Reflect; Spatial Eq - Lexicon PCM 90 - REV 1 User Manual

Mstr Dly, Dly L, Dly R
Dly L and Dly R provide pre-echoes to the left and right channels. Mstr Dly
provides a simple grouped control that modifies the left and right values from 0-
200%.
Mstr Lvl, Lvl L, Lvl R
In Random Hall, Concert Hall and Rich Plate, Lvl L and Lvl R modify the levels
of the reflections (Dly L and R). The range of each is from Full (0dB) to -85dB,
to Off. Mstr Lvl has a range of 0-100%.
Spatial EQ, when used to enhance the spaciousness of stereo material,
increases low frequency differences between left and right channels. An effect
called "negative cross-feed" is created by subtracting a copy of low frequency
on the left from the right channel, and vice-versa. This effect can be dramatic
when used judiciously on live stereo recordings.
Spatial EQ can also be used to reduce low frequency differences and steer the
bass into mono. This might be used in mastering LPs to keep the stylus in the
groove, in TV mixing, or in any situation in which the low frequency load should
be shared by both speakers. Spatial EQ used in this manner is said to have
"positive cross-feed".
In the PCM 90,Spatial EQ is placed in the signal path where it can process the
dry signal, the reverberation, or both.
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 the Spatial EQ effect takes 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 competely mono. This may increase the bass level, which can then be cut
by lowering the BassBoost control.
The Algorithms and Their Parameters

Reflect

Spatial EQ

3-21