Mysterious transient noise (like a lightning storm)

[jhaxton]

At seemingly random points during recording, using MOTU 8pre units together as an aggregate device (not tested with a single unit), and with track count not a significant variable (happens with 11 tracks as easily as with 26 tracks), what sounds like a digital lightning storm occurs in the audio. At times, stopping the recording will provide immediate relief. At others, the recording process is stopped, but the "storm" can still be heard continuing through the headphone out on the MOTU 8pre. Before I heard this problem continue to be present in the audio without any other audio going through the system, I thought it might be related to performance settings. Now, I have no idea. A link to the sample on MOTU is attached. Hopefully, you've heard this sound before and can point me in the direction to fix it. I'm running OS X 10.5.7. (I have a techlink for this on MOTU, but it's been sitting there for 16 days without being read.)

http://downloads.motu.com/tickets/45669 ... sample.mp3

Any advice would be most appreciated. Thank you!!

[jackballed]

I get this same dang noise happening to me all the time with my 2408mk3 and 2408mk2 connected to a PCI-424e. Sometimes it occurs using Aggregate Devices and sometimes it occurs using solely the PCI-424. I'm curious if it's a driver or OS extension?

[jhaxton]

So it's not just 8pre related. I'm looking forward to hearing from MOTU's tech support on this, but they are so, so slow to get to it. If they have an answer for me, I'll post it here. If anyone here has an answer/solution for us, I'll post it on my techlink at motu.com for them to see...

[SmilesLots]

I have had that symptom with bad/cheap mic cables. Seems 48v phantom power was too much. New cable helped/solved.

Another time it was a ground loop caused by improper phase on a sound module that had only the two pronged mains plug.

One the MacBook try reversing the mains plug.

[jhaxton]

When the problem was mic/power related, did the crackling run through every track being recorded? In my example, it was coming through all 24 individual tracks and it even continued to spit at me through the headphones after I stopped the recording, which stopped the monitoring for all tracks so that all I heard was the noise for another 5 seconds until it went away.

[jhaxton]

BTW, thanks for the replies so far.

[newrigel]

At seemingly random points during recording, using MOTU 8pre units together as an aggregate device (not tested with a single unit), and with track count not a significant variable (happens with 11 tracks as easily as with 26 tracks), what sounds like a digital lightning storm occurs in the audio. At times, stopping the recording will provide immediate relief. At others, the recording process is stopped, but the "storm" can still be heard continuing through the headphone out on the MOTU 8pre. Before I heard this problem continue to be present in the audio without any other audio going through the system, I thought it might be related to performance settings. Now, I have no idea. A link to the sample on MOTU is attached. Hopefully, you've heard this sound before and can point me in the direction to fix it. I'm running OS X 10.5.7. (I have a techlink for this on MOTU, but it's been sitting there for 16 days without being read.)

http://downloads.motu.com/tickets/45669" onclick="window.open(this.href);return false; ... sample.mp3

Any advice would be most appreciated. Thank you!!

Has it been doing this since day 1? If not you have some corruption somewhere. Just reinstall your drivers and DP and see what happens... an OS X combo update wouldn't hurt either, just make sure to use something like ONYX before you restart the machine to clear out the caches.. and I mean all of them! Also, you might just want to try the stock audio outputs and see if it's coming out then... if it isn't, you know it's driver related.

[Eleventh Hour Sound]

I found turning off WiFi has stopped a lot of weird glitches I was getting.

[jhaxton]

Thank you, again, for your help. It hasn't happened since day one, so I agree that it could be some kind of corruption. I went as far as to do a time machine restore to back to OSX 10.5.7 (before I had noticed that particular problem) and then make sure my updates for the MOTU drivers and firmware were up to date. That didn't seem to do the trick. My have stuff like wifi, bluetooth, and finder turned off as well.

I have another big show coming up (Moonalice), that I'll be recording. I'll double-check the drivers, apply all OS updates, and clear out the cache.

The show is on March 6th. I'll report back after that.

BTW, it's awesome to have this forum available since MOTU tech support is seemingly non-existent. I'm extremely disappointed with them... to the point where I'm thinking of switching hardware away from MOTU... what the heck happened to their customer care?

[jhaxton]

I used Maintenance (from titanium software) to clean up my 10.5 partition and updated it to 10.5.8, and installed the latest MOTU drivers.

Then I had another thought. Although I wouldn't expect it from a Mac, maybe the M-Audio drivers I installed so that I could use Pro Tools are making a mess of the MOTU drivers being used in the aggregate device(some of my clients have required Pro Tools so that I can do all of the tedious dry mix stuff and then pack it up for delivery to a big studio for the rest of the process). Although the M-Audio gear isn't used in the Aggregate device, and the M-Audio box isn't connected when doing live multi-track recording (for that, I'm all MOTU), and I have no idea how it would mess things up, maybe it is.

So, I decided my test for the Moonalice recording will be done on my 10.6 partition, with the M-Audio drivers and Pro Tools deinstalled (Pro Tools works like crap on 10.6, anyway). I also performed the Maintenance and MOTU driver updates.

Wish me luck

Jason

[jhaxton]

So, I've tried this on multiple Mac OSs now, on different sources, with or without MOTU supplied phantom power, different cables, different microphones. I've scrubbed the computer cache, updated drivers, everything one could reasonably do to troubleshoot this.

I have received no response to my MOTU tech link, which has been sitting out there for two full months. Unless MOTU tech support somehow changes their tune and helps me resolve this issue in the next few days, I'll have to say adios to MOTU altogether. This is really sad, because I've been a MOTU user for 8 years. I don't know what happened to the company, but they certainly aren't here for me anymore.

[HCMarkus]

So what's your setup? Are you using two 8 Pres only? Have your tried using one as a Lightpipe slave and ditching Aggregate Devices?

[jhaxton]

I'm using four. I often need over 24 channels (16 doesn't cut it for live multi-track recording in most cases). This configuration was working for about a year. Something changed or something went bad. I thought it might have been OS, so I rolled back. Still had the same problem. Updated drivers. Same problem. Tried it on 10.6. Same problem. I'm looking around for replacement gear... maybe the new M-Audio units that look about the same as the 8pre. They don't have pre-amps on the 1/4" jacks, I hear, but they are cheaper and compatible with pro tools. I don't know, of course, if their tech support will be any better than MOTU.

[jhaxton]

After sending an email to MOTU customer care, someone picked up my 2-month old case. I'll update here with the resolution, if any. Thank you!

[jhaxton]

While performing a MOTU support requested "audio out only" test today, I decided to re-test my recording patch cords. Turns out, one of the four 8-cable snakes I use has a single intermittent connection. The odds of me having used this particular snake on every recording over the past 6 months is pretty low, but nonetheless possible. If an intermittent cable on a single channel can produce crackling over all channels of the MOTU unit, then this is probably the issue. Although I really don't understand how one bad cable could ruin every track. Still, that seems the most likely explanation right now.