Focal 3 KMAltoparlante medio da 80 mm
Best box: 1.5 L bass reflex tuned to 144.5 Hz · F3 133.6 Hz
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Comparable 3.1" Drivers
Drivers with similar piston area, resonance and Qts — useful alternatives when the Focal 3 KMAltoparlante medio da 80 mm 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
- Xmax is not published, so the port size is an empirical estimate (area ≥ 12 in² per ft³ of net volume, minimum by driver size), not a displacement calculation. Check air velocity in Load Forge Studio.
Recommended Bass Reflex (Vented)
PORT BUILDABLE| Net Box Volume (Vb) | 1.5 Liters |
| Tuning Frequency (Fb) | 144.5 Hz |
| F3 (-3 dB Cutoff) | 133.6 Hz |
| F6 / F10 Extension | 124.8 Hz / 114.4 Hz |
| Port Inner Diameter ESTIMATED | Ø 5.0 cm |
| Port Physical Length | 15.2 cm |
| First Pipe Resonance | 1130.0 Hz |
| Estimated MOL @ F3 | 106.2 dB SPL |
Sealed (Acoustic Suspension) — compromise
SUITS INFINITE / OPEN BAFFLEWith Qts 0.65 a Butterworth (Qtc 0.707) box would be many times Vas. A box equal to Vas reaches Qtc 0.919; for a flat response this driver is better used on an infinite (IB) or open baffle.
| Net Box Volume (Vb) | 0.3 Liters |
| System Q (Qtc) | 0.919 (above Butterworth) |
| System Resonance (Fc) | 240.4 Hz |
| F3 (-3 dB Cutoff) | 203.4 Hz |
| F6 / F10 Extension | 160.5 Hz / 124.5 Hz |
| Air Spring Linearity | High (Zero port compression) |
Thiele/Small Parameters
| Resonance (Fs) | 170.0 Hz |
| Total Q (Qts) | 0.65 |
| Electrical Q (Qes) | 0.717 |
| Mechanical Q (Qms) | 7.0 |
| Equivalent Volume (Vas) | 0.3 Liters |
| Diaphragm Area (Sd) | 30.0 cm² |
| DC Resistance (Re) | 3.0 Ω |
| Efficiency Bandwidth Product (EBP) | 237.3 |
| Linear Excursion (Xmax) | N/A mm |
| Thermal Power (Pe) | 60.0 W |
| Nominal Diameter | 3.1" |
| Catalog Source | Load Forge catalog (manufacturer datasheets and retailer listings) |
Frequently Asked Questions
What is the recommended ported (bass reflex) box volume for Focal 3 KMAltoparlante medio da 80 mm?
Load Forge's calculated alignment puts Focal 3 KMAltoparlante medio da 80 mm in a 1.5 liter vented enclosure tuned to 144.5 Hz, reaching an F3 cutoff of approximately 133.6 Hz.
Can Focal 3 KMAltoparlante medio da 80 mm be used in a sealed box?
Yes. In a sealed (acoustic suspension) enclosure of 0.3 liters with a Qtc of 0.919 (above Butterworth), the system exhibits an F3 of 203.4 Hz.
What port dimensions should be used for Focal 3 KMAltoparlante medio da 80 mm to avoid port chuffing?
Xmax is not published for Focal 3 KMAltoparlante medio da 80 mm, so the port is an empirical estimate: a 5.0 cm diameter with a length of 15.2 cm (area at least 12 in² per ft³ of net volume). Check the air velocity at your power level in Load Forge Studio.
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