Rockford Fosgate T1S1-12
Best box: 32.4 L sealed · Fc 50.9 Hz · F3 42.4 Hz
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Comparable 12.0" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Rockford Fosgate T1S1-12 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
- Straight vent would be 142.7 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.
Textbook Bass Reflex — not recommended
PORT NOT BUILDABLE| Net Box Volume (Vb) | 25.9 Liters |
| Tuning Frequency (Fb) | 30.6 Hz |
| F3 (-3 dB Cutoff) | 47.6 Hz |
| F6 / F10 Extension | 41.2 Hz / 33.4 Hz |
| Port Inner Diameter | Ø 12.5 cm |
| Port Physical Length | 142.7 cm |
| First Pipe Resonance | 120.0 Hz |
| Estimated MOL @ F3 | 113.7 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 1.06 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 1.499; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 32.4 Liters |
| System Q (Qtc) | 1.499 (above Butterworth: Qtc cannot fall below Qts (1.06)) |
| System Resonance (Fc) | 50.9 Hz |
| F3 (-3 dB Cutoff) | 42.4 Hz |
| F6 / F10 Extension | 36.6 Hz / 30.5 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 36.0 Hz |
| Total Q (Qts) | 1.06 |
| Electrical Q (Qes) | 1.171 |
| Mechanical Q (Qms) | 11.22 |
| Equivalent Volume (Vas) | 32.4 Liters |
| Diaphragm Area (Sd) | 560.0 cm² |
| DC Resistance (Re) | 0.9 Ω |
| Efficiency Bandwidth Product (EBP) | 30.8 |
| Linear Excursion (Xmax) | 15.0 mm |
| Thermal Power (Pe) | 600.0 W |
| Nominal Diameter | 12.0" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Rockford Fosgate T1S1-12?
A simple ported box is not recommended for Rockford Fosgate T1S1-12: the textbook alignment (25.9 liters tuned to 30.6 Hz) needs a 142.7 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 Rockford Fosgate T1S1-12 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 32.4 liters with a Qtc of 1.499 (above Butterworth: Qtc cannot fall below Qts (1.06)), the system exhibits an F3 of 42.4 Hz.
What port dimensions should be used for Rockford Fosgate T1S1-12 to avoid port chuffing?
A straight 12.5 cm port would need 142.7 cm of length, which does not fit a practical cabinet. Use a passive radiator or a folded/3D duct instead of a straight tube.
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