iMac late 2013 + Mavericks + USB Sennheiser - input freeze

After a lot of discussion on the other thread, it appears there are four workarounds to this issue:

1. Boot from an external drive
2. Partition the Fusion Drive into SSD + HDD
3. Downgrade to Mountain Lion (unclear if this will work for everyone)
4. Exchange your iMac with Fusion Drive for an iMac with SSD only (not possible for everyone)
5. Wait for Apple to come up with a fix (not clear when or if that will happen)

#1 & #2 aren't appealing to me. I do a lot of photography work and one of the big appeals of the Fusion drive was its fast read speed. In order to replicate that I'd need a TB enclosure with fast SSD and probably another daisy-chained TB enclosure with HDDs in a RAID0, or SSDs in a RAID0. That's $$$$.

#3 is no big loss, as I don't use that many new features with Mavericks, but I'm not sure whether it will work. I guess I'll find out.

#4 is not that appealing either, as it would require me to buy an external TB enclosure with HDDs in RAID0 in order to approach the 700 MB/s read speeds of the Fusion Drive.

#5 is my only choice, unfortunately, if #3 doesn't work. I have seen several mentions on other threads that Apple is aware of this and working on a fix, FWIW.

Also, is there anyone on this thread with a 2013 iMac that has continued to have problems with their USB mic/headset after going back to Mountain Lion?

Yes after reading those other threads. I grabbed an old hard drive and installed mavericks and I am using it as a boot drive via usb2.

Its not a long term solution, perhaps a USB 3 64 GB stick or some sort of SSD or take it back to Apple and get a SSD model, or go back to Mountain Lion. But I plan to test with it the rest of the day. I also am using the headset plugged directly into the Mac which used to deteriote in seconds to a few minutes, and 2 hours later its still fine.

I don't believe its the fresh install of Mavericks that is making the difference as this was something I tried the very first day I got the imac.

But the evidence is indeed pointing the Fusion Drive as part of the problem, Note my late 2012 imac also had a fusion Drive and remains fine.

As much of a pain as it will be, I've decided to try reverting to ML if the impending Mavericks 10.9.1 is of no help for these problems. The beta of the update was apparently released to devs over a week ago, which would normally signal an imminent release unless they report any major issues.

I never had ML on the new 2013 iMac, but I did have Mavericks on the Late 2009 iMac which preceded it and, as mentioned, had none of these problems.

cdanr,

Please do let us know if that solves the problem for you. I'm considering doing the same myself, but am reluctant to go through the trouble unless I am reasonably confident it will work.

I've also heard the 10.9.1 update is imminent, so we can cross our fingers that this might solve the problem.

I just ordered a SanDisk Extreme USB 64 GB thumb drive. I was thinking I'd install ML on it and boot from that to see if I still have the problem. If not, that tells me it's an issue with the Fusion Drive and/or Mavericks, and I'd be more inclined to proceed with downgrading to ML.

To switters, I am also going to try ML again to see if that helps. I'll keep you informed as soon as I test this out. It's an all nighter for me

fleabass,

Thanks a lot. I assume you're going to do a clean install of ML by booting to an external drive, erasing your Fusion Drive, installing ML on it, and then migrating your data back? I don't think there's any other way to do it, is there?

I've got ML installed to an external HD now and will play with it there later to see if I can reproduce the same audio problems. In some quick testing so far, the USB headset works fine.

I want to see if I get the more critical problem of system freezes though, but those are hard to predict. I can't induce them even in Mavericks, they just happen seemingly without warning.

OK, I found a reliable way to lock up the machine in Mavericks: use Plex with the USB headset as the audio device. It locks up within a minute or two.

I will try the same in ML and report back.

I'm curious how you installed ML to an external drive. I just downloaded the ML installer. When I double-click to open it, it says "You cannot install 10.8 on this computer." Normally there's a box with an option to select the drive I want to install to, but that's not the case here.

Okay, this seems a very convoluted way of achieving my goal, but let me know if you think this will work. (Note that my iMac came with ML installed on it.)

1. Clone current Mavericks install to external drive

2. Boot to recovery partition (command-R)

3. Erase internal Fusion Drive

4. Run OS X installer to install ML

5. Test USB audio devices

6. If they work, migrate user data and apps from external clone (using Migration Assistant)

7. Pray that Apple eventually fixes this

The only step I'm not sure of is #6. Is it possible to migrate user data and apps from a Mavericks install back to a ML install? Or does that not matter because it's just user data and apps and doesn't have anything to do with the OS version?

I do not think you can migrate from Mavericks to ML. You may be able to drag most data over as long as the same app version runs on ML....Mail will be a problem.

Thanks Allan. Guess I'd have to move everything manually then.

In order to install ML to the external drive I used Diskmaker X to create a ML USB thumb drive and booted up to that.

You won't be able to install ML from within Mavericks, even to an external drive.

I will finally have time to test the ML install today.

Update: things seem to be much better in ML. I have not been able to get it to lock up yet. To be sure I want to run ML in the same app environment as I am Mavericks. So the next step was migration.

Now I tried using the Migration Assistant by pointing it to Mavericks as the source and it started with no problems. It is now showing 2 hours, 19 minutes remaining. If it completes successfully I will test it more intensively and if the problems seem to in fact be resolved in ML I will then clone it back to the Fusion Drive.