I had been doing some experimentation with the subwoofer’s electrical polarity and obtaining results that didn’t seem to make sense.  Reversing the polarity was giving better results.  So I decided to investigate the impact of the Onkyo TX-NR545 calibration.

The green curve is the baseline.  Notice how nice and flat the bass is from 40 – 80 Hz.  This is the result of inserting the SVS AS-EQ1 into the subwoofer audio loop. This unit employs Audyssey auto-correction algorithms in the bass region.  I’ve always been impressed with the AS-EQ1 – some of the best subwoofer $$$ I ever spent.

The blue curve is with the Onkyo’s equivalent auto-correction applied.  What???  Yes, I double checked this several times.  The dip at 100 Hz is being created by the equalization!  I even downloaded the latest firmware, and same result.  Pretty subpar.  So I turned off the Onkyo equalization 🙁

P.S. These measurements were with bass traps in the corners of the room.