18SOUND 15ND940
18SOUND (Eighteen Sound) 15ND940 — 15" / 15 inch · Woofer/Midrange (WM) · Subwoofer / Bass · Neodymium
3" voice coil · 8 Ω
Part no.: 42A-CHS-TT-18S-0051
Documents
18SOUND 15ND940 — 15" · Woofer
600 W AES · 99 dB Sensitivity · Frequency range 38 Hz – 3500 Hz
Technical data
- Diameter: 15 "
- Voice coil: 3 "
- Power handling: 600 W AES
- Sensitivity: 99 dB
- Impedance: 8 Ω
- Magnet: Neo
- Weight: 4.7 kg
- Mounting depth: 184 mm
- Frequency range: 38 – 3500 Hz
Datasheet (PDF) · Manufacturer page
Series: ND · Part no.: 42A-CHS-TT-18S-0051
18Sound 15ND940: 15" neodymium woofer with 600 W AES, 9.5 mm Xmax and 0.7 mH
The 18Sound 15ND940 is the all-rounder among the neodymium 15" drivers of the ND series: 600 W AES, 99 dB sensitivity, 9.5 mm Xmax and a voice coil inductance of 0.7 mH on a 3" coil. At 4.7 kg it stays light enough for flown tops, and with a rated range of 38 to 3,500 Hz it covers bass and lower midrange.
The Thiele-Small parameters reveal a balanced driver: Fs 38 Hz, Qts 0.28, Vas 174 l, a force factor of 21.9 Tm on 108 g of moving mass and a high Qms of 7.5. The EBP of 131 sits squarely in vented territory without reaching the extreme values of horn-optimised drivers. That makes the 15ND940 flexible: it works in a compact top just as well as in a lower-tuned subwoofer.
Use and enclosure
As a guideline, a vented enclosure of about 68 l tuned to 50 Hz gives a lower cut-off around 59 Hz. That is a manageable volume for a 15"/1.4" top that runs on its own as well as above subwoofers. The sealed alignment of roughly 32 l with a system resonance near 96 Hz serves as a midrange chamber in 3-way systems. For subwoofer alignments with lower tuning you can run larger volumes through the enclosure calculator at 42.audio; the 9.5 mm Xmax provides enough reserve for that.
The 0.7 mH inductance is low enough to couple the 15ND940 cleanly to a compression driver even with a passive network; set the crossover well below 3,500 Hz to avoid beaming and cone resonances. Mounting depth is 184 mm, so check the depth in shallow cabinets. For the amplifier: 600 W AES at 8 Ω with Re 5.4 Ω, and parallel pairs require 4 Ω stability.
What to look out for
- 9.5 mm Xmax and 600 W AES: enough displacement for a top and a lightweight sub.
- Le 0.7 mH: passive crossover possible, active crossover still preferable.
- Qts 0.28, EBP 131: vented box around 68 l as a starting point, larger for more extension.
- 4.7 kg neodymium at 184 mm mounting depth.
- 8 Ω nominal, Re 5.4 Ω, also available as 4 and 16 Ω versions.
Frequently asked questions
15ND940 or 15LW1500, which is better as a subwoofer?
Both have Qts 0.28, but the 15LW1500 has the lower resonance at 34 Hz Fs with 195 l Vas and 96 dB. The 15ND940 sits at 38 Hz and 174 l, delivers 99 dB and weighs far less at 4.7 kg. For maximum extension choose the 15LW1500, for light cabinets with more efficiency the 15ND940.
Can the 15ND940 carry a 2-way top without a subwoofer?
In the guideline box around 68 l it reaches about 59 Hz, which is enough for many applications without a sub. If you want to go lower, choose a larger volume with lower tuning; the 9.5 mm Xmax leaves room for that.
How much amplifier power makes sense?
An amplifier in the region of the 600 W AES rating at 8 Ω, with a limiter. Thanks to 99 dB sensitivity the 15ND940 delivers high level with less power too; a high-pass filter below the tuning frequency matters more.
At 42.audio you get the 18SOUND 15ND940 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 | 38 Hz |
| Total Q Qts | 0.28 |
| Electrical Q Qes | 0.29 |
| Mechanical Q Qms | 7.5 |
| Equivalent volume Vas | 174.0 l |
| Moving mass Mms | 108.0 g |
| Cone area Sd | 881 cm² |
| Linear excursion Xmax | 9.5 mm |
| Force factor BL | 21.9 Tm |
| DC resistance Re | 5.4 Ω |
| Voice coil inductance Le | 0.7 mH |
Enclosure suggestion
The EBP of 131 suggests a bass-reflex enclosure. EBP = fs / Qes = 38 / 0.29
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 32.4 l
- System resonance Fc
- 96 Hz
- Cut-off frequency F3
- 96 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 52.1 l
- Tuning frequency Fb
- 55 Hz
- Cut-off frequency F3
- 65 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 %.
- Oberton 15NXB700fs 38.3 Hz · Qts 0.28 · Vas 106 l · in the database
- B&C Speakers 15TBW100fs 39 Hz · Qts 0.28 · Vas 88 l · in the database
- B&C Speakers 15SW100fs 37 Hz · Qts 0.28 · Vas 99.5 l · in the database
- B&C Speakers 15TBX100fs 35 Hz · Qts 0.28 · Vas 113 l · in the database
- B&C Speakers 15NDL88fs 41 Hz · Qts 0.28 · Vas 154 l · in the database
- 18 Sound 15LW1500fs 34 Hz · Qts 0.28 · Vas 195 l · in the shop
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Low Frequency |
| Series | ND |
| Magnet | Neo |
| Impedance (Ω) | 8 |
| Power handling (W) | 600 |
| Sensitivity (dB) | 99 |
| Frequency from (Hz) | 38 |
| Frequency to (Hz) | 3500 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 15 |
| Voice coil (inch) | 3 |
| Mounting depth (mm) | 184 |
| Weight (kg) | 4.7 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 5.4 |
| Le (mH) | 0.7 |
| Fs (Hz) | 38 |
| Qms | 7.5 |
| Qes | 0.29 |
| Qts | 0.28 |
| Vas (l) | 174 |
| Xmax (mm) | 9.5 |
| BL (Tm) | 21.9 |
| Mms (kg) | 0.108 |
| Sd (m²) | 0.0881 |