Roland AC-90 Guide D'utilisation page 10

Names of Things and What They Do
RICH
This is a stereo chorus that is divided into three frequency
ranges.
Here, the effect is separated into three bands, low-frequency,
midrange, and high-frequency, and by applying the most
suitable amount of chorus effect in each range, it provides a
sense of fullness and breadth that is perfectly suited to the
acoustic guitar.
The low end is firmly in the center, and sound spreads out
more and more as the sound rises from the midrange up
through the higher frequencies.
WIDE
While also relying on the division of sound into separate
bands, this chorus offers even greater expansiveness than
RICH.
The sound image spreads beyond the AC-90's speakers,
producing an effect that seems to envelope the listener in
sound.
12. REVERB/DELAY Knob
You can adjust this knob to switch between the reverb and
delay effects.
You can adjust the amount of effect applied by changing the
position of the knob.
* Turn the knob to "OFF" if you are not using the reverb or
delay effect.
* The markings indicating the reverb and delay positions are
approximate. Listen to the sound to confirm the effect as you
make adjustments.
REVERB
This stereo reverb, developed especially for acoustic
instruments, gives a sense of spaciousness and natural sonic
quality.
Turn the knob to adjust the volume of the reverb effect.
DELAY
This delay, developed especially for acoustic instruments,
adds soft reflections to the original sound.
Turn the knob to change the delay time.
* You can use a foot switch (the optional BOSS FS-5U) to
switch the reverb and delay on and off.
13. FREQUENCY Knob
This selects the frequency at which the anti-feedback
function operates.
Also, the position of the knob determines whether Auto or
Manual settings are selected.
10
fig.031
* Turn the knob to "OFF" if you are not using anti-feedback.
14. START Button
This is used for Auto settings (p. 11). Pressing the button
performs automatic detection of feedback-whine frequencies.
The indicators show the operating status of the automatic
detection function.
Standby: Flashes slowly
During Detection: Flashes rapidly
After Detection: Remains lit
* Holding down the START button for one second or longer
returns the unit to standby for automatic detection.
How to Use ANTI-FEEDBACK
fig.32
Anti-feedback is a function that controls feedback that arises
between the guitar or mic and the amp.
The feedback is suppressed by attenuating the frequency at
which the feedback occurs.
* This is not designed to work with respect to the high-frequency
feedback that can occur when using microphones.
Anti-feedback can be used in two different ways; you can
make use of either the "Auto settings" or the "Manual
settings."
* Use either when feedback whine occurs.
Feedback
This is a phenomenon whereby signals output from the
speakers are picked up again by the mic or pickup, and the
sound is further amplified and output from the speakers,
resulting in an unpleasant oscillating sound.
* If the anti-feedback alone does not control the feedback, adjust
your settings, for example by lowering the volume or cutting
the low frequencies.
* To prevent feedback during a performance, we recommend
making the anti-feedback setting before the performance.
MANUAL