PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms
Best box: 16.4 L bass reflex tuned to 113.9 Hz · F3 118.7 Hz
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Comparable 6.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms 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 (4.1 L at 126.6 Hz) would need a 11.7 cm port; the recommendation is retuned to 16.4 L at 113.9 Hz so the port can be built.
- Limited linear excursion (Xmax: 3.25 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) | 16.4 Liters |
| Tuning Frequency (Fb) | 113.9 Hz |
| F3 (-3 dB Cutoff) | 118.7 Hz |
| F6 / F10 Extension | 94.1 Hz / 86.1 Hz |
| Port Inner Diameter | Ø 10.0 cm |
| Port Physical Length | 3.9 cm |
| First Pipe Resonance | 4393.0 Hz |
| Estimated MOL @ F3 | 120.7 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.12 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.584; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 5.2 Liters |
| System Q (Qtc) | 1.584 (above Butterworth: Qtc cannot fall below Qts (1.12)) |
| System Resonance (Fc) | 210.7 Hz |
| F3 (-3 dB Cutoff) | 175.4 Hz |
| F6 / F10 Extension | 152.7 Hz / 128.0 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 149.0 Hz |
| Total Q (Qts) | 1.12 |
| Electrical Q (Qes) | 1.2 |
| Mechanical Q (Qms) | 16.8 |
| Equivalent Volume (Vas) | 5.2 Liters |
| Diaphragm Area (Sd) | 216.0 cm² |
| DC Resistance (Re) | 3.3 Ω |
| Efficiency Bandwidth Product (EBP) | 124.2 |
| Linear Excursion (Xmax) | 3.2 mm |
| Thermal Power (Pe) | 250.0 W |
| Nominal Diameter | 6.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms?
Load Forge's calculated alignment puts PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms in a 16.4 liter vented enclosure tuned to 113.9 Hz, reaching an F3 cutoff of approximately 118.7 Hz.
Can PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 5.2 liters with a Qtc of 1.584 (above Butterworth: Qtc cannot fall below Qts (1.12)), the system exhibits an F3 of 175.4 Hz.
What port dimensions should be used for PRV Audio 69MR500-4 BULLET 6" x 9" Midrange Speaker 4 Ohms to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 10.0 cm with a length of 3.9 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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