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Deadphish42 Level 1 Level 1

I just got the new iMac that was released two weeks ago yesterday.  All I did was set it up with Logic X, Main Stage, and Aperture all from the app store. nothing else was put on it.  I opened up logic just to check it out and see how much faster the performance would be.  I just wanted to give it a quick test and played some apple loops I immideatly noticed it was making a clipping sound randomly.  The meters were not peaking everything was in the green and if you turned down the gain the clipping just got quiteter.  I called apple support thinking it was a hardware issue.  They had me do some trouble shooting like playing the same loops through quicktime and the clipping persisted. they also had me play a youtube video to see if I could hear the clipping. It wasn't as noticible but it was there. Apple decided that it would be a good idea to reformat the computer tomorrow and start over.  Sounded fine to me seeing how I didn't have much installed yet.  I did a little more trouble shooting on my own after I got off the phone with apple. First I made a copy of three apple loops and put them on my desktop then restarted the computer. Then after a fresh restart and nothing running I opened one of the apple loops off the desktop with quicktime player and it sounded great no clipping. Same with You Tube. I then opened Logic Pro X. Did nothing with it but minimize it. I then went back to quick time player and tried to play the loop again. This time the clipping was back. Same with You Tube. 

My conclusion for some reason when logic is running the audio makes a random clipping sound no matter what audio program you play the audio through. (Clipping sound comes out of the internal speakers as well as headphones) 

All of my software is up to date.


I am running:


27" iMac

3.5GHz Intel Core i7

16 GB 1600 MHz DDR3


If anybody has experienced this same problem or has any recomendations they would be greatly appreciated.

I am going to reformat in the morning and try and start again.

I will post my results


Thank you,



iMac (27-inch, Late 2013), OS X Mountain Lion (10.8.5)
Reply by The Art Of Sound on Oct 14, 2013 8:45 PM Helpful



I have exactly the same 2013 iMac + specs as yourself (Got it about 2 weeks ago) and no such issues here.... So i don't think it is a general model specific issue... but something regarding either your OS X setup or config.. .or a hardware issue relating to your specific Mac. I cannot think what though.. based on what you have described...and tried so far.


There isn't a means of shutting off Airplay btw... but try powering down all your other Airplay devices such as the Apple TVs you have and the Airport Expresses...and see if that makes any difference. I doubt it but you never know.

Reply by The Art Of Sound on Oct 14, 2013 9:08 PM Helpful
Any (new) news on the USB 2/3 design change?



Nothing of note: As has been spoken about before, the main issues with certain hardware not being fully compatible with the changes Apple made to the USB2/3 routines and ports, is down to poor design choices made by the 'cheaper' Devs.... Basically these Devs took shortcuts to save money and didn't follow Apple's hardware design guidelines... and these decisions that have now come back to bite these Dev's customers on the butt.... Mackie in particular were caught out with their devices forcing them to release updated and redesigned interfaces that followed Apple's hardware guidelines correctly (i.e. they gave them a way to be upgraded firmware and driver wise) but in the process they have left many customers who bought the first versions, "left to their own devices" (Pun not intended) with no hope of a fix........... Its also funny how many of the Midi devices that failed under the new routines, all failed because they were all basically copied/stolen from one design... and that one design was created without any reference to the design guidelines isues by Apple... which is why they all failed in the same way!!


If nothing else, many hardware Devs may now have learned the lesson of actually reading and following Apple's guidelines in regards to how to design hardware so it remains fully compatible with any OS X changes in the future.....Certainly the ones attending that 'meeting' had done so.... though based on how many software Devs ignored the "Update your plugins to 64bit now" messages from Apple three years ago.. maybe not.... Time will tell.



Sounds like a partial justification + a dash of truth.


Absolutely! That was the consensus of opinion at that meeting....



I've been a Logic fan since day one, Apple not so much



As you know.. you and I are on much the same page in regards to this......



Ten years ago while driving through the southern US (to get a blues experience) I saw many poor young musicians with terrible equipment (and no computers) who were focused on the heart of music, the hardware mattered little, the expression and execution were everthing.



I still think my best work was back in the late 70's when the equipment was whatever I could lay my hands on.. (and more often than not.. that equipment was, to use a highly technical term... a load of bollocks...) and the music itself and who I managed to play along with... was what it was all about rather than how I created it.... and if i was using the latest /greatest thing.... to do it with!

All replies

  • Pancenter Level 6 Level 6

    First thing to do.


    Check Logic's Audio Preferences. (Not the Mac's audio preferences, Logic's)


    Here's a link to your new friend.... The Manual!   :-)



    Once there you will need to set the Input and Output devices. This is the first thing you do with Logic is setup preferences as Logic is made to work with many systems and professional hardware costing more than most posh homes.


    Set Logic's  I/O buffer to 256 I suggest Line In  for the Input Device and Built-In-Audio for the output device.


    After you get everything set, quit Logic, reboot the Mac and try Logic again.


    Odd that Apple didn't have you check Logic's preferences, it should always be the first step.



    In many ways, it's good to disassociate Logic from the Mac, Logic is for the most part, it's own boss, has it's own set of preferences, this gives it the flexibility of being able to add many types of third party hardware and software.

  • Pancenter Level 6 Level 6

    Since you didn't mention an Audio Interface i would guess you're using the Mac's internal audio?


    Go to Audio-MIDI setup and make sure the Default Input is not set to Digital. Use Linie-In if possible.

  • mats_j Level 1 Level 1

    I have a similar problem. I just got one of the new iMacs, and when I play sound through my interface, a Roland Octa-Capture, I get drop-outs and small clicks. This is regardless of if the sound comes from Logic, Youtube or Spotify. This did not happen on my old iMac.


    When I play sound through the computer's headphone jack everything works just fine.


    There's another thread I posted in where people with Focusrite interfaces experienced something similar, and it seems their problem was solved by a file that Focusrite supplied them with. Something to do with class complience. I tried this file but it did not work for me.


    I contacted Roland, but they were not familiar with any issues with their interfaces and the new iMacs.

  • Deadphish42 Level 1 Level 1

    Hi Pancenter,


    Thanks for the input. I have checked all the preferences in Logic and they are all as they should be, input is set to internal mic and output is internal speakers. As for Audio-MIDI setup the input is set to source internal microphone, Format - 44100.0Hz 2ch - 24bit Integer.


    This is Computer is only two days old and the only software that has been loaded on it came from the Mac App store. And that was only Logic and Aperture. 


    You are correct I am not hooked up to any auidio interface yet.  I have a presonus FireWire that I will have to pick up a thunderbolt to firewire adapter for.


    I am no audio pro. But have been a casual Logic user since Logic 8. It is usually the first thing I set up on a newly formated or purchased computer and have never experienced this problem before. 


    My plan for today is to reformat the computer and install all the updates again then check my sound. When everything is ok.  I will then install logic again only and check again.  If the problem still persists is suspect I will be forwarded to Logic support.


    Thanks again for your help!

  • Deadphish42 Level 1 Level 1

    Hi Mats,


    I get the clicks and pops in the headphones as well as the speakers.  When I had my presonus firewire interface hooked up to my 2011 iMac and tried to use the audio out on it I would experience a similar problem if I was just powering it with the firewire cable but if I plugged in the a/c adapter everything would work fine.  I've got my 2011 and my 2113 sitting side by side both running logic with the same settings and the 11 sounds fine but the 13 has random clicks and pops. Only when logic is runnning.


    Thank you for the response and I will check the other thread you mentioned. 

  • Pancenter Level 6 Level 6

    The thread Mats mentioned is fixing some system compliant devices that provide their own USB driver... (by removing it),  won't help the built-in, internal Audio on the Mac.


    I am curious, don't the new iMacs have a "Line-In" selection that shows up in Logic's audio preferences, you can only selected the internal Mic?


    Maybe a Line In cable has to be inserted first.

  • Deadphish42 Level 1 Level 1

    Hi Pancenter,


    To my surprise the new iMacs do not have a line in jack. Hence no option in Logic. This causes some configuration problems for me.  I used to use that jack for a input from my analog mackie mixer and set it up with the mute 3/4 and pan left and right on certain channels on my mixer.  This gave me two more inputs into logic through my mackie.

    The new iMac does not have Firewire either so if your using a firewire interface you will have to get a thunderbolt adapter.

    I guess I'm in the market for a new interface if anybody knows of a good realiable USB3 or Thunderbolt audio interface with at least 6 ins and 4 outs. Please give a shout.


    I just reformated my computer to out of the box state again and am waiting for a call back from apple in 45 minutes.  Before I formatted I coppied 3 apple loops that I could clearly hear the clipping popping noise in and saved them to a thumb drive.  I just played them through quick time on the computer without logic installed and they played just fine, no clipping or popping (volume maxed) I'm pretty sure they will send me to logic support.


    You suggested setting my I/O to 256. Logic had defaulted mine to 128.  I changed it to 256 and I still got the clipping and I went to my 2011 mac and changed that from 256 to 128 and everything played fine no clipping.


    One other thing I didn't mention the preference window on the new and old Mac have slightly different options on them.  I can send some screen shots for you if you would like to see after I reinstall Logic later in the day.  Another thing I forgot to mention is on my old Mac I had Logic 9 installed that came with mainstage, compressor, Logic node, and some other things. I never uninstalled any of that I just added Logic X from the app store. The new Mac I only downloaded Logic X and Mainstage. If that helps at all.


    My new iMac is a powerhouse with every upgrade and should have no problem running the buffer at 128?


    I really appreaciate all the feedback and will update the thread after I talk to apple today.


    Thanks again,




    27" iMac

    3.5GHz Intel Core i7

    16 GB 1600 MHz DDR3

    3TB fusion drive

  • The Art Of Sound Level 6 Level 6

    You mentioned you are using a Mackie... Which model?


    Are you aware of the design flaw with several Mackie models that prevents them from working correctly when used with USB2/3 slots and Mountain Lion on an iMac? The same issue does not affect Mackie hardware run under Lion or lower OS X versions because earlier OS X versions did not support USB3 and so different libraries are used that the design flaw in Mackie gear, is not affacted by..


    In some cases, Mackie released updated hardware versions of their products with the design flaw corrected... Typically they call the different models version A04 for those with the design flaw and version B00 without the flaw.. and Mackie have publically announced that the older A04 models with the design flaw will never work correctly with Mountain Lion because it concerns a physical hardware design flaw that they cannot fix by means of software or firmware updates.


    Info on an example of this (The Mackie Onyx 820i) can be found here...



    ...though there are several other Mackie models that exhibit the same issue... and required the same fix.


    Its also worth being aware that some users of the B00 versions have reported continuing issues with crackling/popping etc.... even after installing the updated firmware/drivers provided by Mackie though Mackie have said they will continue to work on improving their drivers to fix this ongoing issue for some... so there is some hope there.


    Note: Just to clarify ...This is not an Apple/Mac/OS X related issue.. The problem is caused by a design flaw created by Mackie that makes some of their hardware incompatible with Mountain Lion and the built in/updated libraries used by Apple to handle USB2/3 connected hardware. Similar design flaws have been found in cheap USB to Midi adaptors too... and other hardware (Typically the lower price range models)  from other manufacturers.. though in some cases the hardware could be updated by firmware/driver updates to resolve the issue. Mackie unfortunately didn't provide for this facility in the original designs of some of their hardware, hence the issue. Most hardware by other manufacturers never had any issue at all because they were designed correctly from the outset.


    As far as recommendations for Audio interfaces.. I always recommend Motu products as i have found them to be reliable, robust, practical and effective... with great driver support for many years now... and even my oldest models continue to work well with the current OS X and the forthcoming Mavericks, without issue.

  • Pancenter Level 6 Level 6



    Good luck with the new install, I was going to post the method for deleting both Logic X's preference file and the control surface preference file (which causes a variety of problems) but since you're going for a clean install won't be needed. Personally, I'm distrustful of recent versions of OSX, it's resource heavy.


    Progress doesn't come easy, in fact it's often not progress, but convenience.


    For live recording I use a 5-year old Acer laptop running an optimized WindowsXP, it can record up to 12 tracks at 24-bit 44.1kHz to the single, partitioned 5400rpm internal drive without a single error, I record up to 2hrs straight. I see no reason to change. Does Wireless Internet fine too but that's disabled when recording.

    (Using Two Presonus Firestudios)

  • The Art Of Sound Level 6 Level 6

    I see no reason to change.


    "If it ain't broke, don't fix it......."


    Words to live by in regards to computers i find.......



  • Deadphish42 Level 1 Level 1

    Hi Art of Sound,


    I'm sorry for the confusion.  The mackie I was using on my old computer was just a old 12VLZ Pro.  That I would plug into the analog input.  That would give me a couple extra tracks to record along with the ones going through my audio interface in case I had some friends over and they wanted to plug in and Jam along.


    Thanks for the info though.

  • Deadphish42 Level 1 Level 1

    Hello All that gave me advice on this thread,


    I just got off the phone with Apple's Senior Technical Advisor for Pro Applications and he determined that it was not a software issue.  That it had to either be the speakers, sound card or maybe the logic board.  So my replacement computer will have to be replaced.


    Thank you everyone for your help.

  • Pancenter Level 6 Level 6

    Good news, hope it fixes everything.

  • Deadphish42 Level 1 Level 1

    Hey guys I said I would post some screen shots of the difference in the preferences in Logi X on my 2011 iMac and my 2013 iMac. These shots are from my 2013 iMac my next post will be of the 2011Screen Shot 2013-10-09 at 9.35.14 PM.png

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