I played a sweep tone from the AVIA DVD for the sub from 100hz down to 20hz.....basically sit in your listening position and watch the SPL meter....it will jump around a little as I dont think any one room or position will be 100% flat, but overall the new sub position is only a few DB up or down throughout the frequency range.....the original position had a huge peak around 55-60hz then really died below that with not much below 35hz