BOSS ME-90B Bass Multi-Effects Reference Manual
Panel Descriptions
Top panel
The top panel of the ME-90B features various controls for effect configuration and operation.
- 1. Effect configuration knobs: Used to adjust parameters for the built-in effects. Refer to the "ME-90B Parameter Guide" for details.
- 2. Display: Shows operational information. A blinking [BATTERY LOW] indicator signals the need to replace batteries.
- 3. Buttons:
- [EXIT]: Returns to the previous screen or undoes an operation.
- [WRITE]: Saves memory settings or executes a copy operation.
- [CTL]: Configures the operation of the [CTL] pedal in memory mode.
- [EDIT]: Enters memory edit mode.
- 4. Expression pedal:
- Pressing the toe end switches the [PEDAL FX] indicator on/off, enabling or disabling the pedal effect.
- When the pedal effect is off, it functions as a volume pedal.
- Note: Exercise caution to avoid pinching fingers in the pedal mechanism. Adult supervision is recommended for children.
- 5. [MEMORY/MANUAL] pedal: Switches between memory mode and manual mode. Holding it for two seconds activates the tuner.
- 6. Pedal switch:
- In memory mode, switches between banks and memories.
- In manual mode, toggles individual effects on/off.
- Specific functions for [BANK], [BANK ▲], [1]-[4], and [CTL] pedals are detailed for both memory and manual modes.
- 7. [OUTPUT LEVEL] knob: Adjusts the overall volume for the OUTPUT and PHONES jacks. It does not affect the BALANCED OUTPUT connector.
Rear panel (connecting your equipment)
The rear panel provides various input and output jacks, switches, and connectors.
- 1. BALANCED OUTPUT connector: Connects to PA mixers or audio equipment. Output is always set to "LINE". Pin assignment: 1: GND, 2: HOT, 3: COLD.
- 2. [GND/LIFT] switch: Lifts pin #1 (GND) to prevent ground loop noise. Default is "GND".
- 3. INPUT jack: Connect your bass guitar here.
- 4. OUTPUT jacks: Connect to bass guitar amps, mixers, or powered speakers. Use the L/MONO jack for mono connections.
- 5. [AMP/LINE] switch: Set to "AMP" for bass guitar amps, "LINE" for mixers or powered speakers to optimize output.
- 6. PHONES jack: Connect headphones or a recorder with a stereo mini plug. Set the [AMP/LINE] switch to "LINE".
- 7. SEND/RETURN jacks: Connect external effect units. The SEND/RETURN can be inserted into the signal chain as an effect unit.
- 8. Bluetooth ADAPTOR jack: For connecting the optional BT-DUAL adaptor for wireless music playback and app control.
- 9. USB COMPUTER port: Connect to a computer via USB cable for audio/MIDI transmission, using the dedicated app, and firmware updates. Use a data-transfer USB cable, not a charge-only cable.
- 10. [POWER] switch: Turns the unit's power on and off.
- 11. DC IN jack: Connects to an AC adaptor (BOSS PSA-S series). Use the cord hook for cable management. Always turn down volume and power off units before making connections.
- 12. Ground terminal: Connect to an external earth or ground if necessary.
Installing the batteries
Install four AA alkaline batteries into the battery case, ensuring correct polarity. It is recommended to keep batteries installed even when using an AC adaptor for backup power. Handle the unit carefully when turning it over to avoid damage.
Outputting sound
Turning the power on/off
Always turn down the volume before powering the unit on or off. Minor sound variations during power cycling are normal.
- To turn on: Press the [POWER] switch, then turn on your connected bass amp.
- To turn off: Ensure all connected devices have their volume turned down, save any edited memories, turn off your bass amp and other connected devices, then press the [POWER] switch. Settings being edited are lost if not saved before powering off.
Setting the connected device type
Use the [AMP/LINE] switch based on your connection:
- LINE: For mixers, powered speakers, or headphones.
- AMP: For bass guitar amplifiers.
Selecting a bass amp type (output select)
This setting optimizes the sound for different amp types:
- Switch to manual mode using the [MEMORY/MANUAL] pedal.
- Press the [EDIT] button.
- Use the [BANK ▼] / [BANK ▲] pedals to select the amp type (1 for tweeter-equipped amps, 2 for amps without tweeters).
- Press [WRITE] to save the setting.
Adjusting the volume (output level)
Use the [OUTPUT LEVEL] knob to adjust the overall output volume.
Tuning your bass (tuner)
The built-in tuner helps keep your bass in tune:
- Hold the [MEMORY/MANUAL] pedal for at least two seconds to activate the tuner (the [MEMORY/MANUAL] indicator turns yellow).
- Adjust the reference pitch (435 Hz to 445 Hz) using the [EDIT] button if needed. The setting is saved.
- Play a single note on the string you wish to tune. The display shows the closest pitch.
- Adjust the string until both tuning guides are illuminated, indicating the note is in tune.
- Press any pedal switch to exit the tuner.
Note: Output settings can be configured while the tuner is active; refer to "Configuring the device overall (system settings)" for details. The expression pedal can adjust volume if audio output is enabled.
Effect signal chain
The ME-90B processes effects in a specific order, which can be adjusted:
EFFECT CHAIN: PEDAL FX → COMP/FX1 → FILTER/FX2 → DRIVE/SYNTH → SEND/RETURN → PREAMP/EQ → NS → FOOT VOLUME → MOD → DLY/REV → BLEND
The signal chain automatically optimizes based on the selected effect type. The SEND/RETURN can be repositioned (e.g., after PREAMP/EQ) via system settings. Refer to the "ME-90B Parameter Guide" for effect parameter details.
Effect Explanations:
- PEDAL FX: Utilizes the expression pedal for various effects (e.g., wah) or volume control.
- COMP/FX1: Provides compression and other effects for sustained sound.
- FILTER/FX2: Offers wah effects and filter sweeps.
- DRIVE/SYNTH: Creates distortion or synth-like tones.
- SEND/RETURN: Allows connection of external effect units.
- PREAMP/EQ: Models preamp characteristics and adjusts tone.
- NS: Noise suppressor for bass pickups.
- FOOT VOLUME: Functions as a volume pedal when not controlling other effects.
- MOD: Adds spaciousness or modulation effects.
- DLY/REV: Creates delay and reverb effects for echo or ambiance.
- BLEND: Adjusts the volume of the direct sound.
Signal flow
The signal path is as follows: Bass guitar → EFFECT CHAIN → OUTPUT LEVEL → OUTPUT (L/MONO, R), PHONES, BALANCED OUTPUT. The TUNER can be engaged at any point, and Bluetooth AUDIO can be routed to the outputs.
Saving/recalling sounds (memory mode)
Memory mode allows saving and recalling custom sound settings (memories). Manual mode allows individual effect switching.
How the memories are structured
Memories are combinations of effects and settings. The ME-90B stores 72 memories, organized into 9 preset banks and 9 user banks (each with 4 memories per bank).
Switching between manual/memory mode
Press the [MEMORY/MANUAL] pedal to toggle between modes. The indicator lights red for memory mode and blue for manual mode.
Setting what happens when switching from memory mode to manual mode
System settings (N0/N1) determine whether manual mode uses current knob settings or carries over memory settings. Individual effects can be toggled in memory mode (factory setting). Manual mode settings are retained when switching to memory mode.
Selecting a sound (memory)
Use the [BANK ▼] / [BANK ▲] pedals to select a bank, then use the numbered [1]-[4] pedals to select a memory within that bank.
Checking the knob positions
To verify parameter values against knob positions, hold [EDIT] and turn a knob. The display shows the knob's value. When they match, tuning guides illuminate.
Configuring what happens when switching banks
System settings (h0/h1) control whether bank switching instantly selects the next memory or requires a numbered pedal press. The default (h1) is instant switching.
Saving a sound (memory write)
To save current settings:
- Press the [WRITE] button. The pedal indicator blinks.
- Select the user bank and memory number (destination).
- Press [WRITE] again to save all settings except OUTPUT LEVEL.
Note: Unsaved settings are lost if the unit is powered off or switched to a different memory before writing. The destination memory is overwritten.
MEMO: Memories can be written in either manual or memory mode. Writing a memory switches the unit to memory mode.
Copying memories
Recall a memory and then write it to a new destination to copy it.
Changing the settings for sounds (memory edit mode)
Enter memory edit mode by recalling a memory and pressing [EDIT]. Use knobs and pedals to adjust settings. Save changes using the "Saving a sound (memory write)" procedure.
Useful functions
Adding effects that follow your tempo (tap tempo)
Set the DLY/REV type knob to "TEMPO". Press the [DLY/REV] pedal in time with the music to set the delay timing (e.g., dotted eighth or quarter note). The pedal indicator blinks in sync with the tempo.
Setting the modulation speed or delay time with the pedal
For MOD or DLY/REV effects (when applicable), hold the effect pedal for two seconds, then press it repeatedly at the desired speed to set the timing. The pedal indicator blinks with the tempo. Knob adjustments after pedal setting override the pedal timing.
Note: Certain effects (e.g., TERA ECHO, PHRASE LOOP) cannot be set using this pedal method.
Performing with phrase loops
Record up to 38 seconds of audio for looping and overdubbing.
- Set the DLY/REV type knob to "PHRASE LOOP".
- Press the [DLY/REV] pedal to start recording (indicator is red).
- Press the [DLY/REV] pedal again to stop recording and start playback (indicator is blue).
- To overdub, repeat steps 2 and 3 (indicator is yellow during overdubbing).
- Adjust playback volume with the [E. LEVEL] knob.
- Quickly press the [DLY/REV] pedal twice to end loop playback (indicator blinks blue).
- Press the [DLY/REV] pedal to start playback.
- Long-press the [DLY/REV] pedal to erase the recorded phrase (indicator blinks white).
Pedal indicator statuses:
| Status | Indication |
|---|---|
| Standby | Blinking white (no phrase) |
| Recording | Lit red |
| Overdubbing | Lit yellow |
| Loop playback | Lit blue |
Configuring the [CTL] (control) pedal functions
The [CTL] pedal can toggle multiple effects on/off or set specific knob values per memory.
- Setting the pedal function: Select effects to toggle on/off by pressing their corresponding pedals while in CTL setting mode. The display indicates "Ct" and blinking pedal indicators.
- Setting the value of a certain knob: Adjust a knob to set its value. The display shows "Ct" and the knob number.
- Configuring the pedal operations: Choose between "TOGGLE" (effect switches each press) and "MOMENTARY" (effect active only while pressed) for pedal operations. Save settings via the [WRITE] button.
Note: The [CTL] pedal's indicator state reflects the priority of the effects it controls.
Connecting to and using an external effect unit via the SEND/RETURN jacks
Connect external effects between the SEND and RETURN jacks to integrate them into the ME-90B's signal chain. The SEND/RETURN insertion point and footswitch function can be configured in system settings. Factory default is before PREAMP/EQ and turned on. No sound is output from SEND if RETURN is not connected.
MEMO: Hold [EDIT] + [CTL] to toggle SEND/RETURN on/off. This state can be saved per memory.
Calibrating the expression pedal
If the expression pedal's response degrades, recalibrate it:
- Switch to manual mode.
- Hold [DLY/REV] and press [DELAY]. Display shows "Pd" → "UP".
- Press the heel end of the pedal, release, and press [WRITE]. Display shows "dn".
- Press the toe end of the pedal, release, and press [WRITE].
- Use [BANK ▼] / [BANK ▲] to adjust responsiveness (1-9). Lower values are more responsive.
- Press [WRITE] to save.
MEMO: If the display blinks during steps 3 or 4, ensure the pedal is fully pressed before pressing [WRITE].
Connecting to your computer via USB
The ME-90B facilitates digital audio and MIDI communication with computers via USB.
Installing the USB driver
Download and install the dedicated ME-90B driver from the BOSS website (https://www.boss.info/support/) for optimal audio quality, stable timing, and MIDI control. Follow the "Readme" file instructions for installation.
Transmitting/receiving audio signals between your computer and the ME-90B (USB audio)
Record ME-90B audio on your computer or play computer audio through the ME-90B's outputs. Select from two USB audio inputs ([INPUT], [MIX IN]) and two outputs ([OUTPUT], [DRY OUT]). Refer to your audio software's manual for input source selection.
USB audio settings: Configure signal flow via system settings (p. 16) for parameters like [USB LEVEL], [USB DIRECT MONITOR], and [USB LOOPBACK].
Transmitting/receiving MIDI data between a computer and the ME-90B (USB MIDI)
Use DAW software or the "BOSS TONE STUDIO for ME-90B" app for controlling the ME-90B, editing sounds, and managing memories. The app allows editing user banks, downloading memories, backing up settings, and accessing exclusive effects. It also includes an IR loader.
Switching between memory numbers: Program change messages from external software can change the ME-90B's current memory.
Receiving control change messages: The unit can receive MIDI CC messages to control specific parameters.
Data that can be transmitted/received via MIDI:
| Pedal | Control change message | Value |
|---|---|---|
| Expression pedal | CC#11 | 0-127 |
| Pedal effect on/off (EXP SW) | CC#82 | On: 127 Off: 0 |
| [CTL] pedal | CC#80 | When the pedal is pressed: 127 When the pedal is released: 0 |
Loading IR data to use this unit as a speaker simulator
Use the dedicated IR loader software, accessible via the "BOSS TONE STUDIO for ME-90B" app, to load Impulse Response (IR) data for speaker simulation. Select IRs by holding [EDIT] and pressing numbered pedals [1]-[4].
Speaker simulator selection:
| Pedal | Display | Speaker simulator |
|---|---|---|
| [1] | 0 | Original ME-90B simulator (factory settings) |
| [2] | 1 | IR data loaded into USER 1 |
| [3] | 2 | IR data loaded into USER 2 |
| [4] | 3 | IR data loaded into USER 3 |
Note: IR data is not included for USER 1-3 by default. Speaker simulators can be selected and stored per memory.
Wireless connection with a mobile device
The ME-90B supports wireless connectivity with mobile devices via the optional BT-DUAL adaptor for music playback and app control.
Attaching the BT-DUAL
Turn off the ME-90B and unplug the AC adaptor. Remove the cover and screw from the Bluetooth ADAPTOR jack. Attach the BT-DUAL and secure it with the screw. Ensure proper alignment. Note: Use only the original screw. Avoid touching circuit pathways.
Listening to sound via wireless connection with a mobile device
Bluetooth audio allows playback from a mobile device through the ME-90B's OUTPUT or PHONES jacks (not BALANCED OUTPUT).
Registering a mobile device (pairing)
Pairing establishes recognition between the mobile device and ME-90B.
- Turn on the ME-90B.
- Place the mobile device nearby.
- Hold the BT-DUAL pairing button until the Bluetooth indicator blinks rapidly.
- Turn on the mobile device's Bluetooth function.
- Tap "ME-90B Audio" on the mobile device's Bluetooth screen to pair. The indicator confirms connection. If pairing fails, the indicator darkens.
MEMO: The explanation uses an iPhone as an example; refer to your mobile device's manual for specifics.
Connecting an already-paired mobile device
With the BT-DUAL's indicator off, press the pairing button. Turn on the mobile device's Bluetooth. If connection fails, tap "ME-90B Audio" on the device screen. To disconnect, press the pairing button or turn off the device's Bluetooth.
Disabling Bluetooth functionality
Press the pairing button on the BT-DUAL to turn off Bluetooth functionality and conserve battery power.
Controlling the ME-90B from the dedicated app on your mobile device
Use the "BOSS TONE STUDIO for ME-90B" app to edit effects and settings. Connect via the app's settings screen, not the mobile device's Bluetooth settings. Turn on the ME-90B, place the device nearby, enable Bluetooth, and connect to "ME-90B MIDI" within the app's settings. Do not select "ME-90B Audio" for app control.
Operating the ME-90B wirelessly with an EV-1-WL/FS-1-WL
Wireless expression pedals (EV-1-WL) and footswitches (FS-1-WL) can be connected. Refer to the BOSS website for connection guides.
Configuring the device overall (system settings)
System settings allow customization of various device behaviors.
- Switch to manual mode.
- Press [EDIT] to select a parameter. Press [EDIT] or [CTL] to cycle through parameters.
- Use [BANK ▼] / [BANK ▲] to select a value.
- Press [WRITE] to save the settings.
Parameter list
| Parameter | Display | Explanation | Parameter | Display | Explanation |
|---|---|---|---|---|---|
| OUTPUT SELECT | 1-2 | Specifies the amp connected to OUTPUT jacks. | Switching to manual mode | N0 | When switching to manual mode, current knob settings are applied. |
| Knob motion | n0 n1 |
n0: Value changes instantly when knobs are operated (factory setting). n1: Value changes only when knob position reaches the parameter's current value. |
N1 | When switching to manual mode, memory settings are carried over (factory setting). Manual mode settings are retained when switching to memory mode. | |
| USB LEVEL | L0-L9 | Adjusts the level of audio input from the computer mixed with ME-90B effects. | SEND/RETURN insertion point setting | S0 | SEND/RETURN inserted before PREAMP/EQ (optimal for distortion). |
| USB DIRECT MONITOR | d0 d1 |
d0: ME-90B sound not output from OUTPUT, PHONES, BALANCED OUTPUT. d1: ME-90B sound output from OUTPUT, PHONES, BALANCED OUTPUT. |
S1 | SEND/RETURN inserted after PREAMP/EQ (optimal for delay). | |
| USB LOOPBACK | b0 b1 |
b0: Computer input audio not output via USB OUT. b1: Computer input audio output via USB OUT. |
Preserving/muting the effect sound when switching between memories or turning effects off | o0 | When switching memories, DLY/REV sound is not carried over (not for MOD). |
| MIDI channels | ch 1-ch 9, ch 10-ch 16 | Sets MIDI channels. | o1 | When switching memories, DLY/REV sound is carried over (factory setting, not for MOD). | |
| Output settings when using the tuner | t0 t1 |
t0: No audio output when using tuner. t1: Direct sound output while using tuner. |
LED illumination color | E0-E9 | LEDs can light up in one of ten colors (factory setting). E0-E1 for limited color indication (red, yellow, blue) or classic display. |
| Bank switch operation | h0 | Pressing bank pedal only changes display bank; memory switch requires numbered pedal press. | BLEND footswitch functions | r0 | In manual mode, toggles BLEND on/off (factory setting). |
| h1 | Memory switches instantly when bank pedal or numbered pedal is pressed (factory setting). | r1 | In manual mode, toggles SEND/RETURN on/off. |
Restoring the factory settings (factory reset)
To restore factory settings (excluding expression pedal calibration):
- Switch to manual mode.
- Hold down the [CTL] button and press the [DRV/SYN] pedal. The display shows "FA".
- Press the [WRITE] button (tuning guide blinks).
- Press the [WRITE] button again to execute the reset. The display blinks.
Note: Do not turn off power during the reset process.
Troubleshooting
Common issues and their solutions:
| Problem | Items to check | Cause/Action | |
|---|---|---|---|
| Problems with sound No sound/insufficient volume |
Is there a short in one of the connection cables? | Try replacing the connection cable. | |
| Is this unit properly connected to other devices? | Check connections to other devices (p. 3). | ||
| Is the power to the connected amp or mixer not turned on, or is the volume turned down? | Check settings for connected devices. | ||
| Might the [OUTPUT LEVEL] knob has been lowered? | Adjust knobs to appropriate positions (p. 4). | ||
| Has the tuner been turned on? | Effects are not applied while tuning. | ||
| Is the output setting set to t0 when you are using the tuner? | Set to "t1" (p. 16). | ||
| Has each effect been configured correctly? | Check settings for each effect. | ||
| Is the "USB LEVEL" (p. 16) set too low? | Adjust value as appropriate. | ||
| The batteries might be depleted. | Replace batteries. | ||
| Sound from the device connected to the INPUT jack isn't coming through headphones | "USB DIRECT MONITOR" (p. 16) might have been set to "d0". | Set to "d1". | |
| Oscillating sound or feedback | The gain value or volume-related parameters in the effect settings might be set too high. | Try lowering these values. | |
| Other problems | Cannot switch between memories | The bank switch operation setting (p. 16) might be set to "h0". | If set to "h0", memory changes only after pressing a numbered pedal. |
| Can't control the parameters as desired | Is the effect turned off? | Check if effects controlling the parameter are on. | |
| Do the MIDI controller numbers match? | Verify controller number matches parameter (p. 13). | ||
| The expression pedal might be miscalibrated. | Calibrate the expression pedal (p. 11). | ||
| Can't save a phrase you created using phrase loop | N/A | Phrase loop saves are not supported on the ME-90B. | |
| Can't connect to an Android device via Bluetooth | Location data on the Android device might have been turned off. | Enable location data on the Android device and try connecting via Bluetooth again. |
Main specifications
| Specification | Details |
|---|---|
| Sampling Frequency | 48 kHz |
| AD Conversion | 24 bits + AF method (Adaptive Focus method) |
| DA Conversion | 32 bits |
| Processing | 32-bit floating point |
| Effects | 93 Types |
| Memories | 36 (User) + 36 (Preset) |
| Phrase Loop | 38 sec. (MONO) |
| Internal Tuning Detection Accuracy | ±0.1 cent |
| Nominal Input Level | INPUT: -10 dBu, RETURN: -10 dBu |
| Maximum Input Level | INPUT: +7 dBu, RETURN: +7 dBu |
| Input Impedance | INPUT: 1 MΩ, RETURN: 1 MΩ |
| Nominal Output Level | OUTPUT L/MONO, R: -10 dBu, PHONES: -10 dBu, SEND: -10 dBu, BALANCED OUTPUT: -10 dBu |
| Output Impedance | OUTPUT L/MONO, R: 1 kΩ, PHONES: 44 Ω, SEND: 1 kΩ, BALANCED OUTPUT: 600 Ω |
| Recommended Load Impedance | OUTPUT L/MONO, R: 10 kΩ or greater, PHONES: 44 Ω or greater, SEND: 10 kΩ or greater, BALANCED OUTPUT: 600 Ω or greater |
| Display | 7 segments, 2 characters (LED), Tuning guides (LED) |
| Connectors | INPUT, OUTPUT (L/MONO, R), SEND, RETURN (1/4-inch phone), BALANCED OUTPUT (XLR), PHONES (Stereo miniature phone), USB COMPUTER (USB Type-C®), Bluetooth ADAPTOR (Dedicated connector), DC IN jack. |
| Power Supply | Alkaline battery (AA, LR6) x 4, AC adaptor |
| Current Draw | 195 mA |
| Expected battery life under continuous use | Alkaline battery: Approx. 6 hours (varies by battery and usage conditions) |
| Dimensions | 443 (W) x 220 (L) x 67 (H) mm (17-1/2" W x 8-11/16" D x 2-11/16" H) |
| Maximum height | 443 (W) x 220 (D) x 93 (H) mm (17-1/2" W x 8-11/16" D x 3-11/16" H) |
| Weight (including battery) | 2.9 kg (6 lbs 7 oz) |
| Accessories | Startup Guide, Alkaline battery (AA, LR6) x 4, "USING THE UNIT SAFELY" leaflet. |
| Options (sold separately) | AC adaptor: PSA-S series, Bluetooth® Audio MIDI Dual Adaptor: BT-DUAL, Carry Bag: CB-ME80, CB-BU10. |
Note: 0 dBu = 0.775 Vrms. Specifications are subject to change without notice.
