REDCATT 6NPM
Best box: 2.6 L bass reflex tuned to 113.5 Hz · F3 197.4 Hz
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Comparable 6.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the REDCATT 6NPM 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 (2.1 L at 162.1 Hz) would need a 7.1 cm port; the recommendation is retuned to 2.6 L at 113.5 Hz so the port can be built.
- Limited linear excursion (Xmax: 0.4 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) | 2.6 Liters |
| Tuning Frequency (Fb) | 113.5 Hz |
| F3 (-3 dB Cutoff) | 197.4 Hz |
| F6 / F10 Extension | 118.3 Hz / 94.9 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 14.0 cm |
| First Pipe Resonance | 1229.0 Hz |
| Estimated MOL @ F3 | 101.8 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 0.94 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 291.8 Hz |
| F3 (-3 dB Cutoff) | 287.9 Hz |
| F6 / F10 Extension | 219.7 Hz / 166.5 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 150.0 Hz |
| Total Q (Qts) | 0.35 |
| Electrical Q (Qes) | 0.379 |
| Mechanical Q (Qms) | 4.58 |
| Equivalent Volume (Vas) | 2.9 Liters |
| Diaphragm Area (Sd) | 143.1 cm² |
| DC Resistance (Re) | 6.9 Ω |
| Efficiency Bandwidth Product (EBP) | 395.8 |
| Linear Excursion (Xmax) | 0.4 mm |
| Thermal Power (Pe) | 360.0 W |
| Nominal Diameter | 6.5" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for REDCATT 6NPM?
Load Forge's calculated alignment puts REDCATT 6NPM in a 2.6 liter vented enclosure tuned to 113.5 Hz, reaching an F3 cutoff of approximately 197.4 Hz.
Can REDCATT 6NPM be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.94 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 287.9 Hz.
What port dimensions should be used for REDCATT 6NPM to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 14.0 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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