What Is a MIDI Loop?

A Guitar Pedal & MIDI Controller Perspective

In guitar rigs, MIDI is an incredibly powerful way to control pedals, amps, and rack gear. But with that power comes one common pitfall: the MIDI loop.

A MIDI loop occurs when MIDI messages travel in a circle—returning to the device that originally sent them—and repeat endlessly. This creates an infinite feedback loop of MIDI data that can cause unpredictable and sometimes show-stopping behavior.

Understanding MIDI loops is essential for building a reliable pedalboard, especially when using MIDI foot controllers.

How MIDI Is Supposed to Work on a Pedalboard

In a typical setup:

• A MIDI foot controller (like those made by Morningstar Engineering) sends commands
• MIDI-enabled pedals or amps receive those commands
• The devices change presets, toggle effects, or adjust parameters

For example:

Step on a footswitch → Program Change sent → Delay pedal loads preset 23

The message flows one way and stops. No problems.

How MIDI Loops Happen in Guitar Rigs

MIDI loops usually happen when a pedalboard grows more complex and multiple devices both send and receive MIDI.

1. Connecting MIDI IN and OUT Both Ways

A common mistake:

• Controller MIDI OUT → Pedal MIDI IN
• Pedal MIDI OUT → Controller MIDI IN

If both devices echo or retransmit MIDI, the controller’s message comes right back to itself—over and over.

2. MIDI Thru or Soft Thru on Pedals

Many MIDI pedals have:

• MIDI Thru (hardware copy of incoming MIDI), or
• Soft Thru (software forwarding)

If multiple pedals in the chain have Thru enabled and the chain is connected back to the MIDI Controller, MIDI messages can bounce around the board indefinitely.

3. USB MIDI + DIN MIDI at the Same Time

This is very common with modern pedalboards:

• MIDI foot controller connected to a computer via USB
• Same controller connected to pedals via DIN MIDI

If MIDI is being bridged between USB and DIN without filtering, messages can loop:

Controller → Computer → Controller → Pedals → Controller → …

4. Pedals That Send MIDI Back

Some pedals send MIDI when:

• A preset is changed
• A knob is turned
• An expression pedal moves

If your controller also reacts to incoming MIDI, you can accidentally create a loop where:

Controller changes pedal → Pedal sends MIDI → Controller reacts → Sends MIDI again

What a MIDI Loop Looks Like on a Pedalboard

When a MIDI loop occurs, you might notice:

• 🔁 Presets rapidly changing on their own
• 🎚 Parameters jumping or “wiggling”
• 🔊 Sudden volume changes
• ❌ Stuck notes or frozen pedals
• 🚨 Controller or pedal locking up

Because MIDI data is very lightweight, loops can escalate extremely fast.

Why MIDI Loops Are a Big Deal Live

MIDI won’t physically damage your pedals—but it can:

• Overload pedal processors
• Freeze MIDI foot controllers
• Cause unpredictable switching mid-song

In a live setting, a MIDI loop can instantly derail your performance.

How to Avoid MIDI Loops (Best Practices)

1. Designate a Clear MIDI “Boss”

In most rigs:

• The MIDI foot controller is the main sender
• Pedals are receivers

Only allow pedals to send MIDI if you truly need it.

2. Do not connect MIDI signal back to MIDI Controller

Only do this if you know what you are doing i.e. you have disabled MIDI Thru on the controller and you want to control the Controller via another source.

3. Be Careful with USB + DIN Routing

If your controller mirrors USB MIDI to DIN MIDI (or vice versa), double-check that MIDI isn’t being sent straight back to itself.

4. Trace the Signal Path

Ask one simple question:

“Can this MIDI message find its way back to where it started?”

If yes, you’ve found a potential loop.

A Simple Rule for Guitarists

If a pedalboard device both sends and receives MIDI, you must manage that connection carefully.

Conclusion

A MIDI loop is an infinite cycle where MIDI messages continuously re-trigger themselves. In guitar pedalboards—especially those built around powerful MIDI foot controllers—loops are easy to create accidentally but just as easy to prevent with good routing and filtering.

At Morningstar Engineering, we design MIDI foot controllers with flexible routing, filtering, and control precisely to help musicians build powerful, stable, and performance-ready MIDI rigs.

Updated on: 29/01/2026