PURIFI PTT4.0M08-NAC-04
Best box: 2.8 L bass reflex tuned to 67.4 Hz · F3 66.0 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the PURIFI PTT4.0M08-NAC-04 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 (2.8 L at 58.6 Hz) would need a 57.6 cm port; the recommendation is retuned to 2.8 L at 67.4 Hz so the port can be built.
- Limited linear excursion (Xmax: 2.9 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) | 2.8 Liters |
| Tuning Frequency (Fb) | 67.4 Hz |
| F3 (-3 dB Cutoff) | 66.0 Hz |
| F6 / F10 Extension | 59.2 Hz / 52.2 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 42.7 cm |
| First Pipe Resonance | 403.0 Hz |
| Estimated MOL @ F3 | 105.5 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 1.3 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 109.2 Hz |
| F3 (-3 dB Cutoff) | 105.3 Hz |
| F6 / F10 Extension | 80.3 Hz / 60.8 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 50.0 Hz |
| Total Q (Qts) | 0.32 |
| Electrical Q (Qes) | 0.343 |
| Mechanical Q (Qms) | 4.7 |
| Equivalent Volume (Vas) | 4.9 Liters |
| Diaphragm Area (Sd) | 57.0 cm² |
| DC Resistance (Re) | 5.6 Ω |
| Efficiency Bandwidth Product (EBP) | 145.6 |
| Linear Excursion (Xmax) | 2.9 mm |
| Thermal Power (Pe) | N/A W |
| Nominal Diameter | 4.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for PURIFI PTT4.0M08-NAC-04?
Load Forge's calculated alignment puts PURIFI PTT4.0M08-NAC-04 in a 2.8 liter vented enclosure tuned to 67.4 Hz, reaching an F3 cutoff of approximately 66.0 Hz.
Can PURIFI PTT4.0M08-NAC-04 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 1.3 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 105.3 Hz.
What port dimensions should be used for PURIFI PTT4.0M08-NAC-04 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 42.7 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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