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18SOUND 21NLW9601

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18SOUND (Eighteen Sound) 21NLW9601 — 21" / 21 inch · High-Performance Woofer · Subwoofer / Bass · Neodymium
5.35" voice coil · 8 Ω
Part no.: 42A-CHS-TT-18S-0033

825.00 € 825.0 EUR 825.00 €

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  • Series
  • Magnet
  • Impedance (Ω)
  • Power handling (W)
  • Sensitivity (dB)
  • Frequency from (Hz)
  • Frequency to (Hz)
  • Diameter
  • Voice coil (inch)
  • Mounting depth (mm)
  • Weight (kg)
  • Re (Ω)
  • Le (mH)
  • Fs (Hz)
  • Qms
  • Qes
  • Qts
  • Vas (l)
  • Xmax (mm)
  • BL (Tm)
  • Mms (kg)
  • Sd (m²)

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18SOUND 21NLW9601 — 21" · Woofer

1800 W AES · 98 dB Sensitivity · Frequency range 25 Hz – 2000 Hz

Technical data

  • Diameter: 21 "
  • Voice coil: 5.3 "
  • Power handling: 1800 W AES
  • Sensitivity: 98 dB
  • Impedance: 8 Ω
  • Magnet: Neo
  • Weight: 13.5 kg
  • Mounting depth: 250 mm
  • Frequency range: 25 – 2000 Hz

Datasheet (PDF) · Manufacturer page

Series: NLW · Part no.: 42A-CHS-TT-18S-0033

18Sound 21NLW9601: 21" neodymium subwoofer with BL 43 Tm and 5.3" voice coil

A force factor of 43 Tm is the figure that defines the 21NLW9601 from 18Sound's NLW series. The neodymium motor with 5.3" voice coil (18Sound: 5.35") pulls the cone with enough force for a very low electrical Q: Qes 0.31, Qts 0.29, despite 0.408 kg of moving mass. Power handling 1800 W, sensitivity 98 dB, nominal impedance 8 Ω with Re 5.9 Ω.

The Vas of 175 l is small for a 21", fs sits at 37 Hz, Xmax at 14 mm. This combination – strong motor, small Vas, high mass – is typical of subwoofers meant to produce very high levels from compact reflex boxes with DSP equalisation, rather than playing deep passively in huge volumes. At 13.5 kg and 250 mm mounting depth it stays manageable.

Use and enclosure

An EBP of 119 points towards bass reflex. The classic approximation formulas give a guideline of around 75 l tuned to 47 Hz with f3 near 54 Hz – an unusually small volume for a 21" driver. In practice a driver like this usually goes into a larger box with lower tuning and the response is linearised by DSP; the high power handling and strong motor are there for exactly that. Sealed would give about 35 l at fc 90 Hz. The enclosure calculator at 42.audio helps balance volume, tuning and excursion demand; the operating range starts at 25 Hz.

Le of 3.1 mH is comparatively high, which limits the usable range at the top – irrelevant for a subwoofer with a low crossover. At 8 Ω, two drivers can run in parallel at 4 Ω.

What to look out for

  • BL 43 Tm, Qts 0.29: strong motor, compact reflex boxes with DSP
  • 5.3" voice coil, 1800 W, 98 dB at 8 Ω
  • Xmax 14 mm, Mms 0.408 kg
  • Le 3.1 mH – low crossover, pure subwoofer use
  • 13.5 kg, mounting depth 250 mm

Frequently asked questions

How does the 21NLW9601 compare with the B&C 21SW152?

The 21SW152 is listed in the database at fs 32 Hz, Qts 0.3 and 200 l Vas, the 21NLW9601 at fs 37 Hz, Qts 0.29 and 175 l. Both are drivers for compact, equalised high-output subwoofers; the 18Sound has the slightly smaller Vas.

Why is the bass reflex guideline so small?

Because the classic alignments derived from Qts 0.29 and Vas 175 l produce a small volume with high tuning. Practical subwoofers with this driver are larger and tuned lower, then equalised with DSP – the strong motor allows that.

Which amplifier suits it?

An amplifier around 1800 W at 8 Ω with a limiter; two drivers in parallel at 4 Ω is common practice. A high-pass below the tuning frequency protects against over-excursion at 14 mm Xmax.

At 42.audio you get the 18SOUND 21NLW9601 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 fs37 Hz
Total Q Qts0.29
Electrical Q Qes0.31
Mechanical Q Qms5.5
Equivalent volume Vas175.0 l
Moving mass Mms408.0 g
Cone area Sd1,662 cm²
Linear excursion Xmax14 mm
Force factor BL43 Tm
DC resistance Re5.9 Ω
Voice coil inductance Le3.1 mH

Enclosure suggestion

The EBP of 119 suggests a bass-reflex enclosure. EBP = fs / Qes = 37 / 0.31

Sealed (Qtc 0.707)

Enclosure volume Vb
35.4 l
System resonance Fc
90 Hz
Cut-off frequency F3
90 Hz

Bass reflex (QB3 after Small)recommended

Enclosure volume Vb
58.9 l
Tuning frequency Fb
52 Hz
Cut-off frequency F3
60 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 NLW
Magnet Neo
Impedance (Ω) 8
Power handling (W) 1800
Sensitivity (dB) 98
Frequency from (Hz) 25
Frequency to (Hz) 2000
Abmessungen & Korb
Diameter 21
Voice coil (inch) 5.3
Mounting depth (mm) 250
Weight (kg) 13.5
Thiele-Small-Parameter
Re (Ω) 5.9
Le (mH) 3.1
Fs (Hz) 37
Qms 5.5
Qes 0.31
Qts 0.29
Vas (l) 175
Xmax (mm) 14
BL (Tm) 43
Mms (kg) 0.408
Sd (m²) 0.1662