REDCATT 81XR
Best box: 3.4 L bass reflex tuned to 90.6 Hz · F3 94.8 Hz
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Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the REDCATT 81XR does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 3.4 Liters |
| Tuning Frequency (Fb) | 90.6 Hz |
| F3 (-3 dB Cutoff) | 94.8 Hz |
| F6 / F10 Extension | 82.7 Hz / 71.7 Hz |
| Port Inner Diameter | Ø 7.5 cm |
| Port Physical Length | 42.1 cm |
| First Pipe Resonance | 409.0 Hz |
| Estimated MOL @ F3 | 112.9 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 1.6 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 168.8 Hz |
| F3 (-3 dB Cutoff) | 162.4 Hz |
| F6 / F10 Extension | 124.0 Hz / 93.7 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 73.0 Hz |
| Total Q (Qts) | 0.3 |
| Electrical Q (Qes) | 0.377 |
| Mechanical Q (Qms) | 1.47 |
| Equivalent Volume (Vas) | 7.2 Liters |
| Diaphragm Area (Sd) | 201.0 cm² |
| DC Resistance (Re) | 5.5 Ω |
| Efficiency Bandwidth Product (EBP) | 193.7 |
| Linear Excursion (Xmax) | 6.3 mm |
| Thermal Power (Pe) | 400.0 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 REDCATT 81XR?
Load Forge's calculated alignment puts REDCATT 81XR in a 3.4 liter vented enclosure tuned to 90.6 Hz, reaching an F3 cutoff of approximately 94.8 Hz.
Can REDCATT 81XR be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 1.6 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 162.4 Hz.
What port dimensions should be used for REDCATT 81XR to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 7.5 cm with a length of 42.1 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
Embed this design card on DIYAudio, AVSForum, Reddit, or Facebook. It shows the calculated F3, MOL (when the power rating is published) and box parameters.
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