Audio/Video Stuttering Issues on the 6400/6500

This page contains a growing list of issues related to audio and video stuttering with tips to prevent them. At first it seemed that only Sonnets L2 G3 upgrade was the cause but now it seems that the 6400 in general has stuttering problems and G3 upgrades only intensify them. The 6500 is less prone to audio or video stuttering but there are a few instances that can cause this problem even on the it. I only hope that by posting this info, I can help prevent some of you from getting the problem!

Not everyone has these issues but many do, which is why I now gave this problem its own page :(
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1/28/2000 Flash: Sonnet says OS 8.5 fixes the issue! I do have several Sonnet users confirming that updating to OS 8.5 or newer fixes the sound issues. It is a costly fix but the price for OS 8.5 has come down since it was first released so it might be worth trying now.

Bill is having a tough time getting Avid to do anything but crash since he installed Sonnets G3. Please email him any suggestions you may have. Also let me know when a fix is found. Thanks

I asked him to try the latest version 1.1.5 and the U3 extension. Here is his reply.

7/10/1999 A real problem found with Sonnets G3: Most of us have been having the startup crashes or random freezes with Sonnets G3 but now it seems there is a repeatable problem with Sonnets cards and some sound apps. Peter wrote to Sonnet with some issues he was having and Sonnet told him to return the card as they are aware of these issues! I wonder when they were going to tell us? Thanks Peter. Peter would like to hear from anyone else who is having similar issues and so would I. Thanks

7/23/1999 More sound issues with Sonnets G3's: Regis reports he is having Audio Buffer not ready errors when trying to record sound after his G3 upgrade. Click here to read more on these issues.

Tom, if I don't use the headphone jack in Unreal, I have random freeze too, so I always have a mini jack ready to plug and unplug and the game can continue.

7/30/1999 More reader feedback on the Sound issues with Sonnets G3: Jeff writes with his problems with Sonnets G3. Thanks Jeff.

8/1/1999 More reports on sound issues with Sonnets G3: Jeff is having similar issues to other with his Sonnet G3 but it was just a stutering or skipping and not crashing his system. I suggested he try PowerLogix's G3 cache utility to disable his cache and see if that would clear up the problem. I have a link to PowerLogix's site on my Hack Sonnets Crescendo page. Thanks Jeff.

Travis is having the more severe crashing issues while playing sound apps with his Sonnet G3. I might also suggest that instead of turning the cache off that they try disabling Speculative Addressing which is what my Hack was for. Maybe it will help even with the Crescendo version 1.3.7 which seems to be pretty stable otherwise?

8/7/1999 More info on the Sound issue with Sonnets G3: Egan who is a professional sound recorder sent along some interesting info. Most of it is beyond me as I'm not into digital recording but I hope it helps those of you that are. Thanks Egan. Click here to read a text version of his letters. They are pretty long but pack a lot of info.

I emailed about the Sound quality issue he noted about lowering the system volume actually decreases the quality and not just lowering the volume and here is his reply (also added to the text info)

So anyone wanting the best sound out better turn up the volume and then lower it in all other apps and games or get a set of external speakers and plug them into the front headphone port and use thhe volume knob on the speakers. don't use the back port as it cuts out all low end bass which is passed only to the internal speaker. the headphone jack on the 6400 passes the full range of audio. for a system that was advertised as an audio/video system with certian setups, it sure is a pesty little Mac :)

8/14/1999 More info on the Sound issue with Sonnets G3: Jeff was having stuttering issues and other problems with his Sonnet G3 accelerated 6400 and finally found the problem on his system.

Although I doubt this is the cause on most other peoples 6400's, it is something to consider. Jeff later wrote to let me know that the Apple Platinum Sounds in the Appearance Conrol Panel was causing the random crashes for him. I have this info posted on my OS 8.5 info page and interestingly it was sent to me by another Jeff :)

11/4/1999 Update on sound issues with Sonnets G3: A Sonnet G3 user wrote to let me know he found that VM being on or the sound quality in the Monitors & Sound control panel set at 44Khz caused his garbled sound. Thanks. Click here to read more on this topic.

12/10/1999 Possible fix for Sonnet issues with Sound apps?: ken writes that Sonnet told him that older OS's are the cause of this problem? And for him, updating to at least OS 8.5.1 solved his problem. Thanks Ken. This is a pretty costly fix but may be worth it if you can't stand the freezes!

12/17/1999 Another tip on fixing sound issues with Sonnets G3: Gary found a few extensions that seem to make his system more stable if removed. Thanks Gary.

Just so you know. I have these on both my PB G3 and my Vimage 6400 and neither have sound issues. They were installed by my AGFA camera software. Let me know if you have these and removing them helped.

1/16/2000 OS 8.5 really does seem to fix the sound issues with Sonnets L2 G3: Earlier I had posted info that Sonnet recommends OS 8.5 to clear sound issues you might have while using their L2 G3 cards. David writes that it did cure his sound issues with QuickTime by upgrading to OS 8.5. Thanks David.

2/18/2000 OS 9 may fix sound issues with Sonnets G3?: Regis writes that after updating to OS 9 his sound issues with Performer and his Sonnet G3 have gone away. Thanks Regis. Sonnet has said that OS 8.5.x is needed to get rid of these issues also but a lot of OS 8.6 users seem to have the problem back.

He latter wrote me this.

3/18/2000 Fixing sound issues with L2 G3's installed: I read a posting on Accelerate Your Mac's web site that suggested turning off VM or reducing the sound rate from 44Khz to 22Khz might solve the problem? If this works for you then please let me know.

3/24/2000 Apples PCI Timing Extension to help fix L2 G3 audio issues: I have had several reports now that the PCI Timing Extension made for Power Computings clones help fix instability with audio apps on L2 G3 upgraded Macs.

9/9/2000 Update on G3 upgrades and Audio apps having issues: Here is some info I found on Accelerate Your Macs web site from a company that does not support G3 upgrades with their audio apps! Seems like this issue is much more serious then with just L2 G3 upgrades!

[More Feedback on CPU Upgrades and Audio Apps: - Another reader replied to the recent posts on Audio Apps/cards in older Macs with CPU upgrades:

" Hi Mike, I saw the item on Wednesdays news page about some problems with G3 upgraded Macs and some audio applications. Here is an excerpt from Arboretum's web page:

'G3 Upgrade Cards Not Supported: We are now able to independently verify what we long suspected, which is that G3 processor upgrade cards for older Power Macs (from manufacturers including Newer Technologies and others) exhibit a number of incompatibilities which well may interfere with audio editing programs. The upgrade card manufacturers themselves are beginning to acknowledge the problem; this ends the mystery surrounding a number of heretofore unresolvable technical issues pertaining to G3 upgraded Macs. Our advisory on this topic is therefore reiterated and intensified: We will not be able to guarantee performance on systems with CPU upgrades. Don't use an upgrade card to extend the life of your old Mac. We suggest you consider trading up to a new factory-built G3 instead.'

Arboretum makes several audio applications, with excellent Macintosh support. You can find that quote at, about 2/3rds of the way down the page. Personally I think tellling people to buy a new machine is a bit drastic though.

For what it is worth, I use several audio apps on my G3 upgraded 8500 (PowerLogix 300/300/1Meg upgrade card) and have never had any problems. -Barry Klawans"

As noted in the recent news here, several older Mac owners that were having problems noted either setting the backside cache to write-through modes and/or deinterleaving RAM helped. Not all owners have problems, but there have been some reports in the Rate Your CPU upgrade database.]

2/10/2001 6400 mother board clocked caused sound issue and possible fix?: A reader of my site that had clocked his mother board found he got audio stuttering issue afterwards. He then noticed that if a CD was inserted (any type) that the stuttering stopped! Thanks for the info. I was wondering if this might also help others with ATI Rage128 cards or G3 upgrades that have audio issues? Please let me know. Thanks

[Hello Thomas,
I have found and an interesting thing by accident. When a CD is in the drive and mounted on the sound skipping when playing MP3's! I took the CD out (threw it in the trash ) and the skipping came back! Obviously I am intrigued as to why this is because there has to be a work around. Have any ideas?? Any readers have an idea?
For now I will leave a CD in the CD ROM while I am listening to music!
HB McKinney]

3/23/2001 Sound issues caused by USB support extension?: If you read Thomas's letter below, he says that the USB Support Extension caused sound that seem very similar to the sound stuttering issues with ATI Rage128 cards and Sonnet G3 upgrades installed? He said that just removing the USB Support Extension fixes it but then your USB devices no longer work :( I don't know if I have this problem or not as I don't play any intense games on the 6400 anymore and I have no other sound issues that I am aware of? If you are having sound issues and removing the USB Support Extensions fixes it, please email me the info. Thanks.

[Unfortunately the Support extension is required to run both my printer and SanDisk imagemate. I forgot to mention the I was running 9.1. Although, I have always had sound issues related to USB. I have found that if I hold down the mouse button while I am listening to an mp3 or streaming audio, the problem goes away. My thinking is that it has to do with a some kind of interrupt request between the USB devices and ADB devices. Am I the only one reporting this as an issue? I have not checked to see if the same problems arise with my L2/G3 removed. I will let you know if that is some how causing it. Thanks for your time.

Apple TIL on high sound volumes causing skipping?: Below is a TIL that basically says that in OS 8.1, if you have the volume on your Mac set to full or near full that sounds may skip. Also it states that having the input source set to nothing may induce the same issue? Updating to OS 8.5 is supposed to stop that. I wonder if it doesn't fix it for everyone? Could this be the solution for some of us with sound issues on our 6400/6500's? Please email me if lowering your sound volume or changing the input source fixes your problems. Thanks.

4/21/2001 Voodoo5 fixes audio stuttering issues with Sonnet G3: Bryan reports that replacing an ATI Rage128 with a Voodoo5 card fixed the audio issues he had with games and having a Sonnet G3 upgrade. Thanks Bryan.

[Hello I posted this message in February:
[I have a 6400/180 w/ 136MB of RAM upgraded with a Sonnet L2/G3/400 1MB/200 cache ...... also an ATI RAGE Orion 128 I am having a sound problem that I can't seem to solve. I have tried the PCI Timing Update trick, the 2d accel. Disable trick, and the ATI Extension one.... none have helped me in my situation. The sound is great except for in games .. all games have choppy sound once numerous sounds start happening, or doors open, walking noises, ambient sounds, etc ....

I have MacOS 9.1
ATI Drivers are the ones that come w/ 9.1
OpenGL is version 1.2.1
ATI RAGE Orion 128 Card
Sonnet Driver is v1.4.5

everything is as recent as I can get it and I can't seem to get it.. everyone else seems to be having luck.. well what are they using for OS and etc... ???
Thanks for the help

Well good news!! I solved the problem! It is the ATI Rage card's limitation... not the limitation of the 6400!! :) Anyhow, all I did was replace the Orion with a VooDoo 5 PCI card... yep thats right, it fixed all sound problems and games run much much smoother might I add..
Bryan ]

I still believe its an issue with the 6400 as well as the ATI Rage128 because G3 and G4 systems do not have this problem. Not even systems like the 7500 or 9600. It is some issue with the 6400 which is amplified with the introduction of Sonnets G3. Now ATi also has some issue with their Rage128 that gets affected by this where newer or older versions are not? The RagePro as well as the Radeon both seem to not be affected, as well as other cards like the Voodoo4/5. The Voodoo3 is in the same boat as the Rage128. Some people have no issues and other have some issues? Needless to say, it sounds like getting an even newer video card is the fix :)

10/5/2001 Causes of audio issues on the 6400/6500: I thought I would compile some of the issues that I have gathered as causing audio issues to help you make better upgrade choices.

  • Rage128 card installed - Mostly the VR128 card but the Orion128 and Nexus128 can cause this to
  • Firewire/USB combo cards - It has just come to my attention that some people are having audio stuttering once one of these combo cards are installed. If you remove the USB extensions then the problem goes away. But just using a plain USB card or a plain FW card does not cause this issue. But what about both cards at the same time? I have not heard from a user with one USB card and one FW card installed. If you have both installed, I would like to hear how they are working :) Thanks
  • OS's older then 8.5 according to Sonnet - I have a post on my Sonnet info pages from a reader who received a reply to an inquiry and Sonnet stated that you need at least OS 8.5 to solve audio stuttering with their L2 G3 upgrade.
  • OS's newer then OS 8.5.1 and QuickTime according to Sonnet - Sonnet also replied to another inquiry stating that there is an incompatibility between their Crescendo software and QT in OS 8.6 and up. I am not sure if they ever fixed this with newer versions of the Crescendo but I would use the latest version just to make sure!
  • Virtual Memory in any OS 9.2.1 and older - I found this out myself on my iBook infact. My iTunes audio would always stutter when an app I was working on started to access the HD. When I turned VM off, my iTunes audio never again stuttered. I know this is not a solution for 6400/6500 owners since we are limited on the amount of RAM we can install. I had always used RamDoubler which is supposed to access the HD less then Apples VM so that may be one alternative to just disabling VM and losing VM's benefits.

As you can see, we are pretty limited to what may work 100% but even I won't guarantee that as I am sure there a some people out there with one of the above in use and not having any issues. The above are mainly some suggestions on things to look out for when upgrading your 6400/6500. I know this severely limits your upgrade ability (specially in OS's) so just remember that if you use one of the above items that you could introduce audio issues in games and audio apps like MP3 players.

The 6500 is less prone to audio issues but it has its own problems with some of the above items. Rage128 cards may not work period on the 6500 and FW/USB combo cards need a PRAM patch to work or the FW ports or the entire card may not function. From what I know, Sonnets FW/USB card and OrangeMirco's FW/USB card comes with this patch. And VM can affect any Mac not running OSX as I have found :(

10/21/2001 Sonnet ATA/100 card and their new software do reduce audio stutter!: Now I don't have info on their software working on a 6400 or a 6500 yet but Accelerate Your Mac had some info posted from a 7500 owner who said it got rid of his audio issues completely! This is good news and maybe it will help us as well? But you will sacrifice some performance for this as the software slows the drive access down some to accomplish this :( Here is the info from Accelerate's site.

[7500 Owner Reports Sonnet ATA/100 IDE Card Stuttering Audio Fix Works: -
In the past there have often been reports of stuttering audio when playing back files from IDE drives in older Macs using PCI IDE card. (Not all owners reported this, but many have). Sonnet noted in their press release for their ATA/100 card that it would ship with a software utility to address this. A reader post in the forums noted it works:

" Okay, I bit the bullet... took one for the team... and I'm happy to say that my new Sonnet ATA/100 card works flawlessly in my 7500.
Upon initial installation, I still had audio glitches (but blazing fast booting off the new buss) so I installed the accompanying software. This is a control panel with 4 settings that basically slows the card down to prevent the audio glitches we all know and hate. Works like a charm. I've also been running for a week without having to drag out Disk Warrior for major repairs."]

External FW drive helps audio stuttering issues for one 6400 owner!: Joel wrote to say that he was able to reduce his audio stuttering on his 6400 by placing the iTunes app on a Firewire connected HD but he left the MP3 files on the internal HD. Thanks Joel. If you read his email, you will see that he has every piece of hardware known that causes audio stuttering, yet he was able to reduce it by just having the iTunes app on an external drive! It may be that any other drive other then the boot up drive may help as Ralph had written in the past saying when he booted to a SCSI drive, his audio issues went away, and I bet his iTunes app was on the stock IDE drive. This may be the fix we have been looking for?

[Hello Thomas,
Got to the bottom of your page the other day and saw this item about skipping audio in iTunes on a 6400. I'm running OS9.1 on a 6400/180 with 136MB RAM, 15 GB internal, the 1.6 original equipment IDE drive in an external IDE to Firewire box, OrangeMicro combo card, ATI XClaim 32MB video card, Apple TV/FM tuner and card. When I first downloaded iTunes and tried to play an mp3 that I had imported from a CD it was skipping all over the place. I figured my HD wasn't fast enough. Then I downloaded SoundJam and it worked great. But I got to thinking about this iTunes thing. Why shouldn't it work since it is modeled after SoundJam. So I transferred the iTunes folder to the Firewire drive to try it out. Had a hard time making it see my library on the same disk. (Will be trying this again.) But by running iTunes on the FWHD with the mp3 files in the Documents folder on the internal HD got rid of the skipping. The only time that I get skipping is in loading a new application or duplicating/copying multiple files.

I'm going to keep playing with this a bit. I'm going to try to move the mp3s to the FWHD to see if I can get it to work. (It should, I just think that I had my library configured weird.) I'll let you know my progress when I can.
Hope this helps.

PS Thanks for the info on the combo card and floppy drive. I was prepared to go out and buy a different brand combo card, so you saved me some bucks! Thanks! ]

I would like to hear from anyone that can verify this trick. Try running iTunes from any drive that is not the boot drive and see what happens. Thanks. I must admit that this might be the case as I have been having an issue with iMovie on my B&W G3 where when exporting to video from a FW HD, my internal HD starts to do some kind of access as I hear it start a rhythmic clicking and that causes the video on my monitor to skip but thankfully the video on the tape is unharmed! I then tried moving the iMovie app to my FW drive and I did not have that clicking anymore and the screen never skipped anymore? Very strange. iTunes may have the same problem?

I suggest turning off Virtual Memory to fix the skip when the HD is accessed while saving or loading apps. That has worked for me on my B&W G3 and iBook.

Another possible fix for audio stuttering: This fix comes from Tupring. He says that playing a certain QT movie fixes it for him until he reboots? Interesting. Thanks Tupring.

[I just visited your page again and I feel I need to share some stuff. I can also confirm the sound issue is indeed quicktime related. Load this streaming quicktime movie and when it starts playing close your browser. Sound issue is completely gone for me after loading the movie.

Not just any quicktime movie trailer, just that one, don't ask me why. Certain others may also work but for some reason that stream fixes it until a reboot every time]

11/4/2001 Audio stuttering with MacPicasso 540 video card: Fabounio writes that he has audio stuttering issues when moving windows around the desktop if 2D acceleration is enabled on his MacPicasso 540 video card. Thanks for the info Fabounio.

I have a 6400 with a Sonnet G3/400 processor upgrade and, like a lot of us, I to have audio stutterings but while scrolling or moving windows. This affects only the monitor which is connected to my picasso 540 video card. On the other monitor connected to the original videoport, I have no problems? I can move all windows anywhere I want without audio stutters. By removing extensions one by one, I totally remove my problem with the picasso card. It is the graphic accelerator of the card itself! If I remove that extension, the graphics are slow (no more gx acceleration) but audio does not suffer anymore! It is a cruel dilemma for me because the difference of speed is very important. Fast display or good audio? I have to choose. I wrote to Village Tronic to talk about this, and if they could rewrite their driver. Maybe a timing to reset ? I had a response in July but since then, nothing. I wrote to them 3 times without anymore response.

What is the best I can do? Any idea at this point? Can I overclock the bus on my performa? Maybe with a 50 MHz bus, I will have less problems with audio. Or is that a bad idea?

And the best of all, the audio stuttering does not happen under VirtualPC! Even with the driver of my graphic card installed! ONLY moving Mac OS windows suffer! Anyone here using MacPicasso 540? Thanks for your help.

Has anyone else had this type of audio issue? If so then please write me. Thanks!

11/18/2001 Sound issues using different video cards: Francois did some extensive testing with different video cards regarding sound stuttering and sent me his findings. Thanks Francois!


For your very good 6400's knowledge base: I had tested for a long time four different cards into my 6400:

Matrox Millenium II : no sound issues with a Vimage 240 MHz G3 Card, but with the Sonnet 400 MHz-1Mo slight stuttering sound as Fabounio especially while scrolling finder's window

Formac Proformance III+ (a good European card): bad sound issues, especially when you scroll down a menu (finder and others applications).

ATI Rage 128 (taken from a Blue & white G3): Very bad sound issues (scrolling windows, games...)

For all of these above, the problem disappear when I turn off the 2D acceleration but obviously, no more fast display. Exactly same problems with Mac OS 8.6 and 9.1.

And finally, miraculously!: ATI Radeon Mac edition: entire problems have disappeared! And if you break down sound setting to 22 kHz in the control panel, no problems even with active USB Card ,and in the same time, on the internet!

A very good surprise!. I think that you must recommend this card for each of us, happy 6400's users!

With this graphic Card and Sonnet 400/1Mo, my Mac does run alike my office's G3 White and Blue 400 MHz

Good Night from France,

Well it seems that many video cards will cause sound stuttering in different situations! But the good part at least is that the best of them all does not have this problem (ATI Radeon).

12/2/2001 Sonnet Tango card causing audio stuttering on a 6400: Victor writes that his 6400 was free of audio issues until he installed Sonnets Tango firewire/USB card. He was able to fix it by removing the USB drivers but that's not a great solution so he finally gave up and removed the card. Thanks for the info Victor. This makes the second person to confirm that Sonnets Tango card causes this issue :(

[Hi FYI: I gave up and removed the TANGO USB/Firewire combo card on my 6400, my SRS is back, sound is clear, no distortion. I purchased a preowned Beige G3, I am using the TANGO on it without a sound problem, although I do not have a woofer on the Beige G3 so there is no SRS. I am networking the two systems.]

1/19/2002 ATI Radeon video card may not be immune from audio stuttering for all?: There is a thread on my forums started from a 6400 user who says his Mac is having audio issues even with a Radeon card. Also a 6500 owner says he was completely unsuccessful at getting the Radeon card to even work as long as acceleration was turned on! Seems there just might not be any cure at all for the 6400 regarding audio stuttering and high end video cards or USB cards :( One user swore that just installing a 6500 mother board would fix it. But if the 6500 cannot run a modern video card, what's the point :(

Audio issues - something to think about: I read on a Mac help site the other day that OS 9 and up use a different path for audio CD's then traditionally used on older Macs. They now take the audio right through the SCSI bus (or IDE if you have a Mac with an IDE CD-ROM) instead of using the audio cable directly to the mother board. This is supposed to keep the audio cleaner before it gets to the amplifier. But this also means the CPU is doing work it never did before. Here is a snippet from what I read.

  • [Yes. The traditional path for audio CD playback was as follows:

    CD-ROM reads data off disc -> converts it to analog form -> signal goes over a wire to the Mac's motherboard -> Mac sound chip uses an analog mixer circuit to combine the CD audio with its own output

    These days, the Mac uses the CD-ROM in the same mode used to "rip" audio CD tracks to a file, which simply means the drive sends the digital audio out the IDE/SCSI interface instead of playing it back through its built in DAC. Instead of writing the data to disk, the OS plays it through the sound chip.

    There is a drawback to this: the CPU is now required to do work in order for audio CDs to play back. The performance hit isn't large, but some system load conditions can cause skips and stuttering. The old analog audio CD playback cannot be interrupted that way because it doesn't depend on the CPU at all.

    If you install OS 9.something or later, you always get the new digital playback technique -- older Macs already had all the required hardware. On the other hand, the G4 (Digital Audio) cannot do audio CD playback the traditional way, since Apple removed the analog audio cable between the CD/DVD drive and the motherboard. ]

Is it possible that this is the entire problem for us? Since not everyone sees the problem could it be those games that use CD audio tracks that cause the biggest problem. Does it even work this way on older Macs that where upgraded to OS 9? One way to check is to remove the audio adaptor from the back of your CD-ROM and see if audio CD's still play. Maybe the answer is to downgrade to an older OS? But that means only OS 8.6 as that is the only older OS that can run USB devices and barely at that! I would like to hear from you if you test this theory or have your own opinion. Thanks

2/9/2002 Update on CDROM audio coming from the drive bus rather then the audio cable: Richard did some tests to prove my hypothesis that CD audio now comes from the SCSI bus (or IDE bus on IDE attached CDROMS) instead of the audio cable. He was using OS 9.1. Thanks Richard.

  • [The ControlStrip CD player and the Apple CD Audio Player both apparently take audio from the analog connectors; when there is no analog connection, they'll appear to be working, but with no audio output.

    iTunes, as well as SoundJam and SoundApp, takes it's audio from the SCSI connector. All of them will play audio just fine without the (audio) connector.

    QDesign MVP 1.2 (the free demo player, dunno about any other) freaks out. The CD player window refreshes constantly, never actually showing any track info. Luckily, it doesn't freeze or crash the machine.

    I have no idea what would happen if two CD players were attached to the analog audio connector. My second player, a CDRW, uses the PC connector standard, which won't connect with the Mac cable. Since the higher speed ripping is the crucial attribute and goes through the SCSI ribbon, I don't care.]

Well it appears that I was correct in that CD Audio is now routed through the drives interface bus instead of the audio cable. This means if you are running OS 9 and iTunes, you no longer need to worry about whether the audio cable will attach to any third party CDROM drive. But the reason I had asked is because I think this may be yet another cause of audio stuttering. If the audio is passed through the bus to be processed by the CPU then this is another bit of data dragging the CPU down :(

4/7/2002 QT 5 has significant issues with MIDI playback: I found this info on the MacInTouch web site.

[Kelly writes that a significant issue with QuickTime 5 has apparently fallen through the cracks:
"I'm a professional saxophonist, and one of my key practice tools is Band in a Box (BIAB), a software program that generates surprisingly good rhythm section accompaniments. I use the program every day to work on unfamiliar chord progressions or tunes in challenging keys, and to get fast tunes up to speed, and just for general work on pitch and time.
I installed TurboTax yesterday, and it updated me to QuickTime 5. Later in the day, when I went to practice again, my BIAB rhythm section played like a bunch of drunken idiots! Instead of a rock-steady beat, the time would surge manicly ahead, then screech to a near halt, all within the space of a bar or two. Though I've played with some pretty horrible rhythm sections in my day, the program was now useless.
Since it worked fine in the morning, and the only change had been the TurboTax installation, I suspected the new version of QuickTime right off the bat, since I use the QuickTime Music Synthesizer to generate MIDI sounds for BIAB.
[...] I was surprised to discover through further searching on the web that this is a known issue with QT5 and 3rd party MIDI playback programs - PG Music's site mentions it [Jerky Playback with QT5 <> ], as does the site for another MIDI program [EasyBeat FAQ <> ].
Apparently this timing issue has to do with QT5 and virtual memory; with VM turned off, the program appeared to behave better. However, turning off VM is not a good solution for me, and the only way I was able to entirely restore my Mac to its former reliable self was to trash QT5 and go back to QT 4.1.2 [...]" ]

4/27/02 Tango patch 1.2 fixes some audio stuttering but inserting a CD seems the overall fix?: Corry has a 6400 with the Sonnet Tango FW/USB card installed. He decided to try the PRAM patch that is meant for the 6500 to see if it would have any affect on his system. He used the latest version (1.2) and says it reduced the stuttering a lot! Later he noted though that inserting a CD in the drive connected to his SCSI bus has the best results on reducing the stuttering! Thanks for the info Corry.

[Heya, I just tried the tango patch, and I am quite pleased with the result! I no longer have random stuttering with iTunes or mpeg movies with quicktime 5 player :) I still do have blips when playing mp3's and opening other applications while they load, but this happens without the tango card installed anyways. Also noticed the stuttering persists if I have my dvd extentions loaded, but this is of no matter, as I haven't been able to get a dvd to play in my system anyways, so I have a separate extention set for that when I feel like trying to get it to work anyways. I'm just happy I can use the card full time now!

My setup:
OS 9.1
104 megs ram (doubled to 208 w/ RamDoubler 9)
Sonnet Crescendo L2 G3/300/1M overclocked to 320
Pioneer 305 internal SCSI slot loading dvd
Stock 1.6 gig hd
Quantum 4 gig SCSI hd in upper bay
Sonnet Tango FW/USB PCI card
ATI Radeon Mac Edition PCI
Farallon Comm Slot II 10/100 Ethernet
Yamaha ext. FW burner
iomega ext. SCSI zip 250
Apple MultiScan 1705 display

PS: the mp3's are on a network drive via DAVE (Win 98 networking) on a Powermac 8500/150, playin on the 6400. Also, I had no problems burning with toast 5.0 before, I've yet to try it again with the firmware update.

Thanks for keeping such a great site for our ol 6400's! I have gotten much more use out of mine thanks to you :)

Later he wrote this.

[Hi again, some additional info I just discovered about the audio stuttering. I found the stuttering appears again with a vengence when I eject a cd :( I don't recall not having the same result before the firmware update, but I did read of someone else on your site having the same symptom. Stuttering stops as soon as a cd (of any kind) is put in the cdrom drive. This is true for both iTunes and Macast. Mpeg and quicktime videos also have the same problem with audio when a cd is absent.

Ugh, still an improvement...I'd rather insert a cd and use the card fulltime then have to reboot with a different extention set everytime I wanna use my burner or d/l pix off my camera.

Just noticed also that only inserting a cd into my dvd drive (pioneer 305 SCSI DVD in stock cd position) helps, but inserting one into my external FW burner (Yamaha CDRW 2100) has no effect on stuttering :(

I replied to him with this.

[Thomas wrote:

> Thanks for the info. So its the SCSI bus that is the issue and not the FW.
> What version of Apples CD/DVD extension do you have installed? I had massive
> slowdowns with my B&W unless a ZIP disk was inserted and the issue was the
> CD/DVD driver. Reverting from 1.4.7 to 1.4.3 fixed that.
> Tom

I have a hacked version of 1.3.1 that was hacked to include my pioneer drive. I tried 1.4.3 and nothing would mount on the desktop with that drive, even with toast reader 5.0 loading up. I haven't tested this out with pioneer's driver yet, but I'll see if that helps.

My issue was if you placed the B&W to sleep and then woke it up, it would respond very slowly unless you inserted a ZIP disk. Reverting to the CD/DVD 1.4.3 extension fixed that. So these are a few fixes for you guys to try.

  1. Try the older 1.4.3 CD/DVD extension from Apple
  2. Try inserting a CD when the stuttering happens to see if that helps.
  3. Try the Tango patch update 1.2 if you own the Tango Firewire/USB card.

The patch might be worth trying even if you do not own the Tango card as its not supposed to be needed for the 6400 but he is using it with no issues that he noted. If anyone tries these, please email me your results. Thanks.

6/7/2002 Sonnet gave up on fixing L2 G3 cards causing audio stuttering issues!: John wrote to let me know about his problems with Sonnets L2 G3 causing audio issues as many other people have found. He asked Sonnet for help and eventually they gave up and told him to return the card :( Sigh! Thanks for the info John.

[Well Sonnet technical support finally gave up and told me to return the Crescendo card and use the money to buy a new Mac. The extent of the troubleshooting was to turn off virtual memory, or the Norton disk light, or to update all of my drivers for either my video card or my Comm II network card. Nothing worked!

My final solution was to install a separate firewire card and separate USB card in the two PCI slots and that finally fixed the problem. Unfortunately, I had to pull my ATI Xclaim VR card to make room for the two cards. I gave the Tango card to my sister who has a G3 233 desktop with a Sonnet Encore G4 500 upgrade processor and she had no audio problems with the Tango card installed.

The bottom line is that the Tango card just isn't compatible with the 6400 with a Crescendo L2 card installed.


Personally I do not think the issue was with the Tango card in Johns case. I believe the issue was with the ATI video card as others have mentioned. John just happened to remove both the video card and the Tango card at the same time. But it could really be the issue of Apples USB drivers being used with the Tango card causing his problem. It has mostly been 6500 owners experiencing this problem as mentioned above. Could this be the first incident of the Tango card causing issues on the 6400 as well?

7/14/2002 Booting from a SCSI HD may cure some audio stuttering issues?: Jose wrote to say that he tried a suggestion that was posted on this site about booting to a SCSI HD instead of the IDE HD to fix audio stuttering issues. He tried this on a Beige G3 which was giving him problems and says it worked great! Thanks for the info Jose.

[I booted also from a scsi drive and my audio sync problems seemed to disappear I am so thankful I found your site to help me.]

So for those of you that have access to a SCSI HD and have audio stuttering issues, you may want to give this a try.

11/2/2002 Audio stuttering fixed by using a USB audio out device!: Luc just wrote to say that his audio stuttering problems have been fixed by using the audio output from his iMic. Thanks for the info Luc.

I've just bought an imic for my G4/osX and I had the good idea to try it on my old 6400 running G3/400 sonnet card, keyspan usb card, picasso 540 pci card and ethernet comslot II card. My audio issues disappeared completely using the imic audio out instead of built in.
I can move my windows, scroll, do anything, no more problem ! The imic is quite good in audio out, I haven't tried audio in yet. It is quite inexpensive too and it is a good way to solve this "CENSORED" audio issue ! and to have audio in my G4 too :))
I hope this will be useful for others...
Bye ! thanks for your site !]

I asked him if he had to switch the audio out in the Sound control panel or if it did that automatically. Here is his reply.

[We have to switch in the sound control panel.i have choice. For my in and out devices. No drivers required but if I remove the apple audio extension, the imic is not recognized by the system.

I hope this will help others, I'll have to test audio in to be sure. With imic no more problem with itunes and other audio apps, whatever we do. But we have to test imic with other video cards to be sure.

Bye ! if I can help you, mail me I will be pleased to answer.]

Please email me if you try this yourself. Thanks.

12/16/2002 Confirmation that USB audio out devices do fix audio stuttering!: Kirschen and Scott both wrote to say that audio out from the iMic does not have stuttering problems like the stock audio out has. Thanks guys.

[Hi Thomas,
Just got my brand new iMic - plugged it into the third USB port of my OrangeMicro OrangeLink+ USB/Firewire combo board. Works fine with no stuttering at all! Floppy drive works fine. My current setup is:
Performa 6400/180 with 136MB RAM, Sonnet Crescendo L2 Cache G3 400MHz/1MB Cache. OrangeLink+ USB/Firewire. ATI Rage Orion (16MB VRAM). Farallon Comm Slot II 10/100 BaseT Ethernet. Mac OS 9.1

Thanks for posting that note from Luc.
-- Kirschen]

[The iMic works!! The CD Player app didn't work. I guess some of the older apps are "dumb" when it comes to digital audio. Quicktime movies play smoothly.
iTunes worked great, as did Quicktime. From what I can remember, I think the startup chime came from the machine but once the system was loaded all the sound came through the speakers.

Its possible that older apps like Apples CD Audio Player do not recognize the USB drivers for audio output? Also the CD Audio Player does not gets its input from a digital source. It actually gets its input from the audio cable off the back of the CDROM drive. iTunes however takes the data off the CDROM over the SCSI bus and then will either play it out your stock speakers or through a USB audio out device if you have one. So it seems we have a cure for those with some money to spend on a USB card and USB audio out devices :(

1/9/2003 Evergreen FireWire/USB combo card does not have stuttering issues as Sonnets Tango card does: John wrote to let me know that he tried Evergreens combo card based on info I had posted earlier from another Evergreen user stating that it had no stuttering issues when used with a L2 G3 upgrade. John also found that it eliminated stuttering issues he had due to his Tango card. Thanks John. Click here and scroll to the end of the Evergreen section to read Johns message.

12/22/2003 Partial Solution to audio skipping with USB drivers enabled: Combo card owners have had lots of issues with audio skipping due to the USB drivers being installed. The previous solution was to disable the USB drivers and reboot so you could listen to music without skipping but that's not the best solution. Simon may have come up with a better solution for those of you that have non-Apple CDROM drives attached. Thanks Simon.

[I have a potential partial solution for audio skipping on a 6400 with USB drivers installed. I'm unable to use an iMic. After about 30 seconds, the USB bus just shuts down (Sonnet Tango USB/Firewire) and I need the USB ports (Brother laser printer, Epson Stylus printer, and USB optical mouse). I have an internal CD ROM drive and an external CDRW on the SCSI bus. I noticed that each time the green access light on the CDRW flashed, sound skipped. I disabled the Apple CD driver (in both OS 9.1 and 9.2x) and sound skipping virtually disappeared. I still have the Toast driver installed and the CDRW drive works as both a writer and reader. The only time I get significant skipping is if a scroll through a long document, move windows around, or open and close programs. While I'm typing or reading an Internet page, there is no skipping. Using OS 9.2.x was better in terms of skipping then OS 9.1 but this fix reduces skipping to a tolerable level in both versions of OS 9 on my Performa 6400. This may help users who can't afford to give up USB. If I need to mount a CD with the Apple drivers disabled, I use Silverlining Pro that came with the CDRW drive. Turning off virtual memory does not make a big difference so I leave it on.]

I believe the issue is the way Apple polls all the drives every now and then. This causes enough of a CPU lag to make audio skip. It sounds like Toasts CD driver does not poll the drive as often as Apples does or may do it in a less CPU tasking way?

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This page last updated 1/31/2004