B&C Speakers 8PE21
Best box: 3.4 L bass reflex tuned to 97.7 Hz · F3 167.7 Hz
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Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the B&C Speakers 8PE21 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
- The textbook alignment (1.7 L at 162.9 Hz) would need a 19.3 cm port; the recommendation is retuned to 3.4 L at 97.7 Hz so the port can be built.
- Limited linear excursion (Xmax: 2.5 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 3.4 Liters |
| Tuning Frequency (Fb) | 97.7 Hz |
| F3 (-3 dB Cutoff) | 167.7 Hz |
| F6 / F10 Extension | 107.6 Hz / 87.1 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 14.6 cm |
| First Pipe Resonance | 1181.0 Hz |
| Estimated MOL @ F3 | 114.7 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 1.0 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 309.8 Hz |
| F3 (-3 dB Cutoff) | 250.8 Hz |
| F6 / F10 Extension | 199.1 Hz / 153.0 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 87.0 Hz |
| Total Q (Qts) | 0.19 |
| Electrical Q (Qes) | 0.2 |
| Mechanical Q (Qms) | 3.8 |
| Equivalent Volume (Vas) | 13.0 Liters |
| Diaphragm Area (Sd) | 220.0 cm² |
| DC Resistance (Re) | 5.6 Ω |
| Efficiency Bandwidth Product (EBP) | 435.0 |
| Linear Excursion (Xmax) | 2.5 mm |
| Thermal Power (Pe) | 200.0 W |
| Nominal Diameter | 8.0" |
| 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 8PE21?
Load Forge's calculated alignment puts B&C Speakers 8PE21 in a 3.4 liter vented enclosure tuned to 97.7 Hz, reaching an F3 cutoff of approximately 167.7 Hz.
Can B&C Speakers 8PE21 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 1.0 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 250.8 Hz.
What port dimensions should be used for B&C Speakers 8PE21 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 14.6 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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