18SOUND 10NMB420
18SOUND (Eighteen Sound) 10NMB420 — 10" / 10 inch · Midrange with Lower Midrange (ML) · Midrange · Neodymium
2.5" voice coil · 16 Ω
Part no.: 42A-CHS-MT-18S-0018
Documents
18SOUND 10NMB420 — 10" · Midrange Driver
350 W AES · 99 dB Sensitivity · Frequency range 65 Hz – 5000 Hz
Technical data
- Diameter: 10 "
- Voice coil: 2.5 "
- Power handling: 350 W AES
- Sensitivity: 99 dB
- Impedance: 16 Ω
- Magnet: Neo
- Weight: 3 kg
- Mounting depth: 122 mm
- Frequency range: 65 – 5000 Hz
Datasheet (PDF) · Manufacturer page
Series: NMB · Part no.: 42A-CHS-MT-18S-0018
18Sound 10NMB420: 10" neodymium mid-woofer with 16 Ω for dual-driver cabinets
With Qts 0.33 and Fs 65 Hz the 18Sound 10NMB420 falls outside the pattern of typical PA midranges, which are usually damped much harder. The slightly softer behaviour makes it more versatile: it runs in a bass-reflex box with real low-mid output, but works just as well in the sealed midrange chamber of a three-way system. 99 dB sensitivity, 350 W AES and a 2.5" voice coil place it in the NMB series – neodymium drivers for mid and low-mid duty, here at 3 kg.
The 16 Ω impedance is a deliberate choice. Two 10NMB420 in parallel give 8 Ω, so a dual-10" top or a line-array module can run on a normal amplifier channel without pushing the load below 4 Ω. With Re 10.5 Ω and Le 0.4 mH the impedance curve stays benign across the usable range up to 5,000 Hz. BL 19.5 Tm at 31.5 g moving mass and 4 mm Xmax complete the picture of a strong motor that is not designed for deep bass.
Use and enclosure
For a bass-reflex enclosure the guideline is about 19 l tuned to 74 Hz, with a lower cutoff around 80 Hz – for a 10" low-mid section in a three-way top or as a mid-woofer in a compact two-way box supported by a subwoofer. For a sealed midrange chamber reckon with roughly 8.4 l at a corner frequency of 139 Hz; the crossover to the bass then sits well above the lower limit of 65 Hz. The EBP of 181 confirms it: bass-reflex or horn yes, deep tuning in a sealed box no. Do the exact design with the enclosure calculator at 42.audio.
The upper range to 5,000 Hz leaves plenty of freedom for the crossover to the compression driver; 122 mm mounting depth is rather generous for a 10" neodymium driver, so allow for it in the cabinet.
What to look out for
- 16 Ω: less power from an 8 Ω amplifier when used alone, ideal in parallel pairs.
- Qts 0.33, Vas 30 l: more flexible than typical PA midranges, bass-reflex from about 19 l possible.
- Xmax 4 mm, 350 W AES: low mids yes, sub-bass no.
- 3 kg, neodymium, 122 mm mounting depth: light but not shallow.
- 99 dB: slightly less efficiency than pure midranges, but more bandwidth downwards.
Frequently asked questions
Why 16 Ω, and what does it mean for the amplifier?
On an amplifier rated for 8 Ω a single 16 Ω driver draws only about half the power. The point is parallel connection: two drivers give 8 Ω, four give 4 Ω – that is what line arrays and dual-10" boxes are built on.
How does the 10NMB420 compare with the 10MB600?
Both sit at Qts 0.33; the 10MB600 has Fs 64 Hz and Vas 27.6 l, so nearly identical enclosure requirements. The difference is the magnet: the 10NMB420 uses neodymium at 3 kg, the 10MB600 ferrite.
Does it fit a two-way box?
Yes, as a mid-woofer with subwoofer support. In a bass-reflex box of around 19 l it reaches down to about 80 Hz; without a sub the deep bass is missing below that. Upwards you cross below 5,000 Hz to the tweeter.
At 42.audio you get the 18SOUND 10NMB420 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 | 16 Ω |
|---|---|
| Resonance frequency fs | 65 Hz |
| Total Q Qts | 0.33 |
| Electrical Q Qes | 0.36 |
| Mechanical Q Qms | 4.6 |
| Equivalent volume Vas | 30.0 l |
| Moving mass Mms | 31.5 g |
| Cone area Sd | 346 cm² |
| Linear excursion Xmax | 4 mm |
| Force factor BL | 19.5 Tm |
| DC resistance Re | 10.5 Ω |
| Voice coil inductance Le | 0.4 mH |
Enclosure suggestion
The EBP of 181 suggests a bass-reflex enclosure. EBP = fs / Qes = 65 / 0.36
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 8.4 l
- System resonance Fc
- 139 Hz
- Cut-off frequency F3
- 139 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 15.5 l
- Tuning frequency Fb
- 80 Hz
- Cut-off frequency F3
- 87 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 10MB600fs 64 Hz · Qts 0.33 · Vas 27.6 l · in the database
- 18 Sound 10MB400fs 70 Hz · Qts 0.33 · Vas 41 l · in the database
- Oberton 10NDG500fs 55.9 Hz · Qts 0.34 · Vas 21.5 l · in the database
- Ciare PWA10.64fs 73 Hz · Qts 0.38 · Vas 23 l · in the database
- Volt B251.8fs 31 Hz · Qts 0.36 · Vas 72.6 l · in the database
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Mid Frequency |
| Series | NMB |
| Magnet | Neo |
| Impedance (Ω) | 16 |
| Power handling (W) | 350 |
| Sensitivity (dB) | 99 |
| Frequency from (Hz) | 65 |
| Frequency to (Hz) | 5000 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 10 |
| Voice coil (inch) | 2.5 |
| Mounting depth (mm) | 122 |
| Weight (kg) | 3 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 10.5 |
| Le (mH) | 0.4 |
| Fs (Hz) | 65 |
| Qms | 4.6 |
| Qes | 0.36 |
| Qts | 0.33 |
| Vas (l) | 30 |
| Xmax (mm) | 4 |
| BL (Tm) | 19.5 |
| Mms (kg) | 0.0315 |
| Sd (m²) | 0.0346 |