18SOUND 12MB650
18SOUND (Eighteen Sound) 12MB650 — 12" / 12 inch · Midrange with Lower Midrange (ML) · Midrange · Ferrite
2.5" voice coil · 8 Ω
Part no.: 42A-CHS-MT-18S-0005
Documents
18SOUND 12MB650 — 12" · Midrange Driver
400 W AES · 98 dB Sensitivity · Frequency range 45 Hz – 5000 Hz
Technical data
- Diameter: 12 "
- Voice coil: 2.5 "
- Power handling: 400 W AES
- Sensitivity: 98 dB
- Impedance: 8 Ω
- Magnet: Ferrite
- Weight: 6.8 kg
- Mounting depth: 143 mm
- Frequency range: 45 – 5000 Hz
Datasheet (PDF) · Manufacturer page
Series: MB · Part no.: 42A-CHS-MT-18S-0005
18Sound 12MB650: 12" ferrite mid-woofer with 5.5 mm Xmax from 45 to 5,000 Hz
The 18Sound 12MB650 is the all-rounder of the MB series: 12", ferrite magnet, 2.5" voice coil, 400 W AES, 98 dB – and a usable range of 45 to 5,000 Hz that combines low mids and midrange in one driver. With Fs 48 Hz, Vas 90 l and Xmax 5.5 mm it brings the excursion a midrange with low-mid duties actually needs, without giving up the efficiency of a midrange driver entirely.
Qts 0.23 and Qms 3.2 describe a heavily damped motor with comparatively high mechanical losses; BL 19 Tm at 48 g cone mass provides the control. The 0.83 mH voice-coil inductance is low for a ferrite motor, which makes the use up to 5,000 Hz plausible. 6.8 kg and 143 mm mounting depth are the flip side of the ferrite magnet.
Use and enclosure
For bass-reflex the guideline is 20 l tuned to 76 Hz with a lower cutoff around 98 Hz. That is the typical configuration for a two-way or three-way top: 12" mid-woofer plus compression driver, with a subwoofer below. The EBP of 200 argues against deep tuning in a sealed box; as a pure midrange chamber about 11 l at a 148 Hz corner frequency is enough, with the high-pass well above the lower limit of 45 Hz. For the exact design: enclosure calculator at 42.audio.
The crossover to the treble can sit high thanks to the bandwidth, which also allows 1" drivers on small horns; for maximum SPL headroom a 2" driver on a larger horn is the choice. 98 dB is below the figures of pure midranges, but in return the 12MB650 needs no downward level matching in two-way boxes.
What to look out for
- Xmax 5.5 mm, Fs 48 Hz: low mids in a bass-reflex box from about 20 l.
- 98 dB at 8 Ω: usual figure for 12" mid-woofers, uncritical in passive crossovers.
- 400 W AES on a 2.5" coil: enough for tops with subwoofer, set a high-pass.
- 6.8 kg, 143 mm mounting depth: ferrite, plan the cabinet accordingly.
- 45–5,000 Hz: high crossover to the tweeter possible.
Frequently asked questions
12MB650 or 12MB700 – which one fits?
The 12MB700 has Fs 46 Hz, Qts 0.25 and Vas 100 l, so it needs a larger enclosure; it comes with a 3" coil, the 12MB650 with 2.5" and more excursion. For compact tops with subwoofer the 12MB650 is the handier choice.
Is the 12MB650 enough for a two-way box without subwoofer?
Down to about 98 Hz lower cutoff in the 20 l reflex box – for speech and monitoring yes, for music with deep bass no. A subwoofer belongs below that, and the top's high-pass should sit above the tuning frequency.
Which amplifier?
400 W into 8 Ω per driver is the maximum; with 98 dB efficiency a fraction of that is enough in small rooms. More important is a high-pass so the 5.5 mm of excursion is not wasted below the tuning frequency.
18Sound 12MB650: 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 12MB650 is a 12-inch midrange driver 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 12MB650 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 | 48 Hz |
| Total Q Qts | 0.23 |
| Electrical Q Qes | 0.24 |
| Mechanical Q Qms | 3.2 |
| Equivalent volume Vas | 90.0 l |
| Moving mass Mms | 48.0 g |
| Cone area Sd | 531 cm² |
| Linear excursion Xmax | 5.5 mm |
| Force factor BL | 19 Tm |
| DC resistance Re | 6 Ω |
| Voice coil inductance Le | 0.83 mH |
Enclosure suggestion
The EBP of 200 suggests a bass-reflex enclosure. EBP = fs / Qes = 48 / 0.24
Sealed (Qtc 0.707)
- Enclosure volume Vb
- 10.7 l
- System resonance Fc
- 148 Hz
- Cut-off frequency F3
- 148 Hz
Bass reflex (QB3 after Small)recommended
- Enclosure volume Vb
- 14.1 l
- Tuning frequency Fb
- 85 Hz
- Cut-off frequency F3
- 109 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 12MB700fs 46 Hz · Qts 0.25 · Vas 100 l · in the shop
- 18 Sound 12MB710fs 46 Hz · Qts 0.2 · Vas 81 l · in the database
- 18 Sound 12MB720fs 46 Hz · Qts 0.2 · Vas 81 l · in the database
- 18 Sound 12MB810fs 46 Hz · Qts 0.2 · Vas 81 l · in the database
- 18 Sound 12MB777fs 49 Hz · Qts 0.19 · Vas 101 l · in the database
- 18 Sound 12MB700fs 49 Hz · Qts 0.19 · Vas 101 l · in the database
Specifications
| Allgemein | |
|---|---|
| Manufacturer | 18SOUND |
| Category | Mid Frequency |
| Series | MB |
| Magnet | Ferrite |
| Impedance (Ω) | 8 |
| Power handling (W) | 400 |
| Sensitivity (dB) | 98 |
| Frequency from (Hz) | 45 |
| Frequency to (Hz) | 5000 |
| Abmessungen & Korb | |
|---|---|
| Diameter | 12 |
| Voice coil (inch) | 2.5 |
| Mounting depth (mm) | 143 |
| Weight (kg) | 6.8 |
| Thiele-Small-Parameter | |
|---|---|
| Re (Ω) | 6 |
| Le (mH) | 0.83 |
| Fs (Hz) | 48 |
| Qms | 3.2 |
| Qes | 0.24 |
| Qts | 0.23 |
| Vas (l) | 90 |
| Xmax (mm) | 5.5 |
| BL (Tm) | 19 |
| Mms (kg) | 0.048 |
| Sd (m²) | 0.0531 |