What is the recommended ported (bass reflex) box volume for Beyma LOUDSPEAKER 4"FR40 8 OH?

According to electroacoustic alignment calculations, Beyma LOUDSPEAKER 4"FR40 8 OH performs optimally 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 11.2 liters with a Qtc of 0.984, the system exhibits an F3 of 87.7 Hz with tight transient response and natural roll-off.

What port dimensions should be used for Beyma LOUDSPEAKER 4"FR40 8 OH to avoid port chuffing?

To keep vent air velocity below turbulence limits at rated power, a minimum port diameter of 5.0 cm with a length of 40.2 cm is recommended.

Reflex Optimized

Beyma LOUDSPEAKER 4"FR40 8 OH

Complete Thiele/Small parameters, optimized ported (bass reflex) and sealed enclosure designs, F3/F6/F10 cutoffs, and vent turbulence analysis calculated by Load Forge.

Estimated Retail

30.95 EUR

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⚠️ 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)

OPTIMIZED EXTENSION

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

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Recommended Sealed (Acoustic Suspension)

MAX TRANSIENT DAMPING

Net Box Volume (Vb)	11.2 Liters
System Q (Qtc)	0.984 (Butterworth Q=0.707)
System Resonance (Fc)	100.5 Hz
F3 (-3 dB Cutoff)	87.7 Hz
F6 / F10 Extension	71.9 Hz / 57.4 Hz
Air Spring Linearity	High (Zero port compression)

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Verified 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	Manufacturer Official Datasheet

Shareable Acoustic Card for Forums & Social Media

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Beyma LOUDSPEAKER 4"FR40 8 OH Enclosure Card

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[url=https://loadforge.io/drivers/beyma-loudspeaker-4infr40-8-oh][img]https://loadforge.io/api/v1/card/beyma-loudspeaker-4infr40-8-oh.svg[/img][/url]
[b]Beyma LOUDSPEAKER 4"FR40 8 OH[/b] — 2.2L Bass Reflex tuned to 78.2Hz (F3: 118.5Hz). Designed with [url=https://loadforge.io]Load Forge[/url].

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