diff --git a/app/lib/soundtouch.js b/app/lib/soundtouch.js
index 09b75684..26e9559f 100644
--- a/app/lib/soundtouch.js
+++ b/app/lib/soundtouch.js
@@ -41,6 +41,7 @@ FifoSampleBuffer.prototype.clear = function() {
 // TODO(TECHDEBT): window.BUFFER_SIZE set by mix builder
 window.MAX_BUFFER_SIZE = 16384;
 window.BUFFER_SIZE = window.MAX_BUFFER_SIZE / 8;
+const DSP_BUFFER_LENGTH = 128;
 const SAMPLE_DRIFT_TOLERANCE = 512;
 
 export function SoundtouchBufferSource(buffer) {
@@ -69,8 +70,7 @@ SoundtouchBufferSource.prototype = {
   }
 };
 
-// TODO(TRACKMULTIGRID): audioBpm not a constant
-export function createSoundtouchNode({ audioContext, filter, startTime, offsetTime, endTime, audioBpm, defaultPitch }) {
+export function createSoundtouchNode({ audioContext, filter, startTime, offsetTime, endTime, defaultPitch }) {
   const channelCount = 2;
   const windowBufferSize = window.BUFFER_SIZE;
 
@@ -80,8 +80,6 @@ export function createSoundtouchNode({ audioContext, filter, startTime, offsetTi
     return;
   }
 
-  audioBpm = isValidNumber(audioBpm) ? audioBpm : 128; // TODO(TECHDEBT): share default bpm
-
   const samples = new Float32Array(windowBufferSize * channelCount);
   const sampleRate = audioContext.sampleRate || 44100;
   const startSample = ~~(offsetTime * sampleRate);
@@ -89,6 +87,7 @@ export function createSoundtouchNode({ audioContext, filter, startTime, offsetTi
   filter.sourcePosition = startSample;
 
   const filterStartPosition = filter.position;
+  const soundtouch = filter.pipe;
 
   function onaudioprocess({
     type,
@@ -103,14 +102,9 @@ export function createSoundtouchNode({ audioContext, filter, startTime, offsetTi
     const l = outputs[0][0];
     const r = outputs[0][1];
 
-    // naively take first pitch value for this sample
+    // TODO(MULTIGRID): average tempo, pitch across buffer
     const pitch = parameters.pitch && parameters.pitch[0];
-    const soundtouch = filter.pipe;
-
-    // TODO(MULTIGRID): need to minimize dspBufLength.
-    // is it possible to align dspBufLength with automation clip TICKs?
-    const syncBpm = parameters.bpm && parameters.bpm[0];
-    const tempo = (isValidNumber(syncBpm) && isValidNumber(audioBpm)) ? (syncBpm / audioBpm) : 1;
+    const tempo = parameters.tempo && parameters.tempo[0];
 
     if (isValidNumber(pitch)) {
       soundtouch.pitchSemitones = pitch;
@@ -173,14 +167,15 @@ export function createSoundtouchNode({ audioContext, filter, startTime, offsetTi
     numberOfInputs: 2,
     numberOfOutputs: 2,
     bufferLength: windowBufferSize,
+    dspBufLength: DSP_BUFFER_LENGTH,
     parameters: [
       {
         name: 'pitch',
         defaultValue: defaultPitch,
       },
       {
-        name: 'bpm',
-        defaultValue: 128,
+        name: 'tempo',
+        defaultValue: 1,
       },
       {
         name: 'isPlaying',
diff --git a/app/lib/web-audio/soundtouch-node.js b/app/lib/web-audio/soundtouch-node.js
index d2f8814a..9ac6d3e7 100644
--- a/app/lib/web-audio/soundtouch-node.js
+++ b/app/lib/web-audio/soundtouch-node.js
@@ -21,7 +21,7 @@ export default Ember.ObjectProxy.extend(
   outputNode: null,
 
   // TODO(V2): transpose dynamic
-  start(startTime, offsetTime, endTime, audioBpm, transpose) {
+  start(startTime, offsetTime, endTime, transpose) {
     // Ember.Logger.log('currentTime', this.get('audioContext.currentTime'));
     // Ember.Logger.log('startSource', startTime, offsetTime);
     this.stop();
@@ -36,7 +36,6 @@ export default Ember.ObjectProxy.extend(
         startTime,
         offsetTime,
         endTime,
-        audioBpm,
         defaultPitch: transpose,
       });
       this.set('node', node);
diff --git a/app/mixins/playable-arrangement.js b/app/mixins/playable-arrangement.js
index ae8b9991..df92b8d9 100644
--- a/app/mixins/playable-arrangement.js
+++ b/app/mixins/playable-arrangement.js
@@ -1,5 +1,7 @@
 import Ember from 'ember';
 
+import d3 from 'd3';
+
 import withDefault from 'linx/lib/computed/with-default';
 import Metronome from './playable-arrangement/metronome';
 import WebAudioMergerNode from 'linx/lib/web-audio/merger-node';
@@ -14,7 +16,7 @@ export default Ember.Mixin.create({
 
   // required params
   clips: null,
-  bpmScale: null, // or beatGrid
+  bpmControlPoints: null,
   audioContext: null,
 
   // optional params
@@ -57,6 +59,22 @@ export default Ember.Mixin.create({
     'beatGrid': 'beatGrid',
   }),
 
+  bpmScale: Ember.computed('bpmControlPoints.@each.{beat,value}', 'beatCount', function() {
+    const beatCount = this.get('beatCount');
+    const bpmControlPoints = this.get('bpmControlPoints');
+
+    const bpmControlBeats = bpmControlPoints.mapBy('beat');
+    const bpmControlValues = bpmControlPoints.mapBy('value');
+
+    const firstBpmValue = bpmControlValues.get('firstObject');
+    const lastBpmValue = bpmControlValues.get('lastObject');
+
+    return d3.scale.linear()
+      .domain([0].concat(bpmControlBeats).concat([beatCount]))
+      .range([firstBpmValue].concat(bpmControlValues).concat([lastBpmValue]))
+      .clamp(true);
+  }),
+
   beatGrid: Ember.computed('bpmScale', 'beatCount', 'timeSignature', function() {
     return BeatGrid.create(this.getProperties('bpmScale', 'beatCount', 'timeSignature'));
   }),
diff --git a/app/mixins/playable-arrangement/automatable-clip/control.js b/app/mixins/playable-arrangement/automatable-clip/control.js
index 25853065..2f870314 100644
--- a/app/mixins/playable-arrangement/automatable-clip/control.js
+++ b/app/mixins/playable-arrangement/automatable-clip/control.js
@@ -7,7 +7,8 @@ import RequireAttributes from 'linx/lib/require-attributes';
 import { isValidNumber } from 'linx/lib/utils';
 
 export const CONTROL_TYPE_VOLUME = 'gain';
-export const CONTROL_TYPE_BPM = 'bpm';
+export const CONTROL_TYPE_BPM = 'bpm'; // currently only exists in transition
+export const CONTROL_TYPE_TEMPO = 'tempo';
 export const CONTROL_TYPE_PITCH = 'pitch';
 export const CONTROL_TYPE_DELAY_WET = 'delay-wet';
 export const CONTROL_TYPE_DELAY_CUTOFF = 'delay-cutoff';
@@ -17,6 +18,7 @@ export const CONTROL_TYPE_FILTER_LOWPASS_CUTOFF = 'filter-lowpass-cutoff';
 export const CONTROL_TYPES = [
   CONTROL_TYPE_VOLUME,
   CONTROL_TYPE_BPM,
+  CONTROL_TYPE_TEMPO,
   CONTROL_TYPE_PITCH,
   CONTROL_TYPE_DELAY_WET,
   CONTROL_TYPE_DELAY_CUTOFF,
diff --git a/app/mixins/playable-arrangement/track-clip.js b/app/mixins/playable-arrangement/track-clip.js
index a94dd6d3..34609c68 100644
--- a/app/mixins/playable-arrangement/track-clip.js
+++ b/app/mixins/playable-arrangement/track-clip.js
@@ -24,7 +24,7 @@ import {
 import {
   default as AutomatableClipControlMixin,
   CONTROL_TYPE_VOLUME,
-  CONTROL_TYPE_BPM,
+  CONTROL_TYPE_TEMPO,
   CONTROL_TYPE_PITCH,
   CONTROL_TYPE_DELAY_WET,
   CONTROL_TYPE_DELAY_CUTOFF,
@@ -43,11 +43,11 @@ const TrackVolumeControl = Ember.Object.extend(
   defaultValue: 1,
 });
 
-const TrackBpmControl = Ember.Object.extend(
-  AutomatableClipControlMixin('soundtouchNode.bpm'), {
+const TrackTempoControl = Ember.Object.extend(
+  AutomatableClipControlMixin('soundtouchNode.tempo'), {
 
-  type: CONTROL_TYPE_BPM,
-  defaultValue: 128, // TODO(TECHDEBT): bpm default constant used in many places
+  type: CONTROL_TYPE_TEMPO,
+  defaultValue: 1,
 });
 
 const TrackPitchControl = Ember.Object.extend(
@@ -110,7 +110,7 @@ export default Ember.Mixin.create(
   controls: Ember.computed(function() {
     return [
       TrackVolumeControl.create({ clip: this }),
-      TrackBpmControl.create({ clip: this }),
+      TrackTempoControl.create({ clip: this }),
       TrackPitchControl.create({ clip: this }),
       TrackDelayWetControl.create({ clip: this }),
       TrackDelayCutoffControl.create({ clip: this }),
@@ -140,7 +140,6 @@ export default Ember.Mixin.create(
   audioBeatCount: subtract('audioEndBeat', 'audioStartBeat'),
   audioDuration: subtract('audioEndTime', 'audioStartTime'),
   audioBarCount: subtract('audioEndBar', 'audioStartBar'),
-  audioBpm: Ember.computed.reads('audioMeta.bpm'),
 
   getCurrentAudioBeat() {
     const currentClipBeat = this.getCurrentClipBeat();
@@ -163,14 +162,13 @@ export default Ember.Mixin.create(
     return audioBeatGrid.beatToTime(audioStartBeat + clipBeat);
   },
 
-  // TODO(TRACKMULTIGRID): audioBpm not constant
-  audioScheduleDidChange: Ember.observer('audioBinary.isReady', 'audioStartBeat', 'audioBeatCount', 'audioBpm', 'transpose', 'gain', function() {
+  audioScheduleDidChange: Ember.observer('audioBinary.isReady', 'audioStartBeat', 'audioBeatCount', 'transpose', 'gain', function() {
     Ember.run.once(this, 'startSource');
   }).on('schedule'),
 
   startSource() {
     if (this.get('isScheduled') && this.get('audioBinary.isReady')) {
-      const { audioBpm, transpose } = this.getProperties('audioBpm', 'transpose');
+      const { transpose } = this.getProperties('transpose');
       // if starting in past, start now instead
       let startTime = Math.max(this.getAbsoluteTime(), this.getAbsoluteStartTime());
       let offsetTime = this.getCurrentAudioTime();
@@ -184,7 +182,7 @@ export default Ember.Mixin.create(
 
       Ember.Logger.log('startTrack', this.get('track.title'), startTime, offsetTime, endTime, transpose);
       const node = this.get('soundtouchNode');
-      node && node.start(startTime, offsetTime, endTime, audioBpm, transpose);
+      node && node.start(startTime, offsetTime, endTime, transpose);
     } else {
       this.stopSource();
     }
diff --git a/app/models/mix.js b/app/models/mix.js
index b4cfeeb7..56973ab8 100644
--- a/app/models/mix.js
+++ b/app/models/mix.js
@@ -13,7 +13,7 @@ import { flatten, isValidNumber } from 'linx/lib/utils';
 export default DS.Model.extend(
   CrudMixin,
   PlayableArrangementMixin,
-  OrderedHasManyMixin('_mixItems'), {
+  new OrderedHasManyMixin('_mixItems'), {
 
   // implement ordered has many
   orderedHasManyItemModelName: 'mix/item',
@@ -28,33 +28,7 @@ export default DS.Model.extend(
   // implement playable-arrangement
   session: Ember.inject.service(),
   audioContext: Ember.computed.reads('session.audioContext'),
-  bpmScale: Ember.computed('_bpmControlPoints.@each.{beat,value}', 'beatCount', function() {
-    const beatCount = this.get('beatCount');
-    const bpmControlPoints = this.get('_bpmControlPoints');
-
-    const bpmControlBeats = bpmControlPoints.mapBy('beat');
-    const bpmControlValues = bpmControlPoints.mapBy('value');
-
-    const firstBpmValue = bpmControlValues.get('firstObject');
-    const lastBpmValue = bpmControlValues.get('lastObject');
-
-    return d3.scale.linear()
-      .domain([0].concat(bpmControlBeats).concat([beatCount]))
-      .range([firstBpmValue].concat(bpmControlValues).concat([lastBpmValue]))
-      .clamp(true);
-  }),
-
-  tracks: Ember.computed.mapBy('items', 'track'),
-  transitions: Ember.computed.mapBy('items', 'transition'),
-
-  trackClips: Ember.computed.mapBy('items', 'trackClip'),
-  transitionClips: Ember.computed.mapBy('items', 'transitionClip'),
-  clips: Ember.computed.uniq('trackClips', 'transitionClips'),
-
-  _transitionBpmControlPoints: Ember.computed('transitions.@each.bpmControlPoints', function() {
-    return flatten(this.get('transitions').without(undefined).mapBy('bpmControlPoints')).without(undefined);
-  }),
-  _bpmControlPoints: Ember.computed('bpm',
+  bpmControlPoints: Ember.computed('bpm',
     '_transitionBpmControlPoints.@each.{beat,value,transitionStartBeat}', function() {
     const bpmControlPoints = this.get('_transitionBpmControlPoints');
 
@@ -84,6 +58,17 @@ export default DS.Model.extend(
     }
   }),
 
+  tracks: Ember.computed.mapBy('items', 'track'),
+  transitions: Ember.computed.mapBy('items', 'transition'),
+
+  trackClips: Ember.computed.mapBy('items', 'trackClip'),
+  transitionClips: Ember.computed.mapBy('items', 'transitionClip'),
+  clips: Ember.computed.uniq('trackClips', 'transitionClips'),
+
+  _transitionBpmControlPoints: Ember.computed('transitions.@each.bpmControlPoints', function() {
+    return flatten(this.get('transitions').without(undefined).mapBy('bpmControlPoints')).without(undefined);
+  }),
+
   trackAt(index) {
     const item = this.objectAt(index);
     return item && item.get('track.content');
diff --git a/app/models/mix/transition.js b/app/models/mix/transition.js
index 92caa117..237c58ad 100644
--- a/app/models/mix/transition.js
+++ b/app/models/mix/transition.js
@@ -6,6 +6,7 @@ import _ from 'npm:underscore';
 import ReadinessMixin from 'linx/mixins/readiness';
 import PlayableArrangementMixin from 'linx/mixins/playable-arrangement';
 import DependentRelationshipMixin from 'linx/mixins/models/dependent-relationship';
+import withDefaultModel from 'linx/lib/computed/with-default-model';
 
 import {
   CONTROL_TYPE_VOLUME,
@@ -19,10 +20,12 @@ import { isValidNumber } from 'linx/lib/utils';
 
 export default DS.Model.extend(
   PlayableArrangementMixin,
-  DependentRelationshipMixin('fromTrackAutomationClips'),
-  DependentRelationshipMixin('toTrackAutomationClips'),
-  DependentRelationshipMixin('bpmClip'),
-  ReadinessMixin('isTransitionReady'), {
+  new DependentRelationshipMixin('fromTrackAutomationClips'),
+  new DependentRelationshipMixin('toTrackAutomationClips'),
+  new DependentRelationshipMixin('fromTrackTempoClip'),
+  new DependentRelationshipMixin('toTrackTempoClip'),
+  new DependentRelationshipMixin('bpmClip'),
+  new ReadinessMixin('isTransitionReady'), {
 
   title: DS.attr('string'),
   description: DS.attr('string'),
@@ -33,21 +36,37 @@ export default DS.Model.extend(
   fromTrackClip: Ember.computed.reads('transitionClip.fromTrackClip'),
   toTrackClip: Ember.computed.reads('transitionClip.toTrackClip'),
 
+  _fromTrackTempoClip: DS.belongsTo('mix/transition/from-track-tempo-clip', { async: true }),
+  fromTrackTempoClip: withDefaultModel('_fromTrackTempoClip', function() {
+    return this.get('store').createRecord('mix/transition/from-track-tempo-clip', {
+      transition: this,
+    });
+  }),
+
+  _toTrackTempoClip: DS.belongsTo('mix/transition/to-track-tempo-clip', { async: true }),
+  toTrackTempoClip: withDefaultModel('_toTrackTempoClip', function() {
+    return this.get('store').createRecord('mix/transition/to-track-tempo-clip', {
+      transition: this,
+    });
+  }),
+
   fromTrackAutomationClips: DS.hasMany('mix/transition/from-track-automation-clip'),
   toTrackAutomationClips: DS.hasMany('mix/transition/to-track-automation-clip'),
 
   // implementing PlayableArrangement
   audioContext: Ember.computed.reads('transitionClip.audioContext'),
   outputNode: Ember.computed.reads('transitionClip.outputNode.content'),
-  clips: Ember.computed.uniq('fromTrackAutomationClips', 'toTrackAutomationClips', '_bpmClips'),
-  beatGrid: Ember.computed.reads('transitionClip.mix.beatGrid'),
+  clips: Ember.computed.uniq('fromTrackAutomationClips', 'toTrackAutomationClips', '_tempoClips'),
+  bpmControlPoints: Ember.computed.reads('bpmClip.controlPoints'),
 
-  _bpmClips: Ember.computed('bpmClip', function() {
-    return [this.get('bpmClip')].filter((clip) => !!clip);
+  _tempoClips: Ember.computed('bpmClip', 'fromTrackTempoClip', 'toTrackTempoClip', function() {
+    return [
+      this.get('bpmClip'),
+      this.get('fromTrackTempoClip'),
+      this.get('toTrackTempoClip'),
+    ].filter((clip) => !!clip);
   }),
 
-  bpmControlPoints: Ember.computed.reads('bpmClip.controlPoints'),
-
   // optimizes this transition, with given constraints
   // TODO(REFACTOR2): rethink this. convert to ember-concurrency
   optimize({
@@ -211,7 +230,7 @@ export default DS.Model.extend(
         // TODO(TRACKMULTIGRID): needs update
         let fromTrackBpm = this.get('fromTrackClip.track.audioMeta.bpm');
         fromTrackBpm = isValidNumber(fromTrackBpm) ? fromTrackBpm : 128;
-        let toTrackBpm = this.get('fromTrackClip.track.audioMeta.bpm')
+        let toTrackBpm = this.get('fromTrackClip.track.audioMeta.bpm');
         toTrackBpm = isValidNumber(toTrackBpm) ? toTrackBpm : fromTrackBpm;
 
         bpmClip.addControlPoints([
diff --git a/app/models/mix/transition/automation-clip.js b/app/models/mix/transition/automation-clip.js
index 5c595773..c5d1f415 100644
--- a/app/models/mix/transition/automation-clip.js
+++ b/app/models/mix/transition/automation-clip.js
@@ -15,14 +15,14 @@ export default AutomationClip.extend({
   _controlPoints: DS.hasMany('mix/transition/automation-clip/control-point', { async: true }),
 
   arrangement: Ember.computed.reads('transition'),
-  beatCount: Ember.computed.reads('transition.beatCount'),
+  transitionBeatCount: Ember.computed.reads('transition.beatCount'),
 
   // transition automation-clip must have controlPoints within transition
-  _updateControlPoints: Ember.observer('beatCount', function() {
-    const beatCount = this.get('beatCount')
-    // Ember.Logger.log('_updateControlPoints', beatCount);
+  _updateControlPoints: Ember.observer('transitionBeatCount', function() {
+    const transitionBeatCount = this.get('transitionBeatCount')
+    // Ember.Logger.log('_updateControlPoints', transitionBeatCount);
 
-    if (isValidNumber(beatCount)) {
+    if (isValidNumber(transitionBeatCount)) {
       this.get('controlPoints').forEach((controlPoint) => {
         const oldBeat = controlPoint.get('beat');
 
@@ -30,9 +30,9 @@ export default AutomationClip.extend({
         if (controlPoint.get('isFirstItem')) {
           newBeat = 0;
         } else if (controlPoint.get('isLastItem')) {
-          newBeat = beatCount;
+          newBeat = transitionBeatCount;
         } else {
-          newBeat = clamp(0, oldBeat, beatCount);
+          newBeat = clamp(0, oldBeat, transitionBeatCount);
         }
 
         controlPoint.set('beat', newBeat);
diff --git a/app/models/mix/transition/from-track-automation-clip.js b/app/models/mix/transition/from-track-automation-clip.js
index 97bf6b33..f272542f 100644
--- a/app/models/mix/transition/from-track-automation-clip.js
+++ b/app/models/mix/transition/from-track-automation-clip.js
@@ -4,7 +4,6 @@ import DS from 'ember-data';
 import MixTransitionAutomationClip from './automation-clip';
 
 export default MixTransitionAutomationClip.extend({
-  transition: DS.belongsTo('mix/transition'),
 
   // overrides
   targetClip: Ember.computed.reads('transition.fromTrackClip'),
diff --git a/app/models/mix/transition/from-track-tempo-clip.js b/app/models/mix/transition/from-track-tempo-clip.js
new file mode 100644
index 00000000..87b822ae
--- /dev/null
+++ b/app/models/mix/transition/from-track-tempo-clip.js
@@ -0,0 +1,10 @@
+import Ember from 'ember';
+import DS from 'ember-data';
+
+import MixTransitionTrackTempoClip from './track-tempo-clip';
+
+export default MixTransitionTrackTempoClip.extend({
+
+  // overrides
+  targetClip: Ember.computed.reads('transition.fromTrackClip'),
+});
diff --git a/app/models/mix/transition/to-track-automation-clip.js b/app/models/mix/transition/to-track-automation-clip.js
index 8feb4032..d6976edc 100644
--- a/app/models/mix/transition/to-track-automation-clip.js
+++ b/app/models/mix/transition/to-track-automation-clip.js
@@ -4,7 +4,6 @@ import DS from 'ember-data';
 import MixTransitionAutomationClip from './automation-clip';
 
 export default MixTransitionAutomationClip.extend({
-  transition: DS.belongsTo('mix/transition'),
 
   // overrides
   targetClip: Ember.computed.reads('transition.toTrackClip'),
diff --git a/app/models/mix/transition/to-track-tempo-clip.js b/app/models/mix/transition/to-track-tempo-clip.js
new file mode 100644
index 00000000..a41cce91
--- /dev/null
+++ b/app/models/mix/transition/to-track-tempo-clip.js
@@ -0,0 +1,10 @@
+import Ember from 'ember';
+import DS from 'ember-data';
+
+import MixTransitionTrackTempoClip from './track-tempo-clip';
+
+export default MixTransitionTrackTempoClip.extend({
+
+  // overrides
+  targetClip: Ember.computed.reads('transition.toTrackClip'),
+});
diff --git a/app/models/mix/transition/track-tempo-clip.js b/app/models/mix/transition/track-tempo-clip.js
new file mode 100644
index 00000000..89a66b5a
--- /dev/null
+++ b/app/models/mix/transition/track-tempo-clip.js
@@ -0,0 +1,24 @@
+import Ember from 'ember';
+import DS from 'ember-data';
+
+import MixTransitionAutomationClip from './automation-clip';
+import { CONTROL_TYPE_TEMPO } from 'linx/mixins/playable-arrangement/automatable-clip/control';
+
+export default MixTransitionAutomationClip.extend({
+
+  // overrides
+  targetClip: Ember.computed.reads('transition.toTrackClip'),
+  controlType: CONTROL_TYPE_TEMPO,
+  startBeat: 0,
+  endBeat: Ember.computed.reads('transition.beatCount'),
+
+  // map the transition's bpmScale onto track grid
+  // TODO(TRACKMULTIGRID): audioBpm not constant
+  scale: null, // compute off mixBpmScale, divide by audioBpm
+
+  startValue: 0, // compute off startBeat, scale
+  endValue: 0, // compute off endBeat, scale
+
+
+  transitionBpmScale: null,
+});