21-inch LF driver · 21DS series · 116 mm voice coil · 1,700 W
B&C 21DS115 4Ω
30–500 Hz
£497.00
SteadyBlue Aran · 1 in stock · All 9 offers
- Fs
- 32Hz
- Xmax
- 15mm
- SPL
- 97dB
- Pe
- 1700W
- BL
- 28.6T·m
- Vd
- 2430cm³
- Qts
- 0.21
- Vas
- 219L
Published graphs
B&C 21DS115 is a 21-inch 4 ohm LF driver rated at 1700 W RMS. The validated T/S data includes Fs 32 Hz, Qts 0.21, Vas 219 L, Xmax 15 mm, sensitivity 97.2 dB, plus 2430 cm³ Vd and 145 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 £490.39.
The published T/S values agree with each other
Thiele/Small
- Fs
- 32Hz
- Qts
- 0.21
- Qes
- 0.22
- Qms
- 9.8
- Vas
- 219L
- Re
- 2.1Ω
- Le
- 2.30mH
Motor and cone
- BL
- 28.6T·m
- Sd
- 1620cm²
- Mms
- 409g
- Xmax
- 15mm
- Vd †
- 2430cm³
- Voice coil
- 116mm
- Flux density
- 0.80T
Power and response
- Sensitivity †
- 97.2dB
- Manufacturer sensitivity
- 100dB
- Power
- 1700W
- Nominal power
- 1700W
- Impedance
- 4Ω
- Min. impedance
- 3.1Ω
- Range
- 30–500Hz
- EBP †
- 145 · Leans vented
Size and mounting
- Diameter
- 547mm
- Cutout
- 508mm
- Bolt circle
- 527mm
- Depth
- 255mm
- Weight
- 14.7kg
Sensitivity shows 97.2 dB, calculated from the T/S values. B&C publishes 100.0 dB, 2.8 dB apart.
† Calculated by bits from the published values
What this validation status means
Everything else B&C lists
LF
- BL
- 28.6T·m
- Fs
- 32Hz
- Le
- 2.30mH
- Re
- 2.1Ω
- Sd
- 1620cm²
- Mms
- 409g
- Qes
- 0.22
- Qms
- 9.8
- Qts
- 0.21
- SPL
- 97.2dB
- Vas
- 219L
- Xmax
- 15mm
- Power
- 1700W
- Impedance
- 4Ω
- Flux density
- 0.80T
- Sensitivity
- 100dB
- Low limit
- 30Hz
- Nominal power
- 1700W
- Calculated sensitivity †
- 97.2dB
- High limit
- 500Hz
- Manufacturer sensitivity
- 100dB
- Min. impedance
- 3.1Ω
- Voice coil
- 116mm
- Weight
- 14.7kg
- Diameter
- 547mm
- Depth
- 255mm
- Cutout
- 508mm
- Bolt circle
- 527mm
- Bl
- 28.6 Tm
- Fs
- 32 Hz
- Le
- 2.3 mH
- Re
- 2.1 Ω
- Sd
- 1620 cm² (251.1 in²)
- Ebp
- 145 Hz
- Mms
- 409 g
- Qes
- 0.22
- Qms
- 9.8
- Qts
- 0.21
- Vas
- 219 dm³ (7.73 ft³)
- Η0
- 3.3 %
- Cone
- RCK21DS1154
- Xmax
- 15 mm
- Xvar
- 11.5 mm
- Depth
- 255 mm (10.04 in)
- Spider
- Double Silicone
- Cone shape
- Radial
- Net weight
- 14.7 kg (32.41 lb)
- Pole design
- T-Pole
- Sensitivity
- 100 dB
- Flux density
- 0.8 T
- Shipping box
- 570x570x320 mm (22.44x22.44x12.60 in)
- Winding depth
- 36 mm (1.42 in)
- Shipping units
- 1 pcs
- Surround shape
- Triple Roll
- Former material
- Glass Fibre
- Frequency range
- 30 Hz - 500 Hz
- Magnet material
- Neodymium Inside Slug
- Shipping weight
- 17 kg (37.48 lb)
- Nominal diameter
- 530 mm (21 in)
- Overall diameter
- 547 mm (21.54 in)
- Winding material
- Aluminium
- Minimum impedance
- 3.1 Ω
- Nominal impedance
- 4 Ω
- Magnetic gap depth
- 14 mm (0.55 in)
- Recommended tuning
- 40 Hz
- Voice coil diameter
- 116 mm (4.5 in)
- Bolt circle diameter
- 527 mm (20.7 in)
- Recommended enclosure
- 130 dm³ (4.59 ft³)
- Woofer cone treatment
- TWP Waterproof Both Sides
- Baffle cutout diameter
- 508 mm (20 in)
- Nominal power handling
- 1700 W
- Continuous power handling
- 3400 W
- Flange and gasket thickness
- 13 mm (0.51 in)
- Air volume occupied by driver
- 15 dm³ (0.53 ft³)
02
Designs
Cabinets for the 21DS115: two designs and a suggested box from B&C, and plans builders have published.
All 21DS115 designsHow we find designsB&C’s designs
From the maker, with plans to download
B&C design
S21IB
Extended LF Reflex Isobaric Subwoofer
- Drivers
- 2 × 18DS115, 8 Ω1 × 21DS115, 8 Ω
Designed with the 8 Ω version.
B&C’s suggested box
From B&C’s 21DS115 page
- Net volume
- 130L
- Tuning
- 40Hz
B&C 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 21DS115. Clear differences are green when better and red when worse.
This driver21DS115
Best price
£490.39
Fs
32 Hz
Qts
0.21
Vas
219 L
BL
28.6 T·m
Xmax
15 mm
Sensitivity
97.2 dB
Power
1700 W
SB AudienceNERO-21SW1100D
£343.60 · 30% less, betterFs32 Hz –
Qts0.34 +62%, worse
Vas312.6 L +43%, worse
BL30 T·m +5%
Xmax12.2 mm −19%, worse
Sensitivity96.7 dB −0.5
SB AudienceROSSO-21SW800
£423.44 · 14% less, betterFs38 Hz +19%, worse
Qts0.76 +262%, worse
Vas224.4 L –
BL24.1 T·m −16%, worse
Xmax11.4 mm −24%, worse
Sensitivity93.9 dB −3.3, worse
CelestionTSQ2145
£445.00 · 9% less, betterFs30 Hz −6%
Qts0.34 +64%, worse
Vas253.8 L +16%, worse
BL33.8 T·m +18%, better
Xmax15 mm –
Sensitivity94.8 dB −2.4, worse
RCFLF21N451
£475.00 · 3% lessFs30 Hz −6%
Qts0.26 +24%, worse
Vas375 L +71%, worse
BL34.5 T·m +21%, better
Xmax13 mm −13%, worse
Sensitivity97.8 dB +0.6
LavoceSAN214.50
£481.92 · 2% lessFs33 Hz +3%
Qts0.28 +33%, worse
Vas218.3 L –
BL39.6 T·m +39%, better
Xmax15.4 mm –
Sensitivity96.4 dB −0.8
B&C21SW115
£481.92 · 2% lessFs33 Hz +3%
Qts0.36 +71%, worse
Vas278 L +27%, worse
BL24.8 T·m −13%, worse
Xmax14 mm −7%
Sensitivity96.3 dB −0.9
Eighteen Sound21NLW4100
£512.25 · 4% moreFs34 Hz +6%
Qts0.40 +90%, worse
Vas219 L –
BL22.8 T·m −20%, worse
Xmax15.2 mm –
Sensitivity95.1 dB −2.1, worse
Eighteen Sound21LW1400
£550.00 · 12% more, worseFs28 Hz −13%, better
Qts0.24 +14%, worse
Vas385 L +76%, worse
BL33.5 T·m +17%, better
Xmax9.5 mm −37%, worse
Sensitivity97.5 dB –
B&C21SW152
£585.00 · 19% more, worseFs32 Hz –
Qts0.30 +43%, worse
Vas200 L −9%
BL32.5 T·m +14%, better
Xmax15 mm –
Sensitivity95.3 dB −1.9
Eighteen Sound21NLW9001
£594.65 · 21% more, worseFs31 Hz −3%
Qts0.34 +62%, worse
Vas272 L +24%, worse
BL23.8 T·m −17%, worse
Xmax14 mm −7%
Sensitivity95.4 dB −1.8
Eighteen Sound21NTLW5000
£595.00 · 21% more, worseFs30 Hz −6%
Qts0.32 +52%, worse
Vas300 L +37%, worse
BL25 T·m −13%, worse
Xmax17.5 mm +17%, better
Sensitivity95.9 dB −1.3
Eighteen Sound21NLW9601
£600.74 · 23% more, worseFs41 Hz +28%, worse
Qts0.32 +52%, worse
Vas123 L −44%, better
BL32.7 T·m +14%, better
Xmax14 mm −7%
Sensitivity96.1 dB −1.1
EminenceNSW6021-6
£800.00 · 63% more, worseFs29 Hz −9%
Qts0.31 +48%, worse
Vas224.6 L –
BL33.8 T·m +18%, better
Xmax21 mm +40%, better
Sensitivity94.5 dB −2.7, worse
No photo
Precision DevicesPD.2160-1N
£811.00 · 65% more, worseFs35 Hz +9%
Qts0.30 +43%, worse
Vas177 L −19%, better
BL43 T·m +50%, better
Xmax16 mm +7%
Sensitivity95.9 dB −1.3
B&C21IPAL
£863.28 · 76% more, worseFs37 Hz +16%, worse
Qts0.21 –
Vas155 L −29%, better
BL19.1 T·m −33%, worse
Xmax22 mm +47%, better
Sensitivity97.6 dB –
FaitalPRO21XL3000
£888.46 · 81% more, worseFs32 Hz –
Qts0.22 +5%
Vas223.5 L –
BL35.5 T·m +24%, better
Xmax17.7 mm +18%, better
Sensitivity97.3 dB –
EminenceNSW6021-124
£927.53 · 89% more, worseFs31 Hz −4%
Qts0.32 +52%, worse
Vas224.6 L –
BL30.5 T·m +7%
Xmax21 mm +40%, better
Sensitivity95 dB −2.2, worse
Eighteen Sound21ID
No current priceFs38 Hz +19%, worse
Qts0.23 +10%
Vas143 L −35%, better
BL25.2 T·m −12%, worse
Xmax14 mm −7%
Sensitivity97.2 dB –
No current price
Fs33 Hz +3%
Qts0.36 +71%, worse
Vas241 L +10%, worse
BL30 T·m +5%
Xmax14 mm −7%
Sensitivity95.7 dB −1.5
No photo
Precision DevicesPD.2155-1N
No current priceFs33 Hz +3%
Qts0.36 +71%, worse
Vas241 L +10%, worse
BL30 T·m +5%
Xmax14 mm −7%
Sensitivity95.7 dB −1.5
BishopSoundBWN21/4
No current priceFs29 Hz −9%
Qts0.42 +99%, worse
Vas244.2 L +12%, worse
BL32.6 T·m +14%, better
Xmax15 mm –
Sensitivity93.2 dB −4, worse
BishopSoundBWN21/8
No current priceFs29 Hz −9%
Qts0.42 +99%, worse
Vas244.2 L +12%, worse
BL32.6 T·m +14%, better
Xmax15 mm –
Sensitivity93.2 dB −4, worse
No current price
Fs35 Hz +9%
Qts0.34 +61%, worse
Vas266 L +21%, worse
BL31.3 T·m +9%
Xmax14 mm −7%
Sensitivity97.1 dB –
No photo
Precision DevicesPD.2155-1F
No current priceFs35 Hz +9%
Qts0.34 +61%, worse
Vas266 L +21%, worse
BL31.3 T·m +9%
Xmax14 mm −7%
Sensitivity97.1 dB –
Eighteen Sound21NLW5300
No current priceFs31 Hz −3%
Qts0.32 +52%, worse
Vas325 L +48%, worse
BL31 T·m +8%
Xmax15.3 mm –
Sensitivity96.6 dB −0.6
Eighteen Sound21LW2600
No current priceFs27 Hz −16%, better
Qts0.29 +38%, worse
Vas332 L +52%, worse
BL24.9 T·m −13%, worse
Xmax14.6 mm –
Sensitivity95.6 dB −1.6
Eighteen Sound21NLW9601C
No current priceFs38 Hz +19%, worse
Qts0.29 +38%, worse
Vas140 L −36%, better
BL33.2 T·m +16%, better
Xmax14 mm −7%
Sensitivity96 dB −1.2
CelestionTSQ2160
No current priceFs30 Hz −6%
Qts0.26 +22%, worse
Vas234.8 L +7%
BL43.1 T·m +51%, better
Xmax18.8 mm +25%, better
Sensitivity95.8 dB −1.4
RCFLF21X451
No current priceFs28 Hz −13%, better
Qts0.37 +76%, worse
Vas385 L +76%, worse
BL30.5 T·m +7%
Xmax14 mm −7%
Sensitivity95.4 dB −1.8
Dayton AudioPSS545HE-4
No current priceFs29 Hz −10%
Qts0.27 +29%, worse
Vas212.2 L −3%
BL35.5 T·m +24%, better
Xmax21 mm +40%, better
Sensitivity94.6 dB −2.6, worse
Tune the match
Choose the published values that matter to your design. Size stays matched to this driver.
Qts
Qes
VasL
Xmaxmm
BLTm
- Parts Express5.0 out of 52 ratings · Checked 9 Oct 2026Read reviews on Parts Express
Each shop collects its own ratings. Bits shows them as published and doesn't verify them.
| Shop | Price | Against the lowest | Stock | Link |
|---|---|---|---|---|
Blue Aran | £497.00, the lowest price | 1 in stock | Visit shop at Blue Aran | |
JP Leisure Not currently listed · Last seen 7 Aug 2026 | £504.73 | 1.6% above the lowest price | In stock | Visit shop at JP Leisure |
JP Leisure | £504.73 | 1.6% above the lowest price | In stock | Visit shop at JP Leisure |
Audio Video Parts Import VAT and duty may apply | £431.75 | Special order | Visit shop at Audio Video Parts | |
Parts Express Import VAT and duty may apply | £646.70 | 30% above the lowest price | Back order | Visit shop at Parts Express |
Best price over time
Tracked since 1 Apr
Recent changes
- 23 JunJP Leisure£500.70 → £504.73Up 0.8% from £500.70