ReaSamplOmatic5000: Complete Guide to Reaper's Sampler

ReaSamplOmatic5000 is Reaper's built-in sampler plugin, and it is one of the most underestimated instruments in any DAW. While producers using other software pay for third-party samplers, Reaper includes RS5K with every $60 license. It loads any audio file, maps it across the keyboard, supports velocity layers and round robin, and runs with virtually zero CPU overhead. For beat battle producers who build custom drum kits and instruments from their own samples, RS5K is a powerhouse.

This guide covers everything from loading your first sample to building multi-velocity, round-robin drum kits that sound like they came from a $400 plugin. Every technique here is directly applicable to Audeobox battle production, where custom sounds give you an edge over producers recycling the same preset libraries.

What Is ReaSamplOmatic5000?

ReaSamplOmatic5000 (RS5K) is a sample-playback instrument that ships with Reaper. It lives in your FX Chain like any other plugin and responds to MIDI input. At its simplest, you load a single audio file and RS5K plays it back when it receives a MIDI note. At its most advanced, you stack multiple RS5K instances to create multi-sample instruments with velocity switching, round robin variation, and per-sample envelope shaping.

RS5K is not trying to replace Kontakt or other full-featured samplers with scripting engines and GUI builders. It is a focused, lightweight tool that does one thing exceptionally well: play samples with precise control and negligible CPU cost. In a battle context where every CPU cycle matters, RS5K lets you build custom instruments without the overhead of heavyweight samplers.

Key Features

• Load WAV, AIFF, MP3, FLAC, and other audio formats
• MIDI note range mapping with configurable root note
• Pitch tracking across the keyboard for chromatic playback
• ADSR envelope with attack, decay, sustain, and release controls
• Built-in filter with lowpass, highpass, and bandpass modes
• Sample start and end point adjustment
• Loop mode for sustained playback
• Obey note-off for gate-style behavior
• Multiple output routing through Reaper's track routing system

Loading Your First Sample

1. Create a new track in Reaper by pressing Ctrl+T (Windows) or Cmd+T (Mac).
2. Open the FX Chain for the track by clicking the FX button on the track panel, or press F with the track selected.
3. In the FX Browser, search for "ReaSamplOmatic5000" and double-click it to insert.
4. RS5K opens with an empty sample slot. Click the Browse button or drag an audio file directly from Reaper's Media Explorer or your file system onto the RS5K window.
5. The waveform appears in the display. Play a MIDI note (via your controller or the virtual keyboard in the MIDI Editor) and you hear your sample.

By default, RS5K maps the loaded sample to a single MIDI note (usually C4). The Note start and Note end fields define which MIDI notes trigger this sample. Set both to the same note for one-shot drum sounds, or expand the range for pitched instruments.

Building a Drum Kit

The most common battle application for RS5K is building custom drum kits. Each drum sound gets its own RS5K instance on the same track, with each instance mapped to a different MIDI note.

Method 1: Stacked RS5K Instances

1. Create a track and add your first RS5K instance. Load your kick sample.
2. Set the Note start and Note end both to C1 (MIDI note 36, the standard kick note on most controllers).
3. Add a second RS5K instance to the same track's FX Chain. Load your snare sample.
4. Set this instance's Note start and Note end to D1 (MIDI note 38).
5. Continue adding RS5K instances for hi-hat (F#1/note 42), open hat (A#1/note 46), clap (E1/note 40), and any additional percussion.

All instances live in the same FX Chain and respond to their assigned MIDI notes independently. This approach keeps your track count low while giving you full per-sample control.

Method 2: Multi-Track Drum Rack

For more mixing control, create a folder track and add child tracks for each drum element. Place one RS5K instance on each child track. Route all child tracks to the parent folder. This gives you individual mixer controls, FX chains, and send routing per drum sound, which is essential for serious mixing.

Set each child track to receive MIDI from the parent track by configuring the track routing. Open the parent track's routing dialog (Alt+R on Windows / Option+R on Mac) and add MIDI sends to each child track. On each child track's RS5K, set the note range to match the intended pad.

Multi-Sample Instruments

RS5K becomes a proper instrument when you map multiple samples across the keyboard. This technique lets you create playable pianos, basses, pads, and any other instrument from individual note recordings.

Creating a Multi-Sample Map

1. Record or collect individual notes of the instrument you want to sample. The standard approach is to capture every third semitone (C, Eb, F#, A) across two or three octaves.
2. On your instrument track, add one RS5K instance per sample.
3. For each RS5K, set the Note start and Note end to cover the range between samples. For example, if you sampled C3 and Eb3, the C3 instance covers C3 to D3, and the Eb3 instance covers Eb3 to E3.
4. Set the Pitch adjust center (root note) for each instance to match the original recorded pitch. RS5K uses this as the reference point for transposition.
5. Enable Obey note-offs if you want the sound to stop when you release the key. For sustained instruments, enable Loop mode and set the loop points within the sample.

The more samples you capture per octave, the less RS5K has to transpose each one, and the more natural the instrument sounds. Three samples per octave is the practical minimum. Six per octave produces professional results.

Velocity Layers

Velocity layers make your sampled instruments respond dynamically to how hard you play. Instead of a single sample that just gets louder or quieter, different samples trigger at different velocities, capturing the tonal changes that happen when an instrument is played softly versus hard.

Setting Up Velocity Layers

1. Record the same note at multiple dynamic levels: pianissimo (soft), mezzo-forte (medium), and fortissimo (hard) at minimum. Four to five layers is ideal.
2. On your track, add one RS5K instance per velocity layer. Load the corresponding sample into each.
3. Set all instances to the same Note start and Note end (same MIDI note range).
4. Adjust the Min vel and Max vel fields for each instance to divide the velocity range:
   • Soft sample: Min vel 0, Max vel 42
   • Medium sample: Min vel 43, Max vel 84
   • Hard sample: Min vel 85, Max vel 127
5. Test by playing the same note at different velocities. You should hear the tonal character shift naturally.

For drum kits, velocity layers transform RS5K from a basic one-shot player into something that feels alive. A hi-hat with three velocity layers (ghost note, regular, accent) responds to finger drumming in a way that a single sample never can.

Round Robin Setup

Round robin cycling plays a different sample each time you trigger the same note, preventing the machine-gun effect that makes programmed drums sound robotic. RS5K does not have a built-in round robin mode, but you can achieve it with Reaper's parameter modulation system.

Round Robin Method

1. Add multiple RS5K instances on the same track, each loaded with a different variation of the same drum hit (for example, three slightly different snare recordings).
2. Set all instances to the same MIDI note and velocity range.
3. On each RS5K instance, right-click the Volume/Gain parameter and select Parameter modulation/MIDI link.
4. In the Parameter Modulation dialog, check Enable parameter modulation and select LFO.
5. Set the LFO to a square wave with the speed synchronized to your round robin cycle. Configure each instance's LFO phase offset so only one instance is active at a time (0 degrees, 120 degrees, 240 degrees for three instances).

An alternative approach uses ReaScript. A simple Lua script can randomly mute and unmute RS5K instances on each note trigger, achieving true random round robin without LFO timing. Search the Reaper forums for "RS5K round robin script" for ready-made solutions.

Battle Sampler Techniques

One-Shot Chop Workflow

When you need to chop a loop or sample during a battle, use this workflow:

1. Import your audio file to a track in the arrange view.
2. Use Dynamic Split (select the Item, then Item > Dynamic split items or press D) to automatically detect transients and split the Item into individual hits.
3. Select all the resulting Items, right-click, and choose Copy items to RS5K instances on new track from the SWS extension menu (if installed), or manually drag each slice to an RS5K instance.
4. Each chop is now a playable pad. Open the MIDI Editor and sequence your chopped pattern.

Performance Optimization

RS5K is already extremely lightweight, but when you stack 16 or more instances for a full drum kit with velocity layers and round robin, follow these practices:

• Use 16-bit WAV files instead of 24-bit for drum one-shots. The quality difference is inaudible on short transient sounds, and the memory footprint is smaller.
• Trim your samples to remove silence before and after the sound. RS5K loads the entire file into memory, so unnecessary silence wastes RAM.
• Disable the built-in filter on RS5K instances where you are not using it. Even when the filter is set to pass everything through, it still consumes a small amount of CPU.

Layering with FX Chains

Because RS5K lives in the FX Chain, you can place effects directly after each instance. Add ReaEQ for per-sample EQ, ReaComp for compression, or any third-party effect. The FX Chain processes audio in series, so effects after RS5K shape only that specific sample's output. This gives you mix-ready drum sounds without needing separate mixer tracks.

Frequently Asked Questions