# Tutoral 12: SynthDefs

FoxDot creates music by giving player objects a 'digital instrument'
to play, which are called 'SynthDefs'. You can see the list of pre-installed
'Synths' by executing

``` python
print(SynthDefs)
```

Each one of these represents a `SynthDef` *object*. These objects are then
given to Players to play - like giving an instrument to someone in your
orchestra.

Writing your own Synth Definitions

This is a bit more advanced, but if you have already written SynthDefs in
Supercollider then you might feel at home.  If not, come back to this section
later.

FoxDot can access any SynthDef stored on the SuperCollider server,
but it needs to know it's there. If you have already written a SynthDef
in SuperCollider and named it `#!supercollider \mySynth` then you just create a SynthDef
instance using FoxDot like so:

``` python
mySynth = SynthDef("mySynth")
```

Using the same variable name in FoxDot as in SuperCollider for your SynthDef
is a good idea to avoid confusion. If you want to write (or edit) your own
SynthDef during run-time in FoxDot you can use a SuperCollider API by
importing the SCLang module. All FoxDot SynthDef objects inherit the
base-class behaviour, such as low- and high-pass filters and vibrato,
but these can be overridden or updated easily. If you want to know more
about digital sound processing and SynthDef creation, check out the
SuperCollider documentation. Below is an example of creating one in FoxDot:

Import module for writing SCLang code from Python

``` python
from SCLang import *
```

Create a SynthDef named 'example' (using the same variable name as the SynthDef name is a good idea)

``` python
example = SynthDef("example")
```

Create the oscillator (osc) using a sine wave

``` python
example.osc = SinOsc.ar(ex.freq)
```

And give it a percussive sound envelope (env)

``` python
example.env = Env.perc()
```

Finally, store it!

``` python
example.add()
```

How to create a SynthDef

``` python
with SynthDef("pads") as pads:
    pads.osc = SinOsc.ar(pads.freq)
    pads.env = Env.perc()
```

Equivalent to

``` python
pads = SynthDef("pads")
pads.osc = SinOsc.ar(pads.freq)
pads.env = Env.perc()
pads.add()
```