digital clicks and pops with plugins, CPU meters read low.

[gonzomuso]

Here's my setup

logic pro 7.2.3

M-box 2

Mac Pro Quad, 2.66 GHz

4 Gigs RAM

 

I have my preferances set to the most CPU intensive (32 sample I/O buffer, and smallest CPU level in the preferance pane). When I have two sculptors up and two space designers, and I have all of them running, I hear digital clicks and pops. When monitoring my CPU meters, one of the four cores gets up to about 50%, while the other three remain below 10% or so.

The clicks and pops disappear when I set the I/O buffer higher, and set the CPU level to "large".

Has this happened to anyone else? It would make sense that I wouldn't hear clicks and pops until all four cores were maxed out, and I'm nowhere near that level.

Called Apple, their help was poor. Said that I was using too many plug-ins. Only 4!!

[Simon R.]

I experienced something similar - audio would start stuttering. This was with 3-4 AU instruments, and only one of the cores were up about 60%, the other 3 at 10% or so. I don't know... maybe Logic isn't coded very well to use all cores? This was at a buffer size of 256 samples btw., with a Firewire audio card. Reminds me of the way Logic 5.5 could behave on PC with VST plugins. More evidence that virtual instruments implementation isn't up to scratch? I don't know.

[shivermetimbers]

"...The clicks and pops disappear when I set the I/O buffer higher, and set the CPU level to 'large' "

 

That makes perfect sense...If it pertained to my old iMac, but not on your set up.

 

I am not sure about the M-box, but my US-122 has some buffer settings to change.

 

It may not matter, but what sample rate and bit resolution are you set at?

 

...OH! I usually mention this. Look at your Track mixer (via the audio Environment screen) you may find some unwanted plug-ins hidding there. You may not have put them there, but Don't assume they aren't there. It's worth a look.

[gonzomuso]

Definately no extra plugins. I am also monitoring all my audio object and a master fader, there is no normal clipping.

I am running at 24-bit, 48Khz.

It just doesn't make sense, I literally cannot get my CPU meters to max out. I understand there are limitations to native systems, but my computer is supposed to be a fireball right?I told the Apple Tech that and he said "i can't remember if Logic is meant to use all the cores", and after laughing, I said "then what's the point of multi-CPU computers" and he told me "to multitask", i.e. multiple programs at once. The help was indeed laughable.

I've never had problems with my M-Box 2. In fact, I also have Protools LE on the same computer, and I've loaded the maximum number of tracks (I believe 16 stereo) and I started putting the factory reverbs on each track. I had the "large hall" setting, with a 4 second decay time. The I/O buffer settings were as low as possible. I got more than three reverbs per track, that's more than 48 plugins before there was a hiccup.

 

anymore ideas?

[shivermetimbers]

Duh me!!

 

Raise up your I/O buffer size till the noise disappears. It won't hurt and you will be happier.

 

Here is some tech stuff if your interested.

 

http://developer.apple.com/documentation/DeviceDrivers/Conceptual/WritingAudioDrivers/AudioOnMacOSX/chapter_2_section_4.html

 

(Edit note: I lowered my I/O buffer and played using Sculpute. Clicks and pops galore with hardly any CPU activity. Raised it up and the trouble was gone.)

[blueintheface]

Sending data to the sample buffer is a single thread process - i.e. cannot be shared among CPU's - unlike plug-ins. That's why one of your CPU's is showing a high load - it's the one running the thread for th sample buffer. . . .

[gonzomuso]

Okay, so if i/o is handled by cpu core, then conceivably there still is not much of a point to multiple cpus. Am i missing something? And still, I shouldn't be hearing clicks and pops until at least one of the cores is maxed out.