Subwoofers — Polk Audio PSW 108

The PSW 108 is a powered subwoofer from Polk Audio that now sits in the archive section of the brand's catalogue. Polk aimed it at systems that have no bass unit at all, describing it as a way to fill in the bottom end of a home theater. Its owner's manual lists a black oak finish and shows both a line-level and a speaker-level hookup, so the unit can join either a surround receiver or a plain two-channel amplifier.

Key specs that matter

Driver complement is a single 10-inch (25.4 cm) round Dynamic Balance woofer, driven by Class D electronics rated at 50 W RMS and 100 W dynamic. Polk gives an overall frequency response of 35 Hz to 200 Hz, with -3 dB limits at 40 Hz and 160 Hz. The built-in low-pass filter adjusts between 80 Hz and 160 Hz, and nominal impedance is listed as 8 ohms. The box stands 36.51 cm tall, 35.56 cm wide and 40.96 cm deep and weighs 11.79 kg, or 13.61 kg in its carton. The cabinet is not magnetically shielded.

Engineering and use context

The enclosure is vented through a flared port set into the front panel, and the woofer was optimised with Klippel measurement tools. The power switch has an auto position - the circuit wakes the subwoofer when it detects a programme signal and turns it off again after a few minutes of silence, while the on position avoids the brief start-up delay. Three controls sit on the rear panel. Volume sets the level, the Low Pass control decides how high the sub plays, and a two-position phase switch helps match its output timing to the main speakers from the listening seat. According to the manual, owners using smaller main speakers will usually end up near the upper part of the Low Pass range, and those with larger speakers near the lower part. Polk grants five years of cover on the woofer and cabinet and three years on the electronics, for the original purchaser only.

Pairing

With a receiver that offers a Sub Out, the manual sets all speakers to small, switches the subwoofer to on or present, sets the receiver crossover to 120 Hz and turns the sub's own Low Pass control fully clockwise. Either the left or right RCA input can be used, or both via a Y-split cable. For stereo or Dolby Pro Logic receivers without a Sub Out, the front speaker outputs go to the sub's speaker-level inputs through 16 gauge or thicker cable, the front speakers connect to its speaker-level outputs, and the fronts are set to large with the subwoofer setting off. Only one of these methods should be used at a time.

Alternatives

The Polk PSW 10 is the sibling model in the same PSW family, built around a 10-inch driver in a cabinet of matching size with gold-plated spring terminals.