"Audio device buffer underflowed..." Help rid me of this buffer error
 

I have been using Pro Tools LE MBox Pro 2, version 7.1.3, with my iMac for the last 14 months, without any real problems.

Suddenly, a few weeks ago, I start getting an error message when I playback or record (mostly recording): "Audio device buffer underflowed. If this occurs frequently, try decreasing the H/W Buffer Size in the Playback Engine or remove other Firewire devices (-6085 or -6086)" . The message sometimes comes within a few seconds of starting a session, or can come up to an hour or so into a session. But each time it occurs the session will then no longer allow me to continue either recording or playing back for very long.

My specs:
iMac Intel 2.16 GHz
OS x 10.4.11 (I had 10.4.9 when this error message started a few weeks ago)
Space: 447.33 GB available

I save my Pro Tools sessions to the internal drive. All my sessions are currently being saved in my documents file, although to be honest I tend to delete them after a short time, when I have had the chance to put the final mix onto a CD or Dat tape.

As for external hardware - other than the MBox going into the FW400 port on the back of my Imac, just a printer via USB and my BT router via its thing. No other FW port is in use.

Things I have tried:

*As it suggests in the message, I have tried decreasing the buffer, plus increasing it, to no avail.
*I bought a new Firewire cable (because a Digidesign engineer told me that "The DAE errors 6086,-6085,-6097 all relate to communication error as a result of a interruption or conflict with the data throughput to the unit."). No joy.
*I talked to an engineer about geting an external drive, but they don't think this could help.
*I reinstalled Pro Tools LE.
*I tried the two following workarounds I found on a website (they are meant to work with version 7.3.1, but worth a try with 7.1.3 I reckoned): "Connecting Mbox 2 Pro after the Mac has booted will prevent this behaviour." and "Quit Pro Tools, disconnect then reconnect the Firewire cable, then re-launch Pro Tools". Neither worked, as sooner or later the pesky buffer message comes up.
*Resetting the PRAM hasn't worked
*Repairng permissioms hasn't worked
*I followed the recommended tips to ensure that my iMAC is fully optimised to run, tweaking settings, deleting the preferences etc.

The engineers tell me that 10.4.11 is not supported with my version of Pro Tools, which I accept. However, this error message was coming up when I had OS X 10.4.9, only a few weeks ago, and is still doing it now that I have 10.4.11 (no change), so I can't see how having 10.4.11 is causing this buffer error.

Quite a wretched problem this is turning out to be, having explored so many trouble shooting ideas already I hope someone here might have a fresh idea that might do the trick!

Thanks in advance,
Jim.

Fix
 

Do you have the AC cable plugged in? If so, unplug it and run it with just the firewire, this should fix your problem.

No I don't - the MBox is bus powered only, with an FW foing into the port on the back of my Imac.

Nice thought though. It's got to be something simple, but I can't see why it would have worked so smoothly for a year...

Re: MBox 2 Pro
 

Hmmm... that's strange. When I first got my MBox Pro, I had both the AC cable and the firewire hooked up as per the recommendation in the installation manual. It worked flawless for months and then all of a sudden one day things started to not work. When I talked to Digi, he knew exactly what was going on and said they have been having problems with the AC cable and to just unplug it. After that things worked perfect and have been ever since. Have you tried calling Digi?

TBH I can't recall ever reading that recommendation about using both AC Cable + FW...

Unfortunately, I have to pay for telephone advice now (my 1 year warranty and free advice expired in May 08), and so I've been corresponding with a Digi chap called Dan via email. He has talked me through various troubleshooting measures, most of which I have mentioned in my earlier post.

Most recently Dan has suggested I try switching my processor to number 1 in the playback engine set up, which I will try when I start a new session this evening.

In the meantime, any other ideas?

Work around for audio device buffer underflowed...
 

I may have found a strange workaround for this problem. Here is what I do:
While you have the session open, go to the VIEW menu and open the SESSION item. Once open, you'll see you can view the sample and bit rate, as well as the clock source. It is usually set for INTERNAL. Touch the INTERNAL pull down the menu and set it to S/PDIF. You will get an error message. Clear the error message. Now reset it to INTERNAL. You will then get two more error messages. Once you have cleared them, hit PLAY (or the spacebar). My audio immediately begins playing without any error messages. Very strange but I can replicate it 100% of the time. I should probably just upgrade to Leopard.

I'm running PT LE v7.4cs5 on a Macbook Pro Laptop 2.33 Ghz Intel Core 2 Duo with 3GB RAM. I'm also running 10.4.11. Yes, I know its not approved by Digidesign. I'm also using an MBox 1, MBox 2 mini and an MBox 2 Pro depending upon the project. I have no problem with the MBox 1 and MBox mini 2. However, with the MBox 2 Pro I am constantly running into underbuffer error messages.

Good luck and hope this helps.

I second milbo's experience. PT7.4.2 mbox proII, rear FW on 2.8 8-core, 10GB RAM., DVToolkit 2. Exact problem and sometimes low CPU error (yeah, right) and toggling the clock source fixes it. You'll get an error after selecting SPDIF; just blow right by it. It won't matter since you're changing it back to internal anyway.

Prior to finding this work-around, I had been running the terminal script in the support tools folder, deleting preferences and databases. This worked, too, but it's a pain to reset all my preferences.

It's interesting that this same technique also fixed the intermittent white-noise problem with the first MBox back before Digi released the firmware update. Something about that clock...

...forgot one detail in my last post... OSX 10.5.4

I just fixed this problem on a student's M-Box. Your problem is probably there because you are saving your sessions on the internal drive on your Mac. Remember, PT is a memory hog and if it's trying to do all of it's bells and whistles, AND it's pulling data off the HD at the same time, then even ad midi, the HD is in big trouble. That's why you are getting the message.

Even though it's possible to save and work on sessions by using your internal drive (which needs to be 7200 RPM too) your problem should go away if you park all of your sessions on an external HD, 7200 RPM minimum, and the message should leave your screen. Give it a try and see how it works. I think you will see the problem go away. IF not, send me the bill for the HD. I need more:D Seriously, best of luck and I hope that helped.

Magic! Thanks for the work around. Was making me crazy, have only had this error message for the past week or so. Otherwise it was running flawlessly.
When I was launching other programs the Digi Core said it coudn't find the Mbox 2 Pro, but Final Cut could see it, but not peep out of it.

Running 10.4.11 with 6GB RAM, on 2x2.66 Dual Core Mac Pro, PT LE 7.4