Native Instruments - Knowledge Base
Knowledge Base
I get crackles on my MacBook/MacBook Pro. How can I optimze my system for real-time audio?
Disclaimer: This article mentions a third party tool which is not related to Native Instruments at all. Though we have successfully tested this in-house for a longer time, this and comparable tools can potentially damage your computer and harm the manufacturer's warranty for your computer and connected hardware. If you want to make sure that you do not act against the license agreements or other instructions given for the use of your computer, please contact the manufacturer of your computer or the developer of the third party tool directly.
In order to reduce power consumption of the MacBook / MacBook Pro, OS X reduces CPU rates. Unfortunately this can affect the performance of the computer when it comes to real-time audio processing which causing clicks in the audio signal.
We can recommend two approaches for this problem, described in the following.
1. Third party tool to control clock speed.
This issue can be solved by using third party tools that allow to control the CPU clock speed. One such tool that has been proved to work properly is "Coolbook". You can obtain this software under a commercial license from www.coolbook.se. Attention: Before using this software make sure you have read and understood the information given on this page about compatibility with specific Macbooks and MacbookPros.
The purpose of this article is to give you some basic tips how to optimize the settings of Coolbook for real-time audio. Note that it is highly recommended to read the documentation that comes with this software. This article will refer to this documentation, too.
Coolbook should be used just to prevent the CPU running at lower CPU rates. "Undervolting" is not necessary to be used. Therefore you just need to remove the "pairs" for frequencies lower than 1400 MHz from the list of pairs that may be used. Use the "Clear" button in the software to remove single "pairs" from the list. Attention: find out from the documentation of this software how to use the "Clear" button. After removing the pairs lower than 1400 MHz, press the "save" button and restart your computer.
2. Set your dual core processor to use one core instead of two.
Apple provides a developer tool to disable one of the two cores of the Core Duo processor in your MacBook (Pro). This tool comes with your OS X installation disc.
Enter your OS X installation disc and navigate on this disc to:
Developer/Extras/Preference Panes/
There locate the file "Processors.prefPane" and copy it into:
Macintosh HD/Library/Preference Panes/
After restarting your computer, go to OS X system preferences, you will find the preference pane "Processors" now. Click on it to open it. To disable a core, remove the checkmark for "Core 2". Immediately this core will be disabled, so only the remaining core 1 will be active.
By setting the checkmark again, the second core would immediately become active.
We cannot really say exactly why this helps - we can just say that this method has prooven to overcome speed stepping issues. One reason why this method helps is probably based on the fact that the CPU rate is reduced when the workload on the CPU is low. By disabling one core, the workload on the remaining core is naturally higher, which results in less reduction of the CPU rate.
Note that this method may not be adequate if the CPU load is rather high, as the remaining core may be overloaded. This can be the case escpecially if more than one audio application is used simultanously.
In order to reduce power consumption of the MacBook / MacBook Pro, OS X reduces CPU rates. Unfortunately this can affect the performance of the computer when it comes to real-time audio processing which causing clicks in the audio signal.
We can recommend two approaches for this problem, described in the following.
1. Third party tool to control clock speed.
This issue can be solved by using third party tools that allow to control the CPU clock speed. One such tool that has been proved to work properly is "Coolbook". You can obtain this software under a commercial license from www.coolbook.se. Attention: Before using this software make sure you have read and understood the information given on this page about compatibility with specific Macbooks and MacbookPros.
The purpose of this article is to give you some basic tips how to optimize the settings of Coolbook for real-time audio. Note that it is highly recommended to read the documentation that comes with this software. This article will refer to this documentation, too.
Coolbook should be used just to prevent the CPU running at lower CPU rates. "Undervolting" is not necessary to be used. Therefore you just need to remove the "pairs" for frequencies lower than 1400 MHz from the list of pairs that may be used. Use the "Clear" button in the software to remove single "pairs" from the list. Attention: find out from the documentation of this software how to use the "Clear" button. After removing the pairs lower than 1400 MHz, press the "save" button and restart your computer.
2. Set your dual core processor to use one core instead of two.
Apple provides a developer tool to disable one of the two cores of the Core Duo processor in your MacBook (Pro). This tool comes with your OS X installation disc.
Enter your OS X installation disc and navigate on this disc to:
Developer/Extras/Preference Panes/
There locate the file "Processors.prefPane" and copy it into:
Macintosh HD/Library/Preference Panes/
After restarting your computer, go to OS X system preferences, you will find the preference pane "Processors" now. Click on it to open it. To disable a core, remove the checkmark for "Core 2". Immediately this core will be disabled, so only the remaining core 1 will be active.
By setting the checkmark again, the second core would immediately become active.
We cannot really say exactly why this helps - we can just say that this method has prooven to overcome speed stepping issues. One reason why this method helps is probably based on the fact that the CPU rate is reduced when the workload on the CPU is low. By disabling one core, the workload on the remaining core is naturally higher, which results in less reduction of the CPU rate.
Note that this method may not be adequate if the CPU load is rather high, as the remaining core may be overloaded. This can be the case escpecially if more than one audio application is used simultanously.
39%
60%
