“I want to use Logic as a MIDI Sequencer only, playing back and recording audio with ProTools Software. I’ve heard this is possible via “OMS” but how?”
Back in the (good?) old days before sequencers had decent audio capabilities we had to do this. The procedure below is specific to Logic, but it’s not all that different for most sequencing programs. You can create such a setup with the IAC driver of the OMS. ProTools has to transmit MTC via IAC Logic can also be configured in a way that it remotely controls the ProTools software via MMC. In order to do so, you need a fast computer with lots of RAM. The minimum is a 604 processor with 200 MHz, and at least 128 MB RAM. These settings are required:
In the OMS setup:
Create an IAC driver in OMS. This will be created automatically when scanning for a MIDI Interface, which happens automatically the first time you run it. If this is not the case, manually install OMS and install the IAC driver. Double-click the IAC driver, and create two busses. Call the first one “MTC to Logic.” Call the second one (the one to transmit Logic’s MMC commands to ProTools) “aaaMMC” for PT. The driver name indeed must begin with “aaa.” In the edit menu of OMS, make sure that OMS is running in the background. Save your settings, update your Studio Setup, and close the Setup.
In Logic Audio:
Select Options > Settings > MIDI Interface communication and select Use OMS if available. The option Release Modem and Printer Port in Background if stopped must NOT be activated. Under Options > Settings > OMS Input Connections, select the MTC to Logic IAC bus you just have created. Now go to the OMS Output Map Connection. Whether you need Connection 1 or 2 depends on the way you have connected your MIDI interface. Assign aaaMMC for PT to the connection for Output M0 (P0 if you use the printer port). This is for the MMC commands from Logic to ProTools. Under Options > Settings > MIDI Options, switch off Transmit MTC and Transmit MIDI Clock. Otherwise, a MIDI feedback loop would occur between Logic and ProTools. Auto Sync must be switched off, too. Click-Hold the Sync button in the transport window and activate SMPTE Sync Mode. The sync button turns blue and clicking onto it toggles between internal and external synchronization.
In ProTools:
Open the window “Session Setup” and assign MTC to Port to the Bus MTC to Logic, which you created in OMS. In the Setup menu, select Peripherals, and set #1 to MMC; Select the bus aaaMMC for PT as the MMC source.
That’s it. Finally, make sure that the SMPTE Offset Time is the same in ProTools and in Logic. You can control both linked programs either from Logic or from ProTools (Start, Stop, Moving the Song Position Line…).
Hint: If the song contains several Tempo Changes, export the song as a MIDI file, which can be opened in ProTools. Both programs will then always have the same tempo information.