Q: clipping sound on new iMac when Logix X is running

Allan, AOS,

thanks for your replies. With 'when' I could live, it's the 'if' that bothered me.

But do you figure that the popping sound I experience is indeed related to this problem? It probably is but I'm looking for some reassurance heres ince this is driving me crazy. There are different problems discussed in this thread and (even after Art's summaries) I'm still having some difficulties distinguishing between them. It's certainly not a driver issue since I only see it with my internal microphone and I tested with my replacement machine straight out of the box. Therefore and also since I experienced it on two machines, it probably is the FD-linked problem.

Thanks.

If you saw the same issue on two machines, it is probably not just a bad machine. In my case, I often see the audio starting out clean, then gradually ( many times after a minute or so) becoming noisy. It then often gets increasingly distorted and sometimes with an echo like sound. At this point saying it is distorted is too kind. the problem often gradually goes away after three to ten minutes. Often, if I switch to another USB audio input, it sounds fine there... or not. I tend to agree with those that suspect the fusion drive being somehow involved. I never see the problem when booted off an external drive, even when it has a clone of the internal drive. I have also never seen a problem when running 10.8.5 on a seperate partion on my iMac.

RRaye,

Your description is a perfect example of the FD - Audio issue.... as noted here... and is exactly how it affects internal audio...

Thanks, that quite reassures me.

However, I've just retried with booting from an external hard disk (clean mavericks install) and to the contrary of what I found in my previous test, i do seem to have the same problem after the machine wakesfrom sleep. Does that in any way change your assessment? The fact that I observed this on two different machines and the symptoms themselves make me think it is the fd-audio bug but until now I've read that everyone sees the problems disappear with an external boot.

No.. Some people have found that internal Audio continues to be affected even when booting from an External Drive.... It 'fixes' it for most but not all by any means...

Just make sure you (or any apps you are running) don't access the FD drive in any way... as that too, can cause the issue to reoccur... (Like just opening the FD drive in Finder for example )

Ok, thanks again. Due to lack of sleep because of this first world problem, I simply used spotlight to launch Quicktime to do a quick test recording but thereby launched it from the Fusion Drive... I've tried again, disabling even spotlight indexing on the Fusion Drive but still have the problem. Since it's a clean install that I'm booting from nothing *should* access the FD but prob there still is something interacting.

The other thing is that on its own, the Fusion drive can be moving thingd onto and off of the SSD portion of the fusion drive.

You're right. I wonder why for some people booting from an external is a 'fix' then   .

I'm tending to conclude my iMac indeed suffers from the same problem where a fix is currently under development. I will probably wait for the fix then and not go for the refund. The only thing i still find atypical is that for me the problem never occurs on first boot, only after sleep, the longer the sleep the more frequent the pops, which then gradually improves when the machine is in use. I hope they get the fix soon since I was trained to analyze and solve problems but can't get my mind around this one...

RRaye,

It can also happen even without sleep occuring.. The issue tends to just get worse as time passes for a lot of people... or the greater the loads they place on the Disk and/or Audio systems..until they reboot.

Once you access the FD in any sense you must shut down and then start (not just restart) your iMac to ensure no cache activity is still going on with the FD...

I have not looked at any relationship between sleep and the problem here. I have not seen problems running off external drive or running off a 10.8.5 partition on the internal hard drive..... On the other hand, as soon as I think I have the problem quantified, I seem to find something that disproves what I thought. I still believe it is related to the fusion drive though.

I agree with the Fusion Drive link, in one of the posts above someone copied a mail he/she got from Apple saying it was a conflict with the Fusion Drive software. I was assuming that right after sleep theFusion Drive got busy rearranging or something thereby giving me the problem.

I've personally never had the problem after a first boot and before first sleep. It's possible that I would if I only used the iMac long enough as AOS suggests, but I've never encountered it. In my test last week I *thought* I also didn't have the problem by starting from an external disk but now I can't seem to reproduce that. I tried shut-down and restart as AOS said, made sure nothing known to me accessed the FD (except for it 'optimising' itself maybe as Allan suggested), but still: problem immediately after first sleep.

FYI: My test is simple: make Quicktime recording after startup (mostly of silence these days, got tired of singing :-) ), replay, no crackles. Sleep computer for a couple of minutes, wake up, make quicktime recording, replay, voila: crackles. The longer the sleep, the more the crackles in the recording. The longer the iMac is awake again, the fewer the crackles (though it might degrade again after a longer time). Thankfully I'm not recording silence (or myself singing for that matter) all the time so this shouldn't bother me too much but if I call someone on facetime he or she hears those same crackles.

@atacDIGITAL

Do I understand correctly that he mail you copy in your post is a mail from Apple?

RReye wrote:

 

@atacDIGITAL

 

Do I understand correctly that he mail you copy in your post is a mail from Apple?

I recieved an email from the support advisor who is dealing with my case which confirms Apple are aware of the issues and are 'working round the clock' to resolve the issues. This was an official and well written comminication, I have every faith in the issues being a distant memory very shortly. It's just a shame I have spent so many hours troubleshooting, not to mention the costs of new cables!

At least my new web design business is getting the attention it deserves..

The details of my problems have been somewhat different from most of what I've seen on this thread, but they do seem related. From those I've found and read, this thread appears to best capture the issues and potential solutions.  So I thought I'd share what I've experienced and the current situation. 

I purchased a new iMac 27" with fusion drive about a month ago.  One of the major uses of the iMac for me is sending audio via USB to a DAC for conversion and playback.  I immediately started to have issues with USB playback.  Within minutes of playing music through several DACs I would encounter "pops" and "clicks".  It did not seem to matter what software I was using for playback.  Playback throught the internal speakers never seemed to be show any of the same symtoms, only playback through USB.

I tested all the same DACs and software using a MacBook Air and an older iMac and did not have any issues.

I started working with AppleCare and was put in contact with a higher level technician.  We spend some time running diagnotics, updating software and drivers, doing resets, changing DACs etc... Most of the typical thing you would try, with no success. 

Close to 14 days I sent the iMac back and got a replacement.  I considered getting one with the fusion drive, but wanted to give the new hardward one more try. 

Initially I had the same issues, in fact at times the distortion would grow worse until play back would completely stop.  This time we did a data dump and sent it off to the engineers at Apple.  Unfortuntately I had to leave town for 5 days.  I left the iMac running in the mean time.  Now, upon my return I have been listening for several hours straight with NO pops or clicks. 

Ugh... I really hate intermittent problems and magic fixes.  I don't think there has been a firmware update or OS update in that time, so I'm at a loss as to what has changed!  (Crazy assumption not based on any solid engineering, the fusion drive has made some changes to what it's priortizing and buffering?)   

The AppleCare guys have been awesome, and the first return was conducted with no questions.  My case is still open at this point.  They have indicated that there is "some issue" but at this point no root cause is clear and no fix identified. 

I plan to run like this for a while and see if the performance continues.  I know this is slightly different than the original posters problem, but from the symptoms you guys are describing it's the closest I've seen to mine. I'll post up a progress report and of course anything we learn during troubleshooting.

I'll be running close to the 14 day window soon, and I'd prefer to send this one back for a non-Fusion drive if I continue to have issues, but with this miracle cure I'm waiting to see...

Curious if anyone else has had spontaneous repair, or noticed the problems disappear only to have them come back later?? 

Here are a few hardware and software details of the gear I've been using:

Model Name:          iMac

  Model Identifier:          iMac14,2

  Processor Name:          Intel Core i7

  Processor Speed:          3.5 GHz

  Memory:          32 GB

  Boot ROM Version:          IM142.0118.B00

  SMC Version (system):          2.15f2

NVIDIA GeForce GTX 780M

3 TB Fusion Drive

Running OSX 10.9

Digital to Analog Converters Tested

HeadAmp Pico DAC

Cambridge Audio DacMagic

NAD M51

Software which playback noise/distortion was noticed:

iTunes

YouTube via Safari

YouTube via FireFox

Channel D PureMusic

Audirvana

J River Media Center 19

I understand you completely. The most frustrating of this issue for me is also it's unpredictabiity, not knowing what's coming next. You have to be able to rely on your iMac and not wonder whether it's going to work.

For me, the problem gradually disappears the longer I use the computer. I haven't yet seen it get worse again until after it wakes up from sleep again. And *sometimes* I think it's even better overall, but that might be my getting used to it.

What I would advice is to talk to Apple and try to get a diagnose from them whether your problems fall within the domain they're currently working on fixing. If you even have the slightest doubt, try to push for an extension of your 14 day period. In these situations that's not so hard to obtain. In an extra two weeks you can evaluate whether the problem is really gone for you. I don't believe in magical fixes but hey nothing surprises me anymore :-)