Logic Pro 9 Pops and clicks in audio with MBP, RME UCX


I have been recording a band 12-15 hours days since Saturday and we have had intermittent problems with pops and crackles happening randomly throughout the audio tracks recorded. Here is my setup:

MBP 15" 2.6 GHz i7 - 8 GB 1600 MHz DD3 - Mid 2012 - Model Identifier MBP 9,1
OSX 10.8.3
Apple SSD 250 GB
External Discs - Seagate 2 TB - Firewire 800 Connection & Seagate Go Flex - Thunderbolt connection

UCX - firmware 117, Totalmix .972

Logic 9.1.8

Software monitoring is disabled - Monitoring direct through Totalmix -

Buffer set to 1024

Here is what I have tried so far to troubleshoot:

- Made sure wifi and bluetooth are disabled

- Disabled Notification center

- Remove the word clock connection and adat connection to Focusrite Octopre LE (new piece of gear I got for this week of recording)

- Update OS to 10.8.3

- Run projects off of seagate 1tb drive with thunderbolt connection instead of the 2TB firewire 800 that is plugged into a UAD satellite DSP piece ( I have not used any UAD plugs yet on tracks, just trying to record tracks without pops and crackles first)

- RUN Projects off of internal SSD drive instead of external disc

-When I close Logic and reopen the program the problem seems to go away for a short time only to come back again eventually

Any help would be greatly appreciated. We will still be recording today and tomorrow. Couple of us took off work this week to record as much as possible so it would be nice to get a couple days of problem-free tracking done. It's definitely a good lesson learned.

Thank you very much for any time or help provided!


Are the interface and Logic project sample rate (Project Settings>Audio) the same? (both set to 44.1 or whatever you need?)

What was the I/O when recording? Too low may be an issue. 128 or 256 are good starting points.

Also consider this:


Thank you for the help!

I checked and Logic and the interface are both set to 44.1khz for the sample rate.

My I/O buffer size is set to the highest possible
amount: 1024. We are monitoring directly from the RME interface.

You would think an i7 CPU, 8 gigs of ram with an rme interface could handle 1024 buffer size with low track counts as well. (8-16 tracks currently per song)
Starting to think its background scheduling type of bug.


Sorry for being a master of the obvious, but is clock source is set to internal on the RME? (You mentioned removing word clock and adat...)

Not that is should matter, but how many tracks are recorded in one pass?

I'm not familiar with the UCX. Are your recording any DSP fx?

Given the specs of your set up, and your extensive trouble shooting..., this is a weird and discouraging situation.


Yes the clock was set to internal. When the clicks would happen it would only be one track being recorded. Although sometimes I was recording 10 tracks at once.

It is a bummer that even top of the line gear doesn't keep you safe from these types of issues with computer recording.