18SOUND XO 15 NCX 750
18SOUND (Eighteen Sound) XO 15 NCX 750 — Passive Crossover
für 15NCX750
Part no.: 42A-CHS-FW-18S-0001
Documents
18SOUND XO 15 NCX 750 — Crossover
400 W AES
Technical data
- Power handling: 400 W AES
- Impedance: 8 Ω
Datasheet (PDF) · Manufacturer page
Series: XO · Part no.: 42A-CHS-FW-18S-0001
18Sound XO 15 NCX 750: passive two-way crossover for the 15" coaxial 15NCX750
A 15" coaxial is the most compact way to build a full-size two-way loudspeaker, and the XO 15 NCX 750 is the passive network 18Sound supplies for the 15NCX750. The crossover divides the amplifier signal between the 15" cone and the coaxially mounted compression driver with titanium diaphragm, pads the HF level down and puts the crossover point where the manufacturer intends it for this driver: 1.2 kHz.
The 15NCX750 itself is a neodymium coaxial with a 3" voice coil, 400 W AES, 98 dB sensitivity and 8 Ω. Its working range starts at 55 Hz and extends to 4,500 Hz, the HF dispersion is 80°. Compared with the 12" coaxials of the series it brings considerably more cone area with Vas 141 l and Sd 0.0881 m², and therefore more low end, which makes it attractive for full-range cabinets without a separate subwoofer.
Use and enclosure
With this crossover you build a passive full-range cabinet or a large stage monitor that runs on a single amplifier channel. That simplifies cabling and operation a lot, especially in rental fleets or fixed installations where not every user should have to configure a DSP. The crossover around 1.2 kHz is tuned to the cone-to-HF balance of this model with its 98 dB and is not a value you can transfer to other coaxials.
For the enclosure the relevant figures are Fs 49 Hz, Qts 0.37, Vas 141 l and Xmax 5.5 mm. Run them through the enclosure calculator at 42.audio instead of guessing volumes, because at 141 l Vas the difference between a matched and an arbitrary box is clearly audible. The mounting depth of 185 mm and 4.9 kg weight are moderate for a 15" driver with neodymium motor, which helps the total weight of the cabinet.
What to look out for
- Matched to the 15NCX750, not to other 15" coaxials of the series.
- 8 Ω, one amplifier channel per cabinet, base the power on 400 W AES.
- Vas 141 l: the enclosure ends up larger than for a 12" coaxial, use the enclosure calculator.
- 185 mm mounting depth, 4.9 kg thanks to the neodymium motor.
- Datasheet PDF with all Thiele-Small parameters linked at 42.audio.
Frequently asked questions
Is this crossover also suitable for the stronger 15" coaxial of the NCX series?
No, that driver has its own XO network. The two coaxials differ in sensitivity and motor design, so the HF attenuation only matches the driver each crossover was made for.
How much amplifier power do I need?
The 15NCX750 is rated 400 W AES, an amplifier in that class at 8 Ω is a good fit. With 98 dB sensitivity you reach solid levels with much less power already, but headroom does no harm as long as you drive it cleanly.
Can I convert the cabinet to active operation later?
Yes. For bi-amping you bypass the crossover and drive cone and compression driver from two channels through a DSP that takes over the 1.2 kHz split and the level alignment. The passive crossover then stays available as a fallback.
At 42.audio you get the 18SOUND XO 15 NCX 750 with datasheet PDF, all key data in the driver database. More drivers from this manufacturer: Atlas 18Sound.
Specifications
| Manufacturer | 18SOUND |
| Category | Crossover |
| Series | XO |
| Impedance (Ω) | 8 |
| Power handling (W) | 400 |