Delayed Sound Gremlin with Motu M4

Hardware
1

I’ve been playing out for the past year and a half (over 75 gigs) using GP running on a Mac Mini M1 (8 core, 2020, 16GB Ram, 2TB drive) running Monterey. I’m using a 61 key Arturia Keylab as the GP controller. I also use a Nord Stage 88.

I use an unbalanced stereo cable to run from the Nord L/R (1,2) outputs into the front inputs on the Mutu, and the sound is routed from those ports in GP to the output ports of the Motu, it’s a direct route except for one gain control hooked up to a foot pedal and a bx limiter. The sound is mixed with the VST sounds from GP and routed from the motu into a Direct Box, and then XLR cables are sent to the FOH mixer.

On Saturday night after setting up, I noticed a weired problem where if I played a note on the Nord, there would be a significant delay before that sound was heard at the FOH Mixer, around 2 seconds. This was happening for every patch I tried on the Nord. Sounds generated by the Arturia generated in GP were heard immediately. I tried restarting the Nord, GP, and the mac computer multiple times but the problem always came back.

I verified that there was no delay on the Nord itself by plugging in headphones and running the L/R outputs directly into the board - where it was heard without any delay, but the volume was much lower and totally out of balance, making that approach unusable. I do have a couple of patches where I play sounds from GP using the Nord and those did not have a delay, so the midi out of the Nord was working fine.

Now that I’m back home I can’t reproduce this issue. It seems to be Motu problem somehow. The venue was a sports bar with dozens of Tvs up and runnin throughout, so maybe that created some sort of interference. In fact the only time I’ve ever had any issues with GP has been this same venue (a post I made several months ago about a key largo problem happened there as well, and once the Nord quit producing sound entirely when we were playing on this venues outdoor stage with a ton of bugs flying around). Has anyone else encountered this sort of issue with Motu and/or GP?

In the future I’ll come more prepared with a spare audio interface, cables and DI box in case I need to have more troubleshooting options… I’m also working on adding VST versions of the Nord sounds to my GP patches, so that is this problem happens again, I can push a button in the global section to send midi from the Nord via OSC to play those patches, and just turn down the volume on the Nord. I’ve done that with about a dozen patches so far and it seems to work well.

2

Strange. Did you also power down the Motu in between?

Sounds like a buffer problem. Did you check the audio setiing in GP, try to set a different SR/buffer size and back?

Would be my next steps if that happens again to get any feedback, what fails, or does not react. Especially after you said, at home everything was OK again :thinking:

3

I’m rather intrigued by this problem.

Because it seems related to the venue:

  • I wouldn’t think the TVs and that kind of equipment would generate enough interference in the form of radio waves to disrupt your setup (although I can’t rule it out either)
  • But maybe the power lines could be heavily polluted (in the electrical sense) or just down right below specs. Maybe a next time you could borrow a small UPS just to clean up the power lines?
  • Or a massive ground-loop? That should be of no consequence when you disconnect your equipment from the foh, assuming you use only one powerstrip. (So you could check that)
4

We just booked another show at the same venue for Oct 12th. I’ll bring my spare Motu m4, DI box and extra cables for troubleshooting. Any recommendations for a portable UPS that might work well to stabilize the power, if that turns out the be the problem? My rig already has a Furman SS-6B Surge Suppressor, but that didn’t help last time… I played two shows over the weekend at other venues with zero problems

5

If it’s only meant for stabilizing/cleaning the powerline, a unit with a modest battery autonomy would do. Saves a a lot of weight. I would say APC, but I’m not really into the possible brands. Maybe other people here have better/more appropriate suggestions.