Passive Radiator / Folded Port

SB Acoustics SB26STC-C000-4 / Fabric

Best box: 0.008 L sealed · Fc 1060.7 Hz · F3 883.4 Hz

Predicted SPL response of the SB Acoustics SB26STC-C000-4 / Fabric in the recommended 0.008 L sealed box versus the alternative — open it in the simulator Open and tweak this box live ↗

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⚠️ Engineering Notice for Builders

  • Straight vent would be 1.1 cm long: not physically buildable as a simple tube. Use a passive radiator, a folded slot port or model a 3D folded duct in Load Forge Studio.
  • Limited linear excursion (Xmax: 0.6 mm); set a high-pass subsonic filter at 25–30 Hz when driven with high power.

Textbook Bass Reflex — not recommended

PORT NOT BUILDABLE
Net Box Volume (Vb) 1.5 Liters
Tuning Frequency (Fb) 637.5 Hz
F3 (-3 dB Cutoff) 606.4 Hz
F6 / F10 Extension 585.6 Hz / 557.9 Hz
Port Inner Diameter Ø 20.0 cm
Port Physical Length No real tube length at this tuning — use a passive radiator
First Pipe Resonance 14990.0 Hz
Estimated MOL @ F3 94.5 dB SPL
⚠️ Port feasibility: a straight tube would need 1.1 cm and cannot fit in a practical cabinet, and no nearby retune stays buildable without a bass hump. Prefer the sealed alignment, a passive radiator, or a 3D folded duct in Load Forge Studio.
Simulate This Reflex Box in App →

Sealed (Acoustic Suspension) — compromise

SUITS INFINITE / OPEN BAFFLE

With Qts 1.12 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.584; for a flat response this driver is better used on an infinite (IB) or open baffle.

Net Box Volume (Vb) 0.008 Liters
System Q (Qtc) 1.584 (above Butterworth: Qtc cannot fall below Qts (1.12))
System Resonance (Fc) 1060.7 Hz
F3 (-3 dB Cutoff) 883.4 Hz
F6 / F10 Extension 766.7 Hz / 641.0 Hz
Air Spring Linearity High (Zero port compression)
Simulate This Sealed Box in App →

Thiele/Small Parameters

Resonance (Fs) 750.0 Hz
Total Q (Qts) 1.12
Electrical Q (Qes) 1.787
Mechanical Q (Qms) 3.0
Equivalent Volume (Vas) 0.0 Liters
Diaphragm Area (Sd) 6.2 cm²
DC Resistance (Re) 3.2 Ω
Efficiency Bandwidth Product (EBP) 419.6
Linear Excursion (Xmax) 0.6 mm
Thermal Power (Pe) 120.0 W
Nominal Diameter 1.0"
Catalog Source Load Forge catalog (manufacturer datasheets and retailer listings)

Frequently Asked Questions

What is the recommended ported (bass reflex) box volume for SB Acoustics SB26STC-C000-4 / Fabric?

A simple ported box is not recommended for SB Acoustics SB26STC-C000-4 / Fabric: the textbook alignment (1.5 liters tuned to 637.5 Hz) needs a 1.1 cm port, and no nearby retune stays buildable without a bass hump. A sealed box, a passive radiator or a folded duct is the practical choice.

Can SB Acoustics SB26STC-C000-4 / Fabric be used in a sealed box?

Yes. In a sealed (acoustic suspension) enclosure of 0.008 liters with a Qtc of 1.584 (above Butterworth: Qtc cannot fall below Qts (1.12)), the system exhibits an F3 of 883.4 Hz.

What port dimensions should be used for SB Acoustics SB26STC-C000-4 / Fabric to avoid port chuffing?

A straight 20.0 cm port would need 1.1 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.

Shareable Acoustic Card for Forums & Social Media

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SB Acoustics SB26STC-C000-4 / Fabric Enclosure Card
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