Sound jumps and scratches in Logic Pro 9 - help!

[phas3d]

Your friend advised you wrong. The more you lower the buffer setting the more strain you put on a CPU. You have a powerful enough computer though. What audio interface are you using?

[gdoubleyou]

Are you recording to your system disk?

[Grindonthemind]

I am definitely no expert but I would not be surprised at all if it was your audio interface/sound card. Had similar cracking issue with a bad audio interface...got a Focusrite Scarlett and it's been great ever since.

Are the clicks and scratches random or do they happen in time? That would help you narrow it down.

[DocOck]

I am using the internal sound card in the iMac and the picks and scratches are completely random and sound like the "machine" can't handle it. The problem is there all the time, even if I open a new project and just add a EXS24 synth or a simple audio file.

At the bottom of Logic, where it says CPU / HD, the CPU is maxed out (red) when I hit play, and when I double-click, the audio-bar to the right is maxed out as well. When I check "Activity Monitor" on the Mac, Logic's CPU use is 10% and 40% when I hit play.

What should I do?

[explorer]

1. Use a larger buffer size to prevent CPU overloads (although 256 should probably work ok for your system).

2. Ensure the number of processing threads is set to the highest number (in the audio preferences)

3. Read and understand how logic distributes CPU load across multiple processor cores
Logic Pro/Express: Tips for balancing multi-core performance

[DocOck]

I just learned that it also crackles and crunches when I play in Spotify, so long as Logic is open. Thoughts?

[explorer]

Did you try any of my suggestions?

Also, are you sure its not the audio connection/speakers/amp?

Finally, the audio output on some macs is a little noisy. Make sure you have your gain-staging setup correctly to get the best signal to noise ratio.

[Rudiger]

I'll second the "are you recording to your system disk" question mentioned above.

Or even worse, are you using a different partition on your system disk?

[DocOck]

It seems that the problem is the Bowers & Wilkins speakers I have connected to the iMac through USB. The CPU box at the bottom of Logic doesn't peak at all, and the sound doesn't scratch after I closed the computer, disconnected the speakers and then selected "built-in" as output in Logic.

That probably means I should buy some "standard" computer speakers right? Unfortunately I can not afford an Apogee Duet + some real speakers, so is there anything you can recommend me on a tight budget? Thank you!

[Rudiger]

Here's an heresy but for your case I would recommend a good set of headphones. Not only you can upgrade to a speaker monitoring system in the future without compromising now, you can also overcome acoustic difficulties in your room.

[DocOck]

F*CK!! The problem is back, even with built-in output selected :(