audio device underflow(-6085) during Playback

[M577]

Hello. Playback produces "The audio device underflowed. If this occurs
frequently, try decreasing the "H/W Buffer Size" in the Playback Engine panel or
remove other devices from the adio firewire bus. (-6085)"

my system specs are:

MacBook 2.0 GHz Intel Core 2 Duo (T7200) (MB061LL/A, white) upgraded to 2GB of
RAM and 7200 rpm hardrive

Mbox 2 Pro
OS X 10.4.9
Pro Tools LE 7.3
H/W Buffer size is at 64 samples
RTAS Processor 1 Processor
CPU Usage Limit 70%

Troubleshooting already attempted:

Mbox 2 Pro is the only device connected to my single Firewire 400 bus.

Zapped the PRAM.

Downloaded the tech support folder:

http://www.digidesign.com/index.cfm?...4&itemid=25974

Ran support utility and used it to delete preferences and databases.

Used the Apple disk utility to repair disk permissions.

Wireless networking and bluetooth are turned off.

Reviewed Troubleshooting Pro Tools 6 & 7 on Mac OS X:

http://duc.digidesign.com/showflat.p...&Number=177661

Pro Tools LE 7.3.1cs6 Update for Mac OS X

Please help.

[Phil Ogden]

1. That's a pretty low buffer setting which might in itself 'choke' the Mac if it's a CPU heavy session. I'd experiment with higher buffer settings.
2. Try a different (shorter) FW cable.
3. Recording to the internal HD is not supported (or recommended). The read/write heads have difficulty accessing the audio files and OS at the same time. A FW400 HD with Oxford chipset 'daisy chained' is what you need.
4. Is Firewire Networking turned off?
5. If you're using a 6 pin FW cable, then the MBox Pro is bus powered. Don't use the power adapter as well. This has been known to cause problems.


http://www.myspace.com/philogg

[M577]

I appreciate your response. I will try your fixes. Update forthcoming.

[DigiTechSupt]

Are you possibly using a FW800 hard drive? If so, that would explain the error - FW800 drives will not work with the Mbox 2 Pro.

http://digidesign.com/index.cfm?navi...5&itemid=23114

[M577]

Purchased a 250GB Glyph GT 050 FireWire 400 with 8 msec average seek time and Oxford 911 chipset($225 from Sweetwater free shipping). Problem solved. Thank you!

[glankrudolph]

Question about FW 400 drives: if I purchase a Glyph drive the DigiDesign has qualified ("Hard drives using the Oxford 924 chipset interface have FW800, FW400, USB 2.0, and eSATA ports on them. In our testing, Digidesign qualified Glyph GT Series Hard Drives with the Oxford 924 chipset"), the ones I've found have only one FW 400 connection, therefore I cannot daisy chain them together - my Mac laptop has only one FW 400 connection.
Hence:
Are powered FireWire hubs ok to use with PT LE, or do I have to find an older FW400-only hard drive?

[OddsAre]

yes powered Hubs are ok to use, just remember you are still only utilizing 1 firewire bus, so you won't get any bandwidth gain, but it would be no different than daisy chaining two hard drives together. What Mac Laptop do you have? If its a powerbook or Mac Book pro then get a Firewire PCI express card.

Also any drive from Glyph is going to work with Pro Tools, if Digi hasn't tested them you can guarantee Glyph has... but man they are over priced! Look into OWC Mercury Elite FW drives, wayy cheaper and ROCK solid.

[OddsAre]

M577 have you ever downloaded the Pre-binding script for 10.4.9. I remember having issues like that before I fixed that issue. I would download the OSX 10.4.9 combo updater and run that installer then run the Pre-binding script and see what it says.

But yes, running at 64 samples is very hard on the CPU and buffer. Only use it when you have to. Otherwise bump it up and use Low Latency Monitoring when you can. Then when not inputing anything run it as high as you want. I usually always have mine at 1024 when editing and mixing. You get the most horsepower that way. If you run your sessions at 64 samples all the time you are only utilizing about have the power that the Macbook is capable of if i were running at 1024. As an LE user you need to constantly play with that buffer to get the best performance. Keep it low to start while track count is low and you are inputing lots of audio. Then once you are done recording, bump it up.

[glankrudolph]

I have a PowerBook G4 running OS 10.4.11 (this technically isn't supported but Digi lists only one known issue which mine has not had).

I have used Rockstor 400/800 drives with no problems on another 002 setup, but with my new Mbox2 pro and PowerBook G4 they are not happy at all - constantly giving me the dreaded -6085 "audio underflow" error. I'm afraid of spending yet another $300 on yet another hard drive, so I want to be sure I'm getting the correct one.

I'm also confused: how can I use a PCI card if I have no PCI slots in my laptop? Don't I need one of those external card units?

[OddsAre]

the Powerbook has a PCI card on the side of it, maybe you haven't noticed... it is a slender fairly wide port, looks like a narrow CD drive slot, I believe on the left hand side towards the front. I haven't seen a Powerbook in a while so my memory is shady. But you can get a card for it that would have 2 FW400 ports that would be on a separate bus. And a hard drive from OWC would only run you $120-$150 and a ton of people on here use them every day.

But I don't think that stuff will solve all of your issues. What version of LE are you running? How full is your system drive?