REDCATT 125FPM
Best box: 25.0 L bass reflex tuned to 75.9 Hz · F3 76.6 Hz
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Comparable 12.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the REDCATT 125FPM 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
- Limited linear excursion (Xmax: 2.55 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) | 25.0 Liters |
| Tuning Frequency (Fb) | 75.9 Hz |
| F3 (-3 dB Cutoff) | 76.6 Hz |
| F6 / F10 Extension | 67.6 Hz / 59.1 Hz |
| Port Inner Diameter | Ø 7.5 cm |
| Port Physical Length | 3.8 cm |
| First Pipe Resonance | 4488.0 Hz |
| Estimated MOL @ F3 | 121.3 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 11.4 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 135.9 Hz |
| F3 (-3 dB Cutoff) | 133.2 Hz |
| F6 / F10 Extension | 101.2 Hz / 76.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 63.0 Hz |
| Total Q (Qts) | 0.31 |
| Electrical Q (Qes) | 0.324 |
| Mechanical Q (Qms) | 7.13 |
| Equivalent Volume (Vas) | 48.1 Liters |
| Diaphragm Area (Sd) | 531.0 cm² |
| DC Resistance (Re) | 4.5 Ω |
| Efficiency Bandwidth Product (EBP) | 194.4 |
| Linear Excursion (Xmax) | 2.5 mm |
| Thermal Power (Pe) | 600.0 W |
| Nominal Diameter | 12.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for REDCATT 125FPM?
Load Forge's calculated alignment puts REDCATT 125FPM in a 25.0 liter vented enclosure tuned to 75.9 Hz, reaching an F3 cutoff of approximately 76.6 Hz.
Can REDCATT 125FPM be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 11.4 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 133.2 Hz.
What port dimensions should be used for REDCATT 125FPM to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 7.5 cm with a length of 3.8 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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