PSB LOUDSPEAKERS SUBSERIES 300 SUBWOOFER

Not only a truly great subwoofer but one that will work as well with large floorstanders as it will with bookshelf models.

PSB Speakers was founded by Canadian loudspeaker designer Paul Barton and his wife Sue (Paul and Sue Barton… get it?). Their company became so successful that the privately owned Canadian Lenbrook Group (which also owns NAD and Bluesound) made them an offer for it that they couldn’t refuse… particularly since they wanted Paul to stay on as head designer.

Barton is renowned as a ‘sound first, looks second’ designer, one who won’t sacrifice sound quality for fashion, but his philosophy isn’t exactly evidenced by the SubSeries 300 because, although it’s not particularly small, I think it’s spectacularly good-looking for a subwoofer. Most subwoofers look ‘boxy’ to me, but I think the PSB SubSeries 300 is rather elegant… at least for a subwoofer! It was amongst the first-ever PSB subwoofers to be powered by a Class-D amplifier (not surprisingly, this amplifier is manufactured by NAD). The SubSeries 300 was also one of the first of PSB’s low-cost subwoofers to include Barton’s ‘Smart Bass’ limiter, which had previously been used only in PSB’s flagship models. The SubSeries 300 has been around for a few years now, so PSB is obviously happy with both its performance and its sales figures. As I intimated in the introduction, I really liked the SubSeries 300’s looks, because I rather like the ‘form factor’ of it: rather than being squat and square like most subwoofers, it’s kind of lean and tall, with the height given a big boost by those four tall feet underneath that elevate the bottom of the cabinet a full 90mm above your floor. As you’d expect of Paul Barton, there’s a reason for this elevation, and it’s that the SubSeries 300 is a bass reflex design, and the port exits through the base of the subwoofer. Having such tall feet means you’ll always get the full contribution from the port’s output, even if you’ve placed the subwoofer on a deep pile carpet and positioned it in a corner, where the output from two sides would be blocked off by the adjacent walls.

The front-firing bass driver is sizable: PSB rates it at 300mm in diameter. I couldn’t confirm this, because the way PSB mounts the driver prevented me from measuring the overall diameter, but the moving diameter (that is, from one edge of the rubber surround to the opposite edge) measured 275mm, so 300mm seemed about right. But as regular readers of Australian Hi-Fi Magazine would know, the important measurement is the Thiele/Small diameter, because it’s this that determines the effective cone area, or radiating area (known technically as the Sd). This measured 260mm, giving an Sd of 531cm². The cone is made from polypropylene and has a very large central dustcap. Beneath the dustcap is a 50mm diameter voice coil, driven in part by a magnet that tips the scales at 1.4kg. (If you’re into comparisons, this driver is the same size as the one used in the PSB Series 500 subwoofer, and has the same sized voice coil. The cone of the driver in the 500, however, is made from woven fibreglass, and the magnet is much larger, at 2.27kg.)

The driver is driven by a Class-D amplifier rated with a continuous power output capability of 300-watts, although into what impedance is not stated. It’s from this 300-watt rating that the SubSeries 300 gains its model number. As you can see from the photograph of the SubSeries 300, PSB has positioned the rotary volume and crossover frequency