Subwoofers — Yamaha NS-SW050

The NS-SW050 is a compact powered subwoofer from Yamaha, shipped in a matte black cabinet with gently curved sides and built around a 20 cm cone woofer. One owner's manual covers it together with the bigger NS-SW100, and it is meant for home theatre setups where a receiver or an amplifier with a line output supplies the bass signal.

Key specs that matter

Rated amplifier output is 50 W at 100 Hz into 5 ohm with 10% THD, and Yamaha also quotes a dynamic power figure of 100 W into 5 ohm. Frequency response runs from 28 Hz to 200 Hz. Power consumption is 40 W, and US and Canadian units run on 120 V at 60 Hz, while Asian and general models have a voltage selector for 110 to 120 V or 220 to 240 V at 50 or 60 Hz. The cabinet measures 291 x 292 x 341 mm and weighs 8.5 kg.

Engineering and use context

Bass loading follows Advanced Yamaha Active Servo Technology II with discrete amplifier circuitry. Yamaha introduced the original YST in 1988, linking the amplifier directly to the driver and using negative impedance drive together with the resonance between cabinet volume and port, an approach the company calls an air woofer, so that bass can come from a smaller box than a standard reflex design would need. The second-generation circuit combines negative-impedance drive with constant-current drive to keep control stable as the driver impedance varies with frequency. The port is a Twisted Flare Port whose mouth widens in a gentle twist at each end, which diffuses the vortex that forms at the port edge and suppresses the turbulence noise that ordinary reflex ports produce near their tuning frequency. Because the driver is not shielded, Yamaha warns against placing magnetically sensitive items such as CRT televisions or credit cards on or beside the cabinet.

Pairing

The controls are limited to a volume knob, a power switch with a green indicator and a single INPUT (FROM AMPLIFIER) socket, so any crossover setting has to come from the amplifier or receiver feeding it. Yamaha specifies connection with an RCA cable to the subwoofer output of an amplifier or AV receiver, or to a line output such as PRE OUT when no dedicated subwoofer jack is present. The volume should start at minimum and be raised gradually until the level matches the front speakers.

Alternatives

The Yamaha NS-SW100 uses a 25 cm woofer with the same amplifier rating, reaching 25 Hz to 180 Hz in a 351 x 352 x 408 mm cabinet weighing 12 kg.