The core of this work has been on driver design. All the Image models share long-excursion, very high-output woofers resulting in compact designs with output capabilities claimed to be as high as much larger systems. A highly accurate, one-inch titanium dome tweeter with ferrofluid and a very efficient neodymium magnet structure, borrowed from the Synchrony series, is said to extend output at the frequency extremes.
The SubSeries 1 is designed to offer significant output down to the deep bass range. PSB has created a driver and cabinet combination with a -3 db point of 36 Hz, which is actually pretty low if your room will support it. The SubSeries 1 provides level, low pass filter cutoff and phase controls. It can be powered by a line level, LFE or high-level (speaker) connection.
A non-trivial point is that PSB’s instruction manual for the SubSeries 1 is really well done. It is easy to read and, importantly, offers many good suggestions for placement of the sub to get good results. This is critical because bass is very dependent on room dimensions and subwoofer location within the room.
For this test, I used our small test room, which is 16 x 12 x 9 feet. The Image B4s were stand mounted and placed well out into the room using positions initially suggested by the RPG room analysis software included in The Absolute Sound Golden Ear Club System Setup and Evaluation Kit. I used the NAD 3020BEE integrated amp, with Audioquest speaker cables. Sources were the Esoteric DV-60 SACD and the Musical Fidelity A5 CD players, which were connected via Nordost Blue Heaven interconnects.