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MIDI Loops and Log Jam, Troubleshooting MIDI playback and/or timing problems

Poor MIDI performance such as stuck notes, uneven playback, random patch (program) changes and other controller messages can be attributed to MIDI feedback or clock loop. It can also be attributed to MIDI log jam.

Suspect a MIDI loop problem if the above behavior is consistent with all sequences, and even when using a MOTU MIDI interface in a stand alone operation. Follow the below steps for troubleshooting loops:

  1. If you're using a cablizing interface, hard Reset the Micro/Express/XT, MTP/II/AV. Turn it off, hold down the panic button and turn it on again.
  2. Any device that has a built in sequencer or arpeggiator will send MIDI beat clock. Look for an input light that glows continuously, as well all output light may glow. Either put the device connected to the glowing cable into external mode (especially if you're not using a cablizing interface) or use the console software to mute realtime data on input for that device/cable.
  3. Check for any device that is set to MIDI echo or MIDI overflow and turn that setting off. Drum machines and effects, especially Alesis products like the D4 or the MIDI verb, can configure the output to behave as a Thru port. Thru echos input and can cause feedback loops. Make sure the output MIDI port is set to Out rather than Thru.
  4. Make sure your software is not inadvertently set to transmit beatclock or realtime sync. In Performer > basics menu, transmit sync, make sure there are no sync to port settings.
  5. Make sure local control is off for all input devices.

When you experience stuck notes, choppy MIDI playback, instrument lock or data overflow messages appearing on a MIDI instrument at a specific part of a sequence, suspect that good 'ole 7 bit MIDI bandwidth has been breached.

  1. When using DP or FreeStyle on a serial Mac, launch with the following extension set only:

FreeMIDI Power Plug

FreeMIDI System extension

Serial Tool and/or Serial (built in)

Shared library manager

Shared library manager PPC

SOM Objects

Sound Manager

... to rule out processor strain or extension conflict. On a USB Mac, start with Mac OS base. exclude the serial Tool/Built in and add the MOTU USB driver.

  1. If you're sending lots of continuous data at that part, most sequencers have an option to thin this out. In Performer and Digital Performer's region menu, choose Thin Continuous Data. In most cases thinning out data like pitch bend or pan does not compromise the desired effect.
  2. Sysex messages can eat up MIDI bandwidth. Place these messages in less dense parts of the sequence or move them to the beginning of the sequence, creating a measure of silence before the sequence starts to transmit these messages.