HARMAN PCM91
User Guide

Algorithms and Parameters
SPATIAL EQ (continued)
Premix In Concert Hall, Spatial EQ is placed in the signal path after the reverberator. An additional dry signal is also provided so that the dry input can be sent to the Spatial EQ. In this case, we recommend setting the value of Mix in the Controls row to 100% so that Premix controls the wet/dry mix. Crossover Crossover sets the frequency below which Spatial EQ effects take place. Setting this frequency too high may result in unusual imaging. Gain Gain sets the amount of crossfeed between channels. The signal first goes through a 6 dB/octave low-pass filter whose frequency is set with Crossover. When Gain is set positive (above 0) the crossfeed has a negative sign. This increases the sense of spaciousness. When Gain is set negative (below 0), the crossfeed has a positive sign. This reduces the sense of spaciousness. When the control is set to either maximum or minimum, the gain in the crossfeed circuit is unity. At maximum, low frequency mono signals are completely removed. This represents an extreme setting which should seldom be needed in practice. Raising Gain may reduce the bass level. This effect can be compensated for by raising the overall bass level with BassBoost. Since both controls use the same Crossover setting, this compensation will be quite accurate as long as Gain is set to less than 3 dB boost. With Gain at its lowest setting, low frequency signals are completely mono. This may increase the bass level, which can then be cut by lowering the BassBoost control. 3-34

Lexicon BassBoost A positive value for Gain may reduce low frequencies in program material. Conversely, a negative value for Gain may increase low frequencies. BassBoost allows compensation for this effect by boosting or cutting frequencies below Crossover. The amount of boost or cut required is highly dependent on the material being processed. Start by setting this control to the same value as the Gain control, and then adjust it as necessary.

TIME
The Time row, available in every algorithm, contains parameters that affect the time-based aspects of the reverb effect.

Low Slope and Mid Slope These parameters are found in the all of the Inverse Rvb Time rows. Low Slope determines the shape of the reverb envelope for low frequencies. When set to 0, the level of low reverb remains unchanged over its Duration, then cuts off abruptly (depending on the amount of diffusion in use). Setting Low Slope above 0 causes the level of low frequency reverb to rise smoothly from soft to loud until the sound is cut off. The greater the slope, the softer the initial reverberation and the more pronounced its rise. With negative values, the low frequency reverb drops from its initial level to a quieter one before cutoff. The lower the slope, the more pronounced the dropoff. Mid Slope is similar to Low Slope, but applies to middle and high frequencies. The actual frequencies affected are determined by Crossover. Mid Rt and Low Rt Mid Rt sets reverb time for mid-frequency signals. Because low frequency reverb time (Low Rt) is a multiplier of Mid Rt, Mid Rt acts as a master control for reverb time.