Eighteen Sound design
Manifolded 2x21” band-pass subwoofer
- Drivers
- 21NLW9000or 21LW1400or 21NLW9600
21-inch LF driver · 1,000 W
Eighteen Sound 21LW1400 8Ω
8 Ω · 24–2000 Hz
£622.00
0.5%Thomann · In stock · All 4 offers
- Fs
- 28Hz
- Xmax
- 9.5mm
- SPL
- 98dB
- Pe
- 1000W
- BL
- 33.5T·m
- Vd
- 1577cm³
- Qts
- 0.24
- Vas
- 385L
Manufacturer response and impedance data, with source and trace details below. The left and right arrow keys read every shown curve at a frequency, a twelfth of an octave at a time, or an octave with Shift. Escape clears the reading.
Curve provenanceInspect 1 trace
These plotted lines are Bits digitizations of manufacturer evidence, not new measurements. How provenance works
- Trace datasheet-response-trace-poc/v1
frequency response
Frequency response
240 plotted pointsMedium confidence2,113 selected pixels of 2,386
Published graphs
Eighteen Sound 21LW1400 is a 21-inch 8 ohm LF driver rated at 1000 W RMS. The validated T/S data includes Fs 28 Hz, Qts 0.24, Vas 385 L, Xmax 9.5 mm, sensitivity 97.5 dB, plus 1577 cm³ Vd and 117 EBP. bits tracks UK, EU and US shop prices, price movement, datasheet links, simulator import data, and similar drivers, with a current best price of £543.74.
The published T/S values agree with each other
Thiele/Small
- Fs
- 28Hz
- Qts
- 0.24
- Qes
- 0.24
- Qms
- 9.3
- Vas
- 385L
- Re
- 5Ω
- Le
- 2.85mH
Motor and cone
- BL
- 33.5T·m
- Sd
- 1660cm²
- Mms
- 296g
- Xmax
- 9.5mm
- Vd †
- 1577cm³
Power and response
- Sensitivity †
- 97.5dB
- Manufacturer sensitivity
- 99dB
- Power
- 1000W
- Nominal power
- 1000W
- Impedance
- 8Ω
- Range
- 24–2000Hz
- EBP †
- 117 · Leans vented
Size and mounting
- Diameter
- 545mm
- Cutout
- 492mm
- Bolt circle
- 520mm
- Depth
- 259mm
- Weight
- 17kg
Other published values
- Power Program
- 1600
Sensitivity shows 97.5 dB, calculated from the T/S values. Eighteen Sound publishes 99.0 dB, 1.5 dB apart.
† Calculated by bits from the published values
What this validation status means
Everything else Eighteen Sound lists
LF · Primary · 21″
- BL
- 33.5T·m
- Fs
- 28Hz
- Le
- 2.85mH
- Re
- 5Ω
- Sd
- 1660cm²
- Mms
- 296g
- Qes
- 0.24
- Qms
- 9.3
- Qts
- 0.24
- SPL
- 97.5dB
- Vas
- 385L
- Xmax
- 9.5mm
- Power
- 1000W
- Impedance
- 8Ω
- Sensitivity
- 99dB
- Low limit
- 24Hz
- Nominal power
- 1000W
- Power Program
- 1600
- Calculated sensitivity †
- 97.5dB
- High limit
- 2000Hz
- Manufacturer sensitivity
- 99dB
- Weight
- 17kg
- Diameter
- 545mm
- Depth
- 259mm
- Cutout
- 492mm
- Bolt circle
- 520mm
02
Designs
Cabinets for the 21LW1400: two designs and a suggested box from Eighteen Sound, and flatpack kits of the Manifolded 2x21” band-pass subwoofer.
All 21LW1400 designsHow we find designsEighteen Sound’s designs
From the maker, with plans to download
Cut in the UK
Eighteen Sound design
1x21” band-pass subwoofer
- Drivers
- 21LW1400or 21NLW4100or 21LW2600
Eighteen Sound’s suggested box
From Eighteen Sound’s 21LW1400 page
- Net volume
- 300L
- Tuning
- 30Hz
Eighteen Sound gives the volume and tuning; the port is sized for the driver when you open it.
Modelling the box in 00 Simulator…
03
Compare
Same-size drivers, compared with the 21LW1400. Clear differences are green when better and red when worse.
This driver21LW1400
Best price
£543.74
Fs
28 Hz
Qts
0.24
Vas
385 L
BL
33.5 T·m
Xmax
9.5 mm
Sensitivity
97.5 dB
Power
1000 W
Dayton AudioPSS555-8
£194.48 · 64% less, betterFs28 Hz –
Qts0.33 +38%, worse
Vas444 L +15%, worse
BL29.7 T·m −11%, worse
Xmax11 mm +16%, better
Sensitivity96.4 dB −1.1
SB AudienceNERO-21SW1100D
£343.60 · 37% less, betterFs32 Hz +14%, worse
Qts0.34 +42%, worse
Vas312.6 L −19%, better
BL30 T·m −10%, worse
Xmax12.2 mm +28%, better
Sensitivity96.7 dB −0.8
Eighteen Sound21LW2600
£425.60 · 22% less, betterFs27 Hz −4%
Qts0.33 +38%, worse
Vas333 L −14%, better
BL32.5 T·m –
Xmax14.6 mm +54%, better
Sensitivity94.9 dB −2.6, worse
CelestionTSQ2145
£445.00 · 18% less, betterFs30 Hz +7%
Qts0.34 +43%, worse
Vas253.8 L −34%, better
BL33.8 T·m –
Xmax15 mm +58%, better
Sensitivity94.8 dB −2.7, worse
RCFLF21X451
£448.61 · 17% less, betterFs28 Hz –
Qts0.37 +54%, worse
Vas385 L –
BL30.5 T·m −9%
Xmax14 mm +47%, better
Sensitivity95.4 dB −2.1, worse
Dayton AudioHTS545HE-4
£448.82 · 17% less, betterFs26 Hz −6%
Qts0.28 +17%, worse
Vas179 L −54%, better
BL38.2 T·m +14%, better
Xmax21 mm +121%, better
Sensitivity92.5 dB −5, worse
B&C21SW115
£458.85 · 16% less, betterFs30 Hz +7%
Qts0.37 +54%, worse
Vas318 L −17%, better
BL30.1 T·m −10%, worse
Xmax14 mm +47%, better
Sensitivity95.5 dB −2, worse
RCFLF21N451
£475.00 · 13% less, betterFs30 Hz +7%
Qts0.26 +8%
Vas375 L –
BL34.5 T·m –
Xmax13 mm +37%, better
Sensitivity97.8 dB –
Beyma21LEX1600ND
£475.00 · 13% less, betterFs30 Hz +7%
Qts0.29 +21%, worse
Vas305 L −21%, better
BL36.6 T·m +9%
Xmax14 mm +47%, better
Sensitivity96.4 dB −1.1
B&C21DS115
£475.59 · 13% less, betterFs34 Hz +21%, worse
Qts0.27 +13%, worse
Vas204 L −47%, better
BL39.3 T·m +17%, better
Xmax16.5 mm +74%, better
Sensitivity96.6 dB −0.9
Beyma21QLEX1600FE
£493.97 · 9% less, betterFs30 Hz +7%
Qts0.28 +17%, worse
Vas309 L −20%, better
BL36.4 T·m +9%
Xmax13 mm +37%, better
Sensitivity96.5 dB −1
Eighteen Sound21NLW9001
£549.89 · 1% moreFs32 Hz +14%, worse
Qts0.31 +29%, worse
Vas244 L −37%, better
BL37 T·m +10%, better
Xmax14 mm +47%, better
Sensitivity95.7 dB −1.8
No photo
Precision DevicesPD.2155-1N
£555.00 · 2% moreFs33 Hz +18%, worse
Qts0.36 +50%, worse
Vas241 L −37%, better
BL30 T·m −10%, worse
Xmax14 mm +47%, better
Sensitivity95.7 dB −1.8
Eighteen Sound21NTLW5000
£595.00 · 9% more, worseFs31 Hz +11%, worse
Qts0.36 +50%, worse
Vas270 L −30%, better
BL32 T·m −4%
Xmax17.5 mm +84%, better
Sensitivity95.3 dB −2.2, worse
Eighteen Sound21NLW4000
£608.33 · 12% more, worseFs29 Hz +4%
Qts0.37 +54%, worse
Vas305 L −21%, better
BL30 T·m −10%, worse
Xmax15 mm +58%, better
Sensitivity94.9 dB −2.6, worse
B&C21IPAL
£863.28 · 59% more, worseFs37 Hz +32%, worse
Qts0.21 −13%, better
Vas155 L −60%, better
BL19.1 T·m −43%, worse
Xmax22 mm +132%, better
Sensitivity97.6 dB –
FaitalPRO21XL3000
£899.00 · 65% more, worseFs30 Hz +7%
Qts0.25 +4%
Vas284.6 L −26%, better
BL43 T·m +28%, better
Xmax17.7 mm +86%, better
Sensitivity96.9 dB −0.6
EminenceNSW6021-124
£916.36 · 69% more, worseFs31 Hz +10%
Qts0.32 +33%, worse
Vas224.6 L −42%, better
BL30.5 T·m −9%
Xmax21 mm +121%, better
Sensitivity95 dB −2.5, worse
B&C21SW150
No current priceFs29 Hz +4%
Qts0.26 +8%
Vas254 L −34%, better
BL32.6 T·m –
Xmax15 mm +58%, better
Sensitivity95.6 dB −1.9
CelestionNTR21-5010JD
No current priceFs32 Hz +15%, worse
Qts0.32 +33%, worse
Vas276.7 L −28%, better
BL33.9 T·m –
Xmax9 mm −5%
Sensitivity96.4 dB −1.1
Dayton AudioPSS545HE-4
No current priceFs29 Hz –
Qts0.27 +13%, worse
Vas212.2 L −45%, better
BL35.5 T·m +6%
Xmax21 mm +121%, better
Sensitivity94.6 dB −2.9, worse
Eighteen Sound21ID
No current priceFs38 Hz +36%, worse
Qts0.23 −4%
Vas143 L −63%, better
BL25.2 T·m −25%, worse
Xmax14 mm +47%, better
Sensitivity97.2 dB –
P.AudioSD21-125XB
No current priceFs35 Hz +25%, worse
Qts0.38 +58%, worse
Vas345.6 L −10%, better
BL30.4 T·m −9%
Xmax11.3 mm +18%, better
Sensitivity97.7 dB –
Eighteen Sound21NLW5300
No current priceFs31 Hz +11%, worse
Qts0.32 +33%, worse
Vas325 L −16%, better
BL31 T·m −7%
Xmax15.3 mm +61%, better
Sensitivity96.6 dB −0.9
Sica21 S 4 PL
No current priceFs35 Hz +24%, worse
Qts0.30 +25%, worse
Vas255 L −34%, better
BL36.1 T·m +8%
Xmax5.2 mm −45%, worse
Sensitivity97.4 dB –
Eighteen Sound21NLW9601C
No current priceFs38 Hz +36%, worse
Qts0.29 +21%, worse
Vas140 L −64%, better
BL33.2 T·m –
Xmax14 mm +47%, better
Sensitivity96 dB −1.5
Eighteen Sound21LW2500
No current priceFs29 Hz +4%
Qts0.37 +54%, worse
Vas305 L −21%, better
BL30 T·m −10%, worse
Xmax14 mm +47%, better
Sensitivity94.9 dB −2.6, worse
No current price
Fs35 Hz +25%, worse
Qts0.34 +41%, worse
Vas266 L −31%, better
BL31.3 T·m −7%
Xmax14 mm +47%, better
Sensitivity97.1 dB –
No photo
Precision DevicesPD.2155-1F
No current priceFs35 Hz +25%, worse
Qts0.34 +41%, worse
Vas266 L −31%, better
BL31.3 T·m −7%
Xmax14 mm +47%, better
Sensitivity97.1 dB –
No current price
Fs33 Hz +18%, worse
Qts0.36 +50%, worse
Vas241 L −37%, better
BL30 T·m −10%, worse
Xmax14 mm +47%, better
Sensitivity95.7 dB −1.8
Tune the match
Choose the published values that matter to your design. Size stays matched to this driver.
Qts
Qes
VasL
Xmaxmm
BLTm
- Thomann4.8 out of 511 ratings · Checked 24 Oct 2026Read reviews on Thomann
Each shop collects its own ratings. Bits shows them as published and doesn't verify them.
| Shop | Price | Against the lowest | Stock | Link |
|---|---|---|---|---|
Thomann | £622.00, the lowest price | In stock | Visit shop at Thomann | |
Lean Business | £426.63 | Out of stock | Visit shop at Lean Business | |
Lean Audio | £480.00 | Back order | Visit shop at Lean Audio |
Best price over time
Tracked since 1 Apr
Recent changes
- 23 OctThomann£625.00 → £622.00Down 0.5% from £625.00
- 15 OctThomann£629.00 → £625.00Down 0.6% from £629.00
- 7 OctThomann£635.00 → £629.00Down 0.9% from £635.00