Beyma LOUDSPEAKER 4"FR40 8 OH
Best box: 2.2 L bass reflex tuned to 78.2 Hz · F3 118.5 Hz
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Comparable 4.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Beyma LOUDSPEAKER 4"FR40 8 OH 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: 3.0 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) | 2.2 Liters |
| Tuning Frequency (Fb) | 78.2 Hz |
| F3 (-3 dB Cutoff) | 118.5 Hz |
| F6 / F10 Extension | 100.6 Hz / 79.2 Hz |
| Port Inner Diameter | Ø 5.0 cm |
| Port Physical Length | 40.2 cm |
| First Pipe Resonance | 428.0 Hz |
| Estimated MOL @ F3 | 103.0 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.88 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.245; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 2.8 Liters |
| System Q (Qtc) | 1.245 (above Butterworth: Qtc cannot fall below Qts (0.88)) |
| System Resonance (Fc) | 130.1 Hz |
| F3 (-3 dB Cutoff) | 108.4 Hz |
| F6 / F10 Extension | 91.6 Hz / 74.8 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 92.0 Hz |
| Total Q (Qts) | 0.88 |
| Electrical Q (Qes) | 0.954 |
| Mechanical Q (Qms) | 11.3 |
| Equivalent Volume (Vas) | 2.8 Liters |
| Diaphragm Area (Sd) | 55.0 cm² |
| DC Resistance (Re) | 6.4 Ω |
| Efficiency Bandwidth Product (EBP) | 96.4 |
| Linear Excursion (Xmax) | 3.0 mm |
| Thermal Power (Pe) | 40.0 W |
| Nominal Diameter | 4.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Beyma LOUDSPEAKER 4"FR40 8 OH?
Load Forge's calculated alignment puts Beyma LOUDSPEAKER 4"FR40 8 OH in a 2.2 liter vented enclosure tuned to 78.2 Hz, reaching an F3 cutoff of approximately 118.5 Hz.
Can Beyma LOUDSPEAKER 4"FR40 8 OH be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 2.8 liters with a Qtc of 1.245 (above Butterworth: Qtc cannot fall below Qts (0.88)), the system exhibits an F3 of 108.4 Hz.
What port dimensions should be used for Beyma LOUDSPEAKER 4"FR40 8 OH to avoid port chuffing?
Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 40.2 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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