Systems List › Paradigm › Signature Sub 2
The Sub 2 response shape is incredibly extended for a sealed system indicating the use of a huge amount of EQ boost to extend the response. This would not be feasible without the massive amplifier power and driver displacement. The response with the crossover defeated fits within a 6dB total window from about 14-230Hz. The low pass filter exhibited good correlation and a text book 24dB octave slope.
The response in the time domain shows no significant energy release issues that would be audible. There is a slight increase in the deep bass where the EQ boost is in place but it never reaches 1 cycle of group delay. Due to the unusual driver layout with 3 opposing sides all radiating equally the Sub 2 required an SPL correction file to be developed from a set of distance measurements in order to give a better approximation of its output capabilities relative to single radiator direct firing subs which may have all of their output aimed at the microphone position.
During the very low bass portion of the long term output compression testing the Sub 2 shut down twice during 115dB sweep attempt. At first there was concern that a fuse had blown or something had been damaged in the amplifier but it was simply a protection circuit which takes a few minutes to reset. The large amount of EQ boost in the 12-18Hz frequency range is the area which caused the protection to trigger. Because of this limitation, testing at higher levels with the long term sweep signals was stopped. The maximum level reached is somewhat misrepresentation as the Sub 2 had a large amount of output still available at higher frequencies.
Looking at only the magnitude of the compression reveals the shape of the EQ boosting used to extend the Sub 2ís response. It is likely to be at least 12dB centered at 14Hz. The PBK automatic EQ correction system is among the best of its type that has been encountered yet and flattened the response in room from an rough 14dB window down to a 9dB window from 18-150Hz.
The short term output testing via CEA-2010 shows the Sub 2 to have significant output levels available across the entire 10-125Hz bandwidth, producing greater than 120dB above 40Hz at 2m outdoor ground plane 110dB at 25Hz and a passing result just shy of 95dB at 10Hz. The output is amplifier limited above 16Hz. If distortion is ignored the Sub 2 is just under 97dB at 10Hz and 100dB at 12.5Hz. Overall distortion is rather low and THD is well below 10% above 35Hz and never breaks 16% above 20Hz even when driven into the limiter. The distortion levels can reach about 30% from 10-16Hz, but considering the output levels involved and the sealed design, this is certainly not unexpected or out of the ordinary. The component makeup of the distortion is primarily the more benign second harmonic above 23Hz and third harmonic dominated below that point.
Measuring the Sub 2 connected to both a 120v and a 240v line revealed that the 240V line results in slightly more headroom with the biggest difference in the deepest bass and slightly lowered distortion. The Sub 2 is perfectly usable on either voltage. All in all, a very capable sub as our measurements suggest.