Lab­o­ra­tory test re­suLts

Australian HIFI - - ON TEST -

Newport Test Labs’ fourth graph (why not make it the first, guys?) tells the story here most clearly, with the lab hav­ing mea­sured the PSB SubSeries 200’s fre­quency re­sponse at a dis­tance of two me­tres from the sub­woofer, us­ing pink noise as a test sig­nal. The cap­tured data was then smoothed to one-third oc­tave via post-pro­cess­ing. The black trace on Graph 4 shows the SubSeries 200’s re­sponse when the cross­over is set to 150Hz (its max­i­mum set­ting) and you can see that it is ex­tremely flat from 35Hz to 125Hz and over­all ex­tends from 24Hz to 180Hz ±3dB. This is an out­stand­ing re­sult.

When the cross­over con­trol is set to its min­i­mum (50Hz) set­ting, the re­sponse is at its most flat across the 25–65Hz re­gion after which it rolls off very smoothly. This re­sponse ap­pears to get a lit­tle ex­tra en­ergy down at 25Hz. In this con­fig­u­ra­tion, the PSB SubSeries 200 re­turned a fre­quency re­sponse of 18Hz–75Hz ±3dB.

The first three graphs re­ally show how PSB’s engi­neers achieved th­ese re­sults. Graph 1 shows the nearfield sine re­sponse of the bass driver (black traces) and the port (green traces) with the cross­over set to max­i­mum (dashed traces) and min­i­mum (solid traces). You can see that the bass driver’s nat­u­ral re­sponse peaks at 80Hz but is get­ting quite a bit of ex­tra as­sis­tance from the bass re­flex port across its op­er­at­ing re­gion. The driver’s min­i­mum out­put is at 29Hz. You can see that this doesn’t quite marry with the max­i­mum out­put of the port, which oc­curs at around 27Hz, and it would ap­pear that this is due to PSB’s engi­neers ‘tweak­ing’ the align­ment to get a lit­tle ex­tra low-bass from this de­sign.

Graph 2 shows the dif­fer­ence be­tween us­ing the PSB SubSeries 200 with the cross­over set to 150Hz, and with the cross­over by­passed (by us­ing the LFE in­put). You can see the out­put is es­sen­tially iden­ti­cal below 125Hz, other than a slight dif­fer­ence in level due to the cross­over cir­cuitry. Above 125Hz you can see the SubSeries 200 rolling off the re­sponse fairly steeply when the cross­over is in cir­cuit, whereas the high-fre­quency re­sponse is slightly more ex­tended—and rolls off a lit­tle less steeply—when the LFE in­put is used.

As I said at the be­gin­ning of this sec­tion, it’s Graph 1 that tells the story here, and it’s an ex­cel­lent story, be­cause the PSB SubSeries 200 is a very well-de­signed sub­woofer that has a flat and ex­tended low-fre­quency re­sponse and whose con­trols will en­able it to be in­te­grated with any main speaker sys­tem you might use, whether it’s a bookshelf/ stand­mount model or a floor­stander.

Steve Hold­ing

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