# Control main mixer

``

    set_mixer_control!

The main mixer is the final mixer that all sound passes through. This fn gives you control over the main mixer allowing you to manipulate all the sound playing through Sonic Pi at once. For example, you can sweep a lpf or hpf over the entire sound. You can reset the controls back to their defaults with `reset_mixer!`.

Introduced in v2.7

## Options

pre_amp: | Controls the amplitude of the signal prior to the FX stage of the mixer (prior to lpf/hpf stages). Has slide opts. Default 1.
amp: | Controls the amplitude of the signal after the FX stage. Has slide opts. Default 1.
hpf: | Global hpf FX. Has slide opts. Default 0.
lpf: | Global lpf FX. Has slide opts. Default 135.5.
hpf_bypass: | Bypass the global hpf. 0=no bypass, 1=bypass. Default 0.
lpf_bypass: | Bypass the global lpf. 0=no bypass, 1=bypass. Default 0.
limiter_bypass: | Bypass the final limiter. 0=no bypass, 1=bypass. Default 0.
leak_dc_bypass: | Bypass the final DC leak correction FX. 0=no bypass, 1=bypass. Default 0.

## Example

# Example 1
``
    set_mixer_control! lpf: 30, lpf_slide: 16
| ``
    # slide the global lpf to 30 over 16 beats.