Lexicon 300, Owner'S Manual

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4-17
The Algorithms and their Parameters
LDLY and RDLY
LFBK and R FBK
Stereo Pitch Shift Delay and Feedback Page
LDLY adjusts the length of a delay line in series with the left input. The range is
zero to 510ms in 2ms steps.Pre-delay also affects the delay of any feedback
which is applied. In stereo mode the two pre-delays must be set to the same
value, or the signals will not be in phase. Optimal pitch shift occurs when LDLY
is about 40ms.
RDLY is the same as the LDLY, except that it acts upon the right channel.
L FBK and R FBK control the amount of positive feedback from the output of the
pitch shift to the input of the pre-delay line. The control is adjustable from 0 to
+99%. Some very useful efects can be obtained by combining pitch shift, delay,
and feedback.
BNPS is a band-pass filter which rolls off the frequency responce of the audio
before the splicing algorithm. The -3dB point is 100 Hz. The purpose of the band-
pass filter is to give the pitch shifter
less information than it actually needs to
decide when to make the splice. Typically, this will inprove the performance of
the pitch shifter.
SYNC is only active in STEREO mode. This control forces an exact sync of the
two channels when the control is turned from 0 to 1. When SYNC is 1, there is
an automatic re-syncing any time the two channels differ in phase by about 10
samples. This can occur if PCHL or LDLY is changed. Re-syncing can cause a
small click in the output. If the pitch shifter is being used to manually pitch-correct
classical music using the GLDL control, it may be better to set SYNC to 0, or Off.
There is an automatic sync tracking feature which will keep the two channels
locked to within 2 samples. If precise synchronization is desired, the GLDL or
PCHL controls should be set, SYNC should be set from 0 to 1, and then the pitch
should not be changed. The two channels will remain precisely synchronized,
even though both are continually changing the splice length in response to the
incoming pitches.
BNPS
SYNC