MIDI Controller Test and Per-Model Notes

MIDI Controller Test and Per-Model Notes

The browser reads the raw MIDI stream through the Web MIDI API, so it sees exactly what a controller sends before any DAW processes or remaps it.¹ That makes a browser test the fastest way to separate a hardware fault from a routing problem: a key that stays dark in the virtual piano or a knob that sends the wrong controller number is a device issue, while the same control working here but not in a DAW points at the software. This page merges the per-model controller notes that used to live on their own pages, so one session covers any of them.

Run the shared check first, then read the section for your controller. Each model has one setting that decides whether the test is clean: the arpeggiator on the Akai MPK249, Scale and Chord modes on the Novation models, DAW scripts on the Arturia KeyLab, and the pitch bend lever centred at rest on the Roland A-49. Clearing those before the sweep is most of the work.

How to test a MIDI controller in the browser

Connect the keyboard by USB, click Enable MIDI, approve the permission prompt, and select the device in the input dropdown. Most controllers are class-compliant, so the operating system's own MIDI driver handles them and no manufacturer driver package is required before the browser can list them.² If the dropdown stays empty, close any DAW or companion app that may hold exclusive access to the port, then disconnect and reconnect the cable.

Reading the event log

Start with the message type before judging the value. Note On and Note Off confirm key and pad routing, so the virtual piano and the log together show a dead key as a note that never appears at any pressure. Control Change confirms knobs, faders, encoders and pedals, pitch bend appears as 0xE0 with a 14-bit value, and aftertouch shows as 0xD0 for channel pressure or 0xA0 for polyphonic pressure.³

Each message carries its channel, and separate views cover velocity and the running Lag value. Velocity is the time between two contacts closing under the key rather than a direct force reading, so press each suspect key at three intensities and confirm the logged values span a wide range. A key that always returns the same value regardless of force has either a fixed-velocity setting active or a worn contact strip.

Checking controls beyond the keys

Move each knob or fader slowly from minimum to maximum and watch for a smooth sequence of Control Change values. Status bytes 0xB0 through 0xBF identify a Control Change message, and the low nibble is the MIDI channel, so the log shows the controller number, value and channel for every move.⁴ A gap in the value sequence points to a dead spot on the resistive track, and a controller number that matches neither the printed label nor the companion-software assignment means the control was remapped.

Akai MPK Mini IV MIDI Test

MPK Mini IV works in Chrome without installing Akai software. Connect the keyboard via the supplied USB-C cable, open this page in Chrome or Edge, and click "Enable MIDI" to grant device access.¹ The keyboard exposes standard MIDI ports, so Windows and macOS can recognize it as a USB MIDI device without drivers.² Akai ships the MPK Mini IV with 25 mini-keys, eight velocity-sensitive MPC pads, USB-C MIDI output, and pitch/mod wheels.

Akai recommends checking for firmware updates before first use because updates can improve stability and resolve MIDI port mismatches. If lower-register keys appear less responsive during the test, check your firmware version before concluding a key is dead. The pitch and modulation wheels send controller data; move each wheel while watching the event log to confirm the axis responds and returns to its resting value after release.

Specifications²

Plugging in before Chrome asks for MIDI access

Connecting the MPK Mini IV before opening the browser produces the most reliable detection sequence. Chrome's Web MIDI permission dialogue appears on the first click of "Enable MIDI"; approve it and Chrome stores the preference for all subsequent visits.³ Because the MPK Mini IV exposes standard MIDI ports, no Akai software is necessary for basic MIDI testing. On Windows 10 and 11, the device appears as "MPK Mini IV" in the MIDI input dropdown within seconds of plugging in. Hot-plugging works fully: disconnect and reconnect the cable at any time and the dropdown refreshes automatically without a page reload.

Confirming the USB MIDI port

Select "MPK Mini IV" from the MIDI input dropdown, then press a key or pad to confirm the chosen port updates the event log. If the dropdown shows several related entries, test the first Akai MIDI input before trying adapters or hubs.

Bluetooth is not available on this model. USB-C is the only built-in connection option. A USB-A to USB-C adapter works if your machine lacks a USB-C port. Unpowered hubs can introduce intermittent MIDI dropout, so prefer a direct connection or a powered hub if you see disconnections.

Firmware, velocity and wheel return

Check for firmware updates before troubleshooting low velocity readings. The event log shows lower-than-expected velocity values for gentle touches when a key mechanism or controller setting is not responding as expected. Akai recommends checking for firmware updates before first use because updates can improve stability and resolve MIDI port mismatches.⁴ If some pads need firmer pressure to reach the same velocity as others, tap each pad at the same physical pressure and compare the velocity column in the event log to verify consistent response across all eight.

The pitch and modulation wheels introduce a second testing concern. A wheel that does not spring back to its resting position sends a persistent controller value or a sustained pitch bend offset in the event log. Move each wheel fully in its usable direction, release it, and confirm the logged values return toward their resting position.

Sweeping 25 keys and eight pads

The virtual piano illuminates each key as Note On messages arrive. Any key that remains dark after a firm press is not transmitting MIDI output; the usual causes are a dead contact strip, a faulty PCB trace, or debris under the key. Furthermore, the event log records every Note On and Note Off with its note number, velocity, channel, and timestamp lag. MIDI sends event messages about notes, controller signals, and pitch bend, and the Web MIDI API exposes those device messages to web applications.⁵ Pressing all 25 keys methodically across the range and scanning for dark keys identifies dead zones faster than opening a DAW.

Checking the piano and event log together

Use the virtual piano for the fast sweep, then switch to the event log when a dark key needs proof. CapyToolkit's log records the note number, velocity, channel, and lag for every Note On and Note Off, so a screenshot can show that a specific key never transmitted MIDI. That evidence is more useful than a general statement that the key feels dead.

Beyond the 25 keys, each of the eight MPC pads generates its own Note On event on MIDI channel 10. Tap every pad and verify each one appears in the event log. The log also captures controller messages from the pitch and modulation wheels. The Lag column shows the processing time between the MIDI packet arriving at the browser and the current timestamp.

Choosing a repair path after testing

When the test reveals a dead key, a pad that never responds, or wheel drift that persists after release, check whether the unit is still covered by warranty. Screenshot the event log showing no Note On for the specific note number and the wheel log showing a non-zero resting controller value. Submit those screenshots through the Akai Pro support portal with the firmware version and the purchase date to prove a dead MPK Mini IV key before a warranty claim. A specific event log capture moves the claim forward faster than a written description because it gives the support team a reproducible log to compare against their own test protocol.

Out-of-warranty units have two practical repair options. A dead key section caused by a failed contact strip is a standard repair that most keyboard technicians stock parts for, since each contact strip covers 8 to 16 adjacent keys and one replacement addresses all keys in that zone simultaneously. For wheel drift, a potentiometer replacement at the PCB level is the standard fix.

Estimating repair cost against replacement

Before booking a repair, check the current secondhand price for a tested MPK Mini IV. If the repair quote exceeds 40% of that figure, a used replacement tested with this tool before the seller return period ends is usually the more practical option. Age and condition of the rest of the unit also factor in: a failing wheel on a keyboard with six working years may not justify the repair investment.

Akai MPK249 MIDI Test

For the MPK249, start by connecting the USB-B cable before opening this page. Chrome can read it as a class-compliant MIDI device with no driver installation.¹ Click "Enable MIDI", approve permission, and the keyboard appears in the dropdown. Akai ships the MPK249 with 49 semi-weighted keys, 16 velocity-sensitive MPC pads with aftertouch, 16 assignable knobs, and a built-in arpeggiator and chord mode that can generate multiple MIDI messages per keypress.

The arpeggiator is on by default in some factory presets. When active, holding one key generates a rapid sequence of Note On and Note Off events in the event log. This looks similar to ghost notes but is the arpeggiator working as designed. Disable the arpeggiator (ARP button LED off) before running the dead-key sweep to ensure that each key press produces exactly one Note On and one Note Off per physical press.

Specifications¹

USB-B and separate DIN inputs

Connect the MPK249 via USB-B (the square printer-style connector) before opening this page. Chrome detects it as "MPK249" in the MIDI input dropdown after you grant MIDI access.²³ If a MIDI DIN device is connected to the 5-pin output, it appears as a separate entry. Select the USB entry for direct keyboard testing.

Separating USB and DIN inputs

Choose the USB entry when testing the MPK249's keys and pads. A DIN source connected to the 5-pin output is useful for external gear checks, but it can look like a second keyboard in the dropdown.

Close Akai MPC Beats or any DAW before testing to avoid exclusive port conflicts. The keyboard powers from USB. Hot-plugging is supported. Disconnect and reconnect at any time and the dropdown refreshes automatically.

Arpeggiator bursts that look like ghost notes

The built-in arpeggiator generates rapid Note On bursts that mimic ghost notes in the event log. If the ARP button LED is on, every held key produces a stream of Note On events at the arp rate. Disable it before testing and confirm the log shows exactly one Note On per key press. Similarly, Chord mode generates multiple simultaneous Note On events per physical key press. Disable Chord mode (CHORD button LED off) for a clean dead-key sweep.⁴

The USB-B port can loosen over years of cable plug-in cycles. A loose USB-B port causes intermittent MIDI dropout. The keyboard drops from the MIDI input dropdown mid-session. Try a different USB-B cable first. Furthermore, the 16 MPC pads have aftertouch: pressing harder after the initial pad strike generates additional MIDI events, which appear in the event log as follow-up messages after the Note On.

49 keys, pads and knobs with the arpeggiator off

With the arpeggiator and Chord mode disabled, the virtual piano reflects each physical key press directly. Press all 49 keys and identify any that remain dark. Dead contacts do not transmit Note On at any pressure. The event log shows note number, velocity, channel, and lag for each event.

Confirming pads and knobs after the key sweep

The 16 knobs generate CC messages on rotation. The data wheel generates CC 06 by default.⁵ The 16 MPC pads generate Note On events with velocity and aftertouch. Tap each pad and watch the event log for the Note On; press harder after the initial strike to see the aftertouch data (0xA0 polyphonic aftertouch messages).⁶ Because this keyboard has both USB and MIDI DIN outputs, the DIN output appears as a second MIDI device in Chrome if a DIN cable is connected.²

Polyphonic aftertouch and arpeggiator timing verification

Testing polyphonic aftertouch on the MPK249 pads requires a different approach from velocity testing: to test MPK249 poly aftertouch per pad, tap a pad at normal velocity to generate the initial Note On, then press harder on the same pad surface without releasing. The event log should show a 0xA0 (Polyphonic Key Pressure) message with the note number of that specific pad and a value increasing from 0 as you apply more pressure. Each pad has its own aftertouch sensor, so the 0xA0 message carries the individual pad's note number rather than a global channel pressure value.⁴

Check all 16 pads for aftertouch response by repeating this on each one. Pads that generate Note On events but produce no 0xA0 messages at any pressure have failed aftertouch sensors. Pads that require extreme force before any 0xA0 message appears have sensors with high threshold settings; adjust pad sensitivity through the Akai MPC Beats companion application.

Arpeggiator timing accuracy via event log timestamps

With the arpeggiator enabled and a key held, the event log timestamps let you verify arpeggiator rate accuracy. At 120 BPM with 1/8 note rate, consecutive Note On events should arrive approximately 250 ms apart. At 1/16 note rate they should arrive approximately 125 ms apart.⁷ Consistent drift in the timing suggests the arpeggiator clock is decoupled from USB MIDI timing rather than running at the correct rate.

Arturia MiniLab 3 MIDI Test

Start with the MiniLab 3 plugged into a direct USB port before opening this page. Click "Enable MIDI", approve Chrome's permission, and the keyboard appears as a class-compliant USB MIDI device.¹ Arturia ships the MiniLab 3 with 25 velocity-sensitive slim keys, eight velocity- and pressure-sensitive RGB pads, eight multi-function encoders, four multi-function faders, USB-C bus power, a 5-pin MIDI Out port, and pitch/modulation touch strips.²

Arturia bundles Analog Lab Lite with the MiniLab 3, but that software is irrelevant for MIDI testing. Encoders and faders have factory CC assignments that can be changed in MIDI Control Center; confirm the current mapping in the event log before assigning DAW controls. Slim keys also have a lighter action than synth-action keys, so the same physical force registers lower velocity than on a full-travel keyboard.

Specifications²

Picking the right MiniLab 3 port

Plug the MiniLab 3 into any USB-C or USB-A port (via adapter) before navigating to this page. Chrome detects the device after you grant MIDI permission and lists the exposed MIDI ports in the dropdown.³ The Web MIDI API lets web applications enumerate and select MIDI input and output devices on the client system.⁴ The Arturia MIDI Control Center application is not required for basic MIDI output, so skip it entirely for testing. On macOS, the device appears under Audio MIDI Setup as "MiniLab 3" with the correct input and output ports.

Choosing the primary MIDI input

If the dropdown lists both "MiniLab 3 MIDI" and "MiniLab 3 DAW", choose the first entry for raw testing. The DAW port can filter messages, while the primary MIDI input shows the full hardware output. Arturia registers the DAW port as a separate MIDI endpoint so that DAW software can distinguish between control surface data and standard MIDI traffic.

Hot-plugging is supported. Disconnect and reconnect the cable while the page is open and the dropdown refreshes within two seconds. If you see "MiniLab 3 MIDI" and "MiniLab 3 DAW" as two separate MIDI inputs, select the first entry. That is the primary hardware MIDI output. The DAW entry applies a software filter that can suppress some MIDI messages during raw testing.

Encoder CC bursts and default CC numbers

Encoders that spin too quickly send burst CC messages in rapid succession. The event log may show Arturia/user CC defaults 74, 71, 76, 77, 93, 18, 19, or 16 depending on which encoder you move.⁵ These are not ghost notes but burst CC output. To test each encoder cleanly, rotate it slowly and continuously in one direction and check that the event log shows a smooth sequence of incrementing, decrementing, or absolute values according to its mapping.

Some MiniLab 3 units shipped with one or two slim keys that feel stiff and occasionally miss soft presses. Press each key at progressively lighter forces and watch the velocity logged in the event log. A key that registers no Note On at gentle pressure but fires at medium pressure has a contact strip that needs cleaning or replacement, not a dead key in the traditional sense.

Slim keys and controls beyond the keybed

The virtual piano visualizes all 25 keys and lights each one as its Note On message arrives. Because the MiniLab 3 slim keys are narrower than full-size keys, press each key systematically from left to right to identify dead zones. The event log records the note number, velocity, channel, and timestamp for every event.

Verifying controls beyond the keys

Beyond keys, each of the eight encoders generates CC messages using its assigned CC number during rotation; verify the specific number in the log rather than assuming a fixed range. The four faders generate their assigned CC numbers; move each fader from bottom to top and watch the value sweep. CapyToolkit's log is useful here because it keeps the CC number and value beside the timestamp, so you can compare each control's response without guessing which encoder or fader caused a burst.

The RGB pads produce Note On events on MIDI channel 10 by default and light up on the hardware when tapped, but the color change requires Arturia software and is not tested here.

Assigning encoder and fader CC numbers in your DAW

After confirming each encoder and fader transmits the correct CC number and sweeps cleanly, the event log gives you a ready reference to map MiniLab 3 encoder CC numbers in your DAW. Write down the CC number for each encoder and fader before closing the test; the Arturia/user defaults are not a simple sequential block, so confirm them in the log rather than guessing.⁵ In most DAWs, MIDI Learn identifies CC numbers automatically when you move a control, but having the correct CC number confirmed in the log lets you verify the mapping worked correctly rather than guessing at it later.

Arturia MIDI Control Center allows CC remapping if your preferred assignments differ from the defaults. Download and open MIDI Control Center, connect the MiniLab 3, and the current CC mapping appears in the device editor. Change any encoder or fader to your preferred CC number, save the preset to the keyboard, and retest here to confirm the new assignment appears correctly in the event log. The keyboard stores the preset internally; the new CC numbers persist after disconnecting from MIDI Control Center.

Testing after preset changes

Each time you change the CC mapping in MIDI Control Center and retest, clear the event log before rotating encoders. Old events from the previous CC assignment persist in the log and create confusion when verifying the new assignments. A clean log shows only the new CC numbers from the current preset. After clearing, rotate each encoder slowly and confirm the logged CC number matches the assignment you saved in MIDI Control Center.

Arturia KeyLab Essential 49 mk3 MIDI Test

Before testing the KeyLab Essential 49 mk3, choose the standard Arturia/user mapping and connect the keyboard by USB-C. Chrome then lists the MIDI input after you click "Enable MIDI" and approve permission.¹ Arturia ships the mk3 with a 49-note velocity-sensitive keyboard with hybrid synth-piano feel, 8 touch and pressure-sensitive pads, 1 clickable encoder, 9 rotary encoders, 9 x 30mm faders, modulation and bend wheels, USB-C, a MIDI 5-pin DIN output, and a pedal control input for sustain, expression, or footswitch use.²

The mk3 also includes DAW integration scripts and MCU/HUI compatibility for supported DAW workflows.³ For raw controller testing, use the standard Arturia/user control mapping instead of a DAW-specific script so the faders, encoders, pads, and transport controls match the layout you expect.

Specifications²

USB-C power and the MIDI input

Connect the KeyLab Essential 49 mk3 via USB-C before enabling MIDI access. The keyboard is USB-C powered, so a direct cable and powered computer port are the first things to check if it does not appear in Chrome. Close Arturia Analog Lab, MIDI Control Center, and DAW sessions before testing to avoid exclusive MIDI port access conflicts. Hot-plugging works; disconnect and reconnect at any time and the dropdown refreshes automatically.

Selecting the USB MIDI input

Choose the main KeyLab USB MIDI entry before testing keys, pads, faders, and encoders. A numbered port or external interface may be present, but it is not the direct keyboard input unless you are deliberately routing the DIN output through another device.

Web MIDI access is gated by Chrome's permission prompt, so the page can only enumerate the MIDI interfaces the browser exposes after permission is granted.¹

DAW scripts and unexpected control values

DAW integration is the first setting to check when controls send unexpected values. The mk3 supports DAW scripts and MCU/HUI workflows, which are useful for mixing and transport control but not ideal for a raw hardware sweep.³ Select the standard Arturia/user mapping before checking faders, encoders, and pads.

Keeping DAW scripts out of raw diagnostics

Raw diagnostics need predictable routing. If a fader sends a transport command instead of CC data, the keyboard is not broken; it is probably using a script or preset designed for a DAW. Return to the standard mapping, clear the event log, and test the same control again.

The 8 pads are touch and pressure-sensitive, while the 9 faders and 9 rotary encoders produce controller data in the active mapping. If a pad, fader, or encoder produces no log entry, confirm the active preset and control mapping before treating it as a hardware fault.

The full KeyLab surface

The virtual piano spans the full 49-key range and illuminates each key as Note On messages arrive. Press all 49 keys in order to identify dead contacts. The event log captures note number, velocity, channel, and lag because the Web MIDI API exposes MIDI input and output interfaces and MIDI messages to the web page.⁴⁵

Testing the full controller surface

Tap each of the 8 pads and confirm the event log entry and velocity value. Sweep each fader and rotary encoder through its full movement and watch for controller messages in the log. The MIDI 5-pin DIN output is for external instruments and gear; it is not a separate KeyLab keyboard input to select when testing the USB-connected keys.

CapyToolkit's log keeps these sections visible together, so you can compare key notes, pad channels, fader CC numbers, and encoder jumps without switching between a DAW and a separate MIDI monitor.

Testing external MIDI gear through DIN

Use the KeyLab Essential 49 mk3's MIDI 5-pin DIN output when you want to route KeyLab DIN to external gear. To verify that path in Chrome, connect the DIN output to a USB-MIDI interface that appears as an input device, then select that interface in the dropdown and play the keyboard.

The Web MIDI API can enumerate MIDI input and output devices and receive MIDI messages, but it does not turn the KeyLab's DIN output into a separate MIDI input entry by itself.⁴ If no events arrive, check the DIN cable, the receiving interface, and the active control mapping on the keyboard.

M-Audio Oxygen Pro 49 MIDI Test

The Oxygen Pro 49 can be tested as a class-compliant USB MIDI controller without opening M-Audio software. Connect the USB cable, approve Chrome's MIDI permission, and the keyboard should appear in the input dropdown.¹ M-Audio describes the Oxygen Pro 49 as a 49-key USB powered MIDI controller with Smart Controls, automatic DAW mapping, 16 RGB backlit assignable velocity-sensitive pads, 8 assignable knobs, 9 assignable faders, a PrecisionTouch semi-weighted keybed, and channel aftertouch.²

Channel aftertouch is a MIDI message type (0xD0) transmitted when you press harder on a key after the initial Note On. The Oxygen Pro 49 includes channel aftertouch, so watch the event log for 0xD0 messages when you press and hold a key with increasing pressure after the initial strike.³ If no 0xD0 messages appear at any pressure level, check the active mode and port mapping before treating the keybed as faulty.

Specifications²

Selecting the Oxygen Pro 49 input

Connect the Oxygen Pro 49 with a working USB cable. Click "Enable MIDI", grant access in the permission dialogue, and select "Oxygen Pro 49" from the MIDI input dropdown.

The Web MIDI API exposes the requestMIDIAccess() method, which returns a Promise for access to MIDI devices and may prompt the user for permission before it resolves.⁴ M-Audio describes the Oxygen Pro series as class-compliant and plug-and-play, so no driver installation is required for the MIDI interface. If a DAW or M-Audio editor is already using the controller, close it before testing so Chrome can receive the MIDI stream cleanly.

Testing aftertouch on the Oxygen Pro 49

Aftertouch is the most distinctive feature to verify on the Oxygen Pro 49. Press and hold a key firmly at full velocity, then gradually increase pressure on the key surface without releasing. The event log should show 0xD0 (Channel Pressure) messages with values increasing from 0 as pressure increases.³

Diagnosing aftertouch before blaming the keybed

Aftertouch only appears after the key is already down, so the test motion differs from a normal velocity check. Hold the key at the bottom, then add pressure without lifting. If 0xD0 messages never appear, confirm the active mode and selected MIDI input before treating the keybed as faulty.

M-Audio explains that Oxygen Pro has Preset and DAW modes: DAW mode routes controls through DAW-specific ports such as MIDIIN3, while Preset mode is intended for virtual instrument parameters and controls.¹

Pads, knobs and faders after the keys

The virtual piano illuminates all 49 keys as Note On messages arrive. Press each key across the full range to identify dead contacts. The event log records note number, velocity, channel, and lag for every Note On and Note Off because the Web MIDI API gives the page access to MIDI input and output devices and MIDI messages.⁵

Checking pads, knobs, and faders after the key sweep

The Oxygen Pro 49 includes 16 assignable velocity-sensitive pads, 8 knobs, and 9 faders, so test each control across its active preset mapping. Sweep each fader and knob through its full movement and watch for controller messages in the log. The Web MIDI specification defines MIDI controller signals as messages sent by the protocol, and it treats controller values as 7-bit data rather than a semantic label for the physical control.⁴ CapyToolkit keeps the key sweep and controller sweep in the same log, which helps you separate a keyboard-only problem from a broader controller mapping issue.

Aftertouch sensitivity calibration and threshold adjustment

Aftertouch requires a deliberate testing technique that differs from velocity testing. Velocity measures how fast you press the key; aftertouch measures additional pressure applied after the key reaches the bottom of its travel. Press a key to full velocity and hold it at the bottom, then check Oxygen Pro aftertouch response by gradually increasing downward pressure on the key surface while keeping it depressed.

The Web MIDI API is designed to expose the mechanics of MIDI input and output interfaces and the practical aspects of sending and receiving MIDI messages, rather than to interpret what those messages mean musically. If no 0xD0 messages appear, verify the selected input, avoid DAW-only routing, and try a MIDI monitor outside the browser to separate controller behavior from Chrome access.

Diagnosing complete aftertouch failure

A complete absence of 0xD0 events after checking mode, port selection, and browser permission should be treated as a hardware or firmware issue rather than a settings fault. For an unresponsive key, M-Audio recommends using a MIDI monitor to identify the missing note and cleaning around the key with compressed air without lifting the keys upward.⁶ If cleaning does not restore the aftertouch response on that key, the pressure sensor strip under the key bed may need replacement.

Novation Launchkey 25 MK4 MIDI Test

The Launchkey 25 MK4 is Novation's 25-note USB-C controller aimed at players who need a compact keyboard with full-size keys, 16 RGB pads, and 8 rotary encoders in a single portable unit. After you connect the controller and approve Chrome's MIDI permission, the tool below enumerates it as a standard class-compliant MIDI input.¹ Novation ships the MK4 with 25 full-size synth-style keys, 16 RGB velocity-sensitive pads with polyphonic aftertouch, eight endless rotary encoders, pitch and modulation wheels, USB-C, a 5-pin MIDI Out socket, and a sustain-pedal input.

Scale and Chord modes are the main variables to check before a dead-key sweep. Scale mode can round, filter, or remap notes to fit a selected scale, while Chord modes can make pads and encoders trigger chord voicings instead of single notes.² Disable these modes before testing individual keys so the virtual piano matches the physical key positions.

Specifications³

Closing DAW and Components port conflicts

Connect the Launchkey 25 MK4 via USB-C before enabling MIDI access in Chrome. The keyboard appears in the dropdown as "Launchkey 25 MK4 MIDI". Close any DAW or Novation Components session before testing to avoid exclusive MIDI port access conflicts. Hot-plugging works; disconnect and reconnect at any time and the dropdown refreshes automatically.

Closing port conflicts before testing

If the dropdown stays empty, quit Novation Components and any DAW that may have claimed the MIDI port. Reconnect the USB-C cable, then grant Chrome permission again so the page can enumerate the keyboard directly.

The keyboard is bus-powered and requires no external supply. Web MIDI access is gated by Chrome's permission prompt, so the page can only enumerate the MIDI interfaces the browser exposes after permission is granted.¹

Scale mode and wrong notes

Scale mode is the most important setting to check when a key appears to send the wrong note. In Snap to Scale mode, the keyboard rounds notes outside the selected scale to the nearest scale note; in Filter out of Scale mode, out-of-scale notes do not play; in Easy Scale mode, the selected scale is mapped across the white keys.²

Isolating Scale mode before judging the keybed

Treat Scale mode as a configuration fault until the event log proves otherwise. If the log shows a Note On while the virtual piano stays dark, the key is transmitting but the selected scale is remapping the pitch outside the displayed range. That distinction prevents unnecessary service tickets for a healthy keyboard.

Encoder and pad output can also change depending on the active mode. Novation documents Custom Modes for controls and explains that MIDI parameters can be mapped to pads or encoders in Novation Components, so confirm the active mode before interpreting an encoder or pad event.³

A checklist for the whole Launchkey 25

The virtual piano shows the 25 full-size synth-style keys. With Scale and Chord modes disabled, every key press maps directly to the note shown on the piano. Dark keys after firm presses indicate dead contacts. The event log captures note number, velocity, channel, and lag for every Note On and Note Off because the Web MIDI API exposes MIDI input and output interfaces and MIDI messages to the web page.⁴⁵

Building a complete controller checklist

The 16 pads are velocity-sensitive; tap each pad and confirm the event log entry and velocity value. The 8 encoders generate output when moved in their current mode, and Custom Modes can be configured in Novation Components. Any control element that produces no log entry on movement is not transmitting MIDI. CapyToolkit's event log lets you keep this checklist in one place: note numbers for the keys, CC numbers for encoders, pad channels, and any pitch bend or modulation data from the wheels.

After the first pass, clear the log and repeat only the suspicious section. A clean second pass confirms whether a dark key, skipped pad, or silent encoder was a one-off event or a repeatable fault.

Scale and Chord mode checks

Use this test in standard chromatic mode when you want the virtual piano to mirror the physical keyboard. Turn off Scale mode and Chord mode before checking for dead keys, stuck notes, or unexpected transposition. With both modes disabled, every physical key maps to the note shown on the virtual piano without any firmware remapping, which gives you a one-to-one hardware diagnostic.

Use Scale mode and Chord mode deliberately when you want to verify creative performance behavior. In Chord Map mode, pads and encoders trigger scale-fitting voicings; in Fixed Chord mode, one key plays a whole chord. The Launchkey 25 MK4 offers 30 built-in scales in Scale mode, covering major, minor, pentatonic, and modal options, so testing each scale confirms the keyboard correctly remaps every note rather than silently dropping out-of-scale pitches. When Chord mode is active, a single key press can produce multiple Note On messages simultaneously. Watch the event log for clusters of notes that share the same timestamp; those clusters let you verify Launchkey 25 chord voicings are transmitting correctly. If a pad or encoder triggers only one note when it should trigger a chord, the Chord mode assignment in Novation Components may not match the hardware mode currently selected on the keyboard.

Novation Launchkey Mini MK4 MIDI Test

Open this page with the Launchkey Mini MK4 already connected by USB-C. Chrome treats it as a class-compliant MIDI device after you click "Enable MIDI" and approve permission.¹ Novation ships the MK4 with 25 synth-action mini-keys, 16 RGB velocity-sensitive pads, eight endless rotary encoders, pitch/modulation touch strips, Scale mode, Chord modes, USB-C, a 3.5 mm MIDI Out socket, and a sustain-pedal input.

Scale mode is the most significant variable for testing. When active, keys and pads transmit re-mapped notes rather than the physical note positions; a key labeled C may send a different pitch depending on the scale and root note selected. Disable Scale mode and Chord mode before running a dead-key test by pressing the Scale button until its LED turns off. Testing in standard chromatic mode ensures that the note on the virtual piano matches the physical key pressed.

Specifications²

Single MIDI port and control modes

Connect the Launchkey Mini MK4 via USB-C before clicking "Enable MIDI" on this page. Chrome presents the permission prompt on first use and stores your choice. The keyboard registers as a single MIDI input labeled "Launchkey Mini MK4 MIDI" in the dropdown. Novation documents DAW, Drum, and Custom modes for its pads and encoders, so confirm the active mode before interpreting a control's output.³ If you have Novation Components browser software open at the same time, it may claim the MIDI interface exclusively. Close it or any DAW before testing to avoid port conflicts.

Checking the active control mode

Before testing keys, press the Scale and Chord buttons until their LEDs are off. That puts the keyboard in standard chromatic mode so the virtual piano matches the physical key positions. Scale mode remaps physical keys to the nearest note in the selected scale, which can make some keys appear silent on the virtual piano even though they transmit MIDI normally.

Hot-plugging is supported. Disconnect and reconnect at any time and the dropdown refreshes without a page reload. The keyboard powers via USB and requires no external supply.

Scale mode keys that look dead

Scale mode is the most commonly missed configuration step when testing. A key that appears dead in Scale mode may simply be remapping to a note outside the selected scale, producing no visible highlight on the virtual piano even though the MIDI message was sent.² The event log still captures the Note On event; check there before concluding a key is dead. Disable Scale mode (LED off on the Scale button) for a reliable dead-key sweep.

Separating mode issues from hardware faults

Pad velocity consistency across the 16-pad grid is a reported variation on some MK4 units. Pads in row 2 (pads 9–16) may require slightly more force than row 1 pads to register equivalent velocity. Tap each pad at the same physical pressure and compare velocity values in the log to quantify any difference. If the velocity gap between rows exceeds 20 units at identical force, the pad rubber domes in the weaker row may need replacement.

Key sweep with Scale mode off

With Scale mode disabled, the virtual piano mirrors each physical key press directly. Press all 25 keys and watch for dark keys that register no Note On event. Any dark key is a candidate for a dead contact strip. The event log shows the full MIDI message for every event: note number, velocity, channel, and lag.⁴

All 16 pads generate Note On events on MIDI channel 10 by default in Drum pad mode, and each one lights up its corresponding position on the hardware.³ Tap every pad and verify the event log entry. The rotary encoder generates the CC or other MIDI message assigned to its current Custom Mode; rotate it left and right and confirm the number and value sequence in the log. Furthermore, the transport buttons transmit their own messages; press each one to verify output in the log.

Pad channel routing and Scale mode workflow

Configuring pad channel routing is the most practical setup step after completing the dead-key and pad verification test. By default the MK4 pads transmit on MIDI channel 10 in Drum pad mode, while General MIDI-compatible instruments route channel 10 to percussion.⁵ If you want pads to trigger melodic instruments rather than drums, change the pad channel to 1 through 9 in the keyboard's internal settings using the Novation Components web application. After the change, retest here by tapping pads and confirming the channel column in the event log shows the new channel number, then confirm Launchkey Mini pad channels switch as intended.

Scale mode adds a practical layer to the test results. Once you confirm that all 25 keys respond correctly in chromatic mode, enable Scale mode and select a root note and scale in the keyboard settings. Tap the keys again and verify the event log shows remapped note numbers that correspond to the expected scale tones. A key that appeared dead in Scale mode during the initial test but produces events in the log during this follow-up pass was not dead; it was transmitting an out-of-range note that the virtual piano did not highlight.

Using Chord mode for simultaneous note verification

Chord mode generates multiple simultaneous Note On events per physical key press. Each key press triggers an entire chord. Enable it after the test and press a single key to confirm the event log shows the correct chord voicing as multiple simultaneous notes. Verify the note cluster matches the chord type selected on the keyboard. This is a practical way to stress-test the MIDI output path, since normal playing produces only one or two simultaneous notes.

Roland A-49 MIDI Test

Set the A-49 to Generic, also called Class Compliant, then connect the square USB COMPUTER port to the computer. Chrome can read the keyboard with the operating system's built-in USB driver after you grant MIDI permission.¹ Roland ships the A-49 with 49 velocity-sensitive keys, a pitch bend/modulation lever, two assignable knobs, two assignable switches, and a D-BEAM controller; there are no pads or faders.²

Because the A-49 is a keys-first controller, the full test focuses on key response, pitch bend, and modulation. The pitch bend lever transmits 0xE0 messages and should return to center after release. A lever that rests at any non-zero value generates a persistent pitch shift in a DAW.

Specifications²

The USB COMPUTER port and driver-free mode

Connect the A-49 via the USB-B cable that came with the keyboard. The device appears as "Roland A-49" in the MIDI input dropdown after you click "Enable MIDI" and approve the Chrome permission. No Roland drivers are required when the keyboard uses Generic or Class Compliant USB mode.¹³ Close any DAW before testing to avoid exclusive port access.

Using the USB COMPUTER port

Plug the cable into the square USB COMPUTER port, not the external MIDI OUT connector. The DIN output is useful for external instruments, but the browser test needs the USB MIDI input shown in the dropdown.

The keyboard is bus-powered via USB. Disconnect and reconnect the cable at any time and the browser can rediscover MIDI inputs through the Web MIDI API.³

Pitch bend lever centering and worn contacts

The pitch bend lever is the main mechanical issue to check on the Roland A-49. After bending pitch and releasing the lever, the value should return to center. A lever that stabilizes at a non-zero pitch bend value after release sends a persistent pitch offset to the DAW. The event log shows a sustained 0xE0 message with a non-zero value while the lever is at rest. Push the lever to maximum upward bend and release quickly, watching the event log to see whether it settles at center.

If you suspect worn contacts, press suspect keys at the same intensity as neighboring keys and compare velocity values. A key that requires significantly more force than its neighbors to register a Note On has a worn contact strip.

49-key sweep and lever checks

The virtual piano displays all 49 keys and lights each one as Note On messages arrive. Press every key across the full 49-key range and identify any that remain dark. Those are dead contacts. The event log records note number, velocity, channel, and lag.

Separating key response from lever centering

After the key sweep, keep the event log open and move the pitch bend lever. Pitch bend messages (0xE0) appear in the event log labeled as "Pitch Bend" with a 14-bit value. Move the pitch lever up and down through its full range and confirm the value sweeps from minimum to maximum and back.⁴ The modulation lever generates CC 1 messages; move it from 0 to 127 and verify the smooth sweep.⁵ Furthermore, release both levers and confirm the event log shows pitch bend returning to center and CC 1 returning to 0.

Pitch bend center offset and corrective options

If the test shows a pitch bend lever that does not return to center after release, you can catch A-49 pitch bend not centering in the log and decide between a quick filter fix and a technician repair. The audible pitch shift depends on the DAW or software instrument's pitch bend range, so even a small residual value can be noticeable with a wide bend range.

For persistent offsets, a MIDI pitch bend filter plugin in your DAW can mask the issue by zeroing pitch bend values below a configurable threshold. This is a workaround that keeps the keyboard playable while you arrange service. A permanent repair may require opening the keyboard and calibrating or replacing the pitch bend mechanism, which is a job best handled by a keyboard technician.

Testing the mod wheel alongside pitch bend

The mod wheel on the A-49 transmits CC 1. After testing pitch bend return, sweep the mod wheel from 0 to 127 and back to 0. Confirm the CC value in the event log returns to exactly 0 when the wheel is at its lowest physical position. A mod wheel resting at a non-zero value at minimum position has the same centering issue as the pitch bend lever.⁵