 3-way systems, with a woofer taking over below.
How does it differ from the BMS 8CN552?
The BMS 8CN552 has Fs 87.6 Hz, Qts 0.29 and Vas 10.1 l, so it is suspended somewhat softer. The 8NCX750 with Qts 0.26 and Vas 5.2 l is even tighter and clearly laid out for midrange. Both are listed in the driver database at 42.audio.
Which crossover frequencies make sense?
Downward well above 111 Hz with steep filters, upward at 1.2 kHz to the tweeter. Active crossovers are the most practical solution for this driver because both transitions and the level matching have to be set precisely.
18Sound 8NCX750: manufacturer, spellings and classification
18Sound, 18 Sound and Eighteensound all refer to the same manufacturer: Eighteen Sound S.r.l. of Reggio Emilia, Italy. The 8NCX750 is a 8-inch coaxial driver with neodymium magnet from the NCX series, available from 42.audio, 18Sound dealer in Germany, with datasheet and full specifications in the driver database.
At 42.audio you get the 18SOUND 8NCX750 with datasheet PDF, all key data in the driver database and the enclosure calculator. More drivers from this manufacturer: Atlas 18Sound.
Thiele-Small parameters
| Nominal impedance | 8 Ω |
|---|---|
| Resonance frequency fs | 111 Hz |
| Total Q Qts | 0.26 |
| Electrical Q Qes | 0.27 |
| Mechanical Q Qms | 5 |
| Equivalent volume Vas | 5.2 l |
| Moving mass Mms | 29.0 g |
| Cone area Sd | 227 cm² |
| Linear excursion Xmax | 4 mm |
| Force factor BL | 20 Tm |
| DC resistance Re | 5.4 Ω |
| Voice coil inductance Le | 0.52 mH |
Comparable drivers
Same size, same type, Qts within ±30 %.
- B&C Speakers 8CXN51fs 68 Hz · Qts 0.27 · Vas 17 l · in the database
- BMS 8CN552fs 87.6 Hz · Qts 0.29 · Vas 10.1 l · in the database
- FaitalPRO 8HX230fs 70 Hz · Qts 0.29 · Vas 14.7 l · in the database
- SICA 8C2CPfs 78.5 Hz · Qts 0.3 · Vas 14.7 l · in the database
- FaitalPRO 8HX200fs 76 Hz · Qts 0.3 · Vas 13.1 l · in the database
- Beyma 8CX300Nd/Nfs 61 Hz · Qts 0.29 · Vas 23 l · in the shop
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Coaxial |
| Series | NCX |
| Magnet | Neodymium |
| Impedance (Ω) | 8 |
| Power handling (W) | 300 |
| Sensitivity (dB) | 98 |
| Frequency from (Hz) | 90 |
| Frequency to (Hz) | 1600 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 8 |
| Voice coil (inch) | 3 |
| Mounting depth (mm) | 132 |
| Weight (kg) | 3.95 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 5.4 |
| Le (mH) | 0.52 |
| Fs (Hz) | 111 |
| Qms | 5 |
| Qes | 0.27 |
| Qts | 0.26 |
| Vas (l) | 5.2 |
| Xmax (mm) | 4 |
| BL (Tm) | 20 |
| Mms (kg) | 0.029 |
| Sd (m²) | 0.0227 |