ER-301/Clocked Stretch

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Applications

  • Time-stretching a prepared loop (such as a drum loop) to a given tempo.
  • Auto-warping slices so that their durations match the beat (or a division/multiplication of the beat).

Description

This sample playing unit uses granular techniques to time-stretch (or compress) a sample in relation to the period of an incoming clock without changing its pitch. This unit is very similar to the ER-301/Grain Stretch unit except that here the playback speed is controlled by the incoming tempo clock.

Special Menu Operations

Select from Card

Activating this command will bring you directly to the file browser where you can select and load any audio file that resides on your (front) SD card. If the selected audio file is already loaded into the Sample Pool then this sample data will be re-used and attached to the unit, thereby preventing duplication and wasting of the RAM resources.

Select from Pool

Activating this command will bring you directly to the Sample Pool screen where you can select from any of the buffers already loaded or created. This is especially useful when you want to share audio buffers between units.

Detach

This command detaches the previously attached sample from this unit, effectively returning the unit to the state of having no sample assigned. Please keep in mind that the sample remains in the Sample Pool.

Slice

This command will bring up the sample slicer and editor screen. Here you can add/remove slices, auto-slice, trim, normalize, remove DC offset, silence selections, and add fades.

Play Duration

  • once: Upon receiving a trigger/gate, play once and then stop.
  • repeat: Repeat forever.
  • loop on gate hi: A kind of looping sustain for longer gates. As long as the trigger input is held high, repeat the looped portion (of the selected slice).

Play Extent

  • all: The play head traverses the entire sample.
  • slice: The play head only traverses the selected slice.

Stretch Duration

  • all: Always use the length of the entire sample to calculate the time stretch factor, regardless of the Play Extent setting.
  • slice: (Note to self: This probably should be called actual.) Use the actual length of the portion of the sample that will be played when calculating the time stretch factor. This could be the entire sample or just a slice depending on other settings.

Slice Polarity

This setting controls how playback direction affects the slice selection.

  • left: Forward and reverse playback will both use the slice to the left of the current selection.
  • symmetric Forward playback uses the right slice and reverse playback uses the left slice.
  • right: Forward and reverse playback will both use the slice to the right of the current selection.

CV-to-Slice Mapping

This setting determines how the slice parameter chooses (or maps to) actual slices.

  • nearest: The slice parameter value is mapped linearly to a sample position in the sample buffer (0 - beginning, 1 - ending) and the nearest slice is chosen.
  • index: The slice parameter is mapped linearly to a slice index (0 - first slice, 1 - last slice).
  • 12TET: The slice parameter is interpreted as a V/oct signal and each semitone is mapped to a slice (1st semitone - 1st slice, 2nd semitone - 2nd slice, and so on).

Parameters

clock

Control Type Has Sub-chain? Sub-chain Parameters Behavior
Threshold yes threshold (-1 to 1) trigger


The period of time between the last two pulses is used to determine the playback speed. The exact behavior depends on the Stretch Duration setting. When the 'Stretch Duration' is set to 'slice' then the playback speed will be set so that the current active slice (or the entire sample if no slices) has the same playback duration as the period of this (tempo) clock. When the setting is set to 'all', then regardless of the active slice, the speed will be set so that the entire sample's duration matches the period of this (tempo) clock.

Tip-bulb.png
This parameter only affects the playback speed. If you need to also sync playback to an incoming tempo clock then just assign the same clock signal to both this clock parameter and the gate parameter.


gate

Control Type Has Sub-chain? Sub-chain Parameters Behavior
Threshold yes threshold (-1 to 1) trigger or gate


A rising edge on this parameter will cause the play head to reset to either the beginning of the sample or the beginning of the currently selected slice. The exact meaning of the phrase "beginning of the currently selected slice" depends on the direction of the play head as well as the Slice Polarity setting. Playback continues normally afterwards.

If the Play Duration setting is "loop on gate high" then as long as this parameter receives a high value, the player will loop (i.e. sustain).

If the Play Count setting is "repeat" then a trigger on this parameter can be used to sync the loop to an external event.

slice

Control Type Has Sub-chain? Sub-chain Parameters Fader Scale
Gain/Bias yes gain (-3 to 3)

bias (0 to 1)

linear

This parameter selects a slice. The next incoming edge received at the gate parameter will activate this slice. The mapping of parameter value to the actual slice depends on the Address Mode setting.

Pitfall.png
If the external signal that is selecting the slice is delayed with respect to the trigger that is activating the slice, then you will experience inconsistent slice activation. The solution is to insert a small (~2ms) delay in the sub-chain feeding the trigger parameter so that the trigger arrives after the slice selection signal settles. You can use a Micro Delay unit for this purpose.


shift

Control Type Has Sub-chain? Sub-chain Parameters Fader Scale
Gain/Bias yes gain (-3 to 3)

bias (-5s to 5s)

linear time

As stated before, triggering this unit will cause the play head to reset back to the beginning of the sample or to the active slice. However, if the shift parameter is non-zero then the reset position of the play head will be shifted by a time interval equal to the shift parameter's value. For example, if the shift parameter is 1.2s then a trigger will cause the play head to reset to 1.2s into the sample buffer, or in the case of a sliced sample, 1.2s after the active slice.

Tip-bulb.png
Combine modulation of this parameter with rapid triggering (>10Hz) to simulate modulation of play head position (as opposed to modulation of speed).

duration

Control Type Has Sub-chain? Sub-chain Parameters Fader Scale
Gain/Bias yes gain (-3 to 3)

bias (0s to 1s)

linear time


This parameter determines the (final) playback length of each grain. It also implicitly sets the grain production rate.

jitter

Control Type Has Sub-chain? Fader Range Fader Scale
Simple Fader no 0 to 1 linear


With jitter set to zero, grains are generated at a regular rate which depends on grain duration. Turning up the jitter will delay each grain by a random amount which is proportional to the period between grains. The purpose is to smooth out the metallic character caused by the strong periodicity in the grain production.