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18SOUND 18LW1251

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18SOUND (Eighteen Sound) 18LW1251 — 18" / 18 inch · Woofer · Subwoofer / Bass · Ferrite Magnet
4" voice coil · 8 Ω
Part no.: 42A-CHS-TT-18S-0009

350.00 € 350.0 EUR 350.00 €

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  • Impedance (Ω)
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  • Frequency to (Hz)
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18SOUND 18LW1251 — 18" · Woofer

1000 W AES · 98 dB Sensitivity · Frequency range 35 Hz – 3500 Hz

Technical data

  • Diameter: 18 "
  • Voice coil: 4 "
  • Power handling: 1000 W AES
  • Sensitivity: 98 dB
  • Impedance: 8 Ω
  • Magnet: Ferrite
  • Weight: 13 kg
  • Mounting depth: 207 mm
  • Frequency range: 35 – 3500 Hz

Datasheet (PDF) · Manufacturer page

Series: LW · Part no.: 42A-CHS-TT-18S-0009

18Sound 18LW1251: 18" ferrite woofer with 1,000 W AES and 98 dB for vented subs

If you want an 18" ferrite bass driver that drops into a vented box without fuss, the 18Sound LW series is where to look. The 18LW1251 is its entry into the 4" voice coil class: 1,000 W AES power handling, 98 dB sensitivity and a stated bandwidth from 35 Hz to 3,500 Hz. At 142 g Mms the cone is light for an 18", the motor delivers 23.6 Tm, and the result is a Qts of 0.27 at a free-air resonance of 35 Hz.

A Vas of 268 l means a compliant suspension, so the driver wants a decent volume but pays that back with high efficiency. Among comparable drivers in the database the Beyma 18PW1400Fe/S and the Oberton 18XB1600 sit very close at Qts 0.27 to 0.28; the in-house neodymium counterpart is the 18Sound 18NLW9400 with an identical Vas of 268 l and Qts 0.26. The 18LW1251 is the classic ferrite bass for rental boxes, sound reinforcement subs and DIY builds where price per watt and ruggedness matter.

Use and enclosure

With an EBP of 125 the 18LW1251 clearly belongs in a bass reflex enclosure. The guideline from the Thiele-Small parameters is around 94 l net volume, tuned to 48 Hz, with a lower cut-off f3 near 57 Hz. That makes a compact sub or the bass section of a full-range top that hands over to a midrange or horn above the upper bass. A sealed box would come out at a guideline of 46 l with a resonance of 92 Hz, which effectively gives up the low end. Verify the alignment with the enclosure calculator at 42.audio and add a steep high-pass below the tuning frequency, because with 9 mm Xmax the excursion reserve below tuning is limited.

The inductance of 2.73 mH is normal for a 4" coil but does tame the output towards the top. Even though the nominal range extends to 3,500 Hz, a sensible crossover to a midrange or horn section sits well below that, in the region of a few hundred hertz.

What to look out for

  • 8 Ω, Re 5 Ω: fully used by a channel in the same 1,000 W AES power class.
  • Mounting depth 207 mm, weight 13 kg: ferrite magnet, so size the baffle accordingly.
  • Xmax 9 mm: a high-pass below the tuning frequency is mandatory or the coil will bottom out.
  • Vas 268 l at Qts 0.27: needs volume, rewards you with 98 dB efficiency.

Frequently asked questions

Which enclosure suits the 18LW1251?

A vented box around 94 l tuned to 48 Hz is the guideline from the Thiele-Small parameters. That places the lower cut-off around 57 Hz. Sealed boxes are not worthwhile with this driver, as the EBP of 125 makes clear.

How does the 18LW1251 differ from the 18NLW9400?

Both share Vas 268 l and a similarly low Qts (0.27 versus 0.26), so they work in practically the same box. The 18NLW9400 uses neodymium and saves noticeable weight, while the 18LW1251 brings the ferrite motor at a lower entry price.

How much amplifier power makes sense?

A channel with around 1,000 W into 8 Ω uses the AES rating fully. Thanks to 98 dB, considerably less is enough for high levels. A limiter and a high-pass matter more than the last watt of headroom, because at 9 mm Xmax the mechanical limit arrives before the thermal one.

18Sound 18LW1251: 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 18LW1251 is a 18-inch woofer with ferrite magnet from the LW 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 18LW1251 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 impedance8 Ω
Resonance frequency fs35 Hz
Total Q Qts0.27
Electrical Q Qes0.28
Mechanical Q Qms8
Equivalent volume Vas268.0 l
Moving mass Mms142.0 g
Cone area Sd1,134 cm²
Linear excursion Xmax9 mm
Force factor BL23.6 Tm
DC resistance Re5 Ω
Voice coil inductance Le2.73 mH

Enclosure suggestion

The EBP of 125 suggests a bass-reflex enclosure. EBP = fs / Qes = 35 / 0.28

Sealed (Qtc 0.707)

Enclosure volume Vb
45.8 l
System resonance Fc
92 Hz
Cut-off frequency F3
92 Hz

Bass reflex (QB3 after Small)recommended

Enclosure volume Vb
71.2 l
Tuning frequency Fb
53 Hz
Cut-off frequency F3
63 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 %.

Specifications

Allgemein
Manufacturer 18SOUND
Category Low Frequency
Series LW
Magnet Ferrite
Impedance (Ω) 8
Power handling (W) 1000
Sensitivity (dB) 98
Frequency from (Hz) 35
Frequency to (Hz) 3500
Abmessungen & Korb
Diameter 18
Voice coil (inch) 4
Mounting depth (mm) 207
Weight (kg) 13
Thiele-Small-Parameter
Re (Ω) 5
Le (mH) 2.73
Fs (Hz) 35
Qms 8
Qes 0.28
Qts 0.27
Vas (l) 268
Xmax (mm) 9
BL (Tm) 23.6
Mms (kg) 0.142
Sd (m²) 0.1134