Roland AC-90 - Acoustic Chorus Manual

Introduction

Before using this unit, carefully read the sections entitled:

• IMPORTANT SAFETY INSTRUCTIONS
• USING THE UNIT SAFELY
• IMPORTANT NOTES

These sections provide important information concerning the proper operation of the unit. Additionally, in order to feel assured that you have gained a good grasp of every feature provided by your new unit, Owner's manual should be read in its entirety. The manual should be saved and kept on hand as a convenient reference.

Names of Things and What They Do

Control Panel

1. INPUT
   (GUITAR CHANNEL)
   Connect guitars here.
   (MIC/LINE CHANNEL)
   Connect mics and line-level devices here. You can also connect guitars with pickups equipped with preamps.
   This handles balanced input, so you can connect 1/4" phone TRS jacks and XLR-type connectors.
   
   
   You can use the two channels in combination.
   Refer to "Example of Using Two Channels Combined".
   * Feedback could be produced depending on the location of microphones relative to speakers. This can be remedied by:

• Changing the orientation of the microphone(s).
• Relocating microphone(s) at a greater distance from speakers.
• Lowering volume levels.

2. PICKUP Button
   This switches the input circuitry for either piezo or magnetic pickups, according to the type of pickup on the connected guitar. Press down the button for magnetic pickups.
   * Set this to "MAGNETIC" if your guitar has an active pickup equipped with a preamp.
3. SHAPE Button
   Setting this to ON modifies the midrange to create a bright tone suitable for strumming chords.
   This emphasizes brushing sounds, allowing you to strum with a more edgy feeling.
4. PHANTOM Switch
   This turns the phantom power on and off.
   Set this to "ON" when connecting mics that require phantom power (condenser mic, etc.).
   Set this to "OFF" when connecting mics that do not require phantom power or other devices.
   

• Use the following sequence when connecting mics that require phantom power:

1. Turn the PHANTOM switch off.
2. Connect the mic.
3. Turn the PHANTOM switch on.

• Supplying phantom power to mics that do not require it or supplying it to other devices may cause such equipment to malfunction. Always be sure to turn the switch off before connecting.
  * To protect the circuitry, all output is muted momentarily after the PHANTOM switch is turned on or off.
  * Phantom power is supplied only to the XLR connectors for the MIC/LINE channel INPUT.
  * Noise may be produced if connectors are connected or disconnected while the phantom power is turned on.
  
  Phantom Power
  Because they have a comparatively wider range and better sound quality than dynamic mics, condenser mics are often used for miking acoustic guitars. However, they require a power source to operate. Although some condenser mics run off batteries placed within the mic housing, in many cases a type of power supply known as "phantom power" is required. This power supply uses the existing mic cable to feed power.
  The AC-90's phantom power is output at a constant 48 V, so it conforms to professional specifications required at recording studios.

5. SELECT Button
   This switches the input level to match that of the connected device (mic or line).
   You can connect guitars with magnetic pickups when LINE is selected with the SELECT button.
   * Note that the volume is increased if the switch is set to "MIC" when you have a line-level device connected.
6. VOLUME Knobs
   (GUITAR CHANNEL)
   Adjusts the volume of the GUITAR channel.
   * To accommodate the lower output of piezo pickups, the volume level when the VOLUME knob is between the 7 and 10 positions is set somewhat higher when the PICKUP button is set to PIEZO in comparison with the MAGNETIC setting.
   (MIC/LINE CHANNEL)
   Adjusts the volume of the MIC/LINE channel.
   * When using the AC-90 with the GUITAR channel and MIC/ LINE channel mixed, adjust the volume balance between the two channels with the VOLUME knob.
7. BASS Knobs
   Adjust the level of the low-frequency range.
8. MIDDLE Knobs
   Adjust the level of the midrange.
9. TREBLE Knobs
   Adjust the level of the high-frequency range.
   
   The tone of an acoustic instrument can vary immensely from one instrument to the next. The kind of sound required also varies according to how an instrument is being used in a particular ensemble. Actively use the BASS, MIDDLE, and TREBLE knobs to adjust the tone to suit the instrument you are using and the conditions in which it is being used.
   (Example)
   • When using the AC-90 with the speaker stand attached, you may want to turn up the BASS knob so the lower range is perceived better.
   • If the sound seems too harsh, such as immediately after changing strings, you may want to turn down the TREBLE knob to cut back on the high frequencies.
10. CHORUS Buttons
    Switch chorus on and off.
    When on, the indicator is lit.
    
    You can use a foot switch (the optional BOSS FS-5U) to switch chorus on and off. Turning chorus on and off with the foot switch works on both channels.
11. CHORUS Knob
    Turn this knob to select among the three types of chorus (SPACE, RICH, and WIDE).
    You can adjust the amount of effect applied by changing the position of the knob.
    * This is enabled when the CHORUS button is in the ON position.
    * The markings indicating the SPACE and RICH positions are approximate. Listen to the sound to confirm the effect as you make adjustments.
    SPACE
    This is a spacially synthesized chorus. With spacially synthesized chorus, a method available only in stereo, the chorus effect is created by taking the sound from the right speaker (from which the effect sound is output), and the sound from the left speaker (which outputs the direct sound), and then mixing them in the actual space. This creates a greater lateral spread than that produced when the sounds are mixed electronically, providing a more natural sense of breadth.
    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.
    
    * Turn the knob to "OFF" if you are not using anti-feedback.
14. START Button
    This is used for Auto settings. 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

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.

15. MUTE Button
    This switches the Mute function on and off.
    When you press the button, the MUTE indicator flashes, muting is turned on, and the speaker output and sounds from SUB WOOFER OUT and LINE OUT are muted.
    With the mute function activated, you do not need to turn down the VOLUME knob or MASTER knob to mute the noise when plugging into, or unplugging from your guitar.
    * Sounds from the DI OUT/TUNER OUT and PHONES jacks are not muted.
    
    By connecting a tuner (optional) to DI OUT/TUNER OUT and then pressing the MUTE button, you can tune your instrument without the sound being output from the speakers.
    You can use a foot switch (optional BOSS FS-5U or FS-6) to switch muting on and off. (p. 13)
16. MASTER Knob
    Adjusts the overall volume level. LINE OUT cannot be adjusted.
17. PHONES Jack
    Headphones are connected here. No sounds are output from the speakers or from SUB WOOFER OUT when headphones are connected.
18. POWER Switch
    This turns the AC-90's power on and off.
    The POWER indicator lights up when the power is on.
    If you need to turn off the power completely, first turn off the POWER switch, then unplug the power cord from the power outlet. Refer to Power Supply
    Due to a circuitry protection feature, this unit requires a few moments after it has been turned on before it is ready for normal operation.
    Always make sure to have the volume level turned down before switching on power. Even with the volume all the way down, you may still hear some sound when the power is switched on, but this is normal, and does not indicate a malfunction.

Rear Panel

* When connection cables with resistors are used, the volume level of equipment connected to the inputs may be low.
If this happens, use connection cables that do not contain resistors.

1. LINE OUT Jacks
   You can connect a mixer, recording device, or other device here. The output level is +4 dBu.
   Included here are XLR connectors (L/R: stereo output) and a 1/4" phone jack (mono output).
   
   * You cannot adjust the volume for LINE OUT with the MASTER knob.
   * The chorus effects are designed so they exhibit the greatest effectiveness when you use the unit's built-in speakers. Effectiveness may differ when LINE OUT is used instead of the built-in speakers.
2. SUB WOOFER OUT Jack
   You can connect a powered subwoofer to play back sounds with an even punchier, more powerful low end.
   The volume is adjusted with the MASTER knob.
3. AUX IN Jacks
   You can connect a CD player, drum machine, or other device and play back sounds in stereo. Both RCA phono jacks and 1/4" phone jacks are provided. When connected to only the left 1/4" phone jack, playback is in mono.
   Although the input from AUX IN is output from the speakers, PHONES, and SUB WOOFER OUT, it is not output from LINE OUT. The volume is adjusted with the MASTER knob, and muting on/off for these sounds is controlled with the MUTE button.
   If devices are connected to both the RCA phono jacks and the 1/4" phone jacks, the two inputs are mixed.
4. DI OUT/TUNER OUT Jack
   The direct sound of the device or instrument connected to the GUITAR or MIC/LINE channel is output here. This is a 1/4" phone TRS jack with balanced output.
   You can also use this jack to connect a tuner.
   
   * If balanced output is not required, use a 1/4" phone (mono) plug to connect to this jack.
   
   If balanced output is not required, you can use the special connection cable (the optional PCS-31) to use the DI OUT and TUNER OUT simultaneously.
   
   A phase-inverted signal is output from the COLD side (the red side of the PCS-31). Connect the recording device to the HOT side (the white side of the PCS-31)
5. FOOT SW Jacks
   The AC-90 accepts the BOSS FS-5L (latch type), BOSS FS-5U (momentary type), and BOSS FS-6 foot switch pedals.
   * Set the polarity switch as shown below.
   
   (MUTE, ANTI-FEEDBACK)
   Connecting a foot switch pedal (optional BOSS FS-5L, FS-5U, or FS-6) using a connection cable (the optional PCS-31) makes it possible to use a latch-type foot switch (the FS-5L or FS-6) to switch muting on and off, or to use a momentary-type foot switch (the FS-5U or FS-6) to control the anti-feedback feature.
   * For information on the settings for the FS-6, refer to the owner's manual for the FS-6.
   
   When a 1/4" phone (mono) plug is used to connect only one foot switch, only the Mute on/off function is enabled. In such cases, you should use a latch-type foot switch pedal (such as the BOSS FS-5L)
   * The MUTE button should be set to off when a foot switch is connected for muting.
   You cannot switch the muting off by pressing the foot switch when the MUTE button is on (when the MUTE indicator is lit).
   * When using an FS-5U (momentary type) to switch muting on and off, the muting is switched on only while the switch is held down.
   For anti-feedback, a foot switch will function as follows:
   • When the FREQUENCY knob is positioned in the range from L to H, the switch turns the anti-feedback function on and off.
   • When the FREQUENCY knob is positioned at AUTO, the switch functions as the START switch for the automatic detection. Holding the foot switch down for one second or longer returns the automatic detection function to standby mode.

(CHORUS, DELAY/REVERB)
Using a special connection cable (the optional PCS-31) to connect two foot switches (the optional BOSS FS-5U), you can use one FS-5U to switch the chorus on and off, and use the other FS-5U to switch the delay or reverb on and off.

When a 1/4" phone (mono) plug is used to connect only one foot switch, only the chorus on/off function is enabled.
* The chorus on/off function works on both channels.
* You cannot switch the chorus on and off by pressing the foot switch when the CHORUS button is off.

Example of Using Two Channels Combined

When Using a Mic and a Pickup
GUITAR CHANNEL:
Piezo or Magnetic Pickup
MIC/LINE CHANNEL:
Condenser or Dynamic mic (SELECT button = MIC) This allows you to blend the fat midrange of the pickup with the mic's delicate high end. Set the PHANTOM switch to ON if using a condenser mic.

When Using Two Guitars
GUITAR CHANNEL: Guitar 1 Piezo or Magnetic Pickup
MIC/LINE CHANNEL: Guitar 2 Magnetic Pickup (SELECT button = LINE)
You can switch guitars without having to readjust the volume and tone.

When Using One Guitar with Two Types
of Pickups GUITAR CHANNEL: PiezoPickup (PICKUP button = PIEZO) MIC/LINE CHANNEL: Magnetic Pickup (SELECT button = LINE) You can balance the volume levels using each channel's VOLUME knob, and adjust the tone for each pickup to attain the optimal sound with the equalizer (BASS/MIDDLE/TREBLE) knobs.

How to Use the Folding Stand

When using the AC-90 on floors, or in other low-lying positions, then setting up and using the folding stand can make it easier to hear the sound from the speakers.

• When using the folding stand, always be sure to place it so the AC-90 remains level.
• When not using the folding stand, fold it up.

• Never lift up and carry the AC-90 by holding the folding stand.
• Never place any objects on top of the AC-90 when using the folding stand. Also, never sit or lean on the folding stand.
• When folding the folding stand, be careful not to pinch your fingers.

202 Copyright © 2007 ROLAND CORPORATION
All rights reserved. No part of this publication may be reproduced in any form without the written permission of ROLAND CORPORATION.