Optimizing MacOS for Audio & MIDI
Contents
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Don't run networking/internet software along with MIDI/audio |
Newer Technologies CPU upgrades - set to Write-Through mode Beige G3 - Disable ATI Graphics Accelerator See also: |
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General information
Many seemingly innocuous features can cause problems with digital audio and MIDI programs. Such problems can result in audio pops and clicks, or even audio dropouts. Fortunately, these problems can be avoided by careful configuration of the MacOS system to ensure reliable audio performance, as described below.
Use a minimal extension set
We recommend that you use OASYS PCI with a minimal set of system extensions, containing only the extensions necessary to use OASYS PCI and your audio/MIDI programs. To create a minimal extension set:
1. Open the Extension Manager control panel.
2. Select the MacOS Base Set.
The exact name will be "MacOS 9.04 Base," MacOS 9.1 Base" etc., depending on the version of MacOS installed.
3. Press the Duplicate Set button in the bottom right-hand corner of the window.
4. Give the set a descriptive name, such as "Audio" or "OASYS PCI."
5. Enable all three OASYS PCI extensions.
6. Enable any extensions necessary for your audio/MIDI programs or hardware, such as audio/MIDI sequencers, MIDI interfaces, and other audio hardware.
These extensions might include: DAE, FreeMIDI Power Plug, FreeMIDI System Extension, Open Music System (OMS), OMS, Preferred Device, MOTU USB Driver, ReWire, REX Shared Library, TimeBandit.shlb, USB Floppy Enabler, and USB OMSMIDIDriver.
The above is intended to be a starting place, and is not a comprehensive list of audio/MIDI-related extensions.
IMPORTANT: please consult the manuals for your audio/MIDI software or hardware manuals for a complete list of the extensions which they require.
7. After creating the new extension set, close the Extensions Manager window.
The new Extension Set will not take affect until the computer is re-started.
Disable Virtual Memory
Korg recommends that the MacOS Virtual Memory (VM) be disabled when using the OASYS PCI. (This is done in the Memory control panel.) Many digital audio programs also require that VM be disabled, since it can cause performance degradation.
New Virtual Memory settings will not take affect until the computer is re-started.
Set Disk Cache to minimum
The settings for the system disk cache can affect performance. In some cases, it may help to set the Memory Control Panel's Disk Cache to 512k or lower, down to the lowest possible value. Higher settings can sometimes cause degraded performance, including audio and synchronization problems.
New Disk Cache settings will not take affect until the computer is re-started.
Turn off AppleTalk
Korg recommends that AppleTalk be turned off when using audio/MIDI programs and OASYS PCI.
To turn off AppleTalk, use the Control Strip or the AppleTalk control panel.
If you will be using the Location Manager to switch between setups for audio and general purpose computing (see Tip: use the Location Manager, below), do the following:
1. Open the AppleTalk control panel.
2. In the File menu, select Configurations (command-K).
This opens the Configurations dialog for the control panel. It allows you to save and name the AppleTalk configuration.
3. Press the Duplicate button.
4. Enter a name for the new configuration (such as AppleTalk Off).
5. Press OK to confirm the new name.
6. Press Make Active to confirm the new configuration selection, and close the configuration window.
7. In the Edit menu, select User Mode.
8. Select Advanced, unless you are already using the Administration mode.
9. Press the OK button to confirm the new User Mode.
The control panel will now be bigger, showing more options than in the default Basic mode.
10. Press the Options button.
The AppleTalk Options dialog will appear.
11. Press the Inactive button.
12. Press OK to confirm the change.
13. Close the AppleTalk window.
A dialog box will appear, prompting you to save the new configuration, and warning that changes may disrupt current AppleTalk connections.
14. Press Save.
You can now use Location Manager to recall the saved "AppleTalk Off" configuration.
For more information on AppleTalk and configurations, please see the MacOS Help system.
Turn off File Sharing
Korg recommends that File Sharing be turned off when using audio/MIDI programs and OASYS PCI.
To turn off File Sharing, use the Control Strip or the File Sharing control panel.
Disable "deep sleep"
OASYS PCI does not support MacOS "deep sleep," in which the entire system (not just the monitor and hard drive) goes into sleep mode. Support of deep sleep is a function of the PCI controller hardware, and cannot be changed.
In the past, MacOS systems would not attempt to enter deep sleep mode if they sensed that one or more of the installed devices did not support deep sleep. With some recent models, however, this appears to have changed.
Some users of these recent models have reported problems in which MacOS will not wake after going to sleep. The settings below will solve these problems by avoiding deep sleep.
(As a side point, MacOS seems to have a similar problem with at least one other professional audio card; hopefully Apple will address this issue.)
To prevent the computer from trying to enter "deep sleep" mode:
1. Open the Energy Saver control panel.
2. Press the Show Details button.
3. Check the box labeled "Separate timing for display sleep."
4. Also check the box labeled "Separate timing for hard disk sleep."
5. Set the times for display and hard disk sleep as desired.
6. Set the top slider, labeled "Put the system to sleep whenever...," all the way to the right, to "Never."
This will allow the display and hard drive to sleep, but will prevent the system from going into "deep sleep."
Tip: use the Location
Manager
Apple's Location Manager can store settings for AppleTalk, File Sharing, Extension Manager, and more. You can use this as an easy way to switch between setups for audio and general purpose computing. For more information on Location Manager, see the MacOS Help system.
Don't run networking/internet software along with
MIDI/audio
It's best not to use email, web browsers, ftp clients, and other networking and communications applications while you are running audio/MIDI programs, as these networking programs may interfere with real-time operations.
Physically disconnect networking cables
Disconnect from any dial-up communications, and if possible, it may also help to physically disconnect the computer from any networking devices (ethernet, etc.).
PCI card interaction
The OASYS PCI card relies on being able to transfer small amounts of data across the PCI bus at regular intervals, several thousand times per second. If other PCI devices (such as video, audio, or SCSI cards) tie up the PCI bus for extended periods of time, this can prevent the OASYS PCI from completing one data transfer before the next is scheduled to begin. If this happens, the audio stream will be corrupted. In some cases, this may also result in error messages from OASYS PCI, including -870 and -866 errors.
Some motherboard devices may also share PCI resources, even if they do not use a PCI card - and these can affect the PCI bus as well.
Possible troubleshooting steps include:
1. Try lowering the acceleration settings of other devices on the PCI bus, such as video and SCSI cards. With video cards, this could also include reducing the color bit depth - for instance, try "thousands of colors" instead of "millions."
2. Try swapping the OASYS PCI with other PCI cards, or simply moving OASYS PCI to another PCI slot. As always, remember to turn the computer off first! In some instances, this will result in improved performance.
3. For troubleshooting purposes, you may also wish to temporarily disconnect other peripherals, including USB and Firewire devices.
4. If these steps do not help, temporarily remove all PCI cards which are not necessary to start up the computer, except for OASYS PCI. This includes extra SCSI or ATA controllers, extra video cards, other audio cards, and so on. Once you establish that the OASYS PCI is working properly, add the other cards one by one, until you find the source of the incompatibility. Once you have found the source, look in its manual and contact that company's technical support to see if they have any suggestions, such as changing settings, downloading new drivers or firmware, and so on.
For more information on SCSI, see the article OASYS PCI and PCI SCSI cards.
For more information on USB, see OASYS PCI and USB devices.
Use separate PCI bus on 6-slot CPUs
If you are experiencing PCI card interaction problems on MacOS systems with two PCI buses (all 6-slot towers, including 9500, 9600, and PowerTower Pro), we recommend distributing cards between the two busses, so that each has the maximum PCI bandwidth available. In particular, try placing the OASYS PCI on a separate bus from video, audio, and SCSI cards.
Newer Technologies CPU upgrades - set to Write-Through
mode
If you are using a Newer Technology CPU upgrade card, and are experiencing difficulties with OASYS PCI, we recommend that you use the MaxPower Control Panel to select "Write-Through mode," as opposed to the default "Write-Back mode." Some users have found that this dramatically improves stability with audio hardware, including OASYS PCI.
Beige G3 - CD Update
Apple has identified and fixed a problem with certain Beige G3 Macintosh models, in which the CD-ROM could cause long delays in system response while "waking up," which may happen (for instance) when a new CD-ROM is inserted into the drive. These delays may cause crashes with certain digital audio programs. If you have experienced this problem, you can download the G3 CD Update from Apple's website.
Beige G3 - Disable ATI Graphics Accelerator
On some Beige G3 Macintosh models, the ATI Graphics Accelerator extension may interfere with the OASYS PCI. If you experience problems with audio, Korg recommends that you disable this extension when working with the OASYS PCI. You can do this using the Extensions manager, or other extension-management software, or by simply dragging it out of your System:Extensions folder.
For related information, see Beige G3 with factory-installed ATTO SCSI card.
Disable auto save (optional)
Some audio/MIDI programs include an Auto Save feature, which automatically saves your work after a set period of time. This is a cool feature, but it may interfere with real-time operation. If you are having problems with audio, and auto save is enabled, try disabling it.
Copyright 1999-2002 Korg Inc. FAQ Version: 8/19/02