MOTU M2 on GarageBand 10.4.6 strange noises

[GermRando]

Hello everybody,
I just purchased the MOTU M2 a week ago and I love it.
I use it with GarageBand 10.4.6 on my MacBook Pro 15", mid 2014 with OS 11.7.1
But I have got an issue with it.
When I'm recording, doesn't matter if it is MIDI, Mic or Guitar/Bass, the sound that comes out of my headphones, sometimes becomes really strange. It sounds like the note that I play but with a big humming/buzzing over it. Almost like an overdrive. Sometimes it just disappears after a few minutes and sometimes not. It does not necessarily disappears, when I restart GarageBand. It disappears, when I set the audio in/out to another setting and then back to the M2. I want to fix it, because it bothers me and it takes away the fun.
I hope you guys can help me

[stubbsonic]

Have you installed the latest drivers? That's a good place to start. If so, reach out to MOTU's support and see if this is a common issue.

[mikehalloran]

I'll be using Input and Output interchangeably — it depends on if I'm dwelling on the M2 or GarageBand (GB). A GB track's Output becomes an M2 Input over USB and vise-versa.

I'm pretty certain you have phase distortion from a feedback loop—very possible with your Monitor options and GarageBand In/Outs. Are you monitoring the Output of tracks as you record to them? If so, turn that Off (in GB) and monitor the Output of the M2 only. Of course, monitor the Outputs of tracks you are playing back but not recording.

"Near zero latency" is not Zero latency, a physical impossibility. On tracks you are recording, the closer you get to a 50/50 blend between Input (from GB) and Output (from M2) on the same track, you will hear comb filtering due to phase distortion. Again, not monitoring the GB Output on tracks you are recording eliminates this issue. As you'll see in the manual, the M4 and M6 have an Input/Playback Blend control that lets you set the balance (anywhere but 50/50) but the M2 does not—must be controlled in your DAW, GB in this case.

Here's the latest, searchable M2|M4|M6 manual. Go through the setup to see if anything stands out:
https://cdn-data.motu.com/manuals/usb-c ... _Guide.pdf
I suspect you are good there.

If you have the MOTU drivers installed, how is Loopback setup (not an issue if Core Audio only)? See the manual. If you don't need Loopback, turn it off.

You can post screenshots here if there's anything you want us to see.

[guitar2freak]

I have had the same issue with my MOTU M2....
I am using a MacBook Pro with M1 Pro processor along with the motu M2....

I checked the many possible causes for this issue... I tried a different USB cable (which does make a difference by the way... and a cheap cable will make things worse.... but if you use the cable supplied by Motu then that is not the issue), I tried various ports in case the issue came from the power supply circuitry.... I made use my Mac was a lean as possible (so only the key software was running)....
I tried different sampling frequencies, and higher buffer sizes (up to 256) without success...

I tried using Logic Pro but also the standalone version of TONEX, the standalone version of Amplitude etc....

in all cases I kept getting the issue....

And then I decided to remove Motu's driver (which is quite an adventure) and then..... problem solved...

Using the default Mac driver allowed me to get clean audio at all sampling frequencies and all buffer sizes (including 192kHz/32 samples !).... all without trouble and very stable.

The only issue is that removing Motu's driver is unfortunately not the easiest of task..
For some reason they don't supply software to remove it automatically.... So it's a manual task...
I'll outline the steps here...

Please note that if you remove it, you won't be able to use the loopback function... so if this is required I am afraid that unless they supply a new driver that solves this issue, the only option is to purchase a different device (I would suggest Audient ID4 mkII)....

This Motu M2 is actually a good piece of technology with good round trip latency and good audio quality..... It is a shame they do not supply a driver as good as their hardware...
By the way, As of November 2022, I have tried the latest firmware and driver available for Mac...

Anyway, if you try the steps I describe below, let us know the outcome....

How to remove the Motu M2 driver


Read fully before applying any of the steps described.

Open Finder and go to the library directory. Search and any file that has MOTU in its name and delete them. (There will be one in /Library/LaunchDaemons and in other places)

Once done, you will need to remove the driver extension software which is quite involved.

The drive extension files to remove are located in
/Library/SystemExtensions

The directory name will be something like that B4728694-F288-41BD-B7FE-F1445568EAD8
Inside that directory there will be files and one of the file is com.motu.driver.coreuac.dext.dext
In the steps below, the directory to delete is the one with a name like B4728694-F288-41BD-B7FE-F1445568EAD8. Removing it can only be done in recovery mode.
Finding the directly in recovery mode may be tricky... it will be likely like /Volumes/MacOS/Library/SystemExtension… or the closest to that… you know what you are looking for so you’ll find it eventually…. Please read carefully the links below before attempting anything.
If you feel uncomfortable with the steps below you may want to ask some one familiar with this type of operation to actually perform the driver removal.

How to start MacBook running MacOS Ventura in recovery mode is described here

https://eshop.macsales.com/blog/74502-b ... very-mode/

The key is to keep pushing the power-on button until the Mac shows two options for the boot.

How to remove the dext directory mentioned above (driver extension file) is well described here
https://nektony.com/how-to/remove-kext-on-mac

To keep life simple, first disable firevault (if enabled), remove the file as described and then re-enable too.

How to verify the motu driver is effectively removed
1- open the activity monitor and filter data to find any process with the motu name in it.
2- connect the Motu M2 via USB-C and switch it on
3- the only process that should/may be running would be MOTUCoreUACAudioServerPlugin
4- if you see any process with motu in the name (like com.motu.driver.coreuac.dext) and ending in “ext” then the removal was not effective.

[mikehalloran]

Did you read my post? I’m pretty sure that you are monitoring track playback on Record armed tracks. Turn that off in GB and see what happens.

If, for some reason, you must monitor those tracks as you record them, consider the M4 instead and set the Input/Playback knob anywhere except 50/50. I monitor those tracks because it’s convenient—less switching in my DAW. The M2 doesn’t have that control.

As an M2 owner, you have a free license for Performer Lite. MOTU gives online classes in small groups on a regular basis and those lessons translate pretty well to GarageBand. actually, given the choice between the two, I would use PL instead.