A compact two-way bass reflex speaker with a Folded Motion tweeter and a 102 mm paper woofer: it goes on a stand, on a shelf or on the wall with the supplied bracket, in stereo or as a front and surround speaker in a home cinema.
4i: tweeter, woofer and reflex port
The 4i is the model in the compact family that reaches lowest with a single woofer: a stated 70 Hz from a cabinet 32 cm tall. The credit goes to the rear reflex port, which MartinLogan calls the Cascading Bass Reflex Port: a long tuning tube doubled back on itself like a trombone slide so that it fits such a small volume. The fold slows and controls the airflow, and bass stays well defined even at high level. The 102 mm woofer has a paper cone, a stamped steel basket and a stiffened dust cap.
Above 2,900 Hz the 26 × 36 mm Folded Motion tweeter takes over, with a 133 × 44 mm diaphragm pleated like a bellows. A diaphragm of this kind has very little mass and shifts air by pinching it between the folds: it needs a much shorter stroke than a 25 mm dome would, with a far larger working area and a controlled 80° dispersion in both planes. The filter is a Vojtko crossover, with air-core and laminated-steel inductors plus polyester film capacitors, tuned by ear in a domestic setting.
The curved cabinet gives two mounting angles with the wall bracket provided, so the speaker can be aimed at the listener whether it is fixed high or low; it can also be installed upside down. Otherwise it stands on a speaker stand or on a shelf near the television. Sensitivity is 90 dB with a 4 ohm impedance, and recommended power goes up to 150 watts per channel. The push terminals, recessed and fitted with cable guides, take banana plugs.
Specifications
- Type: compact two-way speaker, rear bass reflex
- Frequency response: 70-23,000 Hz ±3 dB
- Sensitivity: 90 dB (2.83 V at 1 m)
- Impedance: 4 ohms, suits amplifiers rated for 4, 6 or 8 ohms
- Recommended power: 20 to 150 W per channel
- Dispersion: 80° horizontally, 80° vertically
- Crossover point: 2,900 Hz
- Tweeter: 26 × 36 mm Folded Motion, 133 × 44 mm diaphragm
- Woofer: 102 mm paper, stamped steel basket
- Loading: folded reflex port
- Crossover: Vojtko, air-core and low-resistance steel laminate inductors, thermal and current protection
- Terminals: push-type, banana plugs accepted
- Mounting: stand, shelf or wall with supplied bracket
- Dimensions: 320 × 143 × 145 mm (H × W × D)
- Weight: 2.72 kg
- Supplied: sold singly
