Vented Specialist

B & C BAC4MCX36AB

Best box: 1.5 L bass reflex tuned to 127.5 Hz · F3 140.5 Hz

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Comparable 4.0" Drivers

Drivers with similar piston area, resonance and Qts — useful alternatives when the B & C BAC4MCX36AB does not fit your target box volume or tuning. Each entry links to its full enclosure design and Thiele/Small parameters.

B&C Speakers

4MCX36

4.0" · Fs 150.0 Hz · Qts 0.91 · Vas 0.8 L

HELIX

Ci3 M100FM-S3

4.0" · Fs 146.0 Hz · Qts 0.83 · Vas 1.1 L

SICA

4 D 0.8 CS

4.0" · Fs 140.0 Hz · Qts 0.92 · Vas 1.2 L

Peerless

NE123W-04

4.0" · Fs 156.4 Hz · Qts 0.67 · Vas 0.7 L

Ciare

CZ100 (4Ω)

4.0" · Fs 160.0 Hz · Qts 1.05 · Vas 1.2 L

Ciare

HM100

4.0" · Fs 160.0 Hz · Qts 0.7 · Vas 1.1 L

Compare them in the same box → Browse all 4.0" drivers → All B & C drivers →

Recommended Bass Reflex (Vented)

PORT BUILDABLE

Net Box Volume (Vb)	1.5 Liters
Tuning Frequency (Fb)	127.5 Hz
F3 (-3 dB Cutoff)	140.5 Hz
F6 / F10 Extension	111.7 Hz / 95.1 Hz
Port Inner Diameter	Ø 5.0 cm
Port Physical Length	20.6 cm
First Pipe Resonance	837.0 Hz
Estimated MOL @ F3	107.5 dB SPL

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Sealed (Acoustic Suspension) — compromise

SUITS INFINITE / OPEN BAFFLE

With Qts 0.91 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.287; for a flat response this driver is better used on an infinite (IB) or open baffle.

Net Box Volume (Vb)	0.8 Liters
System Q (Qtc)	1.287 (above Butterworth: Qtc cannot fall below Qts (0.91))
System Resonance (Fc)	212.1 Hz
F3 (-3 dB Cutoff)	175.1 Hz
F6 / F10 Extension	148.9 Hz / 122.2 Hz
Air Spring Linearity	High (Zero port compression)

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Thiele/Small Parameters

Resonance (Fs)	150.0 Hz
Total Q (Qts)	0.91
Electrical Q (Qes)	1.187
Mechanical Q (Qms)	3.9

Equivalent Volume (Vas)	0.8 Liters
Diaphragm Area (Sd)	56.0 cm²
DC Resistance (Re)	5.6 Ω
Efficiency Bandwidth Product (EBP)	126.4

Linear Excursion (Xmax)	4.0 mm
Thermal Power (Pe)	100.0 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 B & C BAC4MCX36AB?

Load Forge's calculated alignment puts B & C BAC4MCX36AB in a 1.5 liter vented enclosure tuned to 127.5 Hz, reaching an F3 cutoff of approximately 140.5 Hz.

Can B & C BAC4MCX36AB be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 0.8 liters with a Qtc of 1.287 (above Butterworth: Qtc cannot fall below Qts (0.91)), the system exhibits an F3 of 175.1 Hz.

What port dimensions should be used for B & C BAC4MCX36AB to avoid port chuffing?

Sized from cone displacement (Sd × Xmax), a minimum port diameter of 5.0 cm with a length of 20.6 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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