GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4
Best box: 5.9 L bass reflex tuned to 45.9 Hz · F3 47.8 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4 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 (5.9 L at 41.7 Hz) would need a 53.8 cm port; the recommendation is retuned to 5.9 L at 45.9 Hz so the port can be built.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 5.9 Liters |
| Tuning Frequency (Fb) | 45.9 Hz |
| F3 (-3 dB Cutoff) | 47.8 Hz |
| F6 / F10 Extension | 39.5 Hz / 34.5 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 43.8 cm |
| First Pipe Resonance | 393.0 Hz |
| Estimated MOL @ F3 | 95.0 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 6.1 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 73.6 Hz |
| F3 (-3 dB Cutoff) | 73.6 Hz |
| F6 / F10 Extension | 56.0 Hz / 42.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 58.0 Hz |
| Total Q (Qts) | 0.55 |
| Electrical Q (Qes) | 0.671 |
| Mechanical Q (Qms) | 3.05 |
| Equivalent Volume (Vas) | 4.0 Liters |
| Diaphragm Area (Sd) | 54.0 cm² |
| DC Resistance (Re) | 3.7 Ω |
| Efficiency Bandwidth Product (EBP) | 86.4 |
| Linear Excursion (Xmax) | 4.0 mm |
| Thermal Power (Pe) | 30.0 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 GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4?
Load Forge's calculated alignment puts GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4 in a 5.9 liter vented enclosure tuned to 45.9 Hz, reaching an F3 cutoff of approximately 47.8 Hz.
Can GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 6.1 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 73.6 Hz.
What port dimensions should be used for GRS 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 43.8 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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Not sure if 4" Woofer Surface Mount Poly Cone 4 Ohm 4SMP-4 fits your physical space?
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