Hi @support,
While testing my setup I found a rather annoying issue when playing deep bass test racks.
Specifically from Tidal the following album: Tone Pack by Bass Mekanik.
There is a very loud poping noise when I play any of the available tracks in following situations:
I donât get that when I play the tracks from bandcamp. As you stream the tracks from Tidal, this might be caused by their attempt to provide the best user experience (applying volume auto-leveling and maybe even compression, dynamically to the track). As these arenât real music tracks but pure sine-wave test tracks this doesnât work out well and results in audible artifacts.
This is expected when listening to pure sine-wave test tracks as you start playing just somewhere in the slope of the signal and thus forcing the membrane of your speaker to near instantly displace more or less far away from her rest position (probably with an over shoot) before she starts following the signal again. Additionally the points mentioned above might add up too.
Yep. If youâre playing a very low frequency sine wave and you stop it, youâre basically saying âreturn to zero level immediatelyâ.
This is exactly the same as suddenly introducing a very high frequency signal. You will hear a pop!
Hi guys, thanks for the explanation. Yes, this makes sense.
However when using shairport on the tracks to my sms-200u, there is no popping sound. So it seems shairport is doing something extra to deal with the pure sine waves when user pauses and resumes a track.
Roon could do something similar. Instead of simply cutting the signal when pause is requested, it could simply bring the signal down artificially. Resume would just be the oposite. In think this could solve all the popping noises.
Yep, it could do fade-in fade-out, but that would mean the signal would no longer be bit-perfect as to vary volume, Roon converts to 64bit float to apply the maths, then converts back to whatever bit depth the DAC can support.
As roon already has quite powerful DSP, I suppose this fade-in/fade-out could be added as a feature.
In case of tests like these the bit-perfect stream is less important than damaging my speakers or my hearing.
As eloquently explained by @BlackJack (thanks!), the immediate starting or stopping of a high amplitude sinusoidal tones will often cause audible âpoppingâ like you are experiencing.
If you wish to play the test tones in the album you linked without experiencing this behavior during track transitions, you can enable the âCrossfadeâ setting in Roon to blend the two tracks together. I was able to play the tracks on our test hardware without popping by setting the crossfade time to 1 second.
You can read more about Roonâs crossfade feature here
Hi @john, thanks for the tip. This worked ok, except that the popping sound is still present from time to time. I played around with the value between 1-3sec but was not able to get rid off them completely.
This is for the range between 15-30hz. I suppose itâs becase the sine wave does not get âstitchedâ in the right place using crossfade.
For tracks 30hz up it is ok.