clipping sound on new iMac when Logix X is running

RReye wrote:

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.

This makes perfect sense... when the computer has been on for some time the operating system has eliminated most of the disk writing it does, this includes indexing the drives (Journaling), spotlight buffering, executing maintenance scripts....etc. OSX is a very busy operating system.

The only thing I find strange is that even when I stress the system by putting a load on it, making sure the disk in- and output is very actively used (opening all my apps, playing itunes, converting several movies at once, forcing a spotlight reindexing etc), the problem never reoccurs. Or I haven't been able to make it reoccur I should say. OSX must be doing something specifically after waking from sleep that I can not reproduce.

+1

That is pretty much the same feedback on the issue that I have been receiving too.. that it can diminish over time depending on how the Mac is being used... and then suddenly for no reason come back again...

"Going to sleep" in Mavericks.. now activates the Power Nap feature in some apps increasing possible disk access for example... thereby the issue can get triggered or worsen after a sleep period... and unfortunately some apps have Power Nap hardcoded into them so you cannot disable the feature for that app.... (Mail and Safari for example) whereas some apps have it hardcoded not to be enabled (Logic Pro 9 interestingly enough)

I believe Power Nap is also used by the FD software to 'clean up' its disk and re-arrange files etc... so it might be that is the 'feature' that is causing the problem.. which also occurs during startup with caches and so on... just a guess but it kind of makes sense..

That is pretty much the same feedback on the issue that I have been receiving too.. that it can diminish over time depending on how the Mac is being used... and then suddenly for no reason come back again...

Ugh... not what I wanted to hear. Several hours of listening now and things have been perfect. I'm going to force the computer to sleep for the night and then give it a try again tomorrow.

I'll post how it goes.

Thanks!

Hi Guys,

I guess I am in a similar case as shipsupt. I bought my new iMac 2 weeks ago. It has been working fine until I hooked it up with an headphone Amp/DAC via USB. I am getting the full snap-crackle-and-pop distortion and the occasional drop out when listening via the DAC

spec of my iMac

• 3.5GHz Quad-core Intel Core i7
• 32GB 1600MHz DDR3 SDRAM
• 3TB Fusion Drive
• NVIDIA GeForce GTX 780M

external headphone Amp/DAC: Sennhesier HDVD800

I have been talking with Apple Care, and no one seems to know the fusion drive software issue you guys mentioned. They just asked me to do the usual test and reset, but no improvement at all. I thought I was the only having this issue before I came across this thread.

After reading all 38 pages (which took me 3 nights), I am not 100% sure I am having problem #1 (FD drive software issue) or #2 (the USB2.0 device connecting to a USB3.0 issue). I believe you can work around #1 with an external booting HDD and #2 with a thunderbolt-USB adaptor.....correct?

I really appreciate if you can input some thought. Thanks.

I have not seen the problem when using a clone of my internal drive on an external thunderbolt drive. It must depend on who you talk to at Applecare. The person I talked to, immediately knew what I was talking about and said they were working on a fix. That was on Monday.

by the way, I also trying the Amp/DAC on my other Mac. A 2009 iMac running Mountain Lion and a 2011 Macbook Air running Maverick (of course no fusion drive installed)......and both working fine. So, I am sure it is not Maverick....and hopefully it is not because of my Amp/DAC.

Hi all

Well the 21 late 2013 imac with fusion drive has returned to apple and now have the

27 i7

16gb ram

7200 rpm ata HDD

MAVERICKS and Logic Pro x

Focusrite 2i4 connected into imac USB port directly

Tested for over 3 hrs last night with no pops, crackles etc etc

All worked as it should using soft synths, guitar rig , drummer etc and all sounded good.

Apple loops even sounded better as I think I was getting some partial digital distorting before when using the imac with FD.

So I am happy and can be productive at last, the only slight down side is the 7200 drive boots slightly slower than the fusion drive and apps are take a little more time to start up ...I CAN LIVE WITH THAT

Hope others get the FD fix very soon but if you go down the return to apple route then changinging to taa hdd works.

In future may look at external SSD and load is etc onto that

Paul

Just adding another voice to the mix. Had two new FD iMac's before finding this conversation. Just for the record, the first one came with Mountain Lion installed. Same crackling problem before and after update to Mavericks. Second iMac came with Mavericks and has roughly the same problem.

The Apple support person I spoke to knew about the FD issue but he was Logic specific support. He also assured me there would be a downloadable fix at some point. I'm hanging on the the computer I've got as I don't need it urgently and I can learn how to use Logic in the meantime, everything works for me except playing / recording any external instrument or voice. The first iMac crackled with everything.

Anyway, all the best to everyone else here and let's hope we get a fix soon.

Hi, Some updates.

I tried a solution for the Fusion disk problem: I am booting from external HD running Mavericks.

THE PROBLEM WAS NOT RESOLVED.

after reading this thread, and some other threads here, I thougth booting from External HD will bypass the problem.

unfortunately it does not.

The problem (pops/crackling/noises/clipping - you name it) got better, but still exists, especially on the output.

now I am really frustrated.

maybe i should try it with Mountain Lion, but after dealing with this problem tensely for weeks, i have no more energy.

if i could just get the refound, i would do it.

I hope something will come up soon.

A few days ago, I did some testing where I ran a test running from the FD and then testing on another partition on the same drive , which would be non FD, which was running ML, then going back and running a test on the FD. I repeated three times. Every time, I had problems with the FD and Never on the other partition running ML. I have not tried putting ML and all my data on the FD, since that would be a big job. Other interesting things to try would be to split the SSD and HDD so that there are two seperate drives and data is not automatically going back and forth. My system size and data files are such that I could try that... but it is again a big job. Another thing which would be of interest, is whether anyone who has less that 128 G of data (such that everyting is only on the SSD part of the FD) is still seeing the problem.......If I had only been slower to move everything over to the iMac and put Mavericks on in, I would know.....

Out of curiosity, why did you not get a 256 Gb SSD instead?

I ordered a 27" iMac with FD first but canceled and ordered another one with a 256 SSD instead because of all the issues I have read about. I also have a Scarlett 2i4 so this is really reassuring. Did you download the drivers/whatever is on the Focusrite website for it to work?

I should have ordered the 256 SSD then added more outboard storage but had already upgraded from the 21 costing more money so wanted to keep spend sensible for now, in future will add some more fast USB 3 or thunderbolt storage.

Have not installed any drivers or any class compliant updates as focus right support advised it this way from a fresh machine.

Seems to work well and latency is less for some strange reason. Even if I dial it down don't see any digital distortion and can happily use the guitar rig without a real latency issue with software monitoring in fact it's less laggy than my 12 year old mk1 POD guitar processor. And the amp models are quite interesting

Paul

@Allan

When i received my replacement machine I tested straight out of the box since i wanted to know whether the problem I had on my initial machine would be gone

- iMac 27", 3TB FD, 16GB RAM, 4GB video

- Mountain Lion installed

- no other data migrated to this new iMac, so everything clearly fitted ont he SSD Part

I noticed the problem immediately, the same as on my first machine (clicks in recordings through internal mic, only after iMac sleep).

I then took the following steps and tested after every step, without improvement to the problem

- installed all Mountain Lion updates (I think it came with 10.8.4)

- installed Mavericks

- installed all mavericks app updates

- slowly migrated my data, wondering whether the problem would get worse after having more than 128GB on the machine, it didn't get worse

- all the data has now been on the iMac (1,8TB in total), problem has not gotten worse

So it's not a Mavericks vs Mountain Lion issue and it's there from the start, even with only the OS installed.

Thanks for passing that along. That answers most of the questions other than splitting the fusion drive which I am not yet ready to do