GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm
Best box: 7.6 L sealed · Fc 67.9 Hz · F3 56.1 Hz
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Comparable 6.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm 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
- Port length (54.4 cm) exceeds a straight internal run; use an elbow bend, slotted vent or 3D folded duct to fit the enclosure.
Textbook Bass Reflex — not recommended (3.7 dB bass hump)
PORT NEEDS ELBOW / 3D| Net Box Volume (Vb) | 6.1 Liters |
| Tuning Frequency (Fb) | 40.8 Hz |
| F3 (-3 dB Cutoff) | 63.0 Hz |
| F6 / F10 Extension | 54.7 Hz / 44.2 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 54.4 cm |
| First Pipe Resonance | 316.0 Hz |
| Estimated MOL @ F3 | 97.6 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.08 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.527; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 7.6 Liters |
| System Q (Qtc) | 1.527 (above Butterworth: Qtc cannot fall below Qts (1.08)) |
| System Resonance (Fc) | 67.9 Hz |
| F3 (-3 dB Cutoff) | 56.1 Hz |
| F6 / F10 Extension | 48.5 Hz / 40.5 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 48.0 Hz |
| Total Q (Qts) | 1.08 |
| Electrical Q (Qes) | 1.359 |
| Mechanical Q (Qms) | 5.26 |
| Equivalent Volume (Vas) | 7.6 Liters |
| Diaphragm Area (Sd) | 131.0 cm² |
| DC Resistance (Re) | 3.7 Ω |
| Efficiency Bandwidth Product (EBP) | 35.3 |
| Linear Excursion (Xmax) | 4.0 mm |
| Thermal Power (Pe) | 30.0 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 GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm?
A simple ported box is not recommended for GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm: the textbook alignment (6.1 liters tuned to 40.8 Hz) needs a 54.4 cm port, and no nearby retune stays buildable without a bass hump. A sealed box, a passive radiator or a folded duct is the practical choice.
Can GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 7.6 liters with a Qtc of 1.527 (above Butterworth: Qtc cannot fall below Qts (1.08)), the system exhibits an F3 of 56.1 Hz.
What port dimensions should be used for GRS 6LPSW-4 6-1/2" Low Profile Subwoofer 4 Ohm to avoid port chuffing?
A straight 5.0 cm port would need 54.4 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
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