The Equaliser Preferences alter the way REW carries out its EQ filter calculations.
The Default Equaliser specifies the equaliser that will be used for new measurements. The equaliser used for an existing measurement can be changed via the EQ panel.
If Drop filters if gain is small is selected any Automatic filters which have gain of magnitude less than half the flatness target at the end of the optimisation process will be freed up (their Type will be set to "None")
If Use new optimiser is selected REW uses the optimisation algorithm developed for V5.10, if it is not selected the V5.00 algorithm is used. The V5.10 algorithm is faster and produces more consistent results for equalisers which do not constrain parameter resolution, such as the miniDSP and Generic equaliser settings.
The default values to use for Speaker Type, Cutoff, Crossover slope, LF Slope and LF Cutoff are specified here, these will be used for each new measurement. The LF Cutoff and LF Slope define the lower extension limit for subwoofer's or full range speakers and how quickly that extension rolls off.
The LF Rise and HF Fall settings define the defaults that will be used for a house curve effect on the target shape for new measurements. The target curve will rise below the LF Rise start frequency at the slope selected until reaching the LF Rise end frequency. A rise at low frequencies is often subjectively preferred. Similarly, the target curve will fall above the HF Fall start frequency at the slope selected. Falling HF response is a normal characteristic of in-room measurements at the listening position.