Mbox performance on 500 Mhz iMac

My brand new Mbox is performing far below expectation on my FlowerPower 500 Mhz iMac with 384 MB RAM. I cannot even manage two stereo tracks with a D-Verb on each without running into the dreaded 'CPU usage is holding of USB audio' message. I've carefully followed every advice of the thread in this forum from last month on optimising performance - upgraded to 9.2.2, started from the base set of extensions with just the digidesign and OMS extensions added, buffer is set at max (1024) and cpu usage at 85% - max as well, and the Mbox is not on a usb hub. All the other usual suspects (appletalk etc) are eliminated. I've also removed the Fastlane usb midi interface as I thought it was that. I've also downloaded the latest firmware for the Mbox, and the latest digi usb driver. I've noticed that the CPU performance meter when inserting the two D-verbs is at about 1/3rd green, but with every few seconds a brief spike at +/- 90%. Any clues from you pros before I bring it back to the shop yelling 'usb and audio don't mix - 4 real !' ? I've had more plugfun with ProTools free. Thanks !

Make sure that you eliminate any files related to PT Free, if you had that on the computer previously. You may need to reinstall PTLE after this. THIS ONE WORKED FOR ME ON THE SAME PROBLEM: Trash all preferences related to Pro Tools, Digidesign, and DAE. Then, when launching a new session, select "stereo mix" as opposed to "last used" for I/O settings. Make sure that you allocate plenty of memory to Pro Tools and DAE (preferred memory in the get info box when highlighting the applications' icons). For you this might be 100 MB to PT and 100 MB to DAE.

Thanks c-tone, Did all as you said - even trashed the whole PT (inc. dae, setup, prefs, extensions, control panel) and reinstalled everything - alas. New session (choosing stereo mix), two stereo tracks, two d-verbs and the same message reappeared. Tried a session in 16 bit - ran the two plugs no prob but still with spikes up to 95% ; added maxim plug on the master fader and was back in trouble. Do you have a (similar) (i)Mac as well ? How many plugs can you run ?

Zapped the P-ram 3 times for good measure, PT and dae memory is at 100mb each. Changed the usb cable with the midi interface one. Still using base set 9.2.2 with digi and oms exts added. Just for the check created a new session with just two stereo aux channels with a d-verb on each (so no audio whatsoever), pressed play and ran into the error after 24 measures. Curious thing is that I can see the spikes every few seconds on the cpu usage even when playback is stopped. And it's not as if you can ask it, 'scuse me, what exactly are U doing or checking when spiking ?' (digi folks could, i guess) rrrrrrrr. really appreciate you hangin' in there, c-tone. Do iBooks have faster buss speeds than iMacs ? Or is mine just having a serious headache ? It does run twenty plugless tracks of audio on the internal HD without a bump, which is great. For a start.

Hello I have an Ibook 600 with mbox.I have run 22 tracks with 11 digi4 eq and one D-verb with a buffer at 512.I also wondering why the cpu-meter is moving so much.It can be on 30% and all of a sudden you hit the red light I think the drivers for usb must be the problem.Also if you are in another program before you start PT you only get klicks and popps so I have to quit PT and disconnect Mbox and then it works.I wonder if (or who)tested this product before releasing it.

Hello, I have an ibook 266MHz/192 Mb RAM which corresponds to the requirements to run Protools LE with an MBox. I have a lot of trouble having it running: 8 tracks with no plugins is really unstable, and I receive rather often the "CPU holding off USB audio". I have installed the newest versions, deleted thouroughly all remains of older versions, and made the required setups. I have managed to go from only two tracks to 6 or 8 tracks (but very frale). I have removed ALL plugins. Funny enough, I was running Protools free on the same computer, and it worked really perfectly, with a lot of heavy plugins. I needed more than 8 tracks so decided to buy the Mbox : I cannot even get the same stability and number of tracks as before. I don't know if I'll get my money back, but I think that digidesign is not improving its software at all. I remember in the heroic times, I had a powercomputing 150Mhz/ 96 Mb RAM with which I could run up to 16 tracks with the powermix protools. So really this is going from good to bad to worse. Or maybe I'll have to buy a brand new computer to run the Mbox protools LE ...

Hey Blas, if you check the cpu usage meter while playing, is it spiking into red - or constantly there ? Definitely seems to be a particular problem with some machines, while other / similar Macs run without any trouble. I have reformatted my iMac ground level (zeroing all data) installed 9.2.2 and then NOTHING BUT PT and OMS. Same **** - two d-verbs, no audio playback and still bingo - USB holding off.... Digi anyone ? Come on, guys...