B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030
Best box: 59.4 L bass reflex tuned to 47.3 Hz · F3 56.0 Hz
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Comparable 21.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030 does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
⚠️ Engineering Notice for Builders
- Port length (81.0 cm) exceeds a straight internal run; use an elbow bend, slotted vent or 3D folded duct to fit the enclosure.
Recommended Bass Reflex (Vented)
PORT NEEDS ELBOW / 3D| Net Box Volume (Vb) | 59.4 Liters |
| Tuning Frequency (Fb) | 47.3 Hz |
| F3 (-3 dB Cutoff) | 56.0 Hz |
| F6 / F10 Extension | 47.2 Hz / 40.1 Hz |
| Port Inner Diameter | Ø 23.5 cm |
| Port Physical Length | 81.0 cm |
| First Pipe Resonance | 212.0 Hz |
| Estimated MOL @ F3 | 128.4 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 31.8 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 88.5 Hz |
| F3 (-3 dB Cutoff) | 89.5 Hz |
| F6 / F10 Extension | 67.7 Hz / 51.1 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 30.0 Hz |
| Total Q (Qts) | 0.23 |
| Electrical Q (Qes) | 0.235 |
| Mechanical Q (Qms) | 10.0 |
| Equivalent Volume (Vas) | 269.0 Liters |
| Diaphragm Area (Sd) | 1680.0 cm² |
| DC Resistance (Re) | 5.1 Ω |
| Efficiency Bandwidth Product (EBP) | 127.4 |
| Linear Excursion (Xmax) | 15.0 mm |
| Thermal Power (Pe) | 3400.0 W |
| Nominal Diameter | 21.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030?
Load Forge's calculated alignment puts B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030 in a 59.4 liter vented enclosure tuned to 47.3 Hz, reaching an F3 cutoff of approximately 56.0 Hz.
Can B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 31.8 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 89.5 Hz.
What port dimensions should be used for B&C Speakers B&C 21DS115 DS Series 21" High Energy Neodymium Subwoofer 8 Ohm294-6030 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 23.5 cm with a length of 81.0 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
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