Subwoofers — MAGNAT Alpha RS 12

The Alpha RS 12 is an active subwoofer from MAGNAT that places a 30 cm driver in a front-firing bass reflex cabinet with its own Class D amplifier. Among the two Alpha RS versions it is the bigger one, above the Alpha RS 8, and sits in a subwoofer range that also includes the Omega CS 12, the Base 8 and the Cinema Ultra SUB 300-THX.

Key specs that matter

The 12 inch long-throw woofer has a rigid coated paper cone and a ventilated voice coil. Its amplifier is rated at 120 W continuous and 240 W peak, so the 240 W figure is the peak value. MAGNAT gives a frequency range of 20 Hz to 200 Hz, with a low-pass adjustable across 50 Hz to 150 Hz. Phase switches between 0 and 180 degrees. Inputs are stereo RCA at line level and stereo speaker terminals at high level. The cabinet measures 36 cm wide, 46.5 cm high and 46 cm deep, and the unit weighs 14.1 kg.

Engineering and use context

MAGNAT uses an active equalisation stage it calls the LPC circuit, which shapes the frequency response so the driver and port reach down to the lowest bass. Two Airflex reflex ports vent the MDF enclosure, and their contoured shape is meant to cut air turbulence and port noise when the cone moves a long way. The switching amplifier produces very little heat, which matters inside a wooden enclosure with no fan. Large feet carry rubber inserts that absorb vibration and decouple the cabinet from the floor, and a removable front grille covers the driver. The auto standby function can be switched on or off and draws less than 0.5 W while waiting for a signal. A universal power supply accepts 110 V to 240 V at 50 or 60 Hz, so the same unit works on mains in different regions. The standard finish is black ash, and a mocha version has also been listed for the MDF housing.

Pairing

With an AV receiver, the sub output of the receiver feeds the line-level RCA socket, and the internal low-pass can be turned to its maximum when the receiver already filters the signal. The high-level terminals let the Alpha RS 12 join a stereo amplifier or an older receiver without a subwoofer pre-out, taking its signal from the same speaker outputs that feed the main pair. In a stereo system the adjustable filter lets the owner match the handover point to where the main speakers roll off, with the phase switch used to line up the two.

Alternatives

The MAGNAT Alpha RS 8 is the compact sibling, using a 20 cm woofer and an 80 W continuous amplifier in a 26 x 35 x 37 cm cabinet weighing 8.5 kg.