[Ilkka]

The profile of the frequency response is a little bit strange. It tilts down quite heavily above 40 Hz which can be a problem with higher crossover settings and in rooms with lots of low frequency room gain. The sound becomes too bottom-heavy when the frequency response rises too much toward the low end. The built-in PEQ can help a bit, but an external EQ is preferred. The crossover works as promised and is steep enough for regular 2-channel use. The -6 dB point is at 16.5 Hz which is a very respectable performance. The maximum output below 50 Hz is really high for a single 12” subwoofer, but the upper bass output could be a little bit higher. The output starts to compress at the highest sweep level, especially around the tuning frequency. This tells that the subwoofer is somewhat under ported even at its native tuning. Some audible port chuffing was heard at the highest test levels.

The THD profile is really good. THD stays below 1% at low levels and doesn’t go over 10% until below the tuning frequency. The group delay grows pretty steadily towards the low frequencies, ending up crossing the 1 cycle limit at 25 Hz. The spectral decay graph shows around 160 ms of ringing around the tuning frequency; not the best ported subwoofer I’ve seen but not the worst either.

The SVS PB12-Ultra is a good performer. It is also a very good-looking, though rather large, subwoofer. It really shines in clean output in 20-40 Hz range. The frequency response could benefit from some shaping, and also the upper bass output could be a little bit higher.

+ Very high output in 20-40 Hz range
+ Low distortion
+ Very good extension

- Uneven frequency response
- Medium upper bass output
- High power compression around the tuning frequency
- High group delay and slow decay rate at low frequencies