> For the complete documentation index, see [llms.txt](https://jjazzlab.gitbook.io/user-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jjazzlab.gitbook.io/user-guide/sounds/using-fluidsynth.md).

# Using FluidSynth

JJazzLab bundles a **ready-to-use** Fluidsynth instance **optimally configured** for rendering backing tracks. 

FluidSynth should be enabled by default when you first launch JJazzLab. You can check this in the **Midi Out** tab of the **Options/Preferences**, as shown in the image below.

On Linux and MacOS, it requires that FluidSynth was previously installed on the system. 

{% hint style="danger" %}
If FluidSynth appears disabled, it means that a problem occured while trying to load FluidSynth. Check the [**installation instructions**](/user-guide/installation.md)**.**
{% endhint %}

<figure><img src="/files/pHj9KlW002DpYq37FRW3" alt=""><figcaption></figcaption></figure>

Use the **Default instruments** button to define the FluidSynth instruments to be used by default when a new rhythm is used in a song.

### FluidSynth settings

Some FluidSynth settings can be adjusted via the dialog below.

* **gain**: change it only if adjusting the computer sound volume is not enough
* **audio latency**: change it if, when a song is playing, user interface changes are not in-sync with the sound
* **effects**: apply predefined settings
* **audio driver**: changing the audio driver is **not** recommended. However, on **Linux**, in some cases, it might help to solve an audio configuration issue.

<figure><img src="/files/QJkwfJRBGNPQ0GEb9B3N" alt=""><figcaption></figcaption></figure>

### FluidSynth open-source project

More info at [https://www.fluidsynth.org](https://www.fluidsynth.org/).