diff --git a/noisicaa/audioproc/filter/scale.py b/noisicaa/audioproc/filter/scale.py
index e327cde7..5507af57 100644
--- a/noisicaa/audioproc/filter/scale.py
+++ b/noisicaa/audioproc/filter/scale.py
@@ -16,8 +16,8 @@ class Scale(Node):
     desc.port('out', 'output', 'audio')
     desc.parameter('factor', 'float')
 
-    def __init__(self, factor):
-        super().__init__('scale(%.2f)' % factor)
+    def __init__(self, event_loop, factor):
+        super().__init__(event_loop, name='scale(%.2f)' % factor)
 
         self._input = AudioInputPort('in')
         self.add_input(self._input)
diff --git a/noisicaa/audioproc/filter/scale_test.py b/noisicaa/audioproc/filter/scale_test.py
index 5d0c6b9c..995a219a 100644
--- a/noisicaa/audioproc/filter/scale_test.py
+++ b/noisicaa/audioproc/filter/scale_test.py
@@ -16,7 +16,7 @@ class ScaleTest(asynctest.TestCase):
         source = WhiteNoiseSource()
         pipeline.add_node(source)
 
-        node = scale.Scale(0.5)
+        node = scale.Scale(self.loop, 0.5)
         pipeline.add_node(node)
         node.inputs['in'].connect(source.outputs['out'])
         await node.setup()
diff --git a/noisicaa/music/project_client_test.py b/noisicaa/music/project_client_test.py
index f667135a..79d68130 100644
--- a/noisicaa/music/project_client_test.py
+++ b/noisicaa/music/project_client_test.py
@@ -51,7 +51,6 @@ class TestProjectProcess(
         project_process.ProjectProcessMixin, TestProjectProcessImpl):
     pass
 
-
 class ProxyTest(asynctest.TestCase):
     async def setUp(self):
         self.project_process = TestProjectProcess(self.loop)
diff --git a/noisicaa/music/project_process.py b/noisicaa/music/project_process.py
index a9896b92..f63fa4bd 100644
--- a/noisicaa/music/project_process.py
+++ b/noisicaa/music/project_process.py
@@ -62,7 +62,9 @@ class ProjectProcessMixin(object):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
+        self.audioproc_address = None
         self.audioproc_client = None
+        self.audiostream_address = None
 
     async def setup(self):
         await super().setup()
@@ -82,17 +84,10 @@ class ProjectProcessMixin(object):
         self.sessions = {}
         self.pending_mutations = []
 
-        self.audioproc_address = await self.manager.call(
-            'CREATE_AUDIOPROC_PROCESS', 'project-%s' % id(self))
-        self.audioproc_client = AudioProcClient(
-            self.event_loop, self.server)
-        await self.audioproc_client.setup()
-        await self.audioproc_client.connect(self.audioproc_address)
+        await self.createAudioProcProcess()
 
-        nid = await self.audioproc_client.add_node('wavfile', path='/usr/share/sounds/purple/logout.wav', loop=True)
-        await self.audioproc_client.connect_ports(nid, 'out', 'sink', 'in')
-
-        self.audiostream_address = await self.audioproc_client.set_backend('ipc')
+    async def createAudioProcProcess(self):
+        pass
 
     async def cleanup(self):
         if self.audioproc_client is not None:
@@ -247,4 +242,16 @@ class ProjectProcessMixin(object):
 
 
 class ProjectProcess(ProjectProcessMixin, core.ProcessImpl):
-    pass
+    async def createAudioProcProcess(self):
+        self.audioproc_address = await self.manager.call(
+            'CREATE_AUDIOPROC_PROCESS', 'project-%s' % id(self))
+        self.audioproc_client = AudioProcClient(
+            self.event_loop, self.server)
+        await self.audioproc_client.setup()
+        await self.audioproc_client.connect(self.audioproc_address)
+
+        nid = await self.audioproc_client.add_node('wavfile', path='/usr/share/sounds/purple/logout.wav', loop=True)
+        await self.audioproc_client.connect_ports(nid, 'out', 'sink', 'in')
+
+        self.audiostream_address = await self.audioproc_client.set_backend('ipc')
+
diff --git a/noisicaa/ui/editor_app.py b/noisicaa/ui/editor_app.py
index d79e758c..11008be8 100644
--- a/noisicaa/ui/editor_app.py
+++ b/noisicaa/ui/editor_app.py
@@ -121,16 +121,7 @@ class BaseEditorApp(QApplication):
         self.show_edit_areas_action.setChecked(
             int(self.settings.value('dev/show_edit_areas', '0')))
 
-        self.audioproc_process = await self.process.manager.call(
-            'CREATE_AUDIOPROC_PROCESS', 'main')
-
-        self.audioproc_client = AudioProcClient(
-            self.process.event_loop, self.process.server)
-        await self.audioproc_client.setup()
-        await self.audioproc_client.connect(self.audioproc_process)
-
-        await self.audioproc_client.set_backend(
-            self.settings.value('audio/backend', 'pyaudio'))
+        await self.createAudioProcProcess()
 
     async def cleanup(self):
         logger.info("Cleaning up.")
@@ -161,6 +152,9 @@ class BaseEditorApp(QApplication):
     def createMidiHub(self):
         return devices.MidiHub(self.sequencer)
 
+    async def createAudioProcProcess(self):
+        pass
+
     def dumpSettings(self):
         for key in self.settings.allKeys():
             value = self.settings.value(key)
@@ -284,3 +278,15 @@ class EditorApp(BaseEditorApp):
         # and the console interprets it as UTF-8), 'aconnectgui' shows the
         # encoded bytes.
         return devices.AlsaSequencer('noisicaä')
+
+    async def createAudioProcProcess(self):
+        self.audioproc_process = await self.process.manager.call(
+            'CREATE_AUDIOPROC_PROCESS', 'main')
+
+        self.audioproc_client = AudioProcClient(
+            self.process.event_loop, self.process.server)
+        await self.audioproc_client.setup()
+        await self.audioproc_client.connect(self.audioproc_process)
+
+        await self.audioproc_client.set_backend(
+            self.settings.value('audio/backend', 'pyaudio'))