18SOUND 8MB400
18SOUND (Eighteen Sound) 8MB400 — 8" / 8 inch · Woofer/Midrange (WM) · Bass · Ferrite
2" voice coil · 8 Ω
Part no.: 42A-CHS-TT-18S-0030
Documents
18SOUND 8MB400 — 8" · Woofer
280 W AES · 95 dB Sensitivity · Frequency range 55 Hz – 5200 Hz
Technical data
- Diameter: 8 "
- Voice coil: 2 "
- Power handling: 280 W AES
- Sensitivity: 95 dB
- Impedance: 8 Ω
- Magnet: Ferrite
- Weight: 3.6 kg
- Mounting depth: 99 mm
- Frequency range: 55 – 5200 Hz
Datasheet (PDF) · Manufacturer page
Series: MB · Part no.: 42A-CHS-TT-18S-0030
18Sound 8MB400: 8" woofer/midrange with 2" voice coil, 95 dB and 280 W AES
If you are after an 8" woofer/midrange for compact PA boxes or stage monitors, 18Sound's MB series is where you end up. The 8MB400 pairs a ferrite magnet with a 2" voice coil and reaches 280 W AES at 95 dB sensitivity. Its 55 to 5200 Hz range makes it a genuine two-way driver: bass and mids from one cone, a compression driver above.
With 18 g of moving mass and a BL of 9.3 Tm the motor is tuned for midrange resolution rather than brute excursion; Xmax 5.8 mm and Vas 23.9 l at Fs 64 Hz and Qts 0.38 add up to a driver that works cleanly in small volumes. Mounting depth of 99 mm and 3.6 kg suit monitors, columns and compact cabinets.
Use and enclosure
An EBP of 149 points towards bass reflex. As a guide value the Thiele-Small parameters give a volume of about 22 l tuned to 64 Hz with an f3 near 64 Hz; sealed it would be roughly 9.7 l with a cut-off around 119 Hz, which only makes sense as a midrange chamber or with a subwoofer underneath. Check the actual design in the enclosure calculator at 42.audio.
In a 2-way box the 8MB400 covers everything up to the crossover to a compression driver; the 5200 Hz upper limit leaves room to hand over well below that. In a 3-way system with a separate bass driver it runs as a midrange in a sealed chamber around 9.7 l. Le of 0.96 mH rises towards the treble, which the crossover should account for.
What to look out for
- 8 Ω nominal, Re 5 Ω: an amplifier with 280 W into 8 Ω is enough, more only adds limiter work.
- 2" voice coil on ferrite: solid thermal handling at 3.6 kg.
- Mounting depth 99 mm: fits shallow monitor wedges.
- Xmax 5.8 mm: high-pass below 64 Hz in a reflex box.
- Reflex guide value 22 l: compact enough for an 8" two-way box.
Frequently asked questions
What separates the 8MB400 from the 8NMB420?
The 8NMB420 uses neodymium, has a tighter motor at Qts 0.28 and a larger volume requirement with Vas 33 l. The 8MB400 relies on ferrite, is more forgiving in a small box at Qts 0.38 and weighs 3.6 kg.
Is the 8MB400 suitable for a stage monitor?
Yes, 95 dB sensitivity and 280 W AES fit a compact wedge. A reflex box around 22 l plus a 1" compression driver on a horn gives a common 8" monitor configuration.
Which version, 8MB400 or 8MB500?
The 8MB500 from the same series is tuned higher at Fs 73 Hz and needs less volume with Vas 18.4 l. The 8MB400 with Fs 64 Hz, Qts 0.38 and Vas 23.9 l is the more flexible reflex candidate when the box should also deliver some low-end.
18Sound 8MB400: 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 8MB400 is a 8-inch woofer with ferrite magnet from the MB 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 8MB400 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 | 64 Hz |
| Total Q Qts | 0.38 |
| Electrical Q Qes | 0.43 |
| Mechanical Q Qms | 3.23 |
| Equivalent volume Vas | 23.9 l |
| Moving mass Mms | 18.0 g |
| Cone area Sd | 227 cm² |
| Linear excursion Xmax | 5.8 mm |
| Force factor BL | 9.3 Tm |
| DC resistance Re | 5 Ω |
| Voice coil inductance Le | 0.96 mH |
Enclosure suggestion
The EBP of 149 suggests a bass-reflex enclosure. EBP = fs / Qes = 64 / 0.43
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 9.7 l
- System resonance Fc
- 119 Hz
- Cut-off frequency F3
- 119 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 19.6 l
- Tuning frequency Fb
- 68 Hz
- Cut-off frequency F3
- 70 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 8NMB420fs 66 Hz · Qts 0.41 · Vas 24.53 l · in the database
- 18 Sound 8MB500fs 73 Hz · Qts 0.36 · Vas 18.4 l · in the database
- 18 Sound 8MB500fs 74 Hz · Qts 0.43 · Vas 21.5 l · in the database
- PHL Audio HP2460fs 79 Hz · Qts 0.45 · Vas 13.1 l · in the database
- 18 Sound 8NMB420fs 61 Hz · Qts 0.28 · Vas 33 l · in the shop
- Morel TiCW 958Ftfs 26 Hz · Qts 0.31 · Vas 45.4 l · in the database
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Low Frequency |
| Series | MB |
| Magnet | Ferrite |
| Impedance (Ω) | 8 |
| Power handling (W) | 280 |
| Sensitivity (dB) | 95 |
| Frequency from (Hz) | 55 |
| Frequency to (Hz) | 5200 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 8 |
| Voice coil (inch) | 2 |
| Mounting depth (mm) | 99 |
| Weight (kg) | 3.6 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 5 |
| Le (mH) | 0.96 |
| Fs (Hz) | 64 |
| Qms | 3.23 |
| Qes | 0.43 |
| Qts | 0.38 |
| Vas (l) | 23.9 |
| Xmax (mm) | 5.8 |
| BL (Tm) | 9.3 |
| Mms (kg) | 0.018 |
| Sd (m²) | 0.0227 |