GRS 69AS-4
Best box: 12.5 L bass reflex tuned to 61.2 Hz · F3 96.8 Hz
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Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the GRS 69AS-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
- Limited linear excursion (Xmax: 2.6 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) | 12.5 Liters |
| Tuning Frequency (Fb) | 61.2 Hz |
| F3 (-3 dB Cutoff) | 96.8 Hz |
| F6 / F10 Extension | 86.6 Hz / 73.1 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 9.0 cm |
| First Pipe Resonance | 1912.0 Hz |
| Estimated MOL @ F3 | 109.4 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.53 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 2.164; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 15.6 Liters |
| System Q (Qtc) | 2.164 (above Butterworth: Qtc cannot fall below Qts (1.53)) |
| System Resonance (Fc) | 101.8 Hz |
| F3 (-3 dB Cutoff) | 83.3 Hz |
| F6 / F10 Extension | 74.2 Hz / 63.7 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 72.0 Hz |
| Total Q (Qts) | 1.53 |
| Electrical Q (Qes) | 2.095 |
| Mechanical Q (Qms) | 5.67 |
| Equivalent Volume (Vas) | 15.6 Liters |
| Diaphragm Area (Sd) | 202.0 cm² |
| DC Resistance (Re) | 3.7 Ω |
| Efficiency Bandwidth Product (EBP) | 34.4 |
| Linear Excursion (Xmax) | 2.6 mm |
| Thermal Power (Pe) | 60.0 W |
| Nominal Diameter | 8.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for GRS 69AS-4?
Load Forge's calculated alignment puts GRS 69AS-4 in a 12.5 liter vented enclosure tuned to 61.2 Hz, reaching an F3 cutoff of approximately 96.8 Hz.
Can GRS 69AS-4 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 15.6 liters with a Qtc of 2.164 (above Butterworth: Qtc cannot fall below Qts (1.53)), the system exhibits an F3 of 83.3 Hz.
What port dimensions should be used for GRS 69AS-4 to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 9.0 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
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