How to Use Your iPhone as a MIDI Controller in REAPER

What you need

• An iPhone — the controller. Nothing else to buy.
• NueCtrl — free on the App Store. A one-time Pro in-app purchase adds Max Mode (up to 500 Hz motion capture), unlimited faders, per-fader sensitivity and unlimited presets.
• REAPER on macOS, Windows or Linux. There are no feature tiers to worry about — MIDI learn, parameter modulation and the action list are in every install.
• One connection route — Bluetooth, the same Wi-Fi network as your computer, or a Lightning / USB-C cable.

Part 1 — Connect your iPhone

This part is the same for every DAW, because it happens at the operating-system level before REAPER is involved. Pick one of the three routes below. If you want the full walkthrough with screenshots of each dialog, see the MIDI connection setup guide.

Option A — Bluetooth LE MIDI

The fastest route, and the only one that needs no cable and no shared network. NueCtrl advertises itself over Bluetooth LE when it launches.

1. On your iPhone, open Settings → Bluetooth and make sure Bluetooth is on.
2. Launch NueCtrl and go to Settings → Connection → Bluetooth MIDI, then tap Advertise so the phone is visible.
3. On your Mac, open Audio MIDI Setup (Applications → Utilities), choose Window → Show MIDI Studio, and click the Bluetooth icon.
4. Find NueCtrl BLE in the device list and click Connect. NueCtrl's status indicator will read Connected.

Option B — Wi-Fi (Network / RTP-MIDI)

Lower latency than Bluetooth, still wireless. Roughly 5 ms in practice.

1. Put the iPhone and the computer on the same Wi-Fi network — 5 GHz if you have the choice.
2. macOS: Network MIDI is built in. Open Audio MIDI Setup → Window → Show MIDI Studio, double-click the Network icon, click + under My Sessions and tick Enabled. Select NueCtrl in the Directory panel and click Connect.
3. Windows: there is no built-in Network MIDI. Install rtpMIDI (the free RTP-MIDI driver from Tobias Erichsen), create a session in it, and connect to NueCtrl from its directory list.
4. In REAPER, the input will appear under the session name (for example Session 1), not under the phone's name.

Option C — USB

The lowest latency and the most reliable route — around 2 ms — and the right choice for a take you intend to keep.

1. Connect the iPhone to the Mac with a Lightning or USB-C cable.
2. First time only: in Audio MIDI Setup, choose Window → Show Audio Devices, select your iPhone and click Enable.
3. NueCtrl detects the cable and switches to USB MIDI automatically. The port appears as NueCtrl.

Part 2 — REAPER setup

REAPER is unusually explicit about MIDI inputs: a device is off until you say otherwise, and it has two independent on switches rather than one. Getting the first and missing the second is the single most common reason a correctly connected iPhone appears to do nothing inside REAPER.

Step 1 — Enable the device, and then enable it again

1. Open Options → Preferences, then in the left-hand tree go to Audio → MIDI Devices.
2. In the MIDI inputs list, find the device carrying NueCtrl: NueCtrl BLE for Bluetooth, the session name for Wi-Fi, or NueCtrl for USB.
3. Double-click it. A small device dialog opens.
4. Tick Enable input from this device. This lets the CC stream reach tracks, so you can record raw controller data into an item.
5. Tick Enable input for control messages as well, then confirm. The device row should now show that both are on.

Step 2 — Route 1: learn an FX parameter

1. Open the FX window for the plug-in you want to control.
2. Click Param in that window's toolbar and choose Learn. If you prefer, right-clicking the control itself offers the same learn entry.
3. Move your iPhone so NueCtrl transmits its CC. REAPER captures the incoming message and fills it into the learn dialog.
4. Before confirming, look at the options in that dialog. You can set the range the controller sweeps, switch on soft takeover, and scope the mapping — checkboxes there limit it to when the relevant track or item is selected, or to when that FX window is focused.

Soft takeover is worth switching on almost every time. Without it, the parameter jumps to wherever the phone happens to be pointing the instant the first CC arrives. With it, the parameter waits until your movement passes through its current value and only then picks it up — so a mapped cutoff will not slam open the moment you lift the phone off the desk.

Step 3 — Route 2: parameter modulation and link from MIDI

This is REAPER's real differentiator, and it is worth learning properly rather than treating as an advanced-only feature. From Param → Modulation (or by right-clicking the control), open the parameter modulation window. Alongside the LFO and audio-follower sections there is a link from MIDI section: enable it, pick the CC that NueCtrl is sending, and you now have three shaping controls that a plain learn does not give you.

1. Baseline — where the parameter rests when the controller is not pushing it. A plain learn always starts from zero; a baseline lets you sit a filter at, say, half open and move around that point.
2. Strength — how far the incoming CC is allowed to move the parameter away from the baseline. This is your depth control, and it is the reason one gesture can be subtle on one destination and dramatic on another.
3. Direction — whether the CC pushes the parameter up, down, or symmetrically around the baseline.

Set the same CC up on several parameters with different baselines and strengths and one hand movement becomes a small, purpose-built macro — without any scripting, and without leaving the FX window.

Step 4 — Route 3: actions

Not everything worth controlling is a parameter. For transport, markers, track selection and anything else REAPER exposes as a command, open Actions → Show action list, select the action you want, then use Add… → MIDI/OSC learn and move the phone. Bear in mind that a continuous CC is a poor fit for a discrete command — this route is most useful for the handful of controls you want on a phone tilt threshold rather than as a sweep.

Step 5 — Record the pass as an envelope

A mapped parameter is only written to disk if the track's automation mode says so. In Trim/Read — the default — REAPER plays back existing envelopes and records nothing, which is why a first attempt often produces a perfect-sounding pass and an empty project. Switch the track to Touch, Latch or Write, run the section, and ride the parameter by hand. REAPER draws the movement as an envelope you can then edit point by point, or thin out with its envelope point-reduction options.

Part 3 — What to map in REAPER

NueCtrl converts iPhone motion into continuous MIDI CC, so it belongs on parameters that want to move, not on on/off switches. REAPER's stock plug-in set and its modulation system give a motion controller more to do than most hosts.

Parameter modulation with Baseline and Strength

The most REAPER-native way to use a motion controller, and the first thing to try. Link one CC into three or four destinations across a chain, then give each one its own baseline, its own strength and its own direction. One tilt can open a filter a long way, nudge a send a little, and pull a compressor threshold down slightly — all from one gesture, all shaped independently, and none of it requiring a Rack-style container or any scripting.

ReaEQ band frequency and gain

Sweeping a ReaEQ band by hand is the fastest way to find a resonance, and it is also a usable effect in its own right. Learn the band's frequency to your tilt with a sensible range set in the learn dialog, and put the band's gain on a second fader if you want to hunt and cut in one pass. Because ReaEQ exposes each band separately, you can leave a permanent mapped band on a template track.

ReaComp threshold and ReaXcomp

Riding compression as a performance rather than setting it once is where motion control earns its keep on a mix. Map ReaComp's threshold and you can lean into the compression on the loud phrases and back off on the quiet ones, writing a threshold envelope that no static setting could match. On ReaXcomp the same move works per band, which is how you tame a single boomy passage without dulling the whole track.

ReaVerbate / ReaVerb wet and send levels

Send level to a reverb bus is a classic mix gesture that never sounds right when drawn with a mouse, because it is fundamentally a performance. Map the send, or ReaVerbate's wet control, and push the vocal into the tail at the ends of lines before pulling it back for the next phrase. ReaVerb's wet level works the same way when you are running a convolution space.

JSFX parameters

Every JSFX slider is a learnable parameter, which makes REAPER unusually open to this kind of control. Any of the stock JSFX in the ReaPlugs and JS folders can be mapped exactly like a VST parameter, and if you want a shaping stage that behaves precisely the way you like, a short JSFX — written yourself or grabbed from the community — will slot straight in and expose its sliders to learn and to parameter modulation. NueCtrl itself does not ship or require any JSFX; it just sends CC, and REAPER does the rest.

CC1 and CC11 into sampled and orchestral instruments

If you run sampled or orchestral libraries in REAPER, set NueCtrl to send CC1 (modulation) and CC11 (expression) and the instrument will respond directly — no learn, no modulation window, nothing to enable beyond the device itself, because the library already listens to those controllers. Sustained string and brass lines live or die on the shape of the CC11 curve, and a curve that came from a hand is immediately different from one drawn with a mouse.

Troubleshooting

• Learn does nothing at all. Enable input for control messages is unticked. Double-click the device in Preferences → Audio → MIDI Devices and turn it on. This is the number-one cause and it is worth checking first every time.
• The device is listed but greyed out or marked as not enabled. Being visible in the list is not the same as being enabled. Double-click the row and tick Enable input from this device; a device that is merely present will not pass anything.
• REAPER is showing a stale device list. If you paired or created the session after REAPER was already running, use the reset all MIDI devices control on the same MIDI Devices preferences page, or restart REAPER, so the list is re-enumerated.
• The parameter jumps the moment you move. Turn on soft takeover in the learn dialog for that mapping. The jump happens because the phone's current position does not match the parameter's current value; soft takeover makes the parameter wait until the two meet.
• The mapping is global when you wanted it track-specific, or the reverse. Reopen the learn dialog and look at the scoping checkboxes — they decide whether the mapping applies everywhere, only when the relevant track or item is selected, or only when that FX window is focused.
• Movement is audible but late. Bluetooth runs around 10-15 ms, Wi-Fi around 5 ms, USB around 2 ms, so change route before you blame REAPER. If you are already on USB, lower the block size for your audio device in Preferences → Audio → Device.
• Windows or Linux, and there is no USB route. The USB path depends on macOS exposing the iPhone as a MIDI device. On Windows, install rtpMIDI and use the Wi-Fi route; on Linux you will need an RTP-MIDI implementation for your distribution. Wi-Fi is the low-latency wireless path on both platforms.
• The pass sounded great but no envelope was written. The track was in Trim/Read. Set the automation mode to Touch, Latch or Write before the take — REAPER writes nothing in the read-only modes.

FAQ