title: AudioKit AK3DPanner not working
body: <p>I've been playing aroung with AudioKit v3.3 lately for a new project and am hitting a wall with the 3D spatialization node called AK3DPanner. At one point I got it to run, although it seemed extremely crude, either playing all sound in the left or the right ear. Not at all what one would expect.</p>
  
  <p>In any case, the issue now it that it fails to even start. Putting this in a playground should work s far as I can tell, but it crashes:</p>
  
  <pre><code>let drip = AKDrip(intensity: 1)
  let pan = AK3DPanner(drip)
  AudioKit.output = pan
  
  AudioKit.start() // Crashes here
  
  drip.start()
  
  AKPlaygroundLoop(every: 1) {
      drip.trigger()
  }
  </code></pre>
  
  <p>The console logs this:</p>
  
  <pre><code>2016-09-13 13:52:52.395 FM Oscillator Operation[54225:910643] 13:52:52.395 ERROR:    AVAudioEngineGraph.mm:2510: PerformCommand: error -10875
  2016-09-13 13:52:52.398 FM Oscillator Operation[54225:910643] *** Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'error -10875'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x000000010f22bd85 __exceptionPreprocess + 165
      1   libobjc.A.dylib                     0x000000010ec9fdeb objc_exception_throw + 48
      2   CoreFoundation                      0x000000010f22bbea +[NSException raise:format:arguments:] + 106
      3   libAVFAudio.dylib                   0x000000011c566ff3 _Z19AVAE_RaiseExceptionP8NSStringz + 176
      4   libAVFAudio.dylib                   0x000000011c5783fb _ZNK18AVAudioEngineGraph14PerformCommandER11AUGraphNodeNS_12ENodeCommandEPvj + 1571
      5   libAVFAudio.dylib                   0x000000011c581bcd _ZNSt3__110__function6__funcIZN13AUGraphParser34InitializeActiveNodesInOutputChainER18AVAudioEngineGraph14ETraversalModeR11AUGraphNodeRbE3$_8NS_9allocatorIS9_EEF16ETraversalStatusS7_P17AUGraphConnectionEEclES7_OSE_ + 231
      6   libAVFAudio.dylib                   0x000000011c582c2f _ZNKSt3__18functionIF16ETraversalStatusR11AUGraphNodeP17AUGraphConnectionEEclES3_S5_ + 31
      7   libAVFAudio.dylib                   0x000000011c575208 _ZN13AUGraphParser18TraverseGraphNodesERK18AVAudioEngineGraph10EDirection10ERecursionR11AUGraphNodeP17AUGraphConnectionRKNSt3__18functionIF16ETraversalStatusS6_S8_EEE + 48
      8   libAVFAudio.dylib                   0x000000011c5762bb _ZN13AUGraphParser34InitializeActiveNodesInOutputChainER18AVAudioEngineGraph14ETraversalModeR11AUGraphNodeRb + 833
      9   libAVFAudio.dylib                   0x000000011c57921f _ZN18AVAudioEngineGraph10InitializeEv + 1031
      10  libAVFAudio.dylib                   0x000000011c5b12b5 _ZN17AVAudioEngineImpl10InitializeEv + 29
      11  libAVFAudio.dylib                   0x000000011c5b0827 -[AVAudioEngine prepare] + 58
      12  AudioKit                            0x000000011d23fb92 _TZFC8AudioKit8AudioKit5startfT_T_ + 258
      13  ???                                 0x000000011a3f86d5 0x0 + 4735338197
      14  FM Oscillator Operation             0x000000010e72fab0 main + 0
      15  FM Oscillator Operation             0x000000010e7329a1 _TTRXFo__dT__XFo_iT__iT__ + 17
      16  FM Oscillator Operation             0x000000010e732401 _TPA__TTRXFo__dT__XFo_iT__iT__ + 81
      17  FM Oscillator Operation             0x000000010e7329d0 _TTRXFo_iT__iT__XFo__dT__ + 32
      18  FM Oscillator Operation             0x000000010e732a07 _TTRXFo__dT__XFdCb__dT__ + 39
      19  CoreFoundation                      0x000000010f1512ec __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
      20  CoreFoundation                      0x000000010f146f75 __CFRunLoopDoBlocks + 341
      21  CoreFoundation                      0x000000010f1466d2 __CFRunLoopRun + 850
      22  CoreFoundation                      0x000000010f1460f8 CFRunLoopRunSpecific + 488
      23  GraphicsServices                    0x0000000115d0bad2 GSEventRunModal + 161
      24  UIKit                               0x000000010f5e1f09 UIApplicationMain + 171
      25  FM Oscillator Operation             0x000000010e72ff39 main + 1161
      26  libdyld.dylib                       0x0000000111f7192d start + 1
      27  ???                                 0x0000000000000001 0x0 + 1
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  </code></pre>
  
  <p>Furthermore, if I <code>print(AudioKit.engine)</code> right before the crash I get this:</p>
  
  <pre><code>________ GraphDescription ________
  AVAudioEngineGraph 0x7f97d9437f40: initialized = 0, running = 0, number of nodes = 3
  
       ******** output chain ********
  
       node 0x7f97d9611d90 {'auou' 'rioc' 'appl'}, 'U'
           inputs = 1
               (bus0) &lt;- (bus0) 0x7f97d943c910, {'aumx' '3dem' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
  
       node 0x7f97d943c910 {'aumx' '3dem' 'appl'}, 'U'
           inputs = 33
               (bus0) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus1) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus2) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus3) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus4) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus5) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus6) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus7) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus8) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus9) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus10) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus11) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus12) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus13) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus14) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus15) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus16) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus17) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus18) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus19) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus20) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus21) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus22) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus23) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus24) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus25) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus26) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus27) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus28) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus29) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus30) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus31) &lt;- (bus0) 0x0, {}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
               (bus32) &lt;- (bus0) 0x7f97d9437780, {'augn' 'drip' 'AuKt'}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
           outputs = 1
               (bus0) -&gt; (bus0) 0x7f97d9611d90, {'auou' 'rioc' 'appl'}, [ 2 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
  
       node 0x7f97d9437780 {'augn' 'drip' 'AuKt'}, 'U'
           outputs = 1
               (bus0) -&gt; (bus32) 0x7f97d943c910, {'aumx' '3dem' 'appl'}, [ 1 ch,  44100 Hz, 'lpcm' (0x00000029) 32-bit little-endian float, deinterleaved]
  ______________________________________
  </code></pre>
  
  <p>I should note also that I always get this error when running the AudioKit playgrounds, but things still always work:</p>
  
  <pre><code>2016-09-13 13:52:52.364 FM Oscillator Operation[54225:910777] 13:52:52.363 WARNING:  40: ERROR: couldn't get default input device, ID = 0, err = 0!
  2016-09-13 13:52:52.375 FM Oscillator Operation[54225:910777] 13:52:52.375 WARNING:  803: The default input device 0x0 '(null)' has no input channels.
  </code></pre>
  
  <p>Finally, if I remove the panner node like below, it works fine:</p>
  
  <pre><code>let drip = AKDrip(intensity: 1)
  AudioKit.output = drip
  
  AudioKit.start()
  
  drip.start()
  
  AKPlaygroundLoop(every: 1) {
      drip.trigger()
  }
  </code></pre>
  
  <p>Very grateful for any insight on this. Since binaural audio is crucial for the project, we need to switch audio engines if we can't figure this one out!</p>