CPU is 70% idle - ABLETON audio dropuots

[MEIC101]

Hi! I was searching for a way to optimize my system for Ableton Live. I was also considering buying Mac Pro. But, I started to dig deeper into CPUs, clock and cores to choose the right machine. So, I thought I should conducted a test of my current Macbook Pro running Ableton. I made a chord in U-he DIVA and started to duplicate the track. When I added 6th instance of U-he DIVA, audio dropouts started (Ableton's CPU Load meter was showing 70-105 CPU%) however "activity monitor CPU" was showing idle of 73-74 %. And 7th instance of Diva gave massive and completely unusable audio dropouts while "activity monitor CPU" was about 70% idle. Is that normal behavior for Ableton that it is working with only 30% of my CPU power? Do I miss something? What could be the problem?

My setup:
Macbook Pro 15" mid 2012, running Mac OS X 10.7.5, Live 8.3.4
2.6 Ghz Intel Core i7 "Ivy Bridge"
8 GB ram
2x M4 SSD running on RAID 0

Ableton:
8.3.4 32-bit
Sample rate: 96000
Audio Buffer: 512 samples

[fishmonkey]

Ableton's CPU meter shows the capacity of the system in terms of the ability to play audio at the current settings without drop outs. it doesn't show raw CPU usage, so you can't really compare the output of Activity Monitor.

and you probably already know this, but running at 96 kHz sampling rate works your system a lot harder.

[MEIC101]

Yes, I understand live's meter and I wouldn't have any questions if my CPU was 90% loaded. But Ableton is using 30% of my CPU power.

[fishmonkey]

continuous glitch-free audio playback makes stringent demands on a computer system. raw CPU power in terms of clock cycles is only one of many requirements. in a multiprocessor system, how well the work can be shared between multiple processor cores is another. it is true that for various possible reasons, which have been speculated upon in numerous other threads on the forum, Live isn't able to utilise multiple cores as fully as other (linear) DAWS.

on your system, with 8 virtual processor cores, as soon as the work needing to be done by any one of those cores is too great, you will get audio glitches, even though the other 7 cores might be completely idle. theoretically then you could get audio dropouts with only just over 10% raw CPU usage.

also, running at 96 kHz pushes your system much harder because the audio needs to be generated, processed, and sent to your audio output device at a very fast and consistent rate (plus you are testing with Diva, which is one of the most CPU demanding synths available). try lowering your sample rate and increasing your buffer size and see how that affects CPU use...

[tintala]

64 bit should help with this..

[Vance]

See my similar thread: viewtopic.php?f=1&t=172654

[ian_halsall]

I had a strange one similar to this a few months ago.

I had quite a simple song with maybe 10 tracks playing and I noticed the disk dropout indicator in Live was lighting up.

So I muted each track in turn until I isolated the problem one.

It came down to a couple of samples from a Sonarte collection I bought and I never really found out exactly why these samples were causing a problem.

I sent it Ableton technical support but I couldn't be bothered to follow up in earnest because although I didn't find out the underlying reason I was happy that it was some one-off problems with these samples.

As soon as I stopped using these (I think there were 2 of them) samples the disk indicator light went off - weird eh?