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# Mixer effects

## Crossfeed

Listening to audio on headphones where certain sounds are only present in either the left or the right channel can be a rather distracting and unpleasant experience. This is most noticeable on Dual OPL and CMS (Game Blaster) game soundtracks where instruments are hard-panned 100% left or 100% right in the stereo field.

Crossfeed remedies this by mixing a portion of the left channel’s signal into the right channel, and vice versa, creating a more natural listening experience. The default crossfeed strength is 40%, which is a good general setting.

The crossfeed presets only apply to the OPL and CMS mixer channels by default, as these are the two devices that typically feature hard-panned sounds. You can apply crossfeed to other channels as well with the DOSBox mixer `MIXER` command (e.g., `MIXER GUS x50`).

`off`
  No crossfeed (default).
`on`
  Enables the `normal` preset.
`light`
  Light crossfeed (strength 15).
`normal`
  Normal crossfeed (strength 40).
`strong`
  Strong crossfeed (strength 65).

You can fine-tune per-channel crossfeed levels via mixer commands.

## Reverb

Enable reverb globally to add a sense of space to the sound:

`off`
  No reverb (default).
`on`
  Enables the `medium` preset.
`tiny`
  Simulates the sound of a small integrated speaker in a room; specifically designed for small-speaker audio systems (PC Speaker, Tandy, PS/1 Audio, and LPT DAC devices).
`small`
  Adds a subtle sense of space; good for games that use a single synth channel (typically OPL) for both music and sound effects.
`medium`
  Medium room preset that works well with a wide variety of games.
`large`
  Large hall preset recommended for games that use separate channels for music and digital audio.
`huge`
  A stronger variant of the large hall preset; works really well in some games with more atmospheric soundtracks.

You can fine-tune per-channel reverb levels via mixer commands.

## Chorus

Enable chorus globally to add a sense of stereo movement to the sound:

`off`
  No chorus (default).
`on`
  Enable chorus (normal preset).
`light`
  A light chorus effect (especially suited for synth music that features lots of white noise.)
`normal`
  Normal chorus that works well with a wide variety of games.
`strong`
  An obvious and upfront chorus effect.

You can fine-tune per-channel chorus levels via mixer commands.

## Combining effects

Crossfeed, reverb, and chorus can be combined, and doing so is highly recommended for achieving the best results. Together with the analog output filters, these effects can give old DOS game soundtracks a new life.

Suggested audio configurations for many games are available on the wiki.

## Configuration settings

Mixer effects settings are to be configured in the `[mixer]` section.

##### crossfeed

  Set crossfeed on the OPL and CMS (Game Blaster) mixer channels. Many games pan the instruments 100% left and 100% right in the stereo field on these audio devices which is unpleasant to listen to in headphones. With crossfeed enabled, a portion of the left channel signal is mixed into the right channel and vice versa, creating a more natural listening experience.

  Possible values:

  - `off` default – No crossfeed.
  - `on` – Enable crossfeed (normal preset).
  - `light` – Light crossfeed (strength 15).
  - `normal` – Normal crossfeed (strength 40).
  - `strong` – Strong crossfeed (strength 65).

  Note

  Use the `MIXER` command to apply crossfeed to other audio channels as well and to fine-tune the crossfeed strength per channel.

##### reverb

  Reverb effect that adds a sense of space to the sound.

  Possible values:

  - `off` default – No reverb.
  - `on` – Enable reverb (medium preset).
  - `tiny` – Simulates the sound of a small integrated speaker in a room; specifically designed for small-speaker audio systems (PC speaker, Tandy, PS/1 Audio, and LPT DAC devices).
  - `small` – Adds a subtle sense of space; good for games that use a single synth channel (typically OPL) for both music and sound effects.
  - `medium` – Medium room preset that works well with a wide variety of games.
  - `large` – Large hall preset recommended for games that use separate channels for music and digital audio.
  - `huge` – A stronger variant of the large hall preset; works really well in some games with more atmospheric soundtracks.

  Note

  The presets apply a noticeable amount of reverb to the synth mixer channels (except for synths with built-in reverb, e.g., the Roland MT-32), and a subtle amount to the digital audio channels. Use the `MIXER` command to fine-tune the reverb levels per channel.

##### chorus

  Chorus effect that adds a sense of stereo movement to the sound.

  Possible values:

  - `off` default – No chorus.
  - `on` – Enable chorus (normal preset).
  - `light` – A light chorus effect (especially suited for synth music that features lots of white noise).
  - `normal` – Normal chorus that works well with a wide variety of games.
  - `strong` – An obvious and upfront chorus effect.

  Note

  The presets apply the chorus effect to the synth channels only (except for synths with built-in chorus, e.g., the Roland MT-32). Use the `MIXER` command to fine-tune the chorus levels per channel.