Loop or beat slicing using reaSamploMatic

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general description

ReaSamplomatic allows you to play samples or sounds under midi control. For more information, including a description of what each parameter does you can read about it all on its section on the ReaEffects guide.

some user contributed tips

if you have the updated Reapack, there are actions that turn items into samples that can be triggered with reaSamplomatic and are automatically mapped to keys on your midi keyboard. To do this you take any loop or musical phrase, then slice it in any of the following ways:

Split the items manually

You can play and then pause, then with the left or right arrows (or tab and shift tab) locate the next transient or drum hit, or note, and then press the letter A to select and split the current item at the desired point. You will need to select and cross-fade the items to avoid noise when playing them back, though you could also split items at previous zero crossing (by using alt plus Z but note osara will not give any feedback) or, alternatively you can:

Use the dynamic split items dialog

This handy tool will edit and make the slices for you automatically. Press D to open the dialog and set the following:

  • Split points, at transients, checked.
  • minimum slice length: default is sensibly set at 20 milliseconds, though you can set something different if you like by typing or using the slider.
  • reduce splits. this will just allow you to limit how many splits will be made according to the slider, though it might prove helpful in some cases.
  • Constrain slice length: best to worst, or left to right. They will produce different results, the second one, left to right would give some more precision.
  • In the action to perform you have a variety of options, but the split selected items one works fine for this purpose.
  • Leading and trailing pads. This is useful because you can then check the fade pad checkbox and this will prevent pops and clips as you play your samples, so setting tiny fades is recommended.
  • create chromatic midi item... not really necessary.
  • For the rest of the options, they deal when you have to align items a certain way ETC outside the scope of this article.

You should also play with the transient sensitivity settings and threshold. Normally you can adjust these by using the following actions without having to open any dialogs:

  • Transient detection sensitivity: Increase, or Transient detection sensitivity: Decrease. They will adjust by one percent intervals
  • Transient detection threshold: Increase, or decrease. Works in increments of 0.2 db.
  • You can bind the action Transient detection sensitivity/threshold: Adjust... Which will open a dialog (currently not really accessible on windows) that lets you set these values, however
  • Using any means to focus a particular slider, such as the threshold or sensitivity one (could be NVDA's object navigation commands), then using the actions described before to manipulate them will read the changes automatically.

You can now press the split button. Depending on the material, you will get several transients. You could either remove some of them which contain spurious noise in case they are too many, or undo, and try again by using different transient sensitivity settings. In case you want them to behave just like a rx2 file (in other words, when the tempo is changed the beat slices would not be affected or glitch) you:

  • split the file at the zero crossing just before each beat
  • select all the slices (items) you just created
  • open up the context menu for them->item settings->set item timebase to beats (position only)
  • for convenience, open up the context menu again->group->group selected items

Now, since splits are at zero crossings, audio won't glitch if you move the items. And because the timebase of each item is beats, the slices will remain pinned to their beat position even if the tempo changes.

midi mapping the beat slices

Now that this is out of the way, you can run one of the reaPack actions. I generally use Script: mpl_Export selected items to RS5k instances on selected track. This puts each item on a key on your keyboard chromatically, mirroring the order of where the items are placed. You can select the starting note for the first item (in midi note numbers) and the other items will add on subsequent keys.

  • middle c is midi number note 60
  • c2 (the first note on 61 key keyboards or controllers) is midi note number 36
  • E1 (the first note in 76 key keyboards or controllers) is midi note number 28
  • a0, (first note in 88 key keyboards or controllers) is midi note number 21

There are other actions such as Script: mpl_Export selected items to RS5k instances on selected track (drum mode) which means when you trigger a sample it cuts the last sample off, which can sometimes be desired depending on application. There's a chromatic mode, Script: mpl_Export selected item to RS5k instance on same track as chromatic source, in case you want to spread one sample across the whole keyboard and be able to pitch change it. That's it. Press keys on your keyboard and your samples will play. You can then delete the items should you wish, mute them so they don't play or paste them to another track in case you want to do something with them again. You can get to this simply by searching for rs5k. I mapped Script: mpl_Export selected items to RS5k instances on selected tracks to control alt shift E. No particular reason, but all the S hotkey combinations were taken. It loads each sample in an instance of ReaSamplomatic. This means you can choose attack, release, decay, sustain, volume, pan, pitch bend range and more for each individual sample. The easiest way to do this is probably by pressing p (OSARA: View FX parameters for current track/take (depending on focus)) and navigating to each instance of ReaSamplomatic. Beware that any of these actions will glue several .wav items (place the created slices) into the currently active project directory.


Some of this material is collected from some e-mails from the rwp group, a handy chart dealing with midi note numbers as well as tips from the reaper forums. Thanks David Eagle and Juan Pablo Bello.