FIX: Pro Tools Audio Device Buffer Underflowed

The Error Message

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

Occasionally this error pops up in Pro Tools, usually after I return from a meal in the middle of a long recording or mixing session. The session file will only playback audio for 1 second or less and then the error message pops up. Apparently, Pro Tools 9 is a workaholic and doesn’t like taking lunch breaks, at least when running on the particular combination of MacBook Pro, Mbox 2 Pro, and Western Digital hard drive that I’m using.

Following the directions to decrease the “H/W Buffer Size” in the Playback Engine panel doesn’t seem to help. In fact, not only does decreasing the buffer size seems contrary to the suggested way to solve a buffer underrun, but it then sometimes throws this error message:

A CPU overload occured. If this happens often, try increasing the “H/W Buffer Size” in the Playback Engine Dialog, or removing some plug-ins. (-6101)

The Fix

I’ve tried a lot of things and the problem seems to be related to the hard drive and firewire ports. Here’s how I fix it.

1. Save and Close the session.
2. Quit Pro Tools.
3. Eject the hard drive used for recording audio.
4. Unplug the audio hard drive and Mbox 2 Pro (or the audio interface you’re using).
5. Wait 10 seconds.
6. Reconnect the audio hard drive and audio interface.
7. Restart Pro Tools.
8. Reopen the session and press Play.

If the session plays back without stopping, then it worked. If not, then I don’t know what to tell you, which reminds me of a “Deep Thought” by Jack Handey.

If you ever crawl inside an old hollow log and go to sleep, and while you’re in there some guys come and seal up both ends and then put it on a truck and take it to another city, boy, I don’t know what to tell you.

Hopefully this solution worked for you. Let me know if you’ve had the same problem, what hardware you are running and if this solved the problem.

FIX: Pro Tools hardware is either not installed or used by another program.

Pro Tools hardware is either not installed or used by another program.

If you thought that having Pro Tools 9 installed meant no more “Hey, Mr. Engineer Genius, where’s your fancy hardware?” errors, then this nagging error probably came as a surprise. It did for me. Since installing Pro Tools 9, my workflow has allowed me to jump around from my Mbox 2 Pro, Mbox 2 Micro, and MacBook Pro’s built-in sound card. This has been really handy while trying to finish up my album on the road. But, apparently, all that hardware hopping can cause the playback engine to get stuck in some funky states that don’t so work –if at all. See my previous post “FIX: Pro Tools could not set sample rate to specified value” for a similar issue.

Obviously, the problem has something to do with the playback engine. Since the error dialog only offers an ‘OK’ button, which closes Pro Tools, there doesn’t seem to be a way to work around the problem. There is not even a way to know what hardware Pro Tools is expecting.

Until now.

The Fix

I found a simple solution via this Sweetwater forum. The answer given there details how to get Pro Tools running on a PC, but I found that it worked for Macs too and without having to install any drivers. The fix is kind of like booting Pro Tools in safe mode. Simply hold the ‘N’ key while starting up Pro Tools. This will bypass the normal start up sequence and open up the Playback Engine window. Now you can select the correct playback engine and continue using Pro Tools.

In my situation, Pro Tools was looking for the last connected device (my Mbox 2 Pro), but since it wasn’t available it opted for the next available option: my MacBook Pro’s line input, which doesn’t make a very good playback engine.

Let me know if this fix worked for you.

Note

This problem may have been fixed in the Pro Tools 9.0.2 update that came out yesterday, though I’ve not been able look through the 9.0.2 Readme file in detail or to test this out on the updated software. I’ll update this page when I find out more. Since I still receive regular hits on this post, I’m assuming this problem is not solved yet. Maybe in a future update…