18SOUND 15NCX750H
18SOUND (Eighteen Sound) 15NCX750H — 15" / 15 inch Coaxial Driver · Coax / Coaxial Driver · Neodymium
3"/2.4" voice coils · 8 Ω
Part no.: 42A-CHS-KO-18S-0014
Documents
18SOUND 15NCX750H — 15" · Coaxial Driver
400 W AES · 97 dB Sensitivity · Frequency range 50 Hz – 4700 Hz
Technical data
- Diameter: 15 "
- Voice coil: 3 "
- Power handling: 400 W AES
- Sensitivity: 97 dB
- Impedance: 8 Ω
- Magnet: Neodymium
- Weight: 5.3 kg
- Mounting depth: 185 mm
- Frequency range: 50 – 4700 Hz
- Coverage angle: 70x50 °
- Rec. crossover: 1.2 kHz
Datasheet (PDF) · Manufacturer page
Series: NCX · Part no.: 42A-CHS-KO-18S-0014
18Sound 15NCX750H: 15" coax with 70°x50° horn, 400 W and 97 dB for directional coverage
The H in the name stands for the horn variant: instead of the round cone, the 15NCX750H from 18Sound carries an asymmetric HF horn with 70° horizontal and 50° vertical dispersion. Below it works the same neodymium woofer as in the 15NCX750 with a 3" voice coil, while the tweeter drives a 2.4" coil. Power handling is 400 W AES, sensitivity 97 dB, and the low-frequency section covers 50 Hz to 4700 Hz.
A rectangular horn on a coax is not a matter of style but a decision about room interaction. Where a round cone spreads energy evenly in all directions, the 70°x50° horn keeps it vertically tighter. Less goes to ceiling and floor, more goes straight to the audience. The woofer parameters stay practically identical to the cone model with Fs 49 Hz, Qts 0.37, Vas 141 l, BL 18.5 Tm and a moving mass of 80.6 g, and at 5.3 kg the 15NCX750H is still one of the light 15" coaxials.
Use and enclosure
The same enclosure guidelines apply as for the sister model: bass reflex at about 122 l net, tuned to 50 Hz with f3 around 51 Hz, or sealed at roughly 53 l with fc at 94 Hz. The EBP of 122 says bass reflex, if you can fit the volume. Xmax is 5.5 mm, so a high-pass below the tuning frequency should always be in place. The enclosure calculator at 42.audio provides the details including port dimensions.
The recommended crossover is 1.2 kHz, a value that keeps the 2.4" HF coil at a safe distance from its resonance. When installing, horn orientation is decisive: 70° horizontal and 50° vertical for an upright top, mounted sideways for a floor monitor where the wide axis points up at the performer. Sensible uses are installations in reverberant rooms, compact tops with a sub, and monitors where reduced overhead spill lowers feedback risk.
What to look out for
- 70°x50° dispersion: decide the horn orientation at build time, upright or lying
- 5.3 kg and 185 mm mounting depth: light and shallow enough for wedges
- 97 dB sensitivity at 8 Ω, Re 5.4 Ω: 400 W AES as the power reference
- Vas 141 l and Fs 49 Hz: needs a large reflex box for extension
- Le 0.66 mH: low inductance, uncritical for the crossover design in the transition
Frequently asked questions
Why the H model instead of the 15NCX750?
The woofer is identical; the difference is in the HF: 70°x50° directional versus round conical. In reverberant rooms or monitors with feedback issues the tighter vertical pattern is an advantage, while the cone of the 15NCX750 is more uniform in the near field.
How large does the cabinet need to be?
Bass reflex around 122 l tuned to 50 Hz for full extension, sealed around 53 l for a top or monitor with a subwoofer. Both are guidelines from the Thiele-Small parameters; the enclosure calculator handles the exact design.
Which alternative has similar parameters?
The Beyma 15CXA400Nd with Fs 40 Hz, Qts 0.36 and Vas 196 l goes in a similar direction but needs even more volume. The 18Sound 15NCX910 is more compact with Vas 107 l and more sensitive as well.
18Sound 15NCX750H: 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 15NCX750H is a 15-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 15NCX750H 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 | 49 Hz |
| Total Q Qts | 0.37 |
| Electrical Q Qes | 0.4 |
| Mechanical Q Qms | 6.32 |
| Equivalent volume Vas | 141.0 l |
| Moving mass Mms | 80.6 g |
| Cone area Sd | 881 cm² |
| Linear excursion Xmax | 5.5 mm |
| Force factor BL | 18.5 Tm |
| DC resistance Re | 5.4 Ω |
| Voice coil inductance Le | 0.66 mH |
Enclosure suggestion
The EBP of 122 suggests a bass-reflex enclosure. EBP = fs / Qes = 49 / 0.4
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 53.2 l
- System resonance Fc
- 94 Hz
- Cut-off frequency F3
- 94 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 106.0 l
- Tuning frequency Fb
- 54 Hz
- Cut-off frequency F3
- 56 Hz
Vb is the required net internal volume, Fb the tuning frequency of the reflex port and F3 the frequency at which the level has dropped by 3 dB. Calculated approximation after Small. A starting point for simulation, not a finished build plan.
Comparable drivers
Same size, same type, Qts within ±30 %.
- 18 Sound 15NCX750fs 49 Hz · Qts 0.37 · Vas 141 l · in the shop
- Beyma 15CXA400Ndfs 40 Hz · Qts 0.36 · Vas 196 l · in the shop
- SICA 15Cx3PLfs 44.5 Hz · Qts 0.4 · Vas 152 l · in the database
- 18 Sound 15NCX910fs 55 Hz · Qts 0.33 · Vas 107 l · in the shop
- 18 Sound 15NCX910BEfs 55 Hz · Qts 0.33 · Vas 107 l · in the database
- 18 Sound 15NCX910Nfs 55 Hz · Qts 0.33 · Vas 107 l · in the shop
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Coaxial |
| Series | NCX |
| Magnet | Neodymium |
| Impedance (Ω) | 8 |
| Power handling (W) | 400 |
| Sensitivity (dB) | 97 |
| Frequency from (Hz) | 50 |
| Frequency to (Hz) | 4700 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 15 |
| Voice coil (inch) | 3 |
| Mounting depth (mm) | 185 |
| Weight (kg) | 5.3 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 5.4 |
| Le (mH) | 0.66 |
| Fs (Hz) | 49 |
| Qms | 6.32 |
| Qes | 0.4 |
| Qts | 0.37 |
| Vas (l) | 141 |
| Xmax (mm) | 5.5 |
| BL (Tm) | 18.5 |
| Mms (kg) | 0.0806 |
| Sd (m²) | 0.0881 |