MTX Audio T812S-22
Best box: 59.4 L sealed · Fc 45.0 Hz · F3 38.1 Hz
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Comparable 13.5" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the MTX Audio T812S-22 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 142.2 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) | 47.5 Liters |
| Tuning Frequency (Fb) | 27.0 Hz |
| F3 (-3 dB Cutoff) | 38.8 Hz |
| F6 / F10 Extension | 32.0 Hz / 24.5 Hz |
| Port Inner Diameter | Ø 15.0 cm |
| Port Physical Length | 142.2 cm |
| First Pipe Resonance | 121.0 Hz |
| Estimated MOL @ F3 | 114.5 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.7 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.99; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 59.4 Liters |
| System Q (Qtc) | 0.99 (above Butterworth) |
| System Resonance (Fc) | 45.0 Hz |
| F3 (-3 dB Cutoff) | 38.1 Hz |
| F6 / F10 Extension | 31.3 Hz / 25.0 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 31.8 Hz |
| Total Q (Qts) | 0.7 |
| Electrical Q (Qes) | 0.764 |
| Mechanical Q (Qms) | 8.32 |
| Equivalent Volume (Vas) | 59.4 Liters |
| Diaphragm Area (Sd) | 702.0 cm² |
| DC Resistance (Re) | 3.1 Ω |
| Efficiency Bandwidth Product (EBP) | 41.6 |
| Linear Excursion (Xmax) | 20.0 mm |
| Thermal Power (Pe) | 750.0 W |
| Nominal Diameter | 13.5" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for MTX Audio T812S-22?
A simple ported box is not recommended for MTX Audio T812S-22: the textbook alignment (47.5 liters tuned to 27.0 Hz) needs a 142.2 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 MTX Audio T812S-22 be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 59.4 liters with a Qtc of 0.99 (above Butterworth), the system exhibits an F3 of 38.1 Hz.
What port dimensions should be used for MTX Audio T812S-22 to avoid port chuffing?
A straight 15.0 cm port would need 142.2 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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