Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm
Best box: 14.6 L bass reflex tuned to 108.6 Hz · F3 115.4 Hz
Open and tweak this box live ↗
Will it fit your requirements?
Check the Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm against your space and targets — instant, no sign-up.
Estimated retail 79.99 USD · Check price & availability ↗
Free, no sign-up to simulate · a free account saves your design
Comparable 8.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 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
- The textbook alignment (7.3 L at 120.7 Hz) would need a 5.4 cm port; the recommendation is retuned to 14.6 L at 108.6 Hz so the port can be built.
- 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) | 14.6 Liters |
| Tuning Frequency (Fb) | 108.6 Hz |
| F3 (-3 dB Cutoff) | 115.4 Hz |
| F6 / F10 Extension | 93.8 Hz / 81.1 Hz |
| Port Inner Diameter | Ø 7.5 cm |
| Port Physical Length | 2.3 cm |
| First Pipe Resonance | 7388.0 Hz |
| Estimated MOL @ F3 | 122.9 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.67 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.948; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 9.1 Liters |
| System Q (Qtc) | 0.948 (above Butterworth) |
| System Resonance (Fc) | 200.8 Hz |
| F3 (-3 dB Cutoff) | 161.3 Hz |
| F6 / F10 Extension | 131.5 Hz / 104.4 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 142.0 Hz |
| Total Q (Qts) | 0.67 |
| Electrical Q (Qes) | 0.725 |
| Mechanical Q (Qms) | 8.8 |
| Equivalent Volume (Vas) | 9.1 Liters |
| Diaphragm Area (Sd) | 220.0 cm² |
| DC Resistance (Re) | 3.6 Ω |
| Efficiency Bandwidth Product (EBP) | 195.8 |
| Linear Excursion (Xmax) | 2.5 mm |
| Thermal Power (Pe) | 500.0 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 Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm?
Load Forge's calculated alignment puts Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm in a 14.6 liter vented enclosure tuned to 108.6 Hz, reaching an F3 cutoff of approximately 115.4 Hz.
Can Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 9.1 liters with a Qtc of 0.948 (above Butterworth), the system exhibits an F3 of 161.3 Hz.
What port dimensions should be used for Down4Sound D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 7.5 cm with a length of 2.3 cm is suggested; check the port air velocity at your drive level in the Load Forge Studio.
Shareable Acoustic Card for Forums & Social Media
Embed this design card on DIYAudio, AVSForum, Reddit, or Facebook. It shows the calculated F3, MOL (when the power rating is published) and box parameters.
Not sure if D4S-NMR804 Neo Mid Range Speaker - 8 Inch, 120W RMS, 4 Ohm fits your physical space?
Don't force a driver into the wrong box. Use Bass Match to calculate which of 8,000+ catalog drivers delivers the highest SPL, lowest F3, and cleanest port air velocity for your exact trunk or room dimensions.
Run Bass Match for Your Space