Loud "popping sound" if using UI Sounds and shutting off audio System

This is a minor issue, but I want to solve it.
I get a loud “popp” off my stereo system when i disconnect power only when using UI sounds or disconnect power during playback.
I am using SPDIF optical connector soldered to Odroid N2 - using Stable Matrix Release but this issue is existing since the beginning of CoreELEC and I was “working around” for years now. -.-

“hold audiodevice active” disabled or enabled - doesnt change the behaviour.

Of course I stop playback before I disconnect the power.
If I do this, there is no popping sound, even when UI sounds are activated.
If I use the UI after i stop video (even wait until stereo system says: no digital data) there is the popping sound.
If I disable UI sounds, there is no popping sound - this would be my solution but UI sounds would be nice.

So what is the difference between:

  • stopping audio/video: no popp?
  • getting UI sounds, and wait until no data is output: popping sound?

maybe you can help me solving this with having UI sound :smiley:

Popping sounds from audio equipment are usually down to a connection issue so I want to ask you a few things.

  1. Are you directly connected to the sound equipment or using “passthrough” from a TV to connect to your audio and if so what TV is it?
  2. Have you tried a HDMI connection if your sound equipment supports it as HDMI supports much faster audio than SPDIF Optical?
  3. As its a long running issue have you cleaned the SPDIF connections with an air duster as they can be dust magnets?
  4. Have you tried another optical cable as I know I have personally killed a couple.
  5. Are you using the Odroid HiFi Shield 2 or the HiFi Shield plus as neither are 100% supported on the N2 as I was going to buy one myself from the UK distributor but checked first with them and after exchanging e-mails on the shield I opted to buy a HDMI Audio Extractor Converter similar to this one as it was cheaper than the HiFi Shield.

Finally are your speaker connections bare wire into the speakers or are they on banana plugs or similar?

I have the same issue with my X96Air and external DAC via USB. Only happens on power off/on.
Not serious enough to ever seek a solution though.


  1. directly connectd Odroid N2 with soldered optical Connector to audio system.
  2. no HDMI on audio system
  3. yes i tried cleaning it but this is only happening when using GUI sounds. not happening when GUI sounds are off
  4. yes, its the same
  5. none, i use SPDIF out and soldered optical connector to it.
  6. bare wire connected to suwoofer (with inbuilt amplifier - logitech z5500)

I have a few suggestions to try as its only GUI sounds.

  1. Change the “Number of channels” setting in Kodi to 2.0 and see if the problem still occurs as SPDIF connections only use two channels to send compressed data.
  2. The recommended settings for a 5.1 device are:-
  • Output Configuration = Best Match
  • Stereo Upmix = Disabled
  • Normalize levels on downmix = Disabled
  • Resample quality = Medium
  • Keep audio device alive = 1 Minute

If none of that works and the popping sound only comes out of 1 speaker (usually) the base as its an older unit that goes back to 2004 it may be an indication its time to look at replacements as the audio standards for Dolby and DTS on that device are very depreciated, or just a speaker cable that needs replacing.

@Shoog Drop your USB DAC into one of the USB 2.0 ports on that X96Air tends to get rid of the USB buffer underruns and stops the popping on start-up / shutdown if it gets annoying.

Will give it a try.

  1. If output is set to SPDIF there is no option to select the amount of channels.
  2. i did all your recommendations - the behaviour did not change, sadly.

Which value resistor did you fit on Pin 7 when you installed the SPDIF? 100 or 270 Ohm?

I installed 100 Ohm

This behaviour sounds a little to me like the either the N2’s onboard DAC or the Z5500 might have some aggressive power saving measure when no sound is present. With the low impedance on the Z5500, when the amp is reengaged suddenly after no sound output to an abrupt sound, its likely you’d get a pop. I had a similar issue many years ago with computer speakers. I recall I had to change a power saving option in the windows registry. If that’s the case with this, I have no idea how you’d go about fixing it.

1 Like

@kshi Good thought, I managed to find a manual online for that device and it doesn’t have power saving features according to the manual anyway.

I’m down to 3 ideas now as its only GUI sounds.

  1. Try the Pulseaudio DAC output in Kodi rather than the ALSA DAC
  2. Admit there is a mismatch somewhere and do either a soft reset of Kodi or a clean install.
  3. Increase the Audio Buffer size in the N2, @Shoog is the best person to advise you as he is way more of an audiophile than I am,

I think option 1. is probably his best best. After that you’re down to the undesirable options:

  1. Painstakingly try another speaker setup, see if the problem persists on another system and/or try the Z5500 on another box, if possible. Does the amp/speaker set perform as expected when connected to another audio device. Does it pop there too?

  2. The Nuclear Option: Consider replacing the Z5500? I did some reading on that particular line and there are all kinds of issues with lousy shielding/isolation, the device popping and crackling with other nearby sources of electrical interference present.

Its depends how far your prepared to go to fix the issue. I noticed the difference for my set up when I ditched the bare wire connectors in the speakers and fitted Nakamichi Banana Plugs (£9 for a set of 8) the power on popping on the left speaker went away totally.

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