Correcting A Signal's Time Delay (Phase Delay) - Roland VM-C7100 Owner's Manual

Correcting a signal's time delay (PHASE DELAY)

A channel's input can be delayed to correct phasing problems between the its signal
and the signals of other channels.
When you use more than one microphone on an instrument (or other sound source),
there may be a difference in the amount of time it takes for the sound to reach each
microphone—it takes roughly 3 ms (milliseconds) for sound to travel the distance of
a meter from an instrument to a microphone. When you mix the signals from the
microphones, you may experience the loss of various frequencies in the resulting
signal due to phase differences between the microphones. You can fix such problems
by delaying the signals from those microphones placed closer to the instrument so
that they match the delay in signals from microphones placed further away.
Setting up a channel's PHASE DELAY
1. Press and select [INPUT] or [MULTI IN] in the SECTION area to select the
type of input you want to set up.
2. Press [CH EDIT] for the desired channel.
3. Select the PREAMP page using [PAGE UP]/[PAGE DOWN].
fig.05-01
4. Turn PHASE DELAY on to activate an input delay. Press [F4] (ON). When
PHASE DELAY is turned on, the parameter is highlighted.
Set the desired delay using the V4 knob. PHASE DELAY is measured in samples, the
smallest unit of time in the system. When the current sample rate is:
• 48 kHz, one sample equals about 0.021 ms.
• 44.1 kHz, one sample equals about 0.023 ms.
* The PHASE DELAY parameter works in conjunction with the FEEDBACK
DELAY parameter, which also allows you to delay a channel's signal. Together,
their delay times cannot exceed 14,400 samples in total.
The current setting is displayed as a DISTANCE in meters from the sound source.
The setting is also displayed in TIME as milliseconds based on the current sample
rate.
Chapter 5 Mixing Procedure 1 (Input Channel)
When the PHASE
DELAY feature is used, the
original, un-delayed sound
is not heard—only the
delayed signal is used.
You can jump directly to
this screen by pressing the
PREAMP GAIN STATUS
button while holding down
the channel's [CH EDIT].
Sample rate (p. 244)
DISTANCE is calculated on
a basis of the travel velocity
of sound at one normal
atmosphere and 20 degrees
Centigrade. You can turn
[V4] while holding down
[SHIFT] to move quickly
through the full range of
delay values. You can also
access the PHASE DELAY
parameter by pressing [CH
VIEW] with the channel's
[CH EDIT] (p. 63).
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