PSB Century 400i Speaker System Review

The Canadian-made PSB loudspeakers carry the initials of their designer, the company founder, Paul S. Barton, who has earned a solid reputation for the quality of his products. The PSB line, which has grown considerably in the past few years, currently comprises a broad range of speakers at prices ranging from less than $200 a pair to more than $2,000 a pair.

The Model 400i is part of the eight-model Century series of “tuned-port” PSB speakers, falling roughly in the middle of the group’s size and price range. A compact two-way system in an attractive cabinet finished in dark cherry or black ash woodgrain vinyl, it has a removable black cloth grille covering the entire front panel.

Considering its modest dimensions and price, the speaker is surprisingly heavy, weighing about 18-1/2 pounds.

The grille snaps off to reveal the drivers, a 3/4-inch soft-dome tweeter at the top and below it a (nominal) 6-1/2-inch woofer, whose actual radiating diameter is about 5-1/2 inches. The bass vent has a flared opening (2 inches in diameter) at the bottom of the front panel. On the rear of the cabinet is a pair of recessed gold-plated binding posts that accept lugs, wire ends, or single or dual banana plugs.

The Century 400i comes with basic installation and positioning instructions. Its specifications include a frequency response of 55 Hz to 21 kHz ±3 dB, a crossover frequency of 2.5 kHz, a sensitivity of 89 dB (1 watt input at 1 meter), recommended input power of 15 to 125 watts, and a nominal impedance of 6 ohms.

Like most speakers of comparable size, the PSB Century 400i is recommended for stand-mounting, with the tweeters at or near ear level for a seated listener. The optional SP-25 stands shown in the photo are 25 inches high and very heavy. We used our own stands, which put the tweeters about 39 inches from the floor, close to the recommended height.

The averaged room response of the two speakers, which we placed 8 feet apart and 3 feet from the wall behind them, with the left speaker about 12 feet from the microphone, showed a typical variation of +4 dB from 60 Hz to 10 kHz and an additional 4-dB decline from 10 to 20 kHz. The horizontal angular coverage, measured at 1 foot from the tweeter over a ±45-degree angle to the speaker’s forward axis, was very uniform (+2.5 dB) from 60 Hz to 10 kHz, falling off by 15 dB from 10 to 20 kHz. In this measurement, the on-axis response varied only ± 1.5 dB from 70 Hz to 20 kHz.

The quasi-anechoic MLS frequency response was measured from a single speaker at distances of 1, 2, and 3 meters. The response curves were virtually identical at the three distances, with a typical (and very good) variation of +3 dB from 300 Hz to 20 kHz.

System sensitivity measured 91 dB sound-pressure level (SPL) at 1 meter with a 1-watt input, a little higher than the 89-dB rating. The nominal impedance rating is 6 ohms; our measurement showed a minimum of 4.5 ohms at 150 to 200 Hz and a dip to 5 ohms at 40 Hz, with maximum readings of 16 ohms at 75 Hz and 1.8 kHz. In view of its good sensitivity, the PSB 400i should be easy for any amplifier to drive.

None of these measurements deal with the speaker’s bass response, which in a typical home installation is greatly influenced by the room boundaries and furnishings. The manufacturer’s ratings suggest a lower limit of 50 to 55 Hz, which, though unlikely to rattle small objects in the room, represents very creditable performance for a single woofer of the size used in this speaker.

For the bass-response measurement, we normally place the microphone close to the woofer cone to minimize the influence of the surroundings on the response. In addition, the response of a ported system such as this one must also be measured at the port, which is the principal source of the lowest frequencies. We use two identical microphones for this purpose, one located close to the cone and the other at the port. The two response curves are measured simultaneously with a frequency-swept signal from the Audio Precision System One, and after adjustment of their relative amplitudes in accordance with the relative areas of the two sources (cone and port), the curves are plotted automatically on the computer screen.

In this case the results dramatically confirmed the manufacturer’s ratings. The combined bass response was flat within a fraction of a decibel from 100 to 70 Hz, down 3 dB at 50 Hz, and fell off at 12 dB per octave below that frequency. It was down (from maximum) by 6 dB just below 40 Hz. Above 100 Hz, the response sloped off slightly, to -3 dB at about 300 Hz (our measurement limit).

That is indeed creditable performance from a speaker in this size and price class. Not surprisingly, the Century 400i sounded very good with a variety of program material. As our frequency-response measurements suggested, the overall sound was smooth and uncolored, and the stereo pair created a distinct and natural soundstage. In every respect, the PSB 400i sounded like a lot more speaker than its size and price would imply.

Whenever practical, we make informal A/B comparisons with other speakers on hand for review. As it happened, the only speaker system we had available for that purpose costs about ten times as much as the PSB system and weighs about five times as much.

No, David did not conquer Goliath in this rather unbalanced competition. The most striking difference was in the bottom octave of the bass range (one reason why subwoofers are so popular). But in the midrange frequencies and higher, the difference was surprisingly subtle; there were times when it was not at all obvious which speaker pair we were hearing. All in all, the PSB Century 400i provides first-rate sound at a bargain-basement price. An excellent value!

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