Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm
Best box: 5.7 L bass reflex tuned to 91.7 Hz · F3 113.7 Hz
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Comparable 6.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 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
- Limited linear excursion (Xmax: 2.5 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) | 5.7 Liters |
| Tuning Frequency (Fb) | 91.7 Hz |
| F3 (-3 dB Cutoff) | 113.7 Hz |
| F6 / F10 Extension | 83.0 Hz / 69.9 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 8.7 cm |
| First Pipe Resonance | 1976.0 Hz |
| Estimated MOL @ F3 | 112.7 dB SPL |
Recommended Sealed (Acoustic Suspension)
MAX TRANSIENT DAMPING| Net Box Volume (Vb) | 8.7 Liters |
| System Q (Qtc) | 0.707 (Butterworth) |
| System Resonance (Fc) | 150.9 Hz |
| F3 (-3 dB Cutoff) | 152.4 Hz |
| F6 / F10 Extension | 115.4 Hz / 87.3 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 131.0 Hz |
| Total Q (Qts) | 0.59 |
| Electrical Q (Qes) | 0.638 |
| Mechanical Q (Qms) | 7.8 |
| Equivalent Volume (Vas) | 3.8 Liters |
| Diaphragm Area (Sd) | 132.0 cm² |
| DC Resistance (Re) | 3.6 Ω |
| Efficiency Bandwidth Product (EBP) | 205.2 |
| Linear Excursion (Xmax) | 2.5 mm |
| Thermal Power (Pe) | 500.0 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 Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm?
Load Forge's calculated alignment puts Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm in a 5.7 liter vented enclosure tuned to 91.7 Hz, reaching an F3 cutoff of approximately 113.7 Hz.
Can Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 8.7 liters with a Qtc of 0.707 (Butterworth), the system exhibits an F3 of 152.4 Hz.
What port dimensions should be used for Down4Sound D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 8.7 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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Not sure if D4S-NMR658 Neo Mid Range Speaker - 6.5 Inch, 110W RMS, 8 Ohm fits your physical space?
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