18SOUND 8MB500
18SOUND (Eighteen Sound) 8MB500 — 8" / 8 inch · Woofer/Midrange (WM) · Bass · Ferrite
2" voice coil · 16 Ω
Part no.: 42A-CHS-TT-18S-0029
Documents
18SOUND 8MB500 — 8" · Woofer
280 W AES · 95 dB Sensitivity · Frequency range 60 Hz – 4500 Hz
Technical data
- Diameter: 8 "
- Voice coil: 2 "
- Power handling: 280 W AES
- Sensitivity: 95 dB
- Impedance: 16 Ω
- Magnet: Ferrite
- Weight: 3.4 kg
- Mounting depth: 99 mm
- Frequency range: 60 – 4500 Hz
Datasheet (PDF) · Manufacturer page
Series: MB · Part no.: 42A-CHS-TT-18S-0029
18Sound 8MB500: 8" woofer/midrange in 16 Ω for arrays and sealed midrange chambers
The 8MB500 from 18Sound's MB series is listed here in its 16 Ω version, a detail that makes it attractive for columns and arrays: two drivers in parallel give 8 Ω, four in parallel 4 Ω, with no series wiring and its drawbacks for damping. Mechanically it is an 8" ferrite driver with a 2" voice coil, 280 W AES and 95 dB sensitivity across 60 to 4500 Hz.
The parameters set it apart from its sibling: Fs 73 Hz, Qes 0.58 and Qts 0.5 with Vas 21.3 l and BL 11 Tm. A Qts around 0.5 means the driver reaches a Butterworth alignment in a sealed box without much loss and bass reflex adds little. Xmax 6 mm, 16 g of moving mass, 99 mm mounting depth and 3.4 kg complete the picture of a lean midrange with bass capability.
Use and enclosure
From the Thiele-Small parameters the guide value is a sealed box of about 21 l with a cut-off around 103 Hz. That is the classic midrange chamber in a 3-way system or the basis of a column whose low bass is handled by a subwoofer. You can verify the design in the enclosure calculator at 42.audio; the EBP of 126 formally suggests bass reflex, but with Qts 0.5 the sealed solution turns out simpler in practice.
The range ends at 4500 Hz, and the crossover to the tweeter should sit noticeably lower. In arrays with several 8MB500 it pays to keep the centre spacing small relative to the crossover frequency. The 16 Ω rating comes with an Re of 9.8 Ω and an Le of 0.86 mH, which your crossover calculation needs to use.
What to look out for
- 16 Ω nominal, Re 9.8 Ω: a single driver draws only half the power from an 8 Ω amplifier rating.
- Two in parallel give 8 Ω, ideal for columns and dual-8" boxes.
- Qts 0.5: sealed box around 21 l as a guide value, no reflex port needed.
- Mounting depth 99 mm, 3.4 kg: light enough for shallow array modules.
- Xmax 6 mm: relieve it below the cut-off with a high-pass filter.
Frequently asked questions
Why is the 8MB500 offered in 16 Ω?
For applications where several drivers run in parallel. Two 16 Ω drivers in parallel present 8 Ω, four in parallel 4 Ω, so the amplifier sees a common load without any series wiring.
Which enclosure fits?
Sealed around 21 l with a cut-off near 103 Hz as a guide value. Because of Qts 0.5, bass reflex is not the better choice here; as a midrange a correspondingly smaller sealed chamber is enough.
How low can the 8MB500 be used?
The stated range starts at 60 Hz, but with Fs 73 Hz and 6 mm Xmax the driver is not a bass provider. A sensible approach is a crossover to a subwoofer above the cut-off of the sealed box.
At 42.audio you get the 18SOUND 8MB500 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 | 73 Hz |
| Total Q Qts | 0.5 |
| Electrical Q Qes | 0.58 |
| Mechanical Q Qms | 3.44 |
| Equivalent volume Vas | 21.3 l |
| Moving mass Mms | 16.0 g |
| Cone area Sd | 230 cm² |
| Linear excursion Xmax | 6 mm |
| Force factor BL | 11 Tm |
| DC resistance Re | 9.8 Ω |
| Voice coil inductance Le | 0.86 mH |
Enclosure suggestion
The EBP of 126 suggests a bass-reflex enclosure. EBP = fs / Qes = 73 / 0.58
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 21.3 l
- System resonance Fc
- 103 Hz
- Cut-off frequency F3
- 103 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 43.3 l
- Tuning frequency Fb
- 59 Hz
- Cut-off frequency F3
- 53 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.
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Low Frequency |
| Series | MB |
| Magnet | Ferrite |
| Impedance (Ω) | 16 |
| Power handling (W) | 280 |
| Sensitivity (dB) | 95 |
| Frequency from (Hz) | 60 |
| Frequency to (Hz) | 4500 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 8 |
| Voice coil (inch) | 2 |
| Mounting depth (mm) | 99 |
| Weight (kg) | 3.4 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 9.8 |
| Le (mH) | 0.86 |
| Fs (Hz) | 73 |
| Qms | 3.44 |
| Qes | 0.58 |
| Qts | 0.5 |
| Vas (l) | 21.3 |
| Xmax (mm) | 6 |
| BL (Tm) | 11 |
| Mms (kg) | 0.016 |
| Sd (m²) | 0.023 |