Lexicon 300 - Stereo Adjust

300 ” 3.0 Owner’s Mcmuc~
Lexicon
Stereo Adjust DC Offsets Page
DCSW (DC Offset Nuiling) This control provides three choices: RESET, MANUAL ADJUST and AUTO
ADJUST. RESETdisables all DC adjustment. AUTOADJUSTenables routines
for oorrecting DC offset from material recorded through analog-to-digital con-
vertersthatarenotproperlytrimmedforDC. MANUALADJUSTallows Softknob
selection of offset values.
L-DC and Ft-DC Replacesanypreviouslyobtainedvaluewiththevalue set hereviathe soft knob.
(Lch and Rch DC Offset) The display indicates the percent of the correction.
SHUF (Binauml Shuffler) SHUF controls a spatial equalizer designed to make recordings from a dummy
head, or closely-spaced omni microphones, more suitable for loudspeaker
reproduction. Due to the close spacing of the microphones, there is very little
diiference between the two stereo channels below about 3OOH.z. The shuffler
restores the low frequency separation by first matrixing the Land R signals into
L+R and L-R, bass-boosting the L-R channel, then rematrixing backto Land R.
The effect is to convert small time differences (which are not audible in
loudspeaker reproduction) between the two microphones into level differences,
which are audible. The effect can be dramatic.
The frequency below which the boost acts is set by the SHUF control. A setting
of 5 will give a 3dB L-R boost at about 15OHz; a setting of 10 will be 3dB up at
25OHz. Response rises at 6dBIoctave below this frequency. More than 18dB of
gain can be obtained at 2OHz when SHUF is set to i0.
This control has been optimized for true binaural recordings, where the diifer-
ence signal at low frequencies is minimal. If it is usedonordinary stereo material,
orwith binaural material to which reverberation has been added, excessive low
frequency difference signals can result. On such material, k is better to use the
SPEQ control which will achieve a similar result.
The SHUF control varies from 0 (shuffleroff) to a maximum of 10. While theory
wouldsuggestasettingof loforadummyhead, asettingof5appearstobemore
useful in practice. The setting is very much a matter of taste. If closely spaced
microphones are used, the setting will scale inversely with the microphone
distance in centimeters. For a spacing of 15cm, try a shuffler setting of 5. For a
spacing of 3Ocm, try a setting of 3. For a spacing of 7cm, try a setting of IO.
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