Input

Connect your instrument via a standard ¼” mono cable.

Passive/Active

Switch from passive to active mode. Some active basses can have a hotter signal output which can make the amplifier distort early (feel free to use it on Passive mode even with active basses if such additional distortion is desired).

Microtubes

Engages the Microtubes Engine™ to add natural compression, organic harmonic enhancement, and saturation ranging from mild overdrive to high gain bass rage. The Microtubes Engine operates before the clean section (you can, therefore, use the 4 Band Active EQ for additional tone shaping in addition to the Tone knob described below).

Drive

Sets the Microtubes Engine’s distortion level. Ranging from soft, warm overdrive to devastating saturation plus everything in between.

Tone

Controls the high harmonic content of the Microtubes Engine via a variable low pass filter: crank it up for additional attack and definition or dim it down for a smoother sound. This is handy when running bright EQ settings or cabinets with tweeters.

Level

Controls the Microtubes Engine’s output volume.

Blend

Mixes between the Clean and Distortion signals (Microtubes Engine).

B3K/VMT

Selects between two overdrive circuits: B3K mode will deliver an aggressive, percussive sound while the VMT will bring up the mids for a warmer, more neutral character.

Gain

Changes the volume of the signal driving the Active 4 Band EQ. You can set it low for cleaner tone or set it higher for more aggressive growl.

Bass

+-12dB at 80Hz. Changes the low content of the signal.

Low Mids

+-12dB of the selected frequency via the LOW MIDS ƒ switch (described below).

Low Mids ƒ

Use this switch to change the frequency of the low mid band between 250Hz and 500Hz.

Hi Mids

+-12dB of the selected frequency via the HI MIDS ƒ switch (described below).

Hi Mids ƒ

Use this switch to change the frequency of the hi mid band between 1.5kHz and 3kHZ.

Treble

+-12dB at 5kHz. Changes the high content of the signal.

Master

Controls the overall volume of the amplifier. This control does not affect DI output or effects loop level.

Mute

Mutes the amplifier.

Footswitch

The Footswitch jack allows you to remotely engage and disengage the Microtubes Engine via our Intelligent Footswitch (sold separately). Hold the footswitch to Mute the amplifier. The VMT/B3K push button will remain operational with the Intelligent Footswitch plugged in.
* Use a regular mono instrument cable to connect the amplifier to the footswitch.
* Remove the cable from the footswitch jack in the rear panel if you want to control the amp from the front panel.
* The Microtubes 500 will only work with our proprietary Intelligent Footswitch or Super Intelligent Footswitch (both sold separately). A generic Footswitch will not work with the Microtubes 500.

Speaker Output

Connects the amplifier to your cabinet. This Speakon combo jack allows for either Speakon or ¼” speaker cable operation. The minimum load for the amplifier is 4Ω. For higher impedance loads the maximum output power is reduced. The Microtubes 500 amplifier can run without a cabinet connected to this output. WARNING: Do not use an instrument cable with this jack. Using an instrument cable can damage your amplifier. Do not use a load lower than 4Ω.

Headphone Output

Headphones with 1⁄4” plug connector can be connected to this jack. For quiet operation remove any speaker cabinet connected to the amplifier, as connecting the headphones does not disable the speaker output.

Send

Line level effects loop output. Connect a cable from this jack to the input of any pedals used in the effects loop. The output can be used to connect to another power amplifier or a sound card. The output is not controlled by the Master volume. Gain control can be used to change the signal le

Return

Line level effects loop input. Connect the output from your effects loop pedals to this connector.

Post-Pre

Selects which signal will be sent to the Balanced output. Selecting PRE, sends a clean copy of your input bass signal. Selecting POST delivers the processed signal by the preamplifier (Microtubes Engine, gain, eq.)

Ground Lift

Lifts the ground of the Balanced output. If you are hearing mains frequency hum in your setup, try changing this setting.

Balanced Output

Connects the Microtubes 500 preamplifier to balanced equipment (mic preamp, console, recorder, compressor, audio interface, etc.) via a standard XLR connector. The balanced signal level is not affected by the Master volume.

Fan

The fan cools the amplifier and should run at all times. Be sure to never cover the vent holes on either side of the chassis.

AC Socket

Connects the power cord to the amplifier.

AC Power On/Off

Turns the amplifier on or off.

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