What could be causing this crackling background audio?

Discussion in 'Mac mini' started by GanChan, Jun 25, 2011.

  1. GanChan macrumors 6502a

    Joined:
    Jun 21, 2005
    #1
    I've been noticing a slight crackling noise, ranging from virtually undetectable to significantly annoying, in my one-year-old Mac Mini. The crackling occurs intermittently whenever the audio driver is activated, independent of software, choice of sound files or cables/headphones options. I thought I might be getting some kind of weird interference from the iBook that sits next to it, but when I shut the iBook down the crackling continues.

    Is this a known issue on the Mini, or am I the only person having these particular symptoms? Is there anything in Snow Leopard that might be causing the trouble, or should I assume it's a hardware thing?:confused:
     
  2. MacMini2009 macrumors 68000

    MacMini2009

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    California
    #2
    This sometimes happens to me too. Do you have external speakers?
     
  3. fa8362 macrumors 65816

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    Jul 7, 2008
    #3
    It's probably interference from another device. You've ruled out the laptop. What else is near the mini? Do you have a graphics tablet, phone, or modem/router near your mini?
     
  4. GanChan thread starter macrumors 6502a

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    Jun 21, 2005
    #4
    The external hard drive that serves as my iTunes library sits right next to the mini, and the Mini sits right next to my monitor, but these shouldn't be sending out waves of interference. (And they don't seem to affect laptop's audio, though of course it's possible that the laptop is simply better shielded.) There's not a whole lot of room for stuff on my desk.... I did have a cellphone sitting a couple feet away. I've moved it, and right now I'm not hearing the cracking noise...I'll have to keep listening to make sure, since it comes and goes.....

    I listen through headphones (which seem fine, by the way; I checked them with other equipment), so even slight background noise gets super-bothersome.
     
  5. philipma1957 macrumors 603

    philipma1957

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    Apr 13, 2010
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    Howell, New Jersey
    #5
    cellphone most probable cause. I have heard cellphones making noise just sitting on an old school radio the radio's speaker makes the sound. Radio fully powered off. same with a cell phone sitting on a speaker from my ht. kind of a clicking sound almost the same sound of a rotary phone when you dial the number and wait for the dial to spin the phone clicks.
     
  6. dolphin842 macrumors 65816

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    Jul 14, 2004
    #6
    I have the same problem... it's a symptom of the audio card activating after there's no sound output for a while. I believe it's a hardware problem, because I also use a USB sound card and the issue is non-existent when using it.

    A quick workaround: play a radio stream in iTunes and turn the volume all the way down. That should keep the sound card engaged and prevent the popping (though you'll still have that background static).

    Unfortunately I think the problem is endemic to the hardware Apple is using. All the Intel Macs I've used have this problem to some degree, even after having the logic board replaced in one instance. My old 2004 PowerBook was the only machine that didn't have the problem (looks like the same goes for your PowerPC Mac as well!).
     
  7. GanChan, Jun 26, 2011
    Last edited: Jun 26, 2011

    GanChan thread starter macrumors 6502a

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    Jun 21, 2005
    #7
    Well, the crackling is still with me after all, so I can only assume it's a glitchy sound card or output jack. The Mini is out of warranty, so that's that, I guess. I can do all my MP3 listening through my iBook or iPod -- but since the Mini is my designated Internet box, streaming audio will be no treat until I can eventually afford to repair or replace the computer....(And replace it with WHAT, if all the Intel Macs do this?) :mad:
     
  8. dolphin842, Jun 27, 2011
    Last edited: Jun 27, 2011

    dolphin842 macrumors 65816

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    Jul 14, 2004
    #8
    Here is a link to the M-Audio USB sound card I mentioned above. No crackle or pop, and you get a mic input for non-USB headsets! At $30, it's probably the cheapest way to address the problem (plus you can use it for any future Macs you get that have audio issues).
     
  9. GanChan thread starter macrumors 6502a

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    Jun 21, 2005
    #9
    Thanks. I'm glad there's a solution out there.
     
  10. interconnect macrumors regular

    interconnect

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    Nov 15, 2007
    #10
    I have this same issue. I get a crackling from time to time and sometimes my right speaker will cut in and out. It sounds like a loose connection, however the cable is tight and there are no loose connections. Mine is still under warranty, I wonder if I should take it in.
     
  11. ToothTooth macrumors member

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    Oct 8, 2010
    Location:
    North Carolina, USA
    #11
    2011 Mac mini

    I've got a 2011 mac mini hooked up to external stereo speakers via the headphone mini-jack. This has provided good audio for the last few months, but just recently I've noticed a crackling/ buzzing sound coming from the speakers when there is no other audio being sent to the speakers.

    So I'll have the external speakers on and no music or sounds are playing. It will be silent. Then, when I start downloading something the crackling sound presents itself.

    My first guess was that it was hard drive noise being picked up. But then I noticed that I can also cause the same sound to occur exactly when I'm scrolling or otherwise moving the cursor using the HippoRemote mouse on my ipod touch. I scroll a bit, the noise comes from the speakers. I stop scrolling and then the noise stops.

    I don't have any external hard drives or other peripherals that would cause this noise interference. Any ideas?
     
  12. ToothTooth macrumors member

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    Oct 8, 2010
    Location:
    North Carolina, USA
    #12
    chiriping noise

    I'm pretty sure this is hard drive noise being picked up over the audio cable. Here's what's strange. Using Plex, when I watch movies that are stored on the hard drive, I don't hear the chirping noise over the external speakers.

    However, when I use Plex to stream Netflix movies, the chirping sound is very noticeable over the external speakers and I can hear it happening in a regular, rhythmic pattern.

    Do you think this is just a simple interference issue that I could correct by using shielded audio cables? Or is it possible that the audio jack is crap?
     
  13. dolphin842 macrumors 65816

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    Jul 14, 2004
    #13
    It's pretty much just a matter of trial and error.

    The other week, I was getting occasional Atari-like chirps coming through my speakers, even using the M-Audio device. After shutting down the computer, then unplugging the cable, etc., the interference appeared to be coming either from the speakers themselves or something external in the environment.
     
  14. yannxou macrumors member

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    Jun 7, 2012
    Location:
    Barcelona
    #14
    I'm having the same problem after upgrading my Macbook black (late 2007) to Lion. After some time without sending audio to the integrated minijack analog output it starts crackling like static noise.

    I discarded it being a cable/interference issue because as soon as I play anything the background noise disappears and plays perfectly clean.

    Also I discard it being a hardware issue because previsouly I had installed Snow Leopard and initially Leopard. In none of those I experiencied this background noise.

    My guess is this is a bug in Lion or at least something that could be fixed at software level.


     
  15. dolphin842 macrumors 65816

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    Jul 14, 2004
    #15
    It seems that your audio issue is the opposite of mine: My audio only has crackle that begins once the sound card gets engaged. It's been an issue in one form or another with every Intel Mac I've had, from 10.4 onward.

    As a stopgap measure, you could run an iTunes radio station in the background with the iTunes audio muted: That should keep the sound card engaged. In the future, I may make a small utility that just loops a silent AIFF file to achieve the same effect. Let me know if you'd be interested in it.
     
  16. yannxou macrumors member

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    Jun 7, 2012
    Location:
    Barcelona
    #16
    Thanks dolphin842.

    I've just discovered that the noise disappears when I unplug the ethernet cable! It's interesting though that with the cable plugged in it has this behaviour and the noise disappears only while playing audio.

    The ethernet cable goes to an airport extreme. I also tried with other cables but with same result.

    I'm less worried now that I know the cause but do you know what could I try to fix it?

     
  17. dolphin842 macrumors 65816

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    Jul 14, 2004
    #17
    Sounds like there is some sort of interference issue going on with the logic board. Does it go away when you try the iTunes workaround I mentioned earlier?
     
  18. yannxou macrumors member

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    Jun 7, 2012
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    Barcelona
    #18
    Yes, the noise goes away when I play anything in iTunes but if I disconnect the ethernet cable it goes away forever.


     
  19. yannxou macrumors member

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    Jun 7, 2012
    Location:
    Barcelona
    #19
    I've found that my issue is related to the Airport Extreme. If I connect the ethernet cable directly to my ISP router I don't hear that sound.

    But in my setup, the Airport is connected to the ISP router and the macbook to the Airport. In that case, a very audible static noise comes out from the macbook's headphone jack to the external speakers. The noise is not heard from internal speakers if I disconnect the minijack.

    More interesting is the fact that when I play anything on the macbook the noise disappears but comes back gradually after a minute I stopped playing.

    I tried connecting the Airport to different wall plugins but with same result.

    Does anyone experienced something similar?
     
  20. markjames9 macrumors newbie

    Joined:
    Feb 11, 2014
    #20
    Change Electrical Circuit

    I had a very similar issue. I had a buzzing sound on the speaker system when the sound output was idle. Upon reading this quote I unplugged the Ethernet cable from my Time Capsule and this solved the issue.

    Obviously I can't leave the Ethernet unplugged from the Time Capsule. I have found that moving the time capsule to a different electrical circuit has cured the issue.

    I think the issue is likely to be the Ethernet Cable/Air Devices and the Mac Computer being on the same plug socket/electric circuit.

    My issue is completely solved - been irritating me for months.
     
  21. lamerica80 macrumors 6502a

    lamerica80

    Joined:
    May 22, 2008
    #21
    I had the same thing. It was cause by an old USB 2.0 external harddrive. I notice when i unplug it the sound stopped. Solution: got myself an USB 3.0 external and no more hisses and pops.
     
  22. Schnort macrumors regular

    Joined:
    Oct 24, 2013
    #22
    This are called 'ground loops'. It's where the electrical ground of one device is different than another and there is a path between the two grounds, so current flows along that path.

    This can happen when devices (like USB devices) are self powered and don't electrically isolate the ground pin on the USB port. Another is in stereo equipment where the audio ground reference isn't electrically isolated from the power ground. It's even worse when both of these things are true, and the activity on the USB bus shows up as changes in the audio ground, which are very audible.

    You can fix this by getting better equipment (computer equipment, including Apple's, and most especially USB devices) is notorious about doing a poor job of isolating grounds in pursuit of lower costs. You can also manage to "fix it" by disconnecting the ground (removing the 3rd pin of the power plug). Or try moving all of the devices to a different plug, or to different plugs, etc.
     

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