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USB Audio Problems Late 2013 iMac - Clicking / Popping / Dropouts

I am having audio clicking and popping issues with a brand new late model 2013 iMac and a USB 2.0 multi-channel audio recording interface. Here is what I have learned so far:


Clicking and popping is occurring in both directions - playback and recording. I am not having any issues with internal audio, so this was easy to verify.


The same issue appears in many threads in Apple Support Communities and in various recording/pro audio forums, so this seems to be a common issue.

The issue is independent of the audio interface that is used. (I am using a brand new Focusrite Scarlett 18i20 that I purchased specifically to use with my new iMac, but the forums report the same issues for a variety of other interfaces and audio devices.)

Five potential root causes are mentioned in the various forums:

1) USB 3.0 compatibility issues - poor backward compatibility or other issues

2) Fusion Drive activity - artifacts caused by drive "swapping"

3) OS X version - newer versions may be worse than old versions

4) App Nap - ?

5) Driver issues


Potential short-term solutions include:

1) Change driver - The "Class Compliant Mode" app (that I downloaded from the link on the Focusrite website) improved the issue for me, but clicking and popping occurs every few seconds instead of constantly.

2) Exchange the Fusion Drive for a conventional 7200 RMP hard drive - Forums report that this does not fix the issue.


3) Install older version of OS - Forums report that this does not fix the issue.


4) Disable App Nap - Forums report that this does not fix the issue.


5) Belkin Thunderbolt express dock - Forums report that a Thunderbolt hub with USB gives excellent results, but the only one I am aware of is the Belkin one which is ~$300. (I will not pay $300 to fix thousands of dollars of new equipment that should not need to be fixed!!!)


6) Apple Care's advice was an SMC reset (essentially a reboot), which clearly did not work. The person that I talked to was not aware of this being a known issue.


I am at a point where I need to decide whether or not to get a refund for this iMac since my primary reason for getting this new computer was recording. So...can anyone help to answer these questions:


Has Apple acknowleged this issue? If so, has Apple committed to fixing this issue via a software upgrade or have they admitted that this is a hardware limitation that is not fixable?


Has anyone found a free or inexpensive workaround (i.e. not the $300 Belkin dock) that completely elimiates this issue?

iMac, OS X Mountain Lion (10.8.5)

Posted on Nov 30, 2013 8:38 AM

Reply
98 replies

Feb 22, 2017 10:07 AM in response to Leather Bound Books

Definitely agree with you, this is 100% linked to the USB interface. I have an Arcam rPAC, gives me flexibility on the audio output - system sounds from the built in speakers, music etc. to the external amp/speaker. Having done lots of testing, it is clearly related to the USB interface, I can create the same problem with the same audio on both an iMac (late 2013) and an old MBP from way back... But only via USB, built in speakers never exhibit the problem.


For me, it is only when the audio goes silent, mixing in Logic Pro X, a simple reverb allows me to precisely control when the pop will occur, i.e. when the waveform goes to nothing...


It really is rubbish from Apple 😟

Dec 3, 2013 11:05 AM in response to Barraccus

I have the same problem and went through the same research . Band new imac with mavericks and my audio sound card audio kontrol from native instruments . I get continuous clicks pops using it in my daw , or I tunes internet I just cant use it , I really don't know what to do as apple support told me they have no issue check with native instruments . I called native instruments they told me it's not their problem and have no solution . At this point I want to bring a hammer and knock the mac into pieces I feel robbed.

Dec 3, 2013 8:27 PM in response to Barraccus

I'm also having audio issues on my new late 2013 iMac via the USB headset. Audio starts playing fine and then static starts creeping into the audio until it drowns out the sound. Only way to fix is to unplug the headset and then plug it back into the USB port.


I've tested the headset on other PCs and my older iMac and the issue doesn't show up.


I've re-installed Mavericks on the iMac, without nuking my data, but that still doesn't solve the issue.


I've logged a case with Apple support and they had me run a program which gathered up a bunch of information to send to their engineering team. No updates yet so far.


Just one question for those that also have this issue. Did you restore your data from a Time Machine backup, or is this issue also happening on the Mac that's fresh out of the box?


I'm wondering if this issue could be caused by restoring data from my Time Machine, but I don't want to go through the hassle of nuking my entier hard drive and having to reinstall everything from scratch just to fix this issue.

Dec 4, 2013 9:42 AM in response to Organik76

New iMac purchased 11/12/13 - Haven't been able to get it to work correclty with ANY USB audio interface..works great using just on board speakers - I too use Kontakt and record music...so this is pretty frustrating...does your machine have a fusion drive? I've read that it may be the cause...along with the possiblity of some power issue with the USB2 - USB3 conversion and devices that don't have their own power supply...


So many people buying their products and so many not sure if they should return before time is up or wait out the possibliy of a patch..

Dec 4, 2013 11:06 AM in response to jonesy60

Hi jonesy60 my drive is SSD not the fusion .its terrible situation as the main reason I got it was for home studio . If I wanted to browse the internet I could have used an ipad am not sure whats the use for it right now . If you know that no device provider yet utilize the usb 3 why would apple restrict the ports mainly to 03 not give option of 02 .what where the beta testers reporting , shouldn't they had one one from the music making folks it's pretty obvious external sound cards in market won't work :(

Dec 6, 2013 8:03 PM in response to Barraccus

New iMac, late 2013 27" build 13A603 came with Mavericks


I'm not having issues with any external sound card (I don't have one) but I am having popping and clicking on my external B&W M-1's. These are connected via USB. One fix is to simply use an AUX cable, but then you loose the external DAC which is built in, and the sound quality goes way down. Unfortunately I just noticed it or I would have returned to Apple. I really hope they come up with a solution. I'll be calling them on Monday.

Dec 13, 2013 3:03 PM in response to Barraccus

Today I split my fusion drive according to this article:

http://www.macworld.com/article/2015664/how-to-split-up-a-fusion-drive.html

Then I reinstalled Mavericks 10.9 on the standard HDD partition.


Result: No more clicks and pops through the 18i20 with some basic tests with Garage Band recording/playback, Youtube playback, and iTunes playback!! (I installed the Focusrite class compliant driver again.)


I will be testing further before purchasing Logic - I have not tried to bump up the sample rate and I'd like to give it more time. So far so good though...

Dec 14, 2013 5:54 AM in response to Barraccus

I have a late 2013 iMac with the same problem. I thought that it was my thunderbolt to FW and using old hardware so have tried using a Steinberg UR22 USB audio interface and have the same exact problem. My wife has a 2011 iMac so I installed the USB Audio driver and tried with her machine. It works perfectly. Both iMacs are running Mavericks.

As someone else has written, I only bought this for writing music so I’m stuffed.

I called Applecare and was told to reset the SMC - nothing!

I will take back to the store and see if they can fix.

USB Audio Problems Late 2013 iMac - Clicking / Popping / Dropouts

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